Titanium Pyrophosphate for Removal of Trivalent Heavy Metals and Actinides...

Research ArticleTitanium Pyrophosphate for Removal of Trivalent Heavy Metalsand Actinides Simulated by Retention of Europium

Huemantzin Balan Ortiz-Oliveros12 Rosa Mariacutea Flores-Espinosa3

Eduardo Ordontildeez-Regil3 and SuilmaMarisela Fernaacutendez-Valverde3

1Direccion de Investigacion Tecnologica Instituto Nacional de Investigaciones Nucleares A P 18-1027 Col EscandonDelegacion Miguel Hidalgo CP 11801 Ciudad de Mexico Mexico2Universidad Autonoma del Estado de Mexico Instituto Literario 100 CP 50000 Toluca Estado de Mexico Mexico3Direccion de Investigacion Cientıfica Instituto Nacional de Investigaciones Nucleares A P 18-1027 Col EscandonDelegacion Miguel Hidalgo CP 11801 Ciudad de Mexico Mexico

Correspondence should be addressed to Huemantzin Balan Ortiz-Oliveros hbortizouaemexmx

Received 6 January 2017 Revised 24 April 2017 Accepted 9 May 2017 Published 12 July 2017

Academic Editor Mu Naushad

Copyright copy 2017 Huemantzin Balan Ortiz-Oliveros et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

This work addresses the synthesis of titanium pyrophosphate as well as the characterization and evaluation of the sorptionprocess of europium for removal of trivalent heavy metals and actinides simulate The evaluation of the surface properties oftitanium pyrophosphate was carried out determining the surface roughness and surface acidity constants The values obtainedfrom the determination of the surface roughness of the synthesized solid indicate that the surface of the material presents itselfas slightly smooth The FITEQL program was used to fit the experimental titration curves to obtain the surface acidity constantslog119870+ = 359 plusmn 006 and log119870minus = minus390 plusmn 005 The results of sorption kinetics evidenced that the pseudo-order model explainsthe retention process of europium in which the initial sorption velocity was 83 times 10minus4mg gminus1minminus1 and kinetic constant was 18 times10minus3 gmgminminus1 The maximum sorption capacity was 06mg gminus1 The results obtained from sorption edge showed the existence oftwo bidentate complexes on the surface

1 Introduction

The rapid growth of our population during the last decadeshas led to an ecological imbalance in our environment withsevere consequences and major risks both for our healthand our environment An example for this is the cases ofcontamination of hydric resources The most common waterpollutants are fecal residues from animals and humans pesti-cides used in agricultural activities organic residues derivedfrom oil heavy metals and radionuclides among others [1ndash4] In recent years persistent organic contaminants such asphenols chlorophenols chlorobenzenes and pharmaceuticaldrugs [2] as well as heavy metals like As Cd Cu Cr PbHg and so forth or radionuclides like Ra and actinides arebecoming more common in hydric resources These havecaught the interest of the scientific community due to their

high toxicity easy dispersion bioaccumulation and persis-tency in the environment [5ndash9] particularly for actinideswhose long half-life and high radiotoxicity pose a health risksince they can lead to various diseases such as poisoning ner-vous system damage and cancer [10]The toxicity and behav-ior of persistent organic compounds depend on their concen-tration molecular structure and type of functional groupsAlso heavy metals can react with organic matter form-ing organometallic compounds which may be more toxic toaquatic ecosystems [11]

The contamination of hydric resources with metals andradionuclides is linked to manufacturing processes themetal-mechanic industry oil processing mining transporta-tion processes of erosionmaterial infiltration of subterraneanwaters and nuclear accidents among others [12 13]

Hindawie Scientific World JournalVolume 2017 Article ID 2675897 12 pageshttpsdoiorg10115520172675897

2 The Scientific World Journal

Due to the chemical properties of these metals theirremoval requires specific treatment processes The processesmost used are chemical precipitation coagulationfloccu-lation flotation (with dispersed air or dissolved air) elec-trochemical process photocatalytic process inverse osmosision exchange and sorption [14ndash20] Many of these processesare usually efficient but can be limited by the concentrationand the physicochemical form of the heavy metal as wellas the costs and the difficulties of the operation such as thegeneration of residual sludge

Sorption is one of the most used processes for theremoval of low concentrations (including trace levels) ofheavy metals and radionuclides in an aqueous medium Theterm sorption is used in a generic way to describe physic-ochemical processes in which the dissolved contaminant(metal radionuclide etc) is transferred from the solution tothe solid phase [21 22] either by precipitating on the surfacediffusing on the outside and inside of the pores of the solidphase or by forming complexes on the surface [23]

The phenomena of sorption are also used with successin the construction of engineering barriers to avoid thedispersion of heavy metals and radionuclides in the soiland subsoil where the sorption process is carried out byinteraction of chemical species (metals or radionuclides) insolution with surface functional groups of the components ofthe soil [24 25]

Due to the importance that sorption processes have in thetreatment of industrial wastewater in industrial applicationsor the remediation of soils contaminated withmetals interesthas again risen during the last couple of years in carryingout investigations aimed at understanding the phenomenainvolved in sorption and also the development of differentmaterials or sorbents and in determining their retentionproperties In that regard several investigators have studiedlow cost materials such as biosorbents in which there isthe biomass of residues of vegetable or animal origin orbacteria and fungi [8 26 27] These biosorbents have proventhemselves efficient in the removal of metals in aqueoussolutions In addition new mineral sorbents have beensynthesized and tested that unlike the biosorbents may costmore but have a high retention capacity low solubility andhigh thermic and structural stability even when submittedto intense fields of gamma radiation an example of whichare the tests of sorption of metals and radionuclides inphosphates of isomorphic tetravalent metals perovskite andother synthetic inorganic materials [28ndash31]

As far as phosphates are concerned since the discovery ofLiFePO

4 newmaterials have been synthesized and identified

based on phosphates-based polyanions such as (PO4)3minus

(P2O7)4minus or (P

3O10)5minus [32] which find their application

in different fields of knowledge due to their major struc-tural anomalies such as their anisotropic deformation lowredox potential and low cost of synthesis [32 33] Thesecharacteristics have motivated the study of the retentionof metals in phosphates The sorption of lanthanides anduranyl on different synthetic phosphates has been reportedfor example Wang et al [34] studied the sorption of U (VI)onto Zr

1minus119909Ti119909P2O7and TiP

2O7 Ortiz-Oliveros et al [35]

studied the synthesis of 120572-Ti(HPO4)2H2O and sorption of

Eu3+ and Maslova et al [36] studied the synthesis andsorption properties of amorphous titanium phosphates

Literature reports different synthesis methods of polyan-ions such as (P

2O7)4minus The methods most used are (a)

methods of coprecipitation where organic compounds areused as ion sources and phosphoric acids are used as phos-phate sources [33 34] and (b) hydrothermal methods wheremetallic oxides are used as ion sources and water-solublephosphate salts as phosphate sources in an acid medium[32] Rai et al [33] used the method of coprecipitationto obtain titanium pyrophosphate During this method anaqueous solution of titanium isopropoxide is mixed with asolution of phosphoric acid and diluted hydrochloric acidThe mixture is heated to 343K and agitated for 10-11 h Inthe end the obtained material is heated to 1073K for 3 h ina CO2atmosphere Other authors obtain TiP

2O7using the

sequence proposed by Patoux It consists in mixing TiO2and

(NH4)2HPO4and heating themixture progressively to 1273K

using intermittent gridding sequences [45 46]This work addresses the synthesis of titanium pyrophos-

phate using an improved method Titanium pyrophosphatewas prepared using high purity TiCl

4and concentrated

H3PO4 through precipitation in an atmosphere of nitrogen

The precipitate obtained was heated to 1073K for 3 h Withtitanium pyrophosphate previously characterized the reten-tion capacity of Eu3+ was evaluated as a chemical analogousfor heavy metals (Cr3+ and As3+) and actinides (Ac3+) [4748] It is well known that the europium ionic radius is similarto Cr3+ As3+ and Ac3+ radii which results in a similarphysicochemical behavior [49] Additional modeling thesorption of the europium onto the titanium pyrophosphateas a function of the pH using a surface complexation modelwas performed

2 Experimental

21 Synthesis of TiP2O7 The titanium pyrophosphate wasobtained by the described method by Ortiz-Oliveros et al[35] Synthesis was performed mixing high purity liquidtitanium tetrachloride (999Aldrich) as the ion sourcewithconcentrated phosphoric acid (85 Baker) as the phosphatesource while maintaining a TiP stoichiometric ratio of 1 2under a nitrogen atmosphere in a glovebox TiCl

4was slowly

added to a stirred solution of phosphoric acid and theprecipitate was recuperated and washed with deionizer waterThe precipitate was then centrifuged separated and driedat room temperature Finally the dried solid was heated at1073K for 3 h

22 Material Characterization The solid obtained was char-acterized by X-ray powder diffraction (XRD) patterns ina diffractometer (Siemens D5000) The XRD patterns wereobtained with Cu monochromatic K120572 rays at 35 kV and25mA The 2120579 diffraction angle (4∘ndash70∘) was scanned at ascan rate of 183minminus1 The elemental and structural analysisof the solid was performed in a scanning electronmicroscope(PHILIPS model XL-30) coupled to a microprobe (EDAXmodel DX-4) for energy dispersive X-ray spectroscopy witha resolution of 140 eV Representative samples were fixed on

The Scientific World Journal 3

metal slides with carbon tape and were covered with a thinfilm of conducting material (Au)

Additional samples of titanium pyrophosphate beforeand after europium sorption were investigated by AtomicForce Microscopy (Cypher Asylum Research Microscope)

Finally the specific area (119860119904) was determined in a

GEMINI 2360 Micrometrics surface area analyzer

23 Determination of Surface Properties The surface proper-ties were evaluated using analytical grade reagents potassiumnitrate (Sigma-Aldrich ge 99) and potassium hydroxide(Baker ge 85) All of the solutions were prepared with deion-ized water under a nitrogen flux and potassium nitrate waschosen as the background salt for fix the ionic strength Atthe same time all potentiometric titrations were performedin a potentiometer ThermoOrion 720A+ with a combinedAgAgCl electrode

The evaluation of the surface properties of titaniumpyrophosphate was carried out determining (a) the surfaceroughness and (b) the surface acidity constants (119870+ and119870minus)Surface Roughness The characterization of the superficialirregularity of the material (roughness) was determinedaccording to Ismail and Pfeifer [50] This method consists indetermining the surface fractal dimension by means of N

2

adsorption isotherms and (1)

ln( 119881119881119898

) = Γ + 119860[ln(ln(119875119900119875 ))] (1)

where 119881 represents the volume of adsorbed gas molecules(mL gminus1) at the equilibrium pressure (119875) and saturation pres-sure (119875

119900) 119881119898is the volume of monolayer coverage in mL gminus1

Γ is an exponential factor and 119860 is a power-law exponentdependent on the fractal dimension (119863) and adsorptionmechanism The N

2adsorption isotherm was determined in

a GEMINI 2360 Micrometrics surface area analyzer

Surface Acidity Constants The surface acidity constantswere determined by fitting the experimental potentiometrictitration curves using the FITEQL 4v program [51 52]This computer programdetermines the chemical equilibriumconstants fromexperimental data obtained by potentiometrictitrationsThe equilibriummodelmust be solved at each titra-tion point therefore the parameters are adjusted tominimizethe difference between the experimental values and thosecalculated from the model Several Surface ComplexationModels have been used to simulate the experimental dataand in this case the Constant Capacitance Model (CCM)was used to fit the potentiometric titrations curves Thismodel has been used in many solids such as hydrous ferricoxides phosphates and titanates Our experimental condi-tions (05M)meet the ionic strength restriction in thismodeland this model is preferred because of the relatively lownumber of adjustable parameters These parameters in theCCM are 119870+ and 119870minus constants the inner-layer capacitance(119862) the total concentration of surfaces sites and 119860

119904

24 Sorption Experiments All of the sorption experimentswere carried out in polypropylene tubes at 303K and under a

nitrogen atmosphere with 400mg of titanium pyrophosphatefor 10mL of aqueous solution (1times 10minus4Mof europiumnitrateAldrich 999) Prior to the sorption experiments the solidwas first hydrated with 05 KNO

3solutions for 24 h and

stirred at 45 rpm which was shown to be sufficient to reachequilibrium Afterward the suspensions were centrifugedat 3500 rpm for 15min and all of the supernatant wasremoved

A 10mL aliquot of the europium nitrate stock solutionwas added to the hydrated solid and then the suspensionswere adjusted to the required pH values and contact timerespectively

The experiments carried out were (1) the evaluation ofsorption kinetics and (2) modeling the sorption as a functionof the pH using a surface complexation model For thesorption kinetics of Eu3+ sorption isothermswere performedas a function of contact time by estimating the Eu(NO

3)3

concentrations retained in the titanium pyrophosphate atdifferent contact times (1 3 5 7 16 18 20 22 24 48 and 72 h)The sorption isotherms as function of pH were obtained byadjusting the solutions to the desired pH value (1 to 7) whichwere left for 24 h at 45 rpm

In both experiments the suspensions were then cen-trifuged at 3500 rpm for 15 minutes and separated A solutionwithout europium was used as the reference Finally theeuropium uptake on solid was determined by measuringthe luminescence in a Fluorolog Jobin Yvon Horiba withXenon lamp (450W) Quartz cells were loaded with 500120583Laliquots of the supernatant from each experiment and thestock solution (as a reference) The samples were excitedat 397 The europium emission spectra were recorded from570 nm to 650 nm and the highest peaks were quantifiedat 590 and 610 nm [48] An integration time 10 s and awavelength increment of 05 nm were used The obtainedspectra were analyzed in Fluorolog software

241Modeling Sorption Kinetics There are different sorptionmodels in the literature which try to explain retention ofmetals and radionuclides in solid substrates These can bedivided into empiric and thermodynamicmodelsThe formeris useful when it comes to establishing kinetics and sorptioncapacity as a first step of establishing the interaction mecha-nism between the metal and the solid but without taking intoconsideration that the surface sites strongly depend on the pHof the aqueous medium The latter on the other hand allowsa study of the dependency of the pH from the surface sites ofthe solid from the knowledge on the surface acidity constantsand by means of the estimation of the constants of formationof surface complexes

In the present work four kinetic sorption models wereused with the aim of explaining the obtained experimentaldata and determining the possible sorption mechanism ofEu3+ in titanium pyrophosphate The models used werepseudo-first-order (Lagergrenrsquos equation) Elovich pseudo-second-order and intraparticle diffusion models

Pseudo-First-Order Model First-order kinetic model is pro-posed by Lagergren This model is widely used to explain the


sorption of solutes in aqueous solution [53] The equationused is given as

log (119902119890minus 119902119905) = log (119902

119890) minus 1198961015840119905

2303 (2)

where 119902119890is the sorption capacity at equilibrium (mg gminus1) 119902

119905is

the mass adsorbed (mg gminus1) 119905 is the contact time (min) and1198961015840 is the first-order sorption constant (minminus1)

Elovich Model It is a kinetic model used to describe thekinetics of heterogeneous chemical sorption of gases in solids[54] Also this model has been widely used to describe thechemisorption of the adsorbate by a solid in aqueousmedium[55] The model presents itself mathematically as follows

120575119902119905

120575119905 = 120572 exp (minus120573119905119902119905) (3)

where 120572 is the initial sorption velocity (mg gminus1minminus1) and 120573is the desorption constant (gmgminus1) Other authors relate 120573 tothe activation energy for the chemisorption [55]

Pseudo-Second-Order Model Second-order kinetic model iswidely used to explain the processes of chemisorption ofmetals [56] In (4) the general expression of the model ispresented

120575119902119905

120575119905 = 1198962(119902119890minus 119902119905)2 (4)

where 1198962is the second-order sorption velocity constant

(gmgminus1minminus1)

Intraparticle Diffusion Model It is fractional-order kineticmodel which permits establishing whether the sorptionprocess is limited by intraparticle diffusion [57 58] In (5)the mathematical expression of the model is shown

119902119905= 11989611989411990505 + 119862SL (5)

where 119896119894is the intraparticle diffusion rate (mg gminus1minminus05)

and 119862SL is a constant related to the thickness of the surfacelayer formed on the adsorbed The higher the values of 119862SLthe greater the effect of the surface boundary layer

242 Estimation of Surface Complex The surface complexconstants for the europium species sorbed onto the titaniumpyrophosphate were obtained from the sorption isotherms asfunction of pH using the FITEQL program and the CCMThe input data are119870+119870minus and inner-layer capacitance valuesobtained

In the sorption modeling it was assumed that (a) amonodentate complex is formed by the interaction of aeuropium species in solution with only a single surface siteand (b) a bidentate complex is formed when a europiumspecies in solution interacts with two surface sites

The identification of the chemical species of europium insolution to be used as the initial input in the sorption simu-lation was carried out by MEDUSA program of the SwedenRoyal Institute of Technology [59]

3 Results and Discussions

31 Material Characterization The elementary analysis byEDS showed only oxygen titanium and phosphorous andthe TiP relationship was in agreement with the theoreticalratio in titanium diphosphate Within the detection limits ofthe technique used (119885 gt 12) no contaminants were detectedin the solid obtained Additionally Figure 1 shows a distribu-tionmap of Ti P andOof a sample representative of the solidThe map shows that the material has an elemental homo-genous distribution Figure 2(a) shows the micrograph ofthe solid obtained at 5000x in which polymorphic particlesof laminar appearance with a size of less than 3120583m can beobserved Figure 2(b) shows the micrograph of the solidobtained at 20000x in which particles of spherical appear-ance and irregular surface with an approximate size of 2 120583mcan be observed

Figure 3 shows XDR spectra of the sample prepared at1073K in which three intense reflections located at the angle2120579 2255 2525 and 2771 identified as cubic TiP

2O7with a

Pa3 (205) space group (JCPD 38-1468) can be observed Fur-thermore a slight slipping of the diffraction peaks to the rightwas observed indicating loss of the superstructure It can beexplained considering that in thiswork synthesiswas carriedout at 1073K during 3 h and Norberg et al [60] reportedthat at high temperatures the structure of pyrophosphategroup was disordered due to having unfavorable 180 bondangles

The results obtained from the analysis by AFM are pre-sented in Figure 4 This shows the surface images of thetitanium pyrophosphate before and after the europium sorp-tion Figure 4(a) (before sorption) clearly showed varioussmall and larger particles in the surface morphology ofsolid Additionally we observed that the surface is apparentlysmooth Figure 4(b) (after sorption) shows the influence ofeuropium sorption on the surface morphology of titaniumpyrophosphate As can be clearly seen the surface is fullycovered with a layer of sorbed europium

Furthermore the results from the interpretation adsorp-tion isotherm of N

2(by BET method) showed that the

titanium pyrophosphate synthetized has an 119860119904of 90 plusmn

01m2 gminus132 Determination of Surface Properties

Surface RoughnessFigure 5(a) shows the adsorption isothermof N2 It obeys a reversible isotherm of type II that is concave

at low pressure in relation to 119875119875119900and has originated from

the physisorption of nitrogen and is typical in nonporousmaterials In this figure two perfectly defined regions can beobserved Region I (0 lt 119875119875

119900gt 05) shows the beginning

of an almost linear section (starting from point B) whichindicates the ending of the monolayer Region II (05 lt119875119875119900gt 095) shows the beginning of the curvature of the

isotherm and indicates the inflexion point of the overlap ofthe monolayer and the beginning of the multilayer where119875119875119900

= 05 [61] When 119875119875119900

= 1 the thickness of themultilayer seems to increase without limit and the filling ofthe volume of the pores is caused by capillary condensation


SEBSE 255 None 255

PKa 31 TiKa 24

OKa 15

Figure 1 Elemental distribution of the solid obtained where only Ti P and O are observed

(a) (b)

Figure 2 (a) Micrograph obtained at 5000x magnification where polymorphic particles of laminar appearance could be observed (3120583m)(b) Micrograph obtained at 20000x magnification where spherical particles of irregular surface are observed (2120583m)

Figure 5(b) shows the adjusted results of the isothermof the adsorption of N

2using (1) This figure was drawn up

plotting ln(119881119881119898) versus ln(ln119875

119900119875) In accordance with the

isotherm analysis (Figure 5(a)) it can be deduced that twofractal diameters (119863

1and119863

2) exist which are associated with

two adsorption forces According to Ismail and Pfeifer [50]when van der Waals attraction forces are dominant betweenthe solid and the absorbent film119863 = 3119860+3 then the surfacetension of the liquidgas is insignificant When the capillaryforce is important 119863 = 119860 + 3 From the equation of theadjustment of the experimental data it has been obtained thatthe value of the slope 119860 = minus056 with a statistical correlationcoefficient 1199032 = 099 allows establishing that 119863

1= 131 when

119863 = 3119860 + 3 and 1198632= 243 when 119863 = 119860 + 3 Wang et al

[44] and Cao et al [62] suggest associating the surface ofthe fractal diameter as an average value of 119863

1and 119863

2 the

interval from 131 to 243 equaling 119863119898= 187 From there it

can be inferred that the surface of the synthesized solid is notrough In the same way Ismael and Pfeifer [50] suggest thatwhen applying in (1) the relations 119863 minus 33 and 119863 minus 3 bothmechanisms function simultaneously and an intermediateslope is obtained According to Ismael and Pfeifer [50] theeffect of the surface tension on the slope of the linearizedequation (1) can be established from the equality 120575 = 3(1 +119860) minus 2 = minus069 because when 119863 ge 2 the value of 120575 shouldreach an absolute small value and the surface tension onthe gradient would be negligible When 120575 lt 0 the surfacetension is not considered insignificantWhen considering themagnitude of 119863

2 it can be established that the surface of the

synthesized titanium pyrophosphate is slightly smooth whenmultilayers are formed at high 119875119875

119900 Likewise the magnitude

of 119863 can be associated with the small number of active sites(119873119904= 7 sites nmminus2) [37 38 63] which are linked to the polar

groups (OHminus) present on the surface of the material


10 20 30 40 50 60 70

2

JCPDS 38-1468Tip

2O7 obtained

Inte

nsity

(cps

)

100

200

300

400

0

Figure 3 XDR spectra of the obtained material the lines corre-spond to titanium pyrophosphate pattern to JPCDS 38-1468

Surface Acidity Constants The potentiometric titration curvecan be fit to determine 119870+ 119870minus and 119862 The experimentalerror was estimated to be plusmn02 pH units and 5 for theconcentrations of H+ or OHminus added To reduce the degrees offreedom in the determination of the surface acidity constantsof titanium pyrophosphate using the FITEQL program (IV)[52] initial values were used for the parameters 119873

119904and 119860

119904

thereby reducing the number of parameters to be solved forthe equilibriummodel for the systemThe goodness of the fitcan be determined by the ratio between the weighted sum ofsquares and the total degrees of freedom (WSOSDF) for theanalyzed system this ratio was less than 20 [51 64]

The inner-layer capacitance of the surface acidity constantmust be determined This parameter is difficult to estimatebecause the experimental calculation is not easy The empiri-cal value is often chosen as approximately 1 Fmminus2 for mineraloxides but in these cases the ionic strength considered wasnot higher than 01M [64] Phosphate compounds are highlyinsulating materials and a capacitance value of 308 Fmminus2 hasalready been used successfully for diverse phosphates withionic strengths greater than 01M [52] For this work wetested the previous values and found that the best fit wasobtainedwith an inner-layer capacitance value of 31 Fmminus2 foran ionic strength of 05M

The experimental and simulated curves of the solidare shown in Figure 6 and Table 1 reports the obtainedacidity constants The surface acidity constants determinedfor titanium pyrophosphate were log 119870+ = 359 plusmn 006and log119870minus = minus390 plusmn 005 the goodness of the fit was 9The experimental data could only be fit when consideringonly one surface site these results agree with those observedby other authors in phosphates with the equivP-OH functionalgroup [37 40] As observed in Table 1 there is no significancebetween the values obtained for TiP

2O7 ZrP2O7 and LaPO

4

Th(PO4)4P2O7has higher values of surface acidity constants

The differences among materials with the same functionalgroups are attributed to impurities crystal structures thesynthesis method or the background salt used to determinethe ionic strength [52]

33 Sorption Experiments Prior to the sorption experimentsthe europium chemical equilibrium was determined usingthe MEDUSA program to determine the europium chemicalspecies at the sorption conditions A complimentary searchwas performed to find the europium species reported in theliterature The species and the formation constant obtainedare reported in Table 2 Additional the results determinedusing the MEDUSA program showed that until a pH of 6two major species are present EuNO

3

+ and Eu3+ HoweverEu(OH)

3c precipitated in the pH range of 6 to 11Figure 7 shows the variation in quantity of europium

retained in the solid over timeThese results indicate that thesorption of europium occurs in two phases during the firstof which (119905 le 10 h) the retention velocity is fast and growsexponentially with time reaching its maximum velocity attimes close to 10 h during which time approximately 50 ofthe initial europium quantity (119902

119905= 028mg gminus1) have been

retained During the second phase the maximum sorptionpercentage is reached at times exceeding 35 h where thesorption velocity diminishes significantly until reaching thethermodynamic equilibrium in which the solid is saturatedand unable to retain more Eu3+

331 Modeling Sorption Kinetics The analysis of the exper-imental data of the sorption of europium according totime was carried out using the empiric models previouslydescribed

Figure 8(a) shows the results of the adjustment of theexperimental data using the linearized equation of theElovich model [48 49]Themodel parameters and the statis-tical coefficient were obtained plotting 119902

119905versus log 119905 As can

be seen in the figure the adjustment of the experimental datahas a statistical coefficient 1199032 of 098The slope and ordinate ofthe adjustment equation allowed an estimation of the modelparameters during which it was determined that 120572 lt 0 and120573 = 0168mg gminus1 These results show that the Elovich modelexplains the experimental data mathematically as it countson a good correlation Nevertheless the model assumes thatthe product of 120572120573 ≫ 1 since in our case 120572120573 lt 0 it can beestablished that the sorption process of Eu3+ on solid cannotbe explained phenomenologically with the Elovich model

Figure 8(b) shows the results of the adjustment of theexperimental data using the pseudo-first-order model Thisanalysis was carried out plotting log(119902

119890minus 119902119905) versus 119905 As can

be seen in the graphic the statistical correlation obtained (1199032)was 091 The kinetic parameters 1198961015840 and 119902

119890 whose values are

estimated as 168 times 10minus3minminus1 and 064mg gminus1 respectivelywere calculated using the adjustment equation

Figure 8(c) shows the results of the adjustment of theexperimental data using the pseudo-second-order modeland using the linear adjustment equation proposed by Hoet al [56] which was obtained by plotting 119905119902

119905versus

119905 With the adjustment equation it was estimated that


0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)

Figure 4 Surface imagens of titanium pyrophosphate obtained by AMF (a) before europium sorption and (b) after europium sorption

B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)

Experimental data Fitting data

r2= 099

00 05 10minus05minus15minus20 minus10minus25

04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)

Figure 5 Adsorption isotherm of N2of the titanium pyrophosphate (b) adjusted results of adsorption of the isotherm N

2

ℎ = 835 times 10minus4mg gminus1minminus1 119902119890= 06mggminus1 and 119896

2=

18 times 10minus3 gmgminminus1 The obtained correlation coefficientwas 098 This correlation showed that the model explainsthe experimental data adequately likewise the magnitudesof the kinetic parameters are congruent from a physicalpoint of view which indicates that the retention process ofeuropium on titanium pyrophosphate is possibly achieved bychemisorption

Finally Figure 8(d) shows the adjustment of the experi-mental data using a model of fractional order (intraparticlediffusion model) In this case the adjustment analysis wascarried out by plotting 119902

119905versus 11990505 The results showed

that 119896119894= 0001mg gminus1minminus05 and 119862SL = 0033mg gminus1 with

a 1199032 = 092 This correlation shows that the sorption processof Eu is not limited by intraparticle diffusion albeit it suggeststhat it can be influenced by diffusive phenomena diffusionin the liquidsolid interphase or diffusion on the surfaceDifferent authors have pointed out that when the adjustmentis high and gives a straight line as a result this indicates thatthe process is exclusively controlled by intraparticle diffusionotherwise when the adjustment data respond to more thanone adjustment line this indicates that the sorption process isinfluenced by more than one diffusive phenomenon [53 65]

From the analysis of the adjustment results of the differentmodels it is possible to determine that the pseudo-second-order model can be used to explain the sorption kinetics


Table 1 Surface acidity constants of titanium pyrophosphate

Solid Capacitance(Fmminus2) log119870+ log119870minus Functional group Ref

TiP2O7 308 359 plusmn 006 minus390 plusmn 005 P

2O7

This workZrP2O7 308 32 minus42 P

2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]

Experimental dataSimulate data

Concentration (molL)00minus60 minus40 minus20 20 40 60

times10minus3

2

4

6

8

10

12

pH

Figure 6 Acidbase titrations of TiP2O7in 05M potassium nitrate

solution Experimental (circle) and CCM calculated curve (line)

Table 2 Equilibrium constants of the chemical species of europiumin 05M KNO

3solution

Chemical equilibrium equation log 120573 FI = 05M119879 = 298K Reference

Eu3+ + H2Oharr Eu(OH)2+ minus853 [42]

Eu3+ + 2H2Oharr Eu(OH)

2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3

minus harr Eu(NO3)2+ 029 [43]

Eu3++ CO3

2minus harr Eu(CO3)+ 611 [42]

Eu3+ + 2CO3

2minus harr Eu(CO3)2

minus 1045 [44]

for europium in the titanium pyrophosphate It should benoted that the sorption capacity of the solid studied is likethat observed in other phosphates with P

2O7groups Studies

such as those carried out by Wang et al [34] show that thenanostructured titanium pyrophosphates and the isomor-phous substitution of Zr4+ by Ti4+ result in an enhancementof sorption capacity of actinides Other materials such as thenovel SiO

2-ZrO2-calcium alginate aerogels [66] or graphene

[67] have a higher actinide retention capacity than thesolid studied but their structural stability has not beendemonstrated when subjected to intense fields of thermal andionizing radiation

0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al

Figure 7 Sorption of Eu3+ as a function of time in the solidsynthetized using 1 times 10minus4M solution of EuNO

3 in contact with

400mg of solid at pH 6

Furthermore the testedmodels indicate that the sorptionof europium on the solid occurs through the diffusion ofthe metallic ion in the solidliquid interphase and on thesurface of the solid subsequently through the interactionof the ion with the surface sites or functional groups ofthe titanium pyrophosphate which favors the formation ofstrong bonds between the europium and the material Thisretention mechanism has been observed in different heavymetals such as Cr Cd and Pb [68]

332 Estimation of Surface Complex Surface Figure 9 showsthe europium sorption isotherm of Eu3+ onto titaniumpyrophosphate and the sorption edge spreads between pH= 2 and pH = 55 which indicated that the sorption pro-cess involves more than one surface complex Under theexperimental conditions 50 of the europium was sorbedapproximately at pH values between 2 and 35 and the restof the Eu3+ was sorbed in the interval of 35ndash6

To fit the sorption curve119870+119870minus and 119862 values were fixedat the values determined aboveDuring the experimental dataanalysis the error was estimated to be plusmn02 pH units and 5for the total europium concentration We used this informa-tion to identify the surface complexes that are involved inthe retention of europium by titanium diphosphate Figure 9presents the sorption modeling The results obtained fromthe experimental data show the probable existence of two


Experimental data

0 500 1000 1500 2000 2500

t (min)

Wherek = 168 times 10minus3 minminus1

qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)

Experimental dataData fitting

22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)

ℎ = 835 times 10minus4 mg gminus1 minminus1

qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05

ki = 0001 mg gminus1 min05

CSL = 0033 mg gminus1

r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)

Figure 8 (a) Experimental data fit of the pseudo-first-order model (Lagergrenrsquos equation) (b) experimental data fit using the linearizedequation of the Elovich model 119902

119905= 120572 + 2303120573 log(119905) (c) experimental data fit using the linearized equation of pseudo-second-order model

proposed by Ho et al (2005) 119905119902119905= 119902ℎ + (1119902

119890)119905 (d) experimental data fit using the linearized equation of the intraparticle diffusion model

bidentate complexes on the surface In the pH range of 2to 45 two surface sites are required to form the bidentatecomplex (equivXOH)

2EuNO

3

2+ with the elimination of onehydrogen in a similar way in the pH range of 45 to 7 twosurface sites are required (equivXOminus) to form a bidentate complexwith EuNO

3

2+ ((equivXO)2EuNO

3)

Therefore the europium sorption mechanisms in tita-niumpyrophosphate result from the interaction of aequivXOH

2

+

surface site (pH lt 33) and a equivXOminus surface site (pH gt33) with EuNO

3

2+ and the formation of the inner-spherebidentate surface complexes For pH values greater than7 the mechanism that reduces the concentration of the

europium in the solution is the chemical precipitation of thecondensate species onto the surface

Table 3 shows the values for the sorption constantsobtained from this research of Eu3+ on titanium pyrophos-phate and also those for the Eu3+ complex formed in similarphosphates The result obtained in this work for the firstsurface europium complex is similar to that reported by Finck[38] for the ZrO complexed with europium at 308K whichcould be attributed to (equivTiOH)EuNO

3

2 however the valuefor the P

2O7complex is different Finck [38] reports a value

of minus32 plusmn 03 but Drot et al [40] report a value of 094 plusmn 014for the P

2O7complex in the Th(PO

4)4P2O7 Drotrsquos value is


Table 3 Eu (III) sorption equilibria onto titanium pyrophosphate and other compounds and associated constants

Surface complex log119870 Compound ReferenceequivXOH + Eu3+ + NO

3

minus harr (equivXOH)EuNO3

2+ 58 plusmn 01 TiP2O7

This workequivXOH + Eu3+ + NO

3

minus harr (equivXO)2EuNO

312 plusmn 05 TiP

2O7

This work2(equivZrOH) + Eu3+ harr (equivZrOH)

2Eu3+ 625 plusmn 03 ZrP

2O7

[38]2(equivPOH) + Eu3+ + NO

3

minus harr (equivPO)2Eu + 2H+ minus32 plusmn 03 ZrP

2O7

[38]2equivXOH + Eu3+ + NO

3

minus harr equiv(XOH)2EuNO

3

2+ 749 plusmn 005 ZrP2O7

[40 41]2equivXOH + Eu3+ + NO

3

minus harr equiv(XO)2EuNO

3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3


3+ 2H+ minus223 plusmn 013 (PO

4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3


3+ 2H+ 031 plusmn 05 (oxo) Zr

2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)

Experimental data(XO)2EuNO3

(XOH)2EuNO32+

Simulated

Figure 9 Eu3+ sorption modeling on titanium pyrophosphate andcalculated curves

in good agreement with the value obtained for the secondEu (III) complexation constant in this work 12 plusmn 05 Thisresearch determined that the value for the Eu-PO

4complex

in the same compound was minus223 plusmn 013 similarly Drot [37]found a value of minus30 plusmn 03 for the complex of Eu with (PO

4)

4 Conclusions

The proposed technique allows for the synthesis of a puretitanium pyrophosphate as confirmed by the analytical tech-niques The surface behavior as function of pH shows theformation of equivXOH

2

+ species at pH values lower than 33and equivXOminus at higher pH values Only two species Eu3+ andEuNO

3

2+ were present in the solution in the sorption pHrange of 2 to 55

It has been established that the surface characteristics ofTiP2O7are similar to ZrP

2O7and other phosphates with the

equivP2O7and equivP-OH functional groups However the model-

ing of the sorption curves determined that the mechanismof europium sorption on the solid is first due to external

and surface diffusion and second due to chemisorptionrelated to the possible formation of two types of inner-spherebidentate surface complexes The stability constants of theformed complexes show the feasibility of using titaniumpyrophosphate as an engineering barrier in the containmentof radioactive waste

Conflicts of Interest

The authors declare that there are no conflicts of interest

Acknowledgments

The technicians of DRX MEB and the Chemistry Depart-ment of ININ are acknowledgedThis work is part of ProjectsDR-001 and CB-907

References

[1] S E Manahan Environmental Chemistry Lewis PublishersUSA 6th edition 1994

[2] A Kumar G Sharma M Naushad and S Thakur ldquoSPION120573-cyclodextrin core-shell nanostructures for oil spill remediationand organic pollutant removal from waste waterrdquo ChemicalEngineering Journal vol 280 pp 175ndash187 2015

[3] M Naushad T Ahamad G Sharma et al ldquoSynthesis and char-acterization of a new starchSnO

2nanocomposite for efficient

adsorption of toxic Hg2+ metal ionrdquo Chemical EngineeringJournal vol 300 pp 306ndash316 2016

[4] M Naushad Z A ALOthman G Sharma and InamuddinldquoKinetics isotherm and thermodynamic investigations for theadsorption of Co(II) ion onto crystal violet modified amberliteIR-120 resinrdquo Ionics vol 21 no 5 pp 1453ndash1459 2015

[5] B Koz U Cevik and S Akbulut ldquoHeavy metal analysis aroundMurgul (Artvin) copper mining area of Turkey using moss andsoilrdquo Ecological Indicators vol 20 pp 17ndash23 2012

[6] J Bech M Abreu E Korobova A Lima and C Perez-SirventldquoRadioactive chemical species in soils pollution and remedia-tionrdquo Journal of Geochemical Exploration vol 142 pp 1ndash3 2014

[7] N S Shaban K A Abdou and N E Hassan ldquoImpact of toxicheavy metals and pesticide residues in herbal productsrdquo Beni-Suef University Journal of Basic and Applied Sciences vol 5 no1 pp 102ndash106 2016

[8] W Song J Liang T Wen et al ldquoAccumulation of Co(II)and Eu(III) by the mycelia of Aspergillus niger isolated from


radionuclide-contaminated soilsrdquo Chemical Engineering Jour-nal vol 304 pp 186ndash193 2016

[9] G Zhou C Liu L Chu Y Tang and S Luo ldquoRapid and efficienttreatment of wastewater with high-concentration heavy metalsusing a new type of hydrogel-based adsorption processrdquo Biore-source Technology vol 219 pp 451ndash457 2016

[10] B Hu Q Hu X Li et al ldquoRapid and highly efficient removal ofEu(III) from aqueous solutions using graphene oxiderdquo Journalof Molecular Liquids vol 229 pp 6ndash14 2017

[11] M D LeGrega P L Bukingham and J C Evans HazardousWaste Management McGraw Hill New York NY USA

[12] H Z Mousavi and S R Seyedi ldquoNettle ash as a low cost adsor-bent for the removal of nickel and cadmium from wastewaterrdquoInternational Journal of Environmental Science and Technologyvol 8 no 1 pp 195ndash202 2011

[13] WM Ibrahim andHHMutawie ldquoBioremoval of heavymetalsfrom industrial effluent by fixed-bed column of red macro-algaerdquo Toxicology and Industrial Health vol 29 no 1 pp 38ndash42 2013

[14] R M Flores-Espinosa H B Ortız-Oliveros M T Olguın MR Perusquia-Cueto and R Gallardo-San-Vicente ldquoSeparationand treatment of ion-exchange resins used in cleaning systemsof a research nuclear reactorrdquoChemical Engineering Journal vol188 pp 71ndash76 2012

[15] H B Ortiz-Oliveros H Jimenez-Domınguez D Cruz-Gonzalez R M Flores-Espinosa and M C Jimenez-MoleonldquoDissolved air flotation for treating wastewater of the nuclearindustry preliminary resultsrdquo Journal of Radioanalytical andNuclear Chemistry vol 291 no 3 pp 957ndash965 2012

[16] M A Soliman G M Rashad and M R Mahmoud ldquoFastand efficient cesium removal from simulated radioactive liquidwaste by an isotope dilution-precipitate flotation processrdquoChemical Engineering Journal vol 275 pp 342ndash350 2015

[17] C Cameselle and A Pena ldquoEnhanced electromigration andelectro-osmosis for the remediation of an agricultural soilcontaminated with multiple heavy metalsrdquo Process Safety andEnvironmental Protection vol 104 pp 209ndash217 2016

[18] Y Huang D Wu X Wang W Huang D Lawless and X FengldquoRemoval of heavy metals from water using polyvinylamine bypolymer-enhanced ultrafiltration and flocculationrdquo Separationand Purification Technology vol 158 pp 124ndash136 2016

[19] V Valdovinos F Monroy-Guzman and E Bustos ldquoElectroki-netic removal of radionuclides contained in scintillation liquidsabsorbed in soil type phaeozemrdquo Journal of EnvironmentalRadioactivity vol 162-163 pp 80ndash86 2016

[20] R Katwal H Kaur G Sharma M Naushad and D PathanialdquoElectrochemical synthesized copper oxide nanoparticles forenhanced photocatalytic and antimicrobial activityrdquo Journal ofIndustrial and Engineering Chemistry vol 31 pp 173ndash184 2015

[21] G Sposito The Surface Chemistry of Soils Oxford UniversityPress New York NY USA 1984

[22] W Weber Adsorption Theory Concepts And Models MarcelDekker Inc New York NY USA 1984

[23] D A Dzombak and F M M Morel Surface ComplexationModeling Hydrous Ferric Oxide Wiley New York NY USA1990

[24] G Sheng S Yang D Zhao J Sheng and XWang ldquoAdsorptionof Eu(III) on titanate nanotubes studied by a combination ofbatch and EXAFS techniquerdquo Science China Chemistry vol 55no 1 pp 182ndash194 2012

[25] X Gao G Sheng and Y Huang ldquoMechanism and microstruc-ture of Eu(III) interaction with 120574-MnOOH by a combination ofbatch and high resolution EXAFS investigationrdquo Science ChinaChemistry vol 56 no 11 pp 1658ndash1666 2013

[26] K M Al-Qahtani ldquoWater purification using different wastefruit cortexes for the removal of heavymetalsrdquo Journal of TaibahUniversity for Science vol 10 no 5 pp 700ndash708 2016

[27] W M Ibrahim A F Hassan and Y A Azab ldquoBiosorption oftoxic heavy metals from aqueous solution by Ulva lactuca acti-vated carbonrdquo Egyptian Journal of Basic and Applied Sciencesvol 3 no 3 pp 241ndash249 2016

[28] E Ordonez-Regil H B Ortız-Oliveros S M Fernandez-Valverde and F Granados-Correa ldquoEu (III) sorption from anaqueous solution onto SrTiO

3and surface complex behaviorrdquo

Chemical Engineering Journal vol 254 pp 349ndash356 2014[29] K G Akpomie and F A Dawodu ldquoAcid-modified montmoril-

lonite for sorption of heavy metals from automobile effluentrdquoBeni-Suef University Journal of Basic and Applied Sciences vol5 no 1 pp 1ndash12 2016

[30] F Noli M Kapnisti G Buema and M Harja ldquoRetention ofbarium and europium radionuclides from aqueous solutions onash-based sorbents by application of radiochemical techniquesrdquoApplied Radiation and Isotopes vol 116 pp 102ndash109 2016

[31] F R Peligro I Pavlovic R Rojas and C Barriga ldquoRemoval ofheavymetals from simulated wastewater by in situ formation oflayered double hydroxidesrdquo Chemical Engineering Journal vol306 pp 1035ndash1040 2016

[32] W Wu S Shanbhag A Wise J Chang A Rutt and JF Whitacre ldquoHigh performance TiP

2O7based intercalation

negative electrode for aqueous lithium-ion batteries via a facilesynthetic routerdquo Journal of the Electrochemical Society vol 162no 9 pp A1921ndashA1926 2015

[33] A K Rai J Gim J Song V Mathew L T Anh and J KimldquoElectrochemical and safety characteristics of TiP

2O7-graphene

nanocomposite anode for rechargeable lithium-ion batteriesrdquoElectrochimica Acta vol 75 pp 247ndash253 2012

[34] R Wang J Ye A Rauf et al ldquoMicrowave-induced synthesisof pyrophosphate Zr


2O7with enhanced

sorption capacity for uranium (VI)rdquo Journal of HazardousMaterials vol 315 pp 76ndash85 2016

[35] H B Ortiz-Oliveros R M Flores-Espinosa E Ordonez-Regiland S M Fernandez-Valverde ldquoSynthesis of 120572-Ti(HPO

4)2sdotH2O

and sorption of Eu (III)rdquoChemical Engineering Journal vol 236pp 398ndash405 2014

[36] M VMaslova D Rusanova V Naydenov O N Antzutkin andL G Gerasimova ldquoExtended study on the synthesis of amor-phous titanium phosphates with tailored sorption propertiesrdquoJournal ofNon-Crystalline Solids vol 358 no 22 pp 2943ndash29502012

[37] R Drot Sorption des ions U (VI) et Eu (III) a Irsquointerface soluc-tion-solides phosphates etude structurale et mecanismes [Thesede grade de Docteur en Sciences] Universite de Paris Sud UFRScientifique DrsquoOrsay 1998

[38] N Finck Effets de la temperature sur les mecanismes drsquointer-action entre les ions europium (III) et uranyle et le diphosphatede zirconium [These de grade de Docteur en Sciences] Universitede Paris Sud UFR Scientifique DrsquoOrsay 2006

[39] E Ordonez-Regil R Drot and E Simoni ldquoSurface complexa-tion modeling of uranium (VI) sorbed onto lanthanum mono-phosphaterdquo Journal of Colloid and Interface Science vol 263 no2 pp 391ndash399 2003


[40] R Drot C Lindecker B Fourest and E Simoni ldquoSurface char-acterization of zirconium and thorium phosphate compoundsrdquoNew Journal of Chemistry vol 22 no 10 pp 1105ndash1109 1998

[41] N Dacheux R Podor B Chassigneux V Brandel and MGenet ldquoActinides immobilization in new matrices based onsolid solutions Th

4minus119909MIV119909(PO4)4P2O7 (M119868119881 = 238U239Pu)rdquo

Journal of Alloys and Compounds vol 271-273 pp 236ndash2391998

[42] J H Lee and R H Byrne ldquoExamination of comparative rareearth element complexation behavior using linear free-energyrelationshipsrdquo Geochimica et Cosmochimica Acta vol 56 no 3pp 1127ndash1137 1992

[43] S A Wood ldquoThe aqueous geochemistry of the rare-earth ele-ments and yttrium 1 Review of available low-temperature datafor inorganic complexes and the inorganic REE speciation ofnatural watersrdquo Chemical Geology vol 82 no C pp 159ndash1861990

[44] M Wang H Xue S Tian R W T Wilkins and Z WangldquoFractal characteristics of upper cretaceous lacustrine shalefrom the Songliao Basin NE Chinardquo Marine and PetroleumGeology vol 67 pp 144ndash153 2015

[45] S Patoux and C Masquelier ldquoLithium insertion into titaniumphosphates silicates and sulfatesrdquo Chemistry of Materials vol14 no 12 pp 5057ndash5068 2002

[46] H Wang K Huang Y Zeng S Yang and L Chen ldquoElectro-chemical properties of TiP

2O7and LiTi

2(PO4)3as anode mate-

rial for lithium ion battery with aqueous solution electrolyterdquoElectrochimica Acta vol 52 no 9 pp 3280ndash3285 2007

[47] C Hurel and N Marmier ldquoSorption of europium on a MX-80bentonite sample experimental and modelling resultsrdquo Journalof Radioanalytical and Nuclear Chemistry vol 284 no 1 pp225ndash230 2010

[48] A S Kar B S Tomar S V Godbole and V K ManchandaldquoTime resolved fluorescence spectroscopy and modeling ofEu(III) sorption by silica in presence and absence of alpha hy-droxy isobutyric acidrdquo Colloids and Surfaces A Physicochemicaland Engineering Aspects vol 378 no 1-3 pp 44ndash49 2011

[49] Y Q Wang Q H Fan P Li et al ldquoThe sorption of Eu(III)on calcareous soil effects of pH ionic strength temperatureforeign ions and humic acidrdquo Journal of Radioanalytical andNuclear Chemistry vol 287 no 1 pp 231ndash237 2011

[50] I M K Ismail and P Pfeifer ldquoFractal analysis and surfaceroughness of nonporous carbon fibers and carbon blacksrdquoLangmuir vol 10 no 5 pp 1532ndash1538 1994

[51] K F Hayes G Redden W Ela and J O Leckie ldquoSurface com-plexation models an evaluation of model parameter estimationusing FITEQL and oxide mineral titration datardquo Journal ofColloid And Interface Science vol 142 no 2 pp 448ndash469 1991

[52] E Simoni Metal Sorption on Oxide Silicate and PhosphateSolids Thermodynamical and Structural Point View Encyclo-pedia of Surface and Colloid Science Marcel Dekker London2002

[53] V Fierro V Torne-Fernandez D Montane and A CelzardldquoAdsorption of phenol onto activated carbons having differenttextural and surface propertiesrdquo Microporous and MesoporousMaterials vol 111 no 1ndash3 pp 276ndash284 2008

[54] S H Chien andW R Clayton ldquoApplication of elovich equationto the kinetics of phosphate release and sorption in soilsrdquo SoilScience Society of America Journal vol 44 no 2 pp 265ndash2681980

[55] S Alvarez-Torrellas M Munoz J A Zazo J A Casas andJ Garcıa ldquoSynthesis of high surface area carbon adsorbents

prepared from pine sawdust-Onopordum acanthium L fornonsteroidal anti-inflammatory drugs adsorptionrdquo Journal ofEnvironmental Management vol 183 pp 294ndash305 2016

[56] Y-S Ho T-H Chiang and Y-M Hsueh ldquoRemoval of basic dyefrom aqueous solution using tree fern as a biosorbentrdquo ProcessBiochemistry vol 40 no 1 pp 119ndash124 2005

[57] W J Weber and J C Morris ldquoKinetic of adsorption on carbonfrom solutionrdquo Journal Sanitary Engeering Division ProceedingsAmerican Society of Civil Engineers vol 89 pp 31ndash59 1963

[58] S K Srivastava R Tyagi and N Pant ldquoAdsorption of heavymetal ions on carbonaceous material developed from the wasteslurry generated in local fertilizer plantsrdquo Water Research vol23 no 9 pp 1161ndash1165 1989

[59] I Puigdomenech httpswwwkthseenchemedusadown-loads-1386254

[60] S T Norberg G Svensson and J Albertsson ldquoA TiP2O7super-

structurerdquo Acta Crystallographica Section C Crystal StructureCommunications vol 57 no 3 pp 225ndash227 2001

[61] J Tang L Feng Y Li J Liu and X Liu ldquoFractal and pore struc-ture analysis of Shengli lignite during drying processrdquo PowderTechnology vol 303 pp 251ndash259 2016

[62] T Cao Z Song S Wang and J Xia ldquoCharacterization of porestructure and fractal dimension of Paleozoic shales from thenortheastern Sichuan Basin Chinardquo Journal of Natural GasScience and Engineering vol 35 pp 882ndash895 2016

[63] H Ortiz-Oliveros E Ordonez-Regil and S M Fernszligndez-Valverde ldquoSorption evaluation of Eu (III) onto titanium diphos-phaterdquo Symposium LASANS Cancun Mexico 2007

[64] A L Herbelin and J CWestall ldquoFITEQL A computer programfor determination of chemical equilibrium constants fromexperimental datardquo Tech Rep 97331 Department of ChemistryOregon State University Corvallis Ore USA 1999

[65] P N Diagboya B I Olu-Owolabi and K O AdebowaleldquoMicroscale scavenging of pentachlorophenol in water usingamine and tripolyphosphate-grafted SBA-15 silica batch andmodeling studiesrdquo Journal of Environmental Management vol146 pp 42ndash49 2014

[66] J Zhao X Ding CMeng C Ren H Fu andH Yang ldquoAdsorp-tion and immobilization of actinides using novel SiO

2-ZrO2-

calcium alginate aerogels from high level liquid wasterdquo Progressin Nuclear Energy vol 85 pp 713ndash718 2015

[67] X Chen X Wang S Wang et al ldquoFurfuryl alcohol functional-ized graphene for sorption of radionuclidesrdquoArabian Journal ofChemistry 2016

[68] Y S Ho ldquoReview of second-order models for adsorption sys-temsrdquo Journal of Hazardous Materials vol 136 no 3 pp 681ndash689 2006

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal ofInternational Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


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Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Due to the chemical properties of these metals theirremoval requires specific treatment processes The processesmost used are chemical precipitation coagulationfloccu-lation flotation (with dispersed air or dissolved air) elec-trochemical process photocatalytic process inverse osmosision exchange and sorption [14ndash20] Many of these processesare usually efficient but can be limited by the concentrationand the physicochemical form of the heavy metal as wellas the costs and the difficulties of the operation such as thegeneration of residual sludge

Sorption is one of the most used processes for theremoval of low concentrations (including trace levels) ofheavy metals and radionuclides in an aqueous medium Theterm sorption is used in a generic way to describe physic-ochemical processes in which the dissolved contaminant(metal radionuclide etc) is transferred from the solution tothe solid phase [21 22] either by precipitating on the surfacediffusing on the outside and inside of the pores of the solidphase or by forming complexes on the surface [23]

The phenomena of sorption are also used with successin the construction of engineering barriers to avoid thedispersion of heavy metals and radionuclides in the soiland subsoil where the sorption process is carried out byinteraction of chemical species (metals or radionuclides) insolution with surface functional groups of the components ofthe soil [24 25]

Due to the importance that sorption processes have in thetreatment of industrial wastewater in industrial applicationsor the remediation of soils contaminated withmetals interesthas again risen during the last couple of years in carryingout investigations aimed at understanding the phenomenainvolved in sorption and also the development of differentmaterials or sorbents and in determining their retentionproperties In that regard several investigators have studiedlow cost materials such as biosorbents in which there isthe biomass of residues of vegetable or animal origin orbacteria and fungi [8 26 27] These biosorbents have proventhemselves efficient in the removal of metals in aqueoussolutions In addition new mineral sorbents have beensynthesized and tested that unlike the biosorbents may costmore but have a high retention capacity low solubility andhigh thermic and structural stability even when submittedto intense fields of gamma radiation an example of whichare the tests of sorption of metals and radionuclides inphosphates of isomorphic tetravalent metals perovskite andother synthetic inorganic materials [28ndash31]

As far as phosphates are concerned since the discovery ofLiFePO

4 newmaterials have been synthesized and identified

based on phosphates-based polyanions such as (PO4)3minus

(P2O7)4minus or (P

3O10)5minus [32] which find their application

in different fields of knowledge due to their major struc-tural anomalies such as their anisotropic deformation lowredox potential and low cost of synthesis [32 33] Thesecharacteristics have motivated the study of the retentionof metals in phosphates The sorption of lanthanides anduranyl on different synthetic phosphates has been reportedfor example Wang et al [34] studied the sorption of U (VI)onto Zr


2O7 Ortiz-Oliveros et al [35]

studied the synthesis of 120572-Ti(HPO4)2H2O and sorption of

Eu3+ and Maslova et al [36] studied the synthesis andsorption properties of amorphous titanium phosphates

Literature reports different synthesis methods of polyan-ions such as (P

2O7)4minus The methods most used are (a)

methods of coprecipitation where organic compounds areused as ion sources and phosphoric acids are used as phos-phate sources [33 34] and (b) hydrothermal methods wheremetallic oxides are used as ion sources and water-solublephosphate salts as phosphate sources in an acid medium[32] Rai et al [33] used the method of coprecipitationto obtain titanium pyrophosphate During this method anaqueous solution of titanium isopropoxide is mixed with asolution of phosphoric acid and diluted hydrochloric acidThe mixture is heated to 343K and agitated for 10-11 h Inthe end the obtained material is heated to 1073K for 3 h ina CO2atmosphere Other authors obtain TiP

2O7using the

sequence proposed by Patoux It consists in mixing TiO2and

(NH4)2HPO4and heating themixture progressively to 1273K

using intermittent gridding sequences [45 46]This work addresses the synthesis of titanium pyrophos-

phate using an improved method Titanium pyrophosphatewas prepared using high purity TiCl

4and concentrated

H3PO4 through precipitation in an atmosphere of nitrogen

The precipitate obtained was heated to 1073K for 3 h Withtitanium pyrophosphate previously characterized the reten-tion capacity of Eu3+ was evaluated as a chemical analogousfor heavy metals (Cr3+ and As3+) and actinides (Ac3+) [4748] It is well known that the europium ionic radius is similarto Cr3+ As3+ and Ac3+ radii which results in a similarphysicochemical behavior [49] Additional modeling thesorption of the europium onto the titanium pyrophosphateas a function of the pH using a surface complexation modelwas performed

2 Experimental

21 Synthesis of TiP2O7 The titanium pyrophosphate wasobtained by the described method by Ortiz-Oliveros et al[35] Synthesis was performed mixing high purity liquidtitanium tetrachloride (999Aldrich) as the ion sourcewithconcentrated phosphoric acid (85 Baker) as the phosphatesource while maintaining a TiP stoichiometric ratio of 1 2under a nitrogen atmosphere in a glovebox TiCl

4was slowly

added to a stirred solution of phosphoric acid and theprecipitate was recuperated and washed with deionizer waterThe precipitate was then centrifuged separated and driedat room temperature Finally the dried solid was heated at1073K for 3 h

22 Material Characterization The solid obtained was char-acterized by X-ray powder diffraction (XRD) patterns ina diffractometer (Siemens D5000) The XRD patterns wereobtained with Cu monochromatic K120572 rays at 35 kV and25mA The 2120579 diffraction angle (4∘ndash70∘) was scanned at ascan rate of 183minminus1 The elemental and structural analysisof the solid was performed in a scanning electronmicroscope(PHILIPS model XL-30) coupled to a microprobe (EDAXmodel DX-4) for energy dispersive X-ray spectroscopy witha resolution of 140 eV Representative samples were fixed on








2


ln( 119881119881119898

) = Γ + 119860[ln(ln(119875119900119875 ))] (1)







119904







3)3








log (119902119890minus 119902119905) = log (119902

119890) minus 1198961015840119905

2303 (2)


119905is



120575119902119905

120575119905 = 120572 exp (minus120573119905119902119905) (3)



120575119902119905

120575119905 = 1198962(119902119890minus 119902119905)2 (4)




119902119905= 11989611989411990505 + 119862SL (5)









2O7with a













= 05 [61] When 119875119875119900



SEBSE 255 None 255

PKa 31 TiKa 24

OKa 15


(a) (b)







1and119863



1= 131 when



1and 119863

2 the









10 20 30 40 50 60 70

2

JCPDS 38-1468Tip

2O7 obtained

Inte

nsity

(cps

)

100

200

300

400

0



119904and 119860

119904




2O7 ZrP2O7 and LaPO

4




3
















119905versus



0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)


B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)


r2= 099


04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)


2


2=











2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of








2


ln( 119881119881119898

) = Γ + 119860[ln(ln(119875119900119875 ))] (1)







119904







3)3








log (119902119890minus 119902119905) = log (119902

119890) minus 1198961015840119905

2303 (2)


119905is



120575119902119905

120575119905 = 120572 exp (minus120573119905119902119905) (3)



120575119902119905

120575119905 = 1198962(119902119890minus 119902119905)2 (4)




119902119905= 11989611989411990505 + 119862SL (5)









2O7with a













= 05 [61] When 119875119875119900



SEBSE 255 None 255

PKa 31 TiKa 24

OKa 15


(a) (b)







1and119863



1= 131 when



1and 119863

2 the









10 20 30 40 50 60 70

2

JCPDS 38-1468Tip

2O7 obtained

Inte

nsity

(cps

)

100

200

300

400

0



119904and 119860

119904




2O7 ZrP2O7 and LaPO

4




3
















119905versus



0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)


B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)


r2= 099


04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)


2


2=











2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



log (119902119890minus 119902119905) = log (119902

119890) minus 1198961015840119905

2303 (2)


119905is



120575119902119905

120575119905 = 120572 exp (minus120573119905119902119905) (3)



120575119902119905

120575119905 = 1198962(119902119890minus 119902119905)2 (4)




119902119905= 11989611989411990505 + 119862SL (5)









2O7with a













= 05 [61] When 119875119875119900



SEBSE 255 None 255

PKa 31 TiKa 24

OKa 15


(a) (b)







1and119863



1= 131 when



1and 119863

2 the









10 20 30 40 50 60 70

2

JCPDS 38-1468Tip

2O7 obtained

Inte

nsity

(cps

)

100

200

300

400

0



119904and 119860

119904




2O7 ZrP2O7 and LaPO

4




3
















119905versus



0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)


B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)


r2= 099


04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)


2


2=











2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


SEBSE 255 None 255

PKa 31 TiKa 24

OKa 15


(a) (b)







1and119863



1= 131 when



1and 119863

2 the









10 20 30 40 50 60 70

2

JCPDS 38-1468Tip

2O7 obtained

Inte

nsity

(cps

)

100

200

300

400

0



119904and 119860

119904




2O7 ZrP2O7 and LaPO

4




3
















119905versus



0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)


B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)


r2= 099


04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)


2


2=











2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


10 20 30 40 50 60 70

2

JCPDS 38-1468Tip

2O7 obtained

Inte

nsity

(cps

)

100

200

300

400

0



119904and 119860

119904




2O7 ZrP2O7 and LaPO

4




3
















119905versus



0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)


B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)


r2= 099


04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)


2


2=











2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

100

200

300

400

500(n

m)

82

83

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(a)

0

100

200

300

400

500

(nm

)

84

85

86

87

(nm

)

100 200 300 400 5000(nm)

(b)


B

N2 isotherm

minus5

0

5

10

15

20

25

30

35

V(m

Lg)

02 04 06 08 1000

PP0

(a)


r2= 099


04

06

08

10

12

14

16

18

20

22

24

ln[ln(P0P)]

ln(V

Vm

)

A = minus056

(b)


2


2=











2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





2O7


2O7

[37 38]LaPO

4 308 36 minus54 PO4

[39]Th4(PO4)4P2O7 308 65 minus78 P

2O7

[40 41]



times10minus3

2

4

6

8

10

12

pH




3solution




2

+ minus1731 [42]Eu3+ + 3H

2Oharr Eu(OH)

3minus2635 [42]

Eu3+ + NO3


Eu3++ CO3


Eu3+ + 2CO3


minus 1045 [44]


2O7groups Studies




0 500 1000 1500 2000 2500 3000

Time (min)

removalqt

minus01

00

01

02

03

04

05

06

qt

(mg

g)0

20

40

60

80

100

re

mov

al


3 in contact with






Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Experimental data

0 500 1000 1500 2000 2500

t (min)


qe = 064mg gminus1

r2 = 091minus22

minus20

minus18

minus16

minus14

minus12

minus10

minus08

minus06

minus04

minus02

Data fitting

log(qeminusqt)

(a)


22 24 26 28 30 32 34 36

Where lt 0

= 0168 g mgminus1

lt 1

r2 = 098

00

01

02

03

04

05

06

qt

(mg

g)

log(t)

(b)


qe = 06 mg gminus1

r2 = 098

0 500 1000 1500 2000 2500 3000

1500

2000

2500

3000

3500

4000

4500

5000

5500

Where

Experimental data

t (min)

Data fitting

tqt

(c)

10 20 30 40 50 60

t05



r2 = 092

Where

Experimental data

00

01

02

03

04

05

06qt

(mg

g)

Data fitting

(d)






2EuNO

3


3

2+ ((equivXO)2EuNO

3)


2

+


3




3









3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




3




3


312 plusmn 05 TiP

2O7



2O7


3


2O7


3


3



3


3+ 2H+ 094 plusmn 014 (P

2O7) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Th(PO

4)4P2O7

[37 40 41]2equivXOH + Eu3+ + NO

3



4) Zr

2O(PO

4)2


3



2O(PO

4)2

[37 40]

times10minus5

1 2 3 4 5 6 7 80

pH

0

2

4

6

8

10

Con

cent

ratio

n (m

olL

)


(XOH)2EuNO32+

Simulated



4complex


4)

4 Conclusions


2


3









Acknowledgments


References










































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of
































2O7-graphene




2O7with enhanced



4)2sdotH2O
















2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of











2O7and LiTi

























2-ZrO2-













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Titanium Pyrophosphate for Removal of Trivalent Heavy Metals and Actinides...

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Transcript of Titanium Pyrophosphate for Removal of Trivalent Heavy Metals and Actinides...