KineticStudiesontheRemovalofSomeLanthanideIonsfrom ...acetic acid/acetate solution at pH 7.0 is still preserved and accepted under this condition in order to accomplish the highest

Research ArticleKinetic Studies on the Removal of Some Lanthanide Ions fromAqueous Solutions Using Amidoxime-Hydroxamic Acid Polymer

Fadi Alakhras

Department of Chemistry College of Science Imam Abdulrahman Bin Faisal University PO Box 1982Dammam 31441 Saudi Arabia

Correspondence should be addressed to Fadi Alakhras falakhrasiauedusa

Received 27 March 2018 Revised 28 May 2018 Accepted 20 June 2018 Published 8 July 2018

Academic Editor Manzar Sohail

Copyright copy 2018 Fadi Alakhras )is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Lanthanide metal ions make distinctive and essential contributions to recent global proficiency Extraction and reuse of these ionsis of immense significance especially when the supply is restricted In light of sorption technology poly(amidoxime-hydroxamic)acid sorbents are synthesized and utilized for the removal of various lanthanide ions (La3+ Nd3+ Sm3+ Gd3+ and Tb3+) fromaqueous solutions )e sorption speed of trivalent lanthanides (Ln3+) depending on the contact period is studied by a batchequilibrium method )e results reveal fast rates of metal ion uptake with highest percentage being achieved after 15ndash30min )einteraction of poly(amidoxime-hydroxamic) acid sorbent with Ln3+ ions follows the pseudo-second-order kinetic model witha correlation coefficient R2 extremely high and close to unity Intraparticle diffusion data provide three linear plots indicating thatthe sorption process is affected by two or more steps and the intraparticle diffusion rate constants are raised among reduction ofionic radius of the studied lanthanides

1 Introduction

Fast industrial progress throughout preceding years in-volved improvement and wide handling of special mate-rials in diverse viable products )e handling of heavymetals in manufacturing introduces a huge amount oftoxic metals into the atmosphere in addition to the aquaticand global surroundings [1] Due to the certain physicaland chemical features of rare earth elements (REEs) theyhave been used for particular applications in advancedtechnologies such as special ceramics organic synthesisand their usage in equipment such as batteries sensorsenergy efficient lighting nuclear technologies and tele-communication [2ndash5] REEs can be exploited in theproduction of alloys magnets catalysts electric machinessecurity systems medical applications and in fertilizingperspectives [6ndash10]

In spite of the increasing concern raised by REEshealthiness advantages versus poisonous impacts of thesematters should be taken seriously )ere are several envi-ronmental concerns allied with the production processing

and utilization of REEs [11] A few reports have accountedthat the chemicals used in the refining process of REEs areinvolved in disease and occupational poisoning of localresidents water pollution and farmland destruction It wasconfirmed that REErsquos bioaccumulation through the foodchain can cause diseases because of the contact with humanbeings even at trace concentration [12ndash14] )erefore rareearth metal ions including lanthanides in wastewaters are ofmain environmental interest and necessitate to be treatedprior to their removal into environment

Disposal of rare earth metal ions from large volumes ofwastewaters needs a cost-effectual remediation expertiseUsing novel extraction techniques having great effectivenessand biodegradability will certainly decrease expenses andenvironmental effects permitting the rare earth elements to behandled very extensively as well as escalating the quantitieswhich are regained via recovering [15] Several techniqueshave been used for rare earth elements removal such as solventextraction organic and inorganic ion exchange micellar ul-trafiltration chemical precipitation solid-phase extraction orchromatography Chemical precipitation treatment methods

HindawiJournal of Analytical Methods in ChemistryVolume 2018 Article ID 4058503 7 pageshttpsdoiorg10115520184058503

need large storage facilities for the precipitated sludge andsometimes require additional treatment options Ion ex-change which is expensive and sophisticated would allowmetallic ions recovery Additionally these methods are notamenable to large-scale treatment of contaminated groundwater or drinking water Purification of water contaminatedwith lanthanides requires the ability to selectively remove thelanthanides in the presence of other ions like Ca and Mg [16])erefore it may be of value to design a chemically selectivesorbent material (amidoxime-hydroxamic acid as in thisstudy) capable of selectively sequestering the lanthanides fromwaste streams ground water and drinking water without theneed for any additional solvents or treatment processesAdsorption process which is used in this study is highlyeconomical and capable of removing contaminants even attrace level )e use of this technique in water and wastewatertreatment due to its simplicity and low cost of operation andits wide end-use is highly utilized [17ndash19]

Nevertheless the performance of any adsorption processis exceedingly reliant on the selection of suitable mediumFor the extraction of lanthanides from aqueous systemsdifferent prospective sorbents are studied by several researchgroups [20ndash24] It is confirmed that the sorption of lan-thanides can be affected by the variation of mediumrsquos aciditycontact period temperature and sorbent amount Addi-tionally polymers with certain chelating ligands have beenused to remove valuable ionic species found in liquid sys-tems )ese chelating polymers have attractive propertiesincluding powerful capability great selectivity and quickremoval rates of ionic species with high physical potency andstability [25ndash28]

In connection with our previous work [17] poly(amidoxime-hydroxamic) acid resins were used for thesorption of various lanthanide ions (La3+ Nd3+ Sm3+ Gd3+and Tb3+) from liquid systems )e impacts of pH exposuretime counter ion and cross-linker were investigated )eresults showed that 6 hours of agitation was sufficient toaccomplish utmost metal-ion removal with maximum atpH 7 )e data also specified that the percentage removaldeclined as the quantity of cross-linker enhanced

To understand the influence of exposure time and thekinetics of adsorption of lanthanide ions by amidoxime-hydroxamic acid polymers more investigation were done andpresented in this article Pseudo-first-order and pseudo-second-order kinetics were utilized for data analysis Furthermore theintraparticle diffusion model which is developed to inspect themechanism of sorption for a solid-liquid removal process wasapplied as well

2 Materials and Methods

21 Materials Unless otherwise stated all chemical mate-rials were attained from trade sources and were utilized asobtained Acrylonitrile 224-trimethyl pentane and gela-tine were acquired from BDH Chemicals Ltd (PooleEngland) Benzoyl peroxide and ethylacrylate were boughtfrom Fluka (Buchs Switzerland) Hydroxylamine hydro-chloride was purchased from Aldrich (Milwaukee WI) )efollowing lanthanide salts were also used as received with no

more refinement LaCl3middot6H2O NdCl3middot6H2O SmCl3middot6H2Oand GdCl3middot6H2O from Aldrich and TbCl3middot6H2O from KampKLaboratories Inc (Jamaica NY)

22 Preparation and Characterization of Adsorbent MaterialAmidoxime-hydroxamic acid polymer was synthesized andcharacterized depending on a process reported by Alakhraset al [17] )e polymer (Scheme 1) was prepared throughaddition of acrylonitrile and ethylacrylate by suspensionpolymerization Afterwards hydroxylamine hydrochloridewas added to convert the obtained copolymer into poly(amidoxime-hydroxamic) acid resin A detailed analysis ofIR spectra decomposition point and water regain param-eters of the obtained chelating material was reported in ourprevious work [17]

23 Sorption Kinetics of Lanthanide Ions A batch equilib-rium process was employed to investigate the removal ki-netics for eachmetal ion (La3+ Nd3+ Sm3+ Gd3+ and Tb3+)Perfectly weighted dosage of adsorbent (010 g) was con-stantly shaken at 400 rpm with 15mL of acetic acidacetatesolution with pH 70 for two hours to reach equilibriumAfter that 100mL of metal-ion solution with 150mgmiddotLminus1was added and the mixture was shaken for a definite periodof time )e agitation time was changed from 025 to 24 hAt the end the contents of the flasks were determinedfor residual adsorbates by Complexometric titration withstandard ethylene diamine tetra-acetic acid (EDTA) aque-ous solution using xylenol orange as the indicator [29])e flasks were shaken with a GFL-1083 thermostatedshaker kept at 25degC

)e quantity of metal ions removed at equilibrium Qe(mgmiddotgminus1) was evaluated [30] according tothe followingequation

Qe C0 minusCe( 1113857V

W (1)

where C0 represents the initial metal amount (mgmiddotLminus1) andCe is the final concentration after 24 h )e volume of so-lution (L) is represented by V and W symbolizes the amountof dry sorbent (g) )e removal amount of metal ionschelated at several intervals [31] was computed by means ofthe following equation

Qt C0 minusCt( 1113857V

W (2)

where Ct is the metal ion concentration (mgmiddotLminus1) in solutionat different period t

3 Results and Discussion

31 Sorption Kinetics )e removal rate of trivalent lan-thanides (Ln3+) depending on the contact time was studiedby a batch equilibrium method In this procedure 35ndash60mesh size trials of the dry adsorbent was equilibrated fortwo hours with acetate solution (pH 70) Figure 1 dem-onstrates a representative reliance of lanthanides removal onexposure period )e percentage removal increased with time

2 Journal of Analytical Methods in Chemistry

until it attained a steady state after 5-6 h In addition theoutcome pointed out fast rates of ion sorption with 60maximum percentage achieved after 15ndash30min is be-haviour can be referred to the vacant active sites on theadsorbent surface and to the high electrostatic attractionbetween metal ions and chelating groups [32]

e above results can also be explained depending onmetal ion adsorption modes (Scheme 2) Lanthanide metalions can strongly attach via two sites (N and O) at the sametime with dierent modes which certainly aects on theobtained complex stability

Furthermore results disclosed that the lanthanide ionsremoval follows the following arrangement Tb3+gtGd3+gt Sm3+gtNd3+gt La3+ the polymer shows maximum re-moval ability toward Tb3+ and minimum for La3+ isdivergence in capabilities depicted with the studied ions bythe used polymer can be interpreted by the negative stericeect on coordination with active chelating groups [33] eionic radius for Tb3+ is 1063 pm while 115 pm for La3+ estability of the forming complex is anticipated to be lessconvenient for species of bigger extent this is reliable withprevious research [17 34ndash36]

e removal capacity of the investigated sorbent towardLn3+ was investigated in the pH range 40ndash75 undercontinuous shaking for 24 h at 25degC e eect of pH isdepicted in Figure 2 and the results revealed that metal-ionuptake increased with increase of pH and a steady state wasattained at about pH 70 is behaviour can be attributedto the acid dissociation nature of the hydroxamate andamidoxime groups of the sorbent material At higher pHvalues Ln3+ ions competed favourably toward donor sitescompared with hydrogen ions Consequently more metalions removal was achieved However at pH values higherthan 7 the metal ion solution can be converted to hy-droxide form that has no charge and its interaction can bedecreased clearly by the sorbent e buer capacity ofacetic acidacetate solution at pH 70 is still preserved andaccepted under this condition in order to accomplish thehighest percent removal of lanthanide metal ions usingamidoxime-hydroxamic acid resin

Hydroxamategroup

Amidoximegroup

C

N

H2N

O

C O

HN OLn3+Ln3+

Scheme 2 Lanthanide metal ions adsorption modes

H2C CH CH2 CHC CN

H2N

OHNHOH

O

n

Scheme 1 Structure of poly(amidoxime-hydroxamic) acid sorbent

400

450

500

550

600

650

700

0 500 1000 1500 2000

re

mov

al

La (III)Nd (III)Sm (III)

Gd (III)Tb (III)

t (min)

Figure 1 Eect of contact time on Ln3+ removal (C0 15mgmiddotLminus1T 25degC W 010 g and V 0025 L)

20

30

40

50

60

70

3 4 5 6 7 8

re

mov

al

pH


Gd (III)Tb (III)

Figure 2 Eect of pH on Ln3+ removal (C0 15mgmiddotLminus1 T 25degCW 010 g and V 0025 L)

Journal of Analytical Methods in Chemistry 3

32 Kinetic Analysis of Lanthanide Ions Removal MethodTo verify the kinetic phenomena of the removal process oflanthanide ions three kinetic models were used to evaluatethe experimental data at pH 70 involving pseudo-rst-order pseudo-second-order and intraparticle diusionmodels e rst two models described the whole sorptionprocess without taking into account the diusion stepswhereas the third model is utilized to investigate themechanism of sorption for a solid-liquid removal processthat can normally be depicted by three stages [15 18 32]e representative equations for the kinetic models areoered in Table 1 where Qt and Qe are the quantity of ionsremoved at time t and at equilibrium in mgmiddotgminus1 corre-spondingly k is the rate constant and C is the boundarythickness layer in mgmiddotgminus1

e (Qe)cal and k1 data are presented in Table 2 Cor-relation coecient R2 was varied between 07062 and 08964e experimental Qe values were considerably varied fromthe associated evaluated Qe ones demonstrating that thesorption process was not following the pseudo-rst-ordermodel

Figure 3 displays plotting of tQt against t for lanthanidemetal ions under investigation with obtained straight lineshaving R2 09999 e (Qe)cal data were in tremendousagreement with the investigational statistics (Table 2)Consequently the Ln3+ removal process could be deducedmore constructively by pseudo-second-order kinetic anal-ysise outcomemay propose that the removal of Ln3+ ionsusing amidoxime-hydroxamic acid polymer is based ona chemical adsorption process by means of participation orexchange of electrons between adsorbent and adsorbate[15 37]

Intraparticle diusion mechanism is described as thetransfer of solute from liquid to solid phase during theremoval process on a porous adsorbent In this form kid(mgmiddotgminus1middotminminus12) is representing intraparticle diusion rateconstant while C (mgmiddotgminus1) is demonstrating the thickness ofthe boundary layer Figure 4 shows plotting of Qt versus t12for the sorption of Tb(III) metal ione data provided threelinear plots indicating that the sorption process is aected bytwo or more steps e rst region characterized macroporediusion and the second one represented the slow removal

phase where intraparticle diusion is the rate-limitingstep [38 39] e third region could be considered as thediusion via smaller pores which is followed by the

Table 1 Linearized equations for Ln3+ sorption kinetics

Kinetic model Linear equation PlotPseudo-rst-order ln (QeminusQt) ln Qeminus k1 t ln (QeminusQt) versus tPseudo-second-order (tQt) (1k2Q2

e) + (tQe) tQe versus tIntraparticle diusion Qt kid t12 +C Qt versus t12

Table 2 Kinetic constants for pseudo-rst-order and pseudo-second-order models for Ln3+ sorption

(Qe)exp (mgmiddotgminus1)Pseudo-rst-order Pseudo-second-order

K1 (minminus1) (Qe)cal (mgmiddotgminus1) R21 K2 (gmiddotmgminus1middotminminus1) (Qe)cal (mgmiddotgminus1) R2

2

La3+ 185 161times 10minus3 01593 07754 01831 180 09999Nd3+ 198 138times10minus3 01842 08457 01548 191 09998Sm3+ 228 138times10minus3 01647 08964 01700 222 09999Gd3+ 238 161times 10minus3 01854 07062 01735 231 09997Tb3+ 248 138times10minus3 01759 07304 01887 241 09999

0

100

t (Q

t)

200

300

400

0 200 400 600 800


Gd (III)Tb (III)

t (min)

Figure 3 Pseudo-second-order kinetic plot for Ln3+ sorption

224

228

232

236

24

244

0 5 10 15 20 25 30

Intraparticle diffusion

t12 (min12)

Qt (

mgmiddot

gndash1)

Figure 4 Intraparticle diusion plot for the sorption of Tb(III)metal ion


establishment of equilibrium Additionally the plot did notpass through the origin demonstrating that pore diusioncould not be the only rate-determining step in verifying thekinetics of Ln3+ sorption process and this process might beorganized by a chemical reaction as well

e values of the dierent parameters calculated fromthe plots of Qt versus t12 for the intraparticle diusionregion are presented in Table 3

It is clearly indicated that the intraparticle diusion rateconstants are increased with decrease of ionic radius of the

studied lanthanides (Figure 5(a)) is behaviour suggestedthat ionic radius declined with the atomic number and alsosmaller ions became more convenient to diuse [15] Fur-thermore positive relationship was obtained by plotting kidvalues versus experimental Qe ones (Figure 5(b)) isperformance designated that smaller metal ions can bediused through the outer surface into the pores of thesorbent and removed more easily than bigger ones

4 Conclusions

Amidoxime-hydroxamic acid polymer materials have beensynthesized and exploited for the chelation of dierentlanthanides (La3+ Nd3+ Sm3+ Gd3+ and Tb3+) fromaqueous solutions e sorption rate of the investigated ionsrelying on agitation period was analyzed by the batchequilibrium method e removal process was carried outwith fast kinetic rates and it achieved maximum percentageafter 15ndash30min e sorption of ions followed the followingorder Tb3+gtGd3+gt Sm3+gtNd3+gt La3+ Kinetic studiesrevealed that chemisorption was the rate-determining stepwith correlation coecient remarkably high and close tounity Intraparticle diusion study aorded three regionsdemonstrating that the sorption course is aected by morethan one step and intraparticle diusion might be involvingin controlling the diusion of investigated lanthanides

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e author declares that there are no concurrenicts of interestregarding the publication of this paper

References

[1] R Saravanan and L Ravikumar ldquoe use of new chemicallymodied cellulose for heavy metal ion adsorption and anti-microbial activitiesrdquo Journal of Water Resource and Pro-tection vol 7 no 6 pp 530ndash545 2015

[2] A Fuqiang B Gao X Huang et al ldquoSelectively removal of Al(III) from Pr(III) and Nd(III) rare earth solution using surfaceimprinted polymerrdquo Reactive and Functional Polymersvol 73 no 1 pp 60ndash65 2013

[3] I Celik D Kara C Karadas A Fisher and S J Hill ldquoA novelligandless-dispersive liquidndashliquid microextraction methodfor matrix elimination and the preconcentration of rare earthelements from natural watersrdquo Talanta vol 134 pp 476ndash4812015

[4] S Yesiller A E Eroglu and T Shahwan ldquoRemoval ofaqueous rare earth elements (REEs) using nano-iron basedmaterialsrdquo Journal of Industrial and Engineering Chemistryvol 19 no 3 pp 898ndash907 2013

[5] T Jun Y Jingqun C Kaihong R Guohua J Mintao andC Ruan ldquoExtraction of rare earths from the leach liquor of theweathered crust elution-deposited rare earth ore with non-precipitationrdquo International Journal of Mineral Processingvol 98 no 3-4 pp 125ndash131 2011

Table 3 Intraparticle diusion kinetic parameters for Ln3+

sorption

Ln3+ kid (mgmiddotgminus1middotminminus12) C (mgmiddotgminus1) R2

La3+ 00047 16228 09195Nd3+ 00056 17380 09536Sm3+ 00098 20938 09836Gd3+ 00102 21326 09603Tb3+ 00134 22314 09265

0016

0012

0010

0008

0006

0004

90 92 94 96 98 100 102 104 106

0014

r (A0)

k id (m

gmiddotgndash1

middotmin

12 )

(a)

0016

0012

0010

0008

0006

0004

0014

18 20 22 24 26Qe(exp) (mgmiddotgndash1)

k id (m

gmiddotgndash1

middotmin

12 )

(b)

Figure 5 (a) Plot of ionic radius of Ln3+ versus kid values (b) plotof Qe (exp) of Ln3+ versus kid values


[6] H S Yoon C J Kim K W Chung S D Kim J Y Lee andJ R Kumar ldquoSolvent extraction separation and recovery ofdysprosium (Dy) and neodymium (Nd) from aqueous so-lutions waste recycling strategies for permanent magnetprocessingrdquo Hydrometallurgy vol 165 pp 27ndash43 2016

[7] P K Parhi K H Park C W Nam and J T Park ldquoLiquid-liquid extraction and separation of total rare earth (RE) metalsfrom polymetallic manganese nodule leaching solutionrdquoJournal of Rare Earths vol 33 no 2 pp 207ndash213 2015

[8] P Liang Y Liu and L Guo ldquoDetermination of trace rareearth elements by inductively coupled plasma atomic emis-sion spectrometry after preconcentration with multiwalledcarbon nanotubesrdquo Spectrochimica Acta Part B AtomicSpectroscopy vol 60 no 1 pp 125ndash129 2005

[9] R M Ashour R El-sayed A F Abdel-Magied et al ldquoSe-lective separation of rare earth ions from aqueous solutionusing functionalized magnetite nanoparticles kinetic andthermodynamic studiesrdquo Chemical Engineering Journalvol 327 pp 286ndash296 2017

[10] Y F Xiao X S Liu Z Y Feng et al ldquoRole of mineralsproperties on leaching process of weathered crust elution-deposited rare earth orerdquo Journal of Rare Earths vol 33 no 5pp 545ndash552 2015

[11] K T Rim ldquoEffects of rare earth elements on the environmentand human health a literature reviewrdquo Toxicology and En-vironmental Health Sciences vol 8 no 3 pp 189ndash200 2016

[12] K T Rim K H Koo and J S Park ldquoToxicological evaluationsof rare earths and their health impacts to workers a literaturereviewrdquo Safety and Health at Work vol 4 no 1 pp 12ndash262013

[13] L Wang W Wang Q Zhou and X Huang ldquoCombinedeffects of lanthanum (III) chloride and acid rain on photo-synthetic parameters in ricerdquo Chemosphere vol 112pp 355ndash361 2014

[14] H Herrmann J Nolde S Berger and S Heise ldquoAquaticecotoxicity of lanthanummdasha review and an attempt to derivewater and sediment quality criteriardquo Ecotoxicology and En-vironmental Safety vol 124 pp 213ndash218 2016

[15] H Zhang R G McDowell L R Martin and Y QiangldquoSelective extraction of heavy and light lanthanides fromaqueous solution by advanced magnetic nanosorbentsrdquo Ap-plied Materials and Interfaces vol 8 no 14 pp 9523ndash95312016

[16] W Yantasee G E Fryxell R S Addleman et al ldquoSelectiveremoval of lanthanides from natural waters acidic streamsand dialysaterdquo Journal of HazardousMaterials vol 168 no 2-3 pp 1233ndash1238 2009

[17] F A Alakhras K Abu Dari and M S Mubarak ldquoSynthesisand chelating properties of some poly(amidoxime-hydroxamic acid) resins toward some trivalent lanthanidemetal ionsrdquo Journal of Applied Polymer Science vol 97 no 2pp 691ndash696 2005

[18] H M Marwani H M Albishri T A Jalal and E M SolimanldquoStudy of isotherm and kinetic models of lanthanum ad-sorption on activated carbon loaded with recently synthesizedSchiffrsquos baserdquo Arabian Journal of Chemistry vol 10pp S1032ndashS1040 2017

[19] E A Abdel-Galil A B Ibrahim and M M Abou-MesalamldquoSorption behavior of some lanthanides on polyacrylamidestannic molybdophosphate as organicndashinorganic compositerdquoInternational Journal of Industrial Chemistry vol 7 no 3pp 231ndash240 2016

[20] F Xie T A Zhang D Dreisinger and F Doyle ldquoA criticalreview on solvent extraction of rare earths from aqueoussolutionsrdquo Minerals Engineering vol 56 pp 10ndash28 2014

[21] A N Turanov V K Karandashev N S SukhininaV M Masalov A A Zhokhov and G A Emelchenko ldquoAnovel sorbent for lanthanide adsorption based on tetraoc-tyldiglycolamide modified carbon inverse opalsrdquo RSC Ad-vances vol 5 no 1 pp 529ndash535 2015

[22] Q Chen ldquoRare earth application for heat-resisting alloysrdquoJournal of Rare Earths vol 28 p 125 2010

[23] A N Turanov and V K Karandashevb ldquoAdsorption oflanthanides(III) from aqueous solutions by fullerene blackmodified with di(2-ethylhexyl)phosphoric acidrdquo CentralEuropean Journal of Chemistry vol 7 no 1 p 54 2009

[24] E Farahmand ldquoAdsorption of cerium (IV) from aqueoussolutions using activated carbon developed from rice strawrdquoOpen Journal of Geology vol 6 no 3 pp 189ndash200 2016

[25] N Kabay and H Egawa ldquoChelating polymers for recovery ofuranium from Seawaterrdquo Separation Science and Technologyvol 29 no 1 pp 135ndash150 1994

[26] K A K Ebraheem and S T Hamdi ldquoSynthesis and propertiesof a copper selective chelating resin containing a salicy-laldoxime grouprdquo Reactive and Functional Polymers vol 34no 1 pp 5ndash10 1997

[27] K A K Ebraheem S T Hamdi and J A Al-DuhanldquoSynthesis and properties of a chelating resin containinga salicylaldimine grouprdquo Journal of Macromolecular SciencePart A vol 34 no 9 pp 1691ndash1699 1997

[28] F Vernon ldquoSome aspects of ion exchange in copper hy-drometallurgyrdquo Hydrometallurgy vol 4 no 2 pp 147ndash1571979

[29] A I Ismail K A K Ebraheem M S Mubarak andF I Khalili ldquoChelation properties of some mannich-typepolymers toward lanthanum(III) neodymium(III) samar-ium(III) and gadolinium(III)rdquo Solvent Extraction and IonExchange vol 21 no 1 pp 125ndash137 2003

[30] F Alakhras N Ouerfelli G M Al-Mazaideh T S Ababnehand F M Abouzeid ldquoOptimal pseudo-average order kineticmodel for correlating the removal of nickel ions by adsorptionon nanobentoniterdquo Arabian Journal for Science and Engi-neering 2018

[31] F Alakhras E Al-Abbad N O Alzamel F M Abouzeid andN Ouerfelli ldquoContribution to modelling the effect of tem-perature on removal of nickel ions by adsorption on nano-bentoniterdquo Asian Journal of Chemistry vol 30 no 5pp 1147ndash1156 2018

[32] A Maleki E Pajootan and B J Hayati ldquoEthyl acrylate graftedchitosan for heavy metal removal from wastewater equilib-rium kinetic and thermodynamic studiesrdquo Journal of theTaiwan Institute of Chemical Engineers vol 51 pp 127ndash1342015

[33] Y K Agrawal and H L Kapoor ldquoStability constants of rareearths with hydroxamic acidsrdquo Journal of Inorganic andNuclear Chemistry vol 39 no 3 pp 479ndash482 1977

[34] F Al-Rimawi A Ahmad F I Khalili and M S MubarakldquoChelation properties of some phenolic-formaldehyde poly-mers toward some trivalent lanthanide ionsrdquo Solvent Ex-traction and Ion Exchange vol 22 no 4 pp 721ndash735 2004

[35] K A K Ebraheem M S Mubarak Z J Yassien andF Khalili ldquoChelation properties of poly(8ndashhydroxyquinoline57ndashdiylmethylene) crosslinked with bisphenolndasha towardlanthanum(III) cerium(III) neodimium(III) samarium(III)and gadolinium(III) ionsrdquo Separation Science and Technologyvol 35 no 13 pp 2115ndash2125 2000


[36] C Noureddine A Lekhmici and M S Mubarak ldquoSorptionproperties of the iminodiacetate ion exchange resin amberliteIRC-718 toward divalent metal ionsrdquo Journal of AppliedPolymer Science vol 107 no 2 pp 1316ndash1319 2008

[37] Y S Ho and G McKay ldquoPseudo-second order model forsorption processesrdquo Process Biochemistry vol 34 no 5pp 451ndash465 1999

[38] R R Sheha and A A El-Zahhar ldquoSynthesis of some ferro-magnetic composite resins and their metal removal charac-teristics in aqueous solutionsrdquo Journal of HazardousMaterials vol 150 no 3 pp 795ndash803 2008

[39] N T Abdel-Ghani G A El-Chaghaby and E M ZahranldquoPentachlorophenol (PCP) adsorption from aqueous solutionby activated carbons prepared from corn wastesrdquo In-ternational Journal of Environmental Science and Technologyvol 12 no 1 pp 211ndash222 2015


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need large storage facilities for the precipitated sludge andsometimes require additional treatment options Ion ex-change which is expensive and sophisticated would allowmetallic ions recovery Additionally these methods are notamenable to large-scale treatment of contaminated groundwater or drinking water Purification of water contaminatedwith lanthanides requires the ability to selectively remove thelanthanides in the presence of other ions like Ca and Mg [16])erefore it may be of value to design a chemically selectivesorbent material (amidoxime-hydroxamic acid as in thisstudy) capable of selectively sequestering the lanthanides fromwaste streams ground water and drinking water without theneed for any additional solvents or treatment processesAdsorption process which is used in this study is highlyeconomical and capable of removing contaminants even attrace level )e use of this technique in water and wastewatertreatment due to its simplicity and low cost of operation andits wide end-use is highly utilized [17ndash19]

Nevertheless the performance of any adsorption processis exceedingly reliant on the selection of suitable mediumFor the extraction of lanthanides from aqueous systemsdifferent prospective sorbents are studied by several researchgroups [20ndash24] It is confirmed that the sorption of lan-thanides can be affected by the variation of mediumrsquos aciditycontact period temperature and sorbent amount Addi-tionally polymers with certain chelating ligands have beenused to remove valuable ionic species found in liquid sys-tems )ese chelating polymers have attractive propertiesincluding powerful capability great selectivity and quickremoval rates of ionic species with high physical potency andstability [25ndash28]

In connection with our previous work [17] poly(amidoxime-hydroxamic) acid resins were used for thesorption of various lanthanide ions (La3+ Nd3+ Sm3+ Gd3+and Tb3+) from liquid systems )e impacts of pH exposuretime counter ion and cross-linker were investigated )eresults showed that 6 hours of agitation was sufficient toaccomplish utmost metal-ion removal with maximum atpH 7 )e data also specified that the percentage removaldeclined as the quantity of cross-linker enhanced

To understand the influence of exposure time and thekinetics of adsorption of lanthanide ions by amidoxime-hydroxamic acid polymers more investigation were done andpresented in this article Pseudo-first-order and pseudo-second-order kinetics were utilized for data analysis Furthermore theintraparticle diffusion model which is developed to inspect themechanism of sorption for a solid-liquid removal process wasapplied as well

2 Materials and Methods

21 Materials Unless otherwise stated all chemical mate-rials were attained from trade sources and were utilized asobtained Acrylonitrile 224-trimethyl pentane and gela-tine were acquired from BDH Chemicals Ltd (PooleEngland) Benzoyl peroxide and ethylacrylate were boughtfrom Fluka (Buchs Switzerland) Hydroxylamine hydro-chloride was purchased from Aldrich (Milwaukee WI) )efollowing lanthanide salts were also used as received with no

more refinement LaCl3middot6H2O NdCl3middot6H2O SmCl3middot6H2Oand GdCl3middot6H2O from Aldrich and TbCl3middot6H2O from KampKLaboratories Inc (Jamaica NY)

22 Preparation and Characterization of Adsorbent MaterialAmidoxime-hydroxamic acid polymer was synthesized andcharacterized depending on a process reported by Alakhraset al [17] )e polymer (Scheme 1) was prepared throughaddition of acrylonitrile and ethylacrylate by suspensionpolymerization Afterwards hydroxylamine hydrochloridewas added to convert the obtained copolymer into poly(amidoxime-hydroxamic) acid resin A detailed analysis ofIR spectra decomposition point and water regain param-eters of the obtained chelating material was reported in ourprevious work [17]

23 Sorption Kinetics of Lanthanide Ions A batch equilib-rium process was employed to investigate the removal ki-netics for eachmetal ion (La3+ Nd3+ Sm3+ Gd3+ and Tb3+)Perfectly weighted dosage of adsorbent (010 g) was con-stantly shaken at 400 rpm with 15mL of acetic acidacetatesolution with pH 70 for two hours to reach equilibriumAfter that 100mL of metal-ion solution with 150mgmiddotLminus1was added and the mixture was shaken for a definite periodof time )e agitation time was changed from 025 to 24 hAt the end the contents of the flasks were determinedfor residual adsorbates by Complexometric titration withstandard ethylene diamine tetra-acetic acid (EDTA) aque-ous solution using xylenol orange as the indicator [29])e flasks were shaken with a GFL-1083 thermostatedshaker kept at 25degC

)e quantity of metal ions removed at equilibrium Qe(mgmiddotgminus1) was evaluated [30] according tothe followingequation

Qe C0 minusCe( 1113857V

W (1)

where C0 represents the initial metal amount (mgmiddotLminus1) andCe is the final concentration after 24 h )e volume of so-lution (L) is represented by V and W symbolizes the amountof dry sorbent (g) )e removal amount of metal ionschelated at several intervals [31] was computed by means ofthe following equation

Qt C0 minusCt( 1113857V

W (2)

where Ct is the metal ion concentration (mgmiddotLminus1) in solutionat different period t

3 Results and Discussion

31 Sorption Kinetics )e removal rate of trivalent lan-thanides (Ln3+) depending on the contact time was studiedby a batch equilibrium method In this procedure 35ndash60mesh size trials of the dry adsorbent was equilibrated fortwo hours with acetate solution (pH 70) Figure 1 dem-onstrates a representative reliance of lanthanides removal onexposure period )e percentage removal increased with time






Hydroxamategroup

Amidoximegroup

C

N

H2N

O

C O

HN OLn3+Ln3+


H2C CH CH2 CHC CN

H2N

OHNHOH

O

n


400

450

500

550

600

650

700

0 500 1000 1500 2000

re

mov

al


Gd (III)Tb (III)

t (min)


20

30

40

50

60

70

3 4 5 6 7 8

re

mov

al

pH


Gd (III)Tb (III)














2


0

100

t (Q

t)

200

300

400

0 200 400 600 800


Gd (III)Tb (III)

t (min)


224

228

232

236

24

244

0 5 10 15 20 25 30


t12 (min12)

Qt (

mgmiddot

gndash1)







4 Conclusions


Data Availability




References







sorption


La3+ 00047 16228 09195Nd3+ 00056 17380 09536Sm3+ 00098 20938 09836Gd3+ 00102 21326 09603Tb3+ 00134 22314 09265

0016

0012

0010

0008

0006

0004

90 92 94 96 98 100 102 104 106

0014

r (A0)

k id (m

gmiddotgndash1

middotmin

12 )

(a)

0016

0012

0010

0008

0006

0004

0014


k id (m

gmiddotgndash1

middotmin

12 )

(b)












































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

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ls








Hydroxamategroup

Amidoximegroup

C

N

H2N

O

C O

HN OLn3+Ln3+


H2C CH CH2 CHC CN

H2N

OHNHOH

O

n


400

450

500

550

600

650

700

0 500 1000 1500 2000

re

mov

al


Gd (III)Tb (III)

t (min)


20

30

40

50

60

70

3 4 5 6 7 8

re

mov

al

pH


Gd (III)Tb (III)














2


0

100

t (Q

t)

200

300

400

0 200 400 600 800


Gd (III)Tb (III)

t (min)


224

228

232

236

24

244

0 5 10 15 20 25 30


t12 (min12)

Qt (

mgmiddot

gndash1)







4 Conclusions


Data Availability




References







sorption


La3+ 00047 16228 09195Nd3+ 00056 17380 09536Sm3+ 00098 20938 09836Gd3+ 00102 21326 09603Tb3+ 00134 22314 09265

0016

0012

0010

0008

0006

0004

90 92 94 96 98 100 102 104 106

0014

r (A0)

k id (m

gmiddotgndash1

middotmin

12 )

(a)

0016

0012

0010

0008

0006

0004

0014


k id (m

gmiddotgndash1

middotmin

12 )

(b)












































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls















2


0

100

t (Q

t)

200

300

400

0 200 400 600 800


Gd (III)Tb (III)

t (min)


224

228

232

236

24

244

0 5 10 15 20 25 30


t12 (min12)

Qt (

mgmiddot

gndash1)







4 Conclusions


Data Availability




References







sorption


La3+ 00047 16228 09195Nd3+ 00056 17380 09536Sm3+ 00098 20938 09836Gd3+ 00102 21326 09603Tb3+ 00134 22314 09265

0016

0012

0010

0008

0006

0004

90 92 94 96 98 100 102 104 106

0014

r (A0)

k id (m

gmiddotgndash1

middotmin

12 )

(a)

0016

0012

0010

0008

0006

0004

0014


k id (m

gmiddotgndash1

middotmin

12 )

(b)












































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








4 Conclusions


Data Availability




References







sorption


La3+ 00047 16228 09195Nd3+ 00056 17380 09536Sm3+ 00098 20938 09836Gd3+ 00102 21326 09603Tb3+ 00134 22314 09265

0016

0012

0010

0008

0006

0004

90 92 94 96 98 100 102 104 106

0014

r (A0)

k id (m

gmiddotgndash1

middotmin

12 )

(a)

0016

0012

0010

0008

0006

0004

0014


k id (m

gmiddotgndash1

middotmin

12 )

(b)












































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls













































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls














Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls









Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




Documents

KineticStudiesontheRemovalofSomeLanthanideIonsfrom ...acetic acid/acetate solution at pH 7.0 is still preserved and accepted under this condition in order to accomplish the highest