research article mechanosynthesis of mfe 2 4 (m = co, ni...

Research ArticleMechanosynthesis of MFe2O4 (M = Co Ni and Zn) MagneticNanoparticles for Pb Removal from Aqueous Solution

America R Vazquez-Olmos1 Mohamed Abatal2 Roberto Y Sato-Berru1

G K Pedraza-Basulto2 Valentin Garcia-Vazquez3 Arianee Sainz-Vidal1

R Perez-Bantildeuelos4 and A Quiroz2

1Centro de Ciencias Aplicadas y Desarrollo Tecnologico UNAM Circuito Exterior SN Ciudad UniversitariaAP 70-186 Delegacion Coyoacan CP 04510 Ciudad de Mexico Mexico2Facultad de Ingenierıa UNACAR CP 24180 Ciudad del Carmen CAM Mexico3Instituto de Fısica Luis Rivera Terrazas BUAP Apartado Postal J-48 72570 Puebla PUE Mexico4Facultad de Ciencias de la Electronica BUAP 18 Sur y Av San Claudio Edif 109 72570 Puebla PUE Mexico

Correspondence should be addressed to Mohamed Abatal mabatalpampanounacarmx

Received 30 August 2016 Accepted 12 October 2016

Academic Editor Kimberly Hamad-Schifferli

Copyright copy 2016 America R Vazquez-Olmos 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

Adsorption of Pb(II) from aqueous solution using MFe2O4 nanoferrites (M = Co Ni and Zn) was studied Nanoferrite sampleswere prepared via the mechanochemical method and were characterized by X-ray powder diffraction (XRD) Fourier transforminfrared spectroscopy (FTIR) micro-Raman and vibrating sample magnetometry (VSM) XRD analysis confirms the formationof pure single phases of cubic ferrites with average crystallite sizes of 238 194 and 192 nm for CoFe2O4 NiFe2O4 and ZnFe2O4respectively Only NiFe2O4 and ZnFe2O4 samples show superparamagnetic behavior at room temperature whereas CoFe2O4 isferromagnetic Kinetics and isotherm adsorption studies for adsorption of Pb(II) were carried out A pseudo-second-order kineticdescribes the sorption behavior The experimental data of the isotherms were well fitted to the Langmuir isotherm model Themaximum adsorption capacity of Pb(II) on the nanoferrites was found to be 2058 1776 and 934mgsdotgminus1 for M = Co Ni and Znrespectively

1 Introduction

Spinel ferrites play an important role in technological appli-cations Their interesting electrical magnetic and dielectricproperties make them useful in many applications suchas electronic devices sensors memory devices data stor-age and telecommunications [1ndash9] Recently the possibilityof preparing ferrites in the form of nanoparticles (NPs)has opened a new and exciting research field with rev-olutionary applications not only in electronic technologybut also in the fields of biotechnology [10] and watertreatment [11] due to their nanometer size superparam-agnetic properties and a high surface-to-volume ratio [1213] In recent years NPs have been applied for removingheavy metals and organic pollutants from aqueous solutions[14ndash18]

Particularly the environmental release of lead (Pb) can bemainly attributed to industrial wastewater containing lead-acid battery residues It is known to cause problems likenausea convulsions cancer and coma among others uponlong-term drinking [19] TheWorld Health Organization hasset an upper limit of 005mgL for lead in drinking waterFortunately lead can be directly recovered from waste andtherefore there is a demand of innovative and economicalmethods that can reduce contamination and regenerate Pb[20]

It is well known that the properties of ferrite materialsstrongly depend on the synthesis method Different proce-dures for ferrite synthesis are described in the literatureincluding coprecipitation low-temperature combustion syn-thesis sol-gel mechanical alloying mechanical activationand solid-state synthesis [1 21ndash28] The mechanochemical

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2016 Article ID 9182024 9 pageshttpdxdoiorg10115520169182024

2 Journal of Nanomaterials

synthesis can deliver the desired phases and structuresin a single step with high-energy milling conducted inan enclosed activation chamber at room temperature [2930] Usually the complete formation of spinel ferrites wasobtained only after milling followed by sintering that isby employing two processing steps It has been shown thatthe combined mechanochemical-thermal treatment yieldsa well ordered spinel phase in ferrites at lower annealingtemperatures and shorter durations than those required inconventional ceramic methods [31ndash33]

The soft mechanochemical method has a great poten-tial for the synthesis of inorganic precursors because ofits versatility and simple operational requirements Softmechanochemical reactions usually employ surface hydroxylgroups adsorbed hydrated or contained in a hydroxideMechanochemical derived precursors exhibit significantlyhigher reactivity and thus lower the calcination and sinteringtemperature [34]

In this article we investigated the effectiveness ofCoFe2O4 NiFe2O4 and ZnFe2O4 ferrite nanoparticlesobtained by soft mechanochemical treatment for removinglead from aqueous solution

2 Materials and Methods

21 Materials Ferric chloride hexahydrate FeCl3sdot6H2O(98) nickel chloride hydrate NiCl2sdotH2O (9995)cobalt(II) chloride hexahydrate CoCl2sdot6H2O (98) zinc(II)chloride ZnCl2(99999) potassium hydroxide lead(II)chloride PbCl2 (9999) KOH (9999) and acetoneCO(CH3)2 (995) were obtained from Sigma-Aldrich Allchemicals were used without further purification Ultrapurewater (18MΩcm) was obtained from a Barnsted E-Puredeionization system

22 Synthesis of Spinel Ferrite Nanoparticles 2 times 10minus3 moles(05406 g) of FeCl3sdot6H2O and 1 times 10minus3 moles of MCl2(whereM(II) = Co (02379 g) Ni (01296 g) and Zn (01362 g)) werefirst milled in an agate mortar for ten minutes Thereafter8 times 10minus3 moles (04489 g) of previously grinded KOH wereadded The mixture was milled for approximately thirtyminutes until no change was observedThe obtained powderswere washed four times with distilled water and two timeswith acetone In each case the product was separated bycentrifugation (3000 rpm for 10min) Finally the sampleswere air-dried and then calcined at 800∘C for two hours Thechemical reaction carried out is described as

2FeCl3 +MCl2 + 8KOHMilling997888997888997888997888997888997888997888997888rarr800∘C2 hrs

MFe2O4 + 8KCl

+ 4H2O(1)

where M(II) = Co Ni and Zn

23 Adsorption Study on ZnFe2O4 NiFe2O4 and CoFe2O4 Fer-rite Samples

231 Kinetics Studies Batch mode experiments were per-formed to determine the kinetics removal of Pb(II) by either

ZnFe2O4 NiFe2O4 or CoFe2O4 Sorption experiments forthe kinetic study were conducted as follows 001 g of eachferrite sample was added to a separate 10mL of 100mgLPbCl2 solution at pH = 20 The three mixtures were placedin centrifuge tubes and shaken in a rotary shaker for 5 1530 60 120 and 180min After each specific contact timethe tubes were centrifuged at 3500 rpm for 5min to providethe separation between solid and liquidThe concentration oflead metal was determined using a flame atomic absorptionspectrometer (AAS Thermo Scientific iCE 3000 Series) Inorder to ensure the truthfulness of the results of the productsall experiments were duplicated

Adsorption efficiency capacity 119902119905 (mgg) at specifiedcontact time 119905 (min) was calculated using the followingexpression

119902119905 (119905) =(119862119900 minus 119862119905) 119881

119898 (2)

where1198620 (mgL) is the initialmetal concentration in solution119862119905 (mgL) is the metal concentration in solution at time 119905 119881is the volume of the aqueous phase (L) and119898 (g) is the massof the adsorbent

In this study the experimental kinetic data were analyzedby applying the pseudo-first-order and pseudo-second-orderkinetic models in order to describe the mechanism involvedin the sorption processThe pseudo-first-order kinetic modelassumes that the controlling step in the adsorption process ismass transfer which means that the variation of adsorptionrate with time is directly proportional to the differencebetween the equilibrium concentration of the heavy metalin solution and the concentration of the adsorbate on theadsorbent surface The first-order rate equation is generallyexpressed as

119889119902119905119889119905= 1198961 (119902119890 minus 119902119905) (3)

where 119902119905 (mgg) and 119902119890 (mgg) represent the amount ofPb(II) adsorbed on the adsorbent at time 119905 and at equilibriumtime respectively and 1198961 (minminus1) is the rate constant for thepseudo-first-order adsorption After integrating and applyingboundary conditions the pseudo-first-order equation inlinear form is expressed by

ln (119902119890 minus 119902119905) = ln (119902119890) minus 1198961119905 (4)

Constants 1198961 and 119902119890 are calculated from the intercept andslope by plotting ln(119902119890 minus 119902119905) versus 119905 The pseudo-second-order model assumes that the rate limiting step may bethe chemical sorption involving valence forces by means ofsharing or exchange of electrons between heavy metal ionsand adsorbent

Thepseudo-second-order kinetic equation is expressed as

119889119902119905119889119905= 1198962 (119902119890 minus 119902119905)

2 (5)

where 119902119890 (mgg) and 119902119905 (mgg) represent again the amountof Pb(II) adsorbed on the adsorbent at equilibrium timeand at time 119905 respectively and 1198962 (gsdotmgminus1sdotminminus1) is the

Journal of Nanomaterials 3

pseudo-second-order rate constant By integrating equation(5) and applying boundary conditions the pseudo-second-order equation in linear form is given by

119905

119902119905=1

11989621199021198902+1

119902119890119905 (6)

where parameters 119902119890 and 1198962 are determined from the slop andintercept of the plotting of 119905119902119905 against 119905

232 Isotherms Studies For isotherms studies 001 g ofeither ZnFe2O4 NiFe2O4 or CoFe2O4 ferrite samples wasmixed with 10mL of aqueous solution at pH = 2 for differentconcentrations of Pb(II) (10 40 80 and 100mgL)Then themixtures were shaken for 180min in a rotary shaker at roomtemperature This pH value was chosen in order to avoidmetal precipitation and also because of the high yield shownat this value The supernatants were centrifuged at 4500 rpmfor 5min and decanted The concentration of lead metals inthe supernatant was analyzed by AAS

Langmuir and Freundlich isotherm models are com-monly used by various researchers to describe the equilib-rium of heavy metal ions between solid and solution phases[35] This allows determining whether the sorption is of amonolayer or multilayer nature which can be specificallyuseful to predict the type of adsorption mechanism involvedThe Langmuir isotherm model considers that the bindingsites are homogeneously distributed on the adsorbent surfaceand the adsorption takes place at specific homogeneous siteswithin the adsorbent The Langmuir equation is expressed as

119902119890 =1199021198981198701198711198621198901 + 119870119871119862119890

(7)

where 119902119890 is the amount adsorbed at equilibrium (mgg) 119862119890is the equilibrium concentration (mgL) 119870119871 is the Langmuirconstant related to the affinity of binding site (Lmg) and119902119898 is the maximum amount of solute adsorbed (mgg) Theconstants in the Langmuir isotherm can be obtained fromthe slope and intercept by plotting (1119902119890) versus (1119862119890) andmaking use of the above equation rewritten as

1

119902119890=1

119902119898+1

119902119898119870119871sdot1

119862119890 (8)

On the other hand the Freundlich isotherm is commonlyused to describe the adsorption on the heterogeneous surfaceThe mathematical expression for the Freundlich isotherm isgiven as

119902119890 = 1198701198651198621198901119899 (9)

where 119870119865 (mgg)(Lg)1n and 119899 are the equilibrium Fre-undlich constant indicative of the adsorption capacity andthe adsorption intensity respectively [36] When 119899 gt 1the adsorption process is considered favorable In contrastfor 119899 lt 1 the bond between the active sites and metal isweaker and therefore the sorption nature corresponds tophysisorption or ion exchangeThe linear form of Freundlichisotherm is given by

ln 119902119890 = ln 119902119870119865 +1

119899ln119862119890 (10)

Constants119870119865 and 119899 are obtained from the slope and interceptof the plot of ln(119902119890) versus ln(119862119890)

24 Characterization Techniques The structure and phaseidentification of CoFe2O4 NiFe2O4 and ZnFe2O4 ferritesamples were done by X-ray diffraction For this purposean APD 2000 PRO X-ray diffractometer was used XRDpatterns of the materials were obtained using CuK120572 radiation(120582 = 15418 A) at 35 kV and 25mA and a variation of 2120579= 10∘ to 70∘ with a scanning speed of 0025 degs and astep time of 10 s The Fourier transformed infrared (FTIR)technique was conducted using a Nicolet Nexus 670 FTIRinfrared spectrometer within a range from 4000 to 400 cmminus1with a resolution of 4 cmminus1 in a KBr wafer Micro-Ramanspectra were recorded with an Almega XR dispersive Ramanspectrometer An Olympus microscope 50 and 085NA(numerical aperture) was used for focusing the laser on solidsamples Raman spectra were accumulated over 25 s witha resolution of 4 cmminus1 The excitation source was 532 nmradiation fromaNdYVO4 laser (frequency-doubled) and thelaser power on the sample was 5mW Magnetic propertieswere examined using a Quantum Design PPMS DynaCool-9Systemwith a vibrating samplemagnetometer (VSM) optionIsothermal magnetization (119872) versus applied magnetic field(119867) measurements were performed at 300 and 10K usingfields up to plusmn80 kOe Saturation magnetization 119872119904 valueswere calculated through the interception of 119872 versus 1119867curve with the vertical axis

3 Results and Discussion

31 Characterization of ZnFe2O4 NiFe2O4 and CoFe2O4Ferrite Samples Figure 1 shows the X-ray diffraction spectraof ZnFe2O4 NiFe2O4 and CoFe2O4 Analysis of each XRDpattern using the MATCH program [37] showed the forma-tion of ferrite phases (JCPDS card 89-7412) with the mainreflections 2120579 at 3015∘ 3532∘ 4318∘ 5349∘ and 5715∘ Thecorresponding peaks are well indexed to the crystal planes ofspinel ferrite (hkl) (220) (311) (400) and (511) respectively[38 39] A slight shift in the XRD peak position of ZnFe2O4NiFe2O4 and CoFe2O4 is observed and is attributed to thedifference in the ion radius of Zn Ni and Co From Scherrerequation and taking into account the (311) diffraction peakscrystallite sizes of 238 194 and 192 nm were estimated forCoFe2O4 NiFe2O4 and ZnFe2O4 respectively

The IR spectra of ferrite NPs show two characteristicvibrational modes The higher wave number 1205921 band isreported to occur between 550 cmminus1 and 600 cmminus1 and iscaused by the stretching vibrations of the metal-oxygen (M-O) bond in the tetrahedral sites The lower wave numberrange is reported to appear between 365 cmminus1 and 425 cmminus1and is attributed to theM-Obond vibrations in the octahedralsites The different band positions for the tetrahedral andoctahedral complexes are due to the different values of theFe(M)-O bond lengths in their respective sites [22] In oursamples 1205921 and 1205922 frequencies were observed at 589 cm

minus1 forCoFe2O4 596 cm

minus1 and 404 cmminus1 for NiFe2O4 and 564 cmminus1

and 428 cmminus1 for ZnFe2O4 (Figure 2) The replacement of


500

1000

1500

2000

2500

3000

3500

4000

4500

(511

)

(422

)(400

)

(311

)

(220

)

Inte

nsity

(au

)

NiFe2O4ZnFe2O4

CoFe2O4

30 35 40 45 50 55

2Θ

Figure 1 XRD patterns of ZnFe2O4 NiFe2O4 and CoFe2O4

1200 1100 1000 900 800 700 600 500 400

10

20

30

40

50

60

70

tr

ansm

ittan

ce

589

596404

564428

Wavenumber (cmminus1)

NiFe2O4ZnFe2O4CoFe2O4

Figure 2 IR spectra of ZnFe2O4 NiFe2O4 and CoFe2O4 nanopar-ticles

Co2+ by Ni2+ or Zn2+ has effects on Fe3+-O2minus bond Ingeneral a decrease in wave number and force constantis expected in accordance with the ionic radius increaseCoFe2O4 and NiFe2O4 are inverse spinels with tetrahedralsites completely filled with Fe3+ and octahedral sites occupiedin equal molar amounts by the remaining Fe3+ and Ni2+ orCo2+ cationsThis inversion occurs because nickel and cobalthave a higher preference for the octahedral sites than the oneiron has Similarly ZnFe2O4 is a normal spinel because Zn2+tends to adopt tetrahedral sites

Figure 3 shows the room-temperature Raman spectraof CoFe2O4 NiFe2O4 and ZnFe2O4 NPs from 100 cmminus1 up

300 400 500 600 700 800

Ram

an in

tens

ity

NiFe2O4ZnFe2O4

CoFe2O4


A1g

F2g(2)

F2g(3)

Eg

F2g(1)

Figure 3 Raman spectra of ZnFe2O4 NiFe2O4 and CoFe2O4nanoparticles

to 800 cmminus1 Raman spectra of cubic ferrites exhibit fivecharacteristic bands (A1g + Eg + 3F2g) around 267 335 483571 and 697 cmminus1 for CoFe2O4 and NiFe2O4 NPs The A1gmode is due to symmetric stretching of oxygen atoms alongFe-O (or M-O) tetrahedral bonds Eg and F2g(3) are due tosymmetric and asymmetric bending of oxygenwith respect toFe (or M) respectively and F2g(2) is assigned to asymmetricstretching of Fe(M)-O bond whereas F2g(1) is attributableto translational movement of the whole tetrahedron [34]In the Raman spectra of ZnFe2O4 NPs however the bandsappear less well defined and those corresponding to F2g(2)are not observed In addition a red shift of the Raman peakis observed because of the optical phonon confinement inthese nanoparticlesThis behavior has been observed in othermetallic oxides when the grain size decreases

The magnetization (119872) versus magnetic field (119867) curvesare shown in Figures 4 and 5 NiFe2O4 (Figure 4(a)) andZnFe2O4 (Figure 4(b)) NPs do not exhibit hysteresis at 300Kindicating that both ferrites NPs are superparamagnetic atroom temperatureMagnetization levels at 300Kmeasured atthe highest magnetic field 80 kOe (not shown) are 3331 and2587 emug for NiFe2O4 and ZnFe2O4 respectively whereasthe saturation magnetization 119872119904 values calculated by theinterception of119872 versus 1119867 curve are 42 plusmn 002 and 39 plusmn001 emug for NiFe2O4 and ZnFe2O4 respectively Thesevalues are smaller than the corresponding bulk counterparts[40 41] At 10 K the two samples show a ferromagneticbehavior with coercivity of 713 plusmn 38 and 913 plusmn 39Oe forNiFe2O4 and ZnFe2O4 respectively At 10 K 119872119904 values forNi-ferrite and Zn-ferrite samples are 4916 plusmn 002 and 791 plusmn01 emug respectively

On the other hand CoFe2O4 NPs show a ferromagneticbehavior with coercivity enhancement at lower temperaturesAt 10 K Co-ferrite nanoparticles exhibit a coercive field


minus20

minus30

minus10

0

20

10

30

NiFe2O4M(e

mu

g)

T = 10KT = 300K

minus10 minus5 0 5 10

Magnetic field (kOe)

(a)

ZnFe2O4

T = 10KT = 300K



minus20

minus30

minus10

0

20

10

30

M(e

mu

g)

(b)

Figure 4 Magnetization versus applied magnetic field at 10 and 300K for (a) NiFe2O4 and (b) ZnFe2O4 nanoparticles

minus80

minus40

0

40

80

M(e

mu

g)

CoFe2O4

Magnetic field (kOe)minus80 minus40 0 40 80

T = 10K(a)

minus80

minus40

0

40

80M

(em

ug)

CoFe2O4


T = 300K(b)

Figure 5 Isothermal magnetization curves of CoFe2O4 nanoparticles measured at (a) 10 K and (b) 300K

strength H119888 of 16819 plusmn 185Oe (Figure 5(a)) which is muchhigher than the coercivity found in Ni-ferrite and Zn-ferriteNPs at the same temperature (Figure 4) These results areexpected because of the high anisotropy in Co-ferrite Theincorporation of the Co cation in the Fe-O matrix increasesthe magnetic anisotropy whereas the incorporation of theNi or Zn cations reduces it [42] Saturation magnetization119872119904 of CoFe2O4 at 10 K is 8034 plusmn 002 emug which is veryclose to that found in ZnFe2O4 (791plusmn01 emug) at the sametemperature Figure 5(b) shows the magnetization versusfield curve of CoFe2O4 measured at 300K The saturationmagnetization is 683 plusmn 002 emugThe magnetization curve

of CoFe2O4 at room temperature exhibits hysteresis withcoercivity of 556plusmn5Oe Coercivity enhancement in CoFe2O4has been observed by other authors [37 43 44]

32 Kinetic Study The removal of Pb(II) for ZnFe2O4NiFe2O4 and CoFe2O4 nanoparticles was examined at dif-ferent time intervals and the results are shown in Figure 6(a)As can be seen in this figure the adsorption capacity of Pbions with 119862119894 = 100mgLminus1 increases rapidly with increasingagitation time up to 30 minutes and then it increases veryslowly and becomes nearly constant after 60 minutes Theinitial rapid adsorption of Pb(II) can be attributed to the


Table 1 Parameters of the pseudo-second-order kinetic model for ZnFe2O4 NiFe2O4 and CoFe2O4

Adsorbent type Pseudo-second-order model1198962 (gmgminus1sdotminminus1) 119902119890Cal (mgsdotgminus1) 119902119890exp (mgsdotgminus1) 1198772

CoFe2O4 0095 797 788 0999NiFe2O4 0139 1183 1202 0999ZnFe2O4 0389 1522 1514 0999

0

2

4

6

8

10

12

14

16

q (m

gg)

NiFe2O4ZnFe2O4

CoFe2O4

Time (min)0 20 40 60 80 100 120 140 160 180

(a)

0

5

10

15

20

Time (min)

NiFe2O4ZnFe2O4

CoFe2O4

0 20 40 60 80 100 120 140 160 180

tqt

(minmiddotgmiddotm

gminus1)

(b)

Figure 6 (a) Effect of contact time on the Pb(II) absorption by nanoferrites (b) Pseudo-second-order sorption kinetics of Pb(II) sorptionby MFe2O4 ferrite

presence of a large number of vacant sites and as a result toan enhancement in the concentration gradient that is createdbetween the adsorbate in the solution and the adsorbatein the adsorbent surface After 60min of contact time thisgradient is reduced due to the accumulation of Pb(II) on thevacant sites causing a decrease in the adsorption gradientThe experimental data were fitted to the pseudo-first-orderand pseudo-second-order models (Figure 6(b)) 119902119890calc valuesof the calculated equilibrium sorption capacity in the case ofthe second-order model are very close to experimental 119902119890expvalues In addition based on the values of the correlationcoefficient which is above 099 the second-order kineticmodel was suitable to describe the adsorption process forPb(II) adsorption (Table 1) It can be noted that the pseudo-second-order rate constant for ZnFe2O4 is higher than theother ferrites This result can be attributed to the rapidredox reaction occurred between Pb species and the externaladsorbent surface [45]

33 Isotherms Figure 7 illustrates the plot of equilibriumconcentrations of Pb(II) ions in the solid (ZnFe2O4 NiFe2O4and CoFe2O4) and aqueous phases The experimental datawere fitted to the linear forms of the Langmuir andFreundlichisotherms The values of the correlation coefficients (1198772) of

the Langmuir isotherm model fit are above 099 indicatinga good fit with the experimental data The values of theisotherm constants are presented in Table 2 This confirmsthat the sorption occurred in the monolayer This modelassumes that a monolayer adsorption depends on the activesites of the adsorbent surface and there is no interactionbetween adsorbed species Therefore it can be concludedthat the metal adsorption on the nanoparticles is possibly aphysical adsorption process

4 Conclusions

In summary we investigated the effectiveness of CoFe2O4NiFe2O4 and ZnFe2O4 ferrite nanoparticles for removinglead from aqueous solution MFe2O4 (M = Co Ni andZn) nanoparticles were successfully synthesized using amechanochemical method The formation of single-phasenanosized powders was confirmed by XRD analysis as well asIR and Raman spectroscopy Magnetic measurements showthat only NiFe2O4 and ZnFe2O4 samples exhibit superpara-magnetic behavior at room temperature whereas CoFe2O4is ferromagnetic The nanoparticles were effectively used toremove lead ions from aqueous solution ZnFe2O4being themost efficient followed by NiFe2O4 and CoFe2O4 Samples


3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)

1Ce (Lmiddotmgminus1)000 002 004 006 008 010 012 014

(b)

Figure 7 (a) Pb(II) adsorption isotherm on MFe2O4 ferrite (b) Langmuir adsorption isotherm plot

Table 2 Parameters obtained from the Langmuir model thatdescribes the sorption of Pb2+ for ZnFe2O4 NiFe2O4 and CoFe2O4

Adsorbent type Langmuir Isotherm model119870119871 (dm

3sdotmgminus1) 119902119898 (mgsdotgminus1) 1198772

CoFe2O4 0064 934 099NiFe2O4 0061 1776 099ZnFe2O4 0061 2058 099

that present superparamagnetism at room temperature seemto have a better Pb(II) adsorption

Competing Interests

The authors declare that they have no competing interests

Acknowledgments

The authors acknowledge the financial support provided byCONACyT (Grants nos CB-169133 230530 and 128460)SEP and VIEP-BUAP

References

[1] R Valenzuela ldquoNovel applications of ferritesrdquo Physics ResearchInternational vol 2012 Article ID 591839 9 pages 2012

[2] P S Antonel C L P Oliveira G A Jorge O E Perez AG Leyva and R M Negri ldquoSynthesis and characterizationof CoFe2O4 magnetic nanotubes nanorods and nanowiresFormation ofmagnetic structured elastomers bymagnetic field-induced alignment of CoFe2O4 nanorodsrdquo Journal of Nanopar-ticle Research vol 17 article 294 2015

[3] A Singh A Singh S Singh P Tandon B C Yadav and RR Yadav ldquoSynthesis characterization and performance of zincferrite nanorods for room temperature sensing applicationsrdquoJournal of Alloys and Compounds vol 618 pp 475ndash483 2015

[4] S Singh P Srivastava and G Singh ldquoNanorods nanospheresnanocubes synthesis characterization and catalytic activity ofnanoferrites ofMnCoNi Part-89rdquoMaterials Research Bulletinvol 48 no 2 pp 739ndash746 2013

[5] E R Kumar P S P Reddy G S Devi and S Sathiyaraj ldquoStruc-tural dielectric and gas sensing behavior of Mn substitutedspinel MFe2O4 (M= Zn Cu Ni and Co) ferrite nanoparticlesrdquoJournal of Magnetism and Magnetic Materials vol 398 pp 281ndash288 2016

[6] S Joshi V B Kamble M Kumar A M Umarji and GSrivastava ldquoNickel substitution induced effects on gas sensingproperties of cobalt ferrite nanoparticlesrdquo Journal of Alloys andCompounds vol 654 pp 460ndash466 2016

[7] A A Bagade and K Y Rajpure ldquoDevelopment of CoFe2O4thin films for nitrogen dioxide sensing at moderate operatingtemperaturerdquo Journal of Alloys and Compounds vol 657 pp414ndash421 2016

[8] A Shan X Wu J Lu C Chen and R Wang ldquoPhase forma-tions and magnetic properties of single crystal nickel ferrite(NiFe2O4) with different morphologiesrdquo CrystEngComm vol17 no 7 pp 1603ndash1608 2015

[9] G H Jaffari A K Rumaiz J C Woicik and S I ShahldquoInfluence of oxygen vacancies on the electronic structure andmagnetic properties of NiFe2O4 thin filmsrdquo Journal of AppliedPhysics vol 111 no 9 Article ID 093906 2012

[10] W S Galvao D M A Neto R M Freire and P B A FechineldquoSuper-paramagnetic nanoparticles with spinel structure areview of synthesis and biomedical applicationsrdquo Solid StatePhenomena vol 241 pp 139ndash176 2016


[11] X Piao G M Zeng D L Huang et al ldquoUse of iron oxidenanomaterials in wastewater treatment a reviewrdquo Science of theTotal Environment vol 424 pp 1ndash10 2012

[12] D H K Reddy and Y S Yun ldquoSpinel ferrite magneticadsorbents alternative future materials for water purificationrdquoCoordination Chemistry Reviews vol 315 pp 90ndash111 2016

[13] A K Gupta and M Gupta ldquoSynthesis and surface engineeringof iron oxide nanoparticles for biomedical applicationsrdquoBioma-terials vol 26 no 18 pp 3995ndash4021 2005

[14] Y C Sharma V Srivastava V K Singh S N Kaul and C HWeng ldquoNano-adsorbents for the removal of metallic pollutantsfrom water and wastewaterrdquo Environmental Technology vol 30no 6 pp 583ndash609 2009

[15] S Chowdhury and R Balasubramanian ldquoRecent advances inthe use of graphene-family nanoadsorbents for removal of toxicpollutants from wastewaterrdquo Advances in Colloid and InterfaceScience vol 204 pp 35ndash56 2014

[16] M Hua S Zhang B Pan W Zhang L Lv and Q ZhangldquoHeavy metal removal from waterwastewater by nanosizedmetal oxides a reviewrdquo Journal of HazardousMaterials vol 211-212 pp 317ndash331 2012

[17] X Hou J Feng X Liu et al ldquoSynthesis of 3D porous ferromag-neticNiFe2O4 and using as novel adsorbent to treat wastewaterrdquoJournal of Colloid and Interface Science vol 362 no 2 pp 477ndash485 2011

[18] N Sezgin M Sahin A Yalcin and Y Koseoglu ldquoSynthesischaracterization and the heavy metal removal efficiency ofMFe2O4 (M=Ni Cu) nanoparticlesrdquo Ekoloji vol 22 no 89 pp89ndash96 2013

[19] F Fu and Q Wang ldquoRemoval of heavy metal ions fromwastewaters a reviewrdquo Journal of Environmental Managementvol 92 no 3 pp 407ndash418 2011

[20] D Mehtaa S Mazumdarb and S K Singha ldquoMagnetic adsor-bents for the treatment of waterwastewatermdasha reviewrdquo Journalof Water Process Engineering vol 7 pp 244ndash265 2015

[21] P Sivakumar R Ramesh A Ramanand S Ponnusamy and CMuthamizhchelvan ldquoSynthesis and characterization ofNiFe2O4nanoparticles and nanorodsrdquo Journal of Alloys and Compoundsvol 563 pp 6ndash11 2013

[22] M G Naseri E B Saion and A Kamali ldquoAn overview onnanocrystallineZnFe2O4 MnFe2O4 and CoFe2O4 synthesizedby a thermal treatment methodrdquo ISRN Nanotechnology vol2012 Article ID 604241 11 pages 2012

[23] J Fu J Zhang Y Peng et al ldquoUnique magnetic propertiesand magnetization reversal process of CoFe2O4 nanotubesfabricated by electrospinningrdquo Nanoscale vol 4 no 13 pp3932ndash3936 2012

[24] B Aslibeiki P Kameli M H Ehsani et al ldquoSynthesis ofMnFe2O4 nanoparticles The role of polymer coating on mor-phology and magnetic propertiesrdquo Journal of Magnetism andMagnetic Materials vol 399 pp 236ndash244 2016

[25] A A Bagade V V Ganbavle andK Y Rajpure ldquoPhysicochemi-cal properties of spray-depositedCoFe2O4 thin filmsrdquo Journal ofMaterials Engineering and Performance vol 23 no 8 pp 2787ndash2794 2014

[26] A Sutka J Zavickis G Mezinskis D Jakovlevs and J BarlotildquoEthanol monitoring by ZnFe2O4 thin film obtained by spraypyrolysisrdquo Sensors and Actuators B Chemical vol 176 pp 330ndash334 2013

[27] M M Rahman S B Khan M Faisal A M Asiri and K AAlamry ldquoHighly sensitive formaldehyde chemical sensor basedon hydrothermally prepared spinel ZnFe2O4 nanorodsrdquo Sensorsand Actuators B Chemical vol 171-172 pp 932ndash937 2012

[28] J-L Li Z Yu K Sun X-N Jiang and Z-W Lan ldquoStructuraland magnetic properties of ZnFe2O4 films deposited by lowsputtering powerrdquo International Journal of Minerals Metallurgyand Materials vol 19 no 10 pp 964ndash968 2012

[29] E AvvakumovM Senna andNKosova SoftMechanochemicalSynthesis A Basis for New Chemical Technologies KluwerAcademic Publishers Boston Mass USA 2001

[30] Z Z Lazarevic C Jovalekic D Sekulic et al ldquoCharacter-ization of nanostructured spinel NiFe2O4 obtained by softmechanochemical synthesisrdquo Science of Sintering vol 44 no 3pp 331ndash339 2012

[31] V Sepelak I Bergmann A Feldhoff et al ldquoNanocrystallinenickel ferrite NiFe2O4 mechanosynthesis nonequilibriumcation distribution canted spin arrangement and magneticbehaviorrdquo The Journal of Physical Chemistry C vol 111 no 13pp 5026ndash5033 2007

[32] V Sepelak M Menzel K D Becker and F KrumeichldquoMechanochemical reduction of magnesium ferriterdquo Journal ofPhysical Chemistry B vol 106 no 26 pp 6672ndash6678 2002

[33] V Sepelak A Feldhoff P Heitjans et al ldquoNonequilibriumcation distribution canted spin arrangement and enhancedmagnetization in nanosized MgFe2O4 prepared by a one-stepmechanochemical routerdquo Chemistry of Materials vol 18 no 13pp 3057ndash3067 2006

[34] Z Z Lazarevic C Jovalekic A Milutinovic et al ldquoStudyof NiFe2O4 and ZnFe2O4 spinel ferrites prepared by softmechanochemical synthesisrdquo Ferroelectrics vol 448 no 1 pp1ndash11 2013

[35] W S W Ngah S Ab Ghani and A Kamari ldquoAdsorptionbehaviour of Fe(II) and Fe(III) ions in aqueous solution on chi-tosan and cross-linked chitosan beadsrdquo Bioresource Technologyvol 96 no 4 pp 443ndash450 2005

[36] S Rengaraj K-H Yeon and S-H Moon ldquoRemoval ofchromium from water and wastewater by ion exchange resinsrdquoJournal of Hazardous Materials vol 87 no 1ndash3 pp 273ndash2872001

[37] httpwwwcrystalimpactcommatch[38] M Gunay H Erdemi A Baykal H Sozeri and M S Toprak

ldquoTriethylene glycol stabilizedMnFe2O4 nanoparticle Synthesismagnetic and electrical characterizationrdquo Materials ResearchBulletin vol 48 no 3 pp 1057ndash1064 2013

[39] Y Koseoglu F Alan M Tan R Yilgin and M Ozturk ldquoLowtemperature hydrothermal synthesis and characterization ofMn doped cobalt ferrite nanoparticlesrdquo Ceramics Internationalvol 38 no 5 pp 3625ndash3634 2012

[40] V A M Brabers ldquoProgress in spinel ferrite researchrdquo inHandbook of Magnetic Materials K H J Buschow Ed vol 8chapter 3 pp 189ndash324 Elsevier New York NY USA 1995

[41] A Goldman Modern Ferrites Technology Springer New YorkNY USA 2nd edition 2006

[42] S Sun H Zeng D B Robinson et al ldquoMonodisperse MFe2O4(M = Fe Co Mn) nanoparticlesrdquo Journal of American ChemicalSociety vol 126 no 1 pp 273ndash279 2004

[43] WWang Z Ding X Zhao et al ldquoMicrostructure andmagneticproperties ofMFe2O4 (M=CoNi andMn) ferrite nanocrystals


prepared using colloid mill and hydrothermal methodrdquo Journalof Applied Physics vol 117 Article ID 17A328 4 pages 2015

[44] D Gherca N Cornei O Mentre H Kabbour S Daviero-Minaud and A Pui ldquoIn situ surface treatment of nanocrys-talline MFe2O4 (M = Co Mg Mn Ni) spinel ferrites usinglinseed oilrdquo Applied Surface Science vol 287 pp 490ndash498 2013

[45] J Hu I M C Lo and G Chen ldquoComparative study of variousmagnetic nanoparticles for Cr(VI) removalrdquo Separation andPurification Technology vol 56 no 3 pp 249ndash256 2007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


synthesis can deliver the desired phases and structuresin a single step with high-energy milling conducted inan enclosed activation chamber at room temperature [2930] Usually the complete formation of spinel ferrites wasobtained only after milling followed by sintering that isby employing two processing steps It has been shown thatthe combined mechanochemical-thermal treatment yieldsa well ordered spinel phase in ferrites at lower annealingtemperatures and shorter durations than those required inconventional ceramic methods [31ndash33]

The soft mechanochemical method has a great poten-tial for the synthesis of inorganic precursors because ofits versatility and simple operational requirements Softmechanochemical reactions usually employ surface hydroxylgroups adsorbed hydrated or contained in a hydroxideMechanochemical derived precursors exhibit significantlyhigher reactivity and thus lower the calcination and sinteringtemperature [34]

In this article we investigated the effectiveness ofCoFe2O4 NiFe2O4 and ZnFe2O4 ferrite nanoparticlesobtained by soft mechanochemical treatment for removinglead from aqueous solution

2 Materials and Methods

21 Materials Ferric chloride hexahydrate FeCl3sdot6H2O(98) nickel chloride hydrate NiCl2sdotH2O (9995)cobalt(II) chloride hexahydrate CoCl2sdot6H2O (98) zinc(II)chloride ZnCl2(99999) potassium hydroxide lead(II)chloride PbCl2 (9999) KOH (9999) and acetoneCO(CH3)2 (995) were obtained from Sigma-Aldrich Allchemicals were used without further purification Ultrapurewater (18MΩcm) was obtained from a Barnsted E-Puredeionization system

22 Synthesis of Spinel Ferrite Nanoparticles 2 times 10minus3 moles(05406 g) of FeCl3sdot6H2O and 1 times 10minus3 moles of MCl2(whereM(II) = Co (02379 g) Ni (01296 g) and Zn (01362 g)) werefirst milled in an agate mortar for ten minutes Thereafter8 times 10minus3 moles (04489 g) of previously grinded KOH wereadded The mixture was milled for approximately thirtyminutes until no change was observedThe obtained powderswere washed four times with distilled water and two timeswith acetone In each case the product was separated bycentrifugation (3000 rpm for 10min) Finally the sampleswere air-dried and then calcined at 800∘C for two hours Thechemical reaction carried out is described as

2FeCl3 +MCl2 + 8KOHMilling997888997888997888997888997888997888997888997888rarr800∘C2 hrs

MFe2O4 + 8KCl

+ 4H2O(1)

where M(II) = Co Ni and Zn

23 Adsorption Study on ZnFe2O4 NiFe2O4 and CoFe2O4 Fer-rite Samples

231 Kinetics Studies Batch mode experiments were per-formed to determine the kinetics removal of Pb(II) by either

ZnFe2O4 NiFe2O4 or CoFe2O4 Sorption experiments forthe kinetic study were conducted as follows 001 g of eachferrite sample was added to a separate 10mL of 100mgLPbCl2 solution at pH = 20 The three mixtures were placedin centrifuge tubes and shaken in a rotary shaker for 5 1530 60 120 and 180min After each specific contact timethe tubes were centrifuged at 3500 rpm for 5min to providethe separation between solid and liquidThe concentration oflead metal was determined using a flame atomic absorptionspectrometer (AAS Thermo Scientific iCE 3000 Series) Inorder to ensure the truthfulness of the results of the productsall experiments were duplicated

Adsorption efficiency capacity 119902119905 (mgg) at specifiedcontact time 119905 (min) was calculated using the followingexpression

119902119905 (119905) =(119862119900 minus 119862119905) 119881

119898 (2)

where1198620 (mgL) is the initialmetal concentration in solution119862119905 (mgL) is the metal concentration in solution at time 119905 119881is the volume of the aqueous phase (L) and119898 (g) is the massof the adsorbent

In this study the experimental kinetic data were analyzedby applying the pseudo-first-order and pseudo-second-orderkinetic models in order to describe the mechanism involvedin the sorption processThe pseudo-first-order kinetic modelassumes that the controlling step in the adsorption process ismass transfer which means that the variation of adsorptionrate with time is directly proportional to the differencebetween the equilibrium concentration of the heavy metalin solution and the concentration of the adsorbate on theadsorbent surface The first-order rate equation is generallyexpressed as

119889119902119905119889119905= 1198961 (119902119890 minus 119902119905) (3)

where 119902119905 (mgg) and 119902119890 (mgg) represent the amount ofPb(II) adsorbed on the adsorbent at time 119905 and at equilibriumtime respectively and 1198961 (minminus1) is the rate constant for thepseudo-first-order adsorption After integrating and applyingboundary conditions the pseudo-first-order equation inlinear form is expressed by

ln (119902119890 minus 119902119905) = ln (119902119890) minus 1198961119905 (4)

Constants 1198961 and 119902119890 are calculated from the intercept andslope by plotting ln(119902119890 minus 119902119905) versus 119905 The pseudo-second-order model assumes that the rate limiting step may bethe chemical sorption involving valence forces by means ofsharing or exchange of electrons between heavy metal ionsand adsorbent

Thepseudo-second-order kinetic equation is expressed as

119889119902119905119889119905= 1198962 (119902119890 minus 119902119905)

2 (5)

where 119902119890 (mgg) and 119902119905 (mgg) represent again the amountof Pb(II) adsorbed on the adsorbent at equilibrium timeand at time 119905 respectively and 1198962 (gsdotmgminus1sdotminminus1) is the



119905

119902119905=1

11989621199021198902+1

119902119890119905 (6)




119902119890 =1199021198981198701198711198621198901 + 119870119871119862119890

(7)


1

119902119890=1

119902119898+1

119902119898119870119871sdot1

119862119890 (8)


119902119890 = 1198701198651198621198901119899 (9)


ln 119902119890 = ln 119902119870119865 +1

119899ln119862119890 (10)










500

1000

1500

2000

2500

3000

3500

4000

4500

(511

)

(422

)(400

)

(311

)

(220

)

Inte

nsity

(au

)

NiFe2O4ZnFe2O4

CoFe2O4

30 35 40 45 50 55

2Θ


1200 1100 1000 900 800 700 600 500 400

10

20

30

40

50

60

70

tr

ansm

ittan

ce

589

596404

564428






300 400 500 600 700 800

Ram

an in

tens

ity

NiFe2O4ZnFe2O4

CoFe2O4


A1g

F2g(2)

F2g(3)

Eg

F2g(1)






minus20

minus30

minus10

0

20

10

30

NiFe2O4M(e

mu

g)

T = 10KT = 300K



(a)

ZnFe2O4

T = 10KT = 300K



minus20

minus30

minus10

0

20

10

30

M(e

mu

g)

(b)


minus80

minus40

0

40

80

M(e

mu

g)

CoFe2O4


T = 10K(a)

minus80

minus40

0

40

80M

(em

ug)

CoFe2O4


T = 300K(b)









0

2

4

6

8

10

12

14

16

q (m

gg)

NiFe2O4ZnFe2O4

CoFe2O4

Time (min)0 20 40 60 80 100 120 140 160 180

(a)

0

5

10

15

20

Time (min)

NiFe2O4ZnFe2O4

CoFe2O4

0 20 40 60 80 100 120 140 160 180

tqt

(minmiddotgmiddotm

gminus1)

(b)





4 Conclusions



3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)


(b)







Competing Interests


Acknowledgments


References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





119905

119902119905=1

11989621199021198902+1

119902119890119905 (6)




119902119890 =1199021198981198701198711198621198901 + 119870119871119862119890

(7)


1

119902119890=1

119902119898+1

119902119898119870119871sdot1

119862119890 (8)


119902119890 = 1198701198651198621198901119899 (9)


ln 119902119890 = ln 119902119870119865 +1

119899ln119862119890 (10)










500

1000

1500

2000

2500

3000

3500

4000

4500

(511

)

(422

)(400

)

(311

)

(220

)

Inte

nsity

(au

)

NiFe2O4ZnFe2O4

CoFe2O4

30 35 40 45 50 55

2Θ


1200 1100 1000 900 800 700 600 500 400

10

20

30

40

50

60

70

tr

ansm

ittan

ce

589

596404

564428






300 400 500 600 700 800

Ram

an in

tens

ity

NiFe2O4ZnFe2O4

CoFe2O4


A1g

F2g(2)

F2g(3)

Eg

F2g(1)






minus20

minus30

minus10

0

20

10

30

NiFe2O4M(e

mu

g)

T = 10KT = 300K



(a)

ZnFe2O4

T = 10KT = 300K



minus20

minus30

minus10

0

20

10

30

M(e

mu

g)

(b)


minus80

minus40

0

40

80

M(e

mu

g)

CoFe2O4


T = 10K(a)

minus80

minus40

0

40

80M

(em

ug)

CoFe2O4


T = 300K(b)









0

2

4

6

8

10

12

14

16

q (m

gg)

NiFe2O4ZnFe2O4

CoFe2O4

Time (min)0 20 40 60 80 100 120 140 160 180

(a)

0

5

10

15

20

Time (min)

NiFe2O4ZnFe2O4

CoFe2O4

0 20 40 60 80 100 120 140 160 180

tqt

(minmiddotgmiddotm

gminus1)

(b)





4 Conclusions



3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)


(b)







Competing Interests


Acknowledgments


References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




500

1000

1500

2000

2500

3000

3500

4000

4500

(511

)

(422

)(400

)

(311

)

(220

)

Inte

nsity

(au

)

NiFe2O4ZnFe2O4

CoFe2O4

30 35 40 45 50 55

2Θ


1200 1100 1000 900 800 700 600 500 400

10

20

30

40

50

60

70

tr

ansm

ittan

ce

589

596404

564428






300 400 500 600 700 800

Ram

an in

tens

ity

NiFe2O4ZnFe2O4

CoFe2O4


A1g

F2g(2)

F2g(3)

Eg

F2g(1)






minus20

minus30

minus10

0

20

10

30

NiFe2O4M(e

mu

g)

T = 10KT = 300K



(a)

ZnFe2O4

T = 10KT = 300K



minus20

minus30

minus10

0

20

10

30

M(e

mu

g)

(b)


minus80

minus40

0

40

80

M(e

mu

g)

CoFe2O4


T = 10K(a)

minus80

minus40

0

40

80M

(em

ug)

CoFe2O4


T = 300K(b)









0

2

4

6

8

10

12

14

16

q (m

gg)

NiFe2O4ZnFe2O4

CoFe2O4

Time (min)0 20 40 60 80 100 120 140 160 180

(a)

0

5

10

15

20

Time (min)

NiFe2O4ZnFe2O4

CoFe2O4

0 20 40 60 80 100 120 140 160 180

tqt

(minmiddotgmiddotm

gminus1)

(b)





4 Conclusions



3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)


(b)







Competing Interests


Acknowledgments


References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




minus20

minus30

minus10

0

20

10

30

NiFe2O4M(e

mu

g)

T = 10KT = 300K



(a)

ZnFe2O4

T = 10KT = 300K



minus20

minus30

minus10

0

20

10

30

M(e

mu

g)

(b)


minus80

minus40

0

40

80

M(e

mu

g)

CoFe2O4


T = 10K(a)

minus80

minus40

0

40

80M

(em

ug)

CoFe2O4


T = 300K(b)









0

2

4

6

8

10

12

14

16

q (m

gg)

NiFe2O4ZnFe2O4

CoFe2O4

Time (min)0 20 40 60 80 100 120 140 160 180

(a)

0

5

10

15

20

Time (min)

NiFe2O4ZnFe2O4

CoFe2O4

0 20 40 60 80 100 120 140 160 180

tqt

(minmiddotgmiddotm

gminus1)

(b)





4 Conclusions



3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)


(b)







Competing Interests


Acknowledgments


References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







0

2

4

6

8

10

12

14

16

q (m

gg)

NiFe2O4ZnFe2O4

CoFe2O4

Time (min)0 20 40 60 80 100 120 140 160 180

(a)

0

5

10

15

20

Time (min)

NiFe2O4ZnFe2O4

CoFe2O4

0 20 40 60 80 100 120 140 160 180

tqt

(minmiddotgmiddotm

gminus1)

(b)





4 Conclusions



3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)


(b)







Competing Interests


Acknowledgments


References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




3456789

10111213141516171819

0 20 40 60 80 100

NiFe2O4ZnFe2O4

CoFe2O4

qe

(mg

g)

Ce (mgL)

(a)

004006008010012014016018020022024026028030032

NiFe2O4ZnFe2O4

CoFe2O4

1qe

(gmiddotm

gminus1)


(b)







Competing Interests


Acknowledgments


References
























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials
















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article mechanosynthesis of mfe 2 4 (m = co, ni...

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