yan, jinhua; yang, huanlei; da silva, juliana c.; rojas

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Yan Jinhua Yang Huanlei da Silva Juliana C Rojas Orlando JLoading of Iron (II III) Oxide Nanoparticles in Cryogels Based on Microfibrillar Cellulose forHeavy Metal Ion Separation

Published inADVANCES IN POLYMER TECHNOLOGY

DOI10115520209261378

Published 03032020

Document VersionPublishers PDF also known as Version of record

Published under the following licenseCC BY

Please cite the original versionYan J Yang H da Silva J C amp Rojas O J (2020) Loading of Iron (II III) Oxide Nanoparticles in CryogelsBased on Microfibrillar Cellulose for Heavy Metal Ion Separation ADVANCES IN POLYMER TECHNOLOGY2020 [9261378] httpsdoiorg10115520209261378

Research ArticleLoading of Iron (II III) Oxide Nanoparticles in Cryogels Based onMicrofibrillar Cellulose for Heavy Metal Ion Separation

Jinhua Yan 1 Huanlei Yang1 Juliana C da Silva2 and Orlando J Rojas 3

1Guangdong Industry Polytechnic Guangzhou 510300 China2Department of Forest Sciences Universidade Federal de Viccedilosa Viccedilosa Brazil3Bio-Based Colloids and Materials Department of Bioproducts and Biosystems Aalto University Vuorimiehentie 1Espoo 02150 Finland

Correspondence should be addressed to Jinhua Yan jhyan2013163com

Received 30 May 2019 Accepted 28 July 2019 Published 3 March 2020

Academic Editor Mingzhi Huang

Copyright copy 2020 Jinhua Yan et al 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

Cryogels based on microfibrillar cellulose (MFC) and reinforced with chitosan to endow water resistance were loaded withmagnetite nanoparticles (MNPs) and characterized by TEM XRD and TGA e MNP-loaded cryogels were tested for heavymetal ion removal from aqueous matrices e adsorption capacity under equilibrium conditions for Cr(VI) Pd(II) Cd(II) andZn(II) was measured to be 2755 2155 3015 and 4100mgg respectively e results indicate the potential of the introducedbicomponent cryogels for nanoparticle loading leading to a remarkably high metal ion sorption capacity

1 Introduction

Magnetic nanoparticles have been a topic of interest in awide range of applications including catalysis [1 2] bio-technologybiomedicine [3] and environmental remedia-tion [4 5] In most of the envisaged applications theparticles perform best when their sizes are below a criticalvalue typically around 10ndash20 nm In such a case thenanoparticles are a single magnetic domain and showsuperparamagnetic behavior at temperatures above the so-called blocking temperature [6]

Among the wide variety of magnetic materials that canbe prepared in the form of nanoparticles iron oxides havebeen considered the most intensive one while being safe Inaddition iron oxide (magnetite) nanoparticles can be easilyprepared through coprecipitation of iron salts in alkalineaqueous solutions in the presence of stabilizers [7] Suchcoprecipitation is also a convenient way to synthesize ironoxides (either Fe3O4 or c-Fe2O3) from aqueous Fe2+Fe3+

salt solutions by the addition of a base under the inert at-mosphere at room or elevated temperatures Using properstabilizing agents with carboxylate or hydroxyl carboxylategroups it is possible to produce monodispersed iron oxide

magnetic nanoparticles Moreover surface complexesreadily form between Fe2+Fe3+ and the stabilizing agentundergoing nucleation and crystal growth favoring theformation of small units and preventing aggregation

Micronanofibrillar cellulose (MFC) is isolated fromnatural cellulose fibers by mechanical action after optionalenzymatic or chemical pretreatment MFCrsquos high aspectratio biocompatibility and abundant active hydroxyl andcarboxyl groups make it attractive for applications as a hostfor particles [8 9] such as silica [10] silver [11] magnetic[12] and drug [13] nanoparticlese respective preparationcan be carried out in the slurry form which implies a rel-atively large usage of water to remove loosely bound reac-tants and particles Moreover since associated reactionsoccur in the system with typical high surface areas largereactant amounts are consumed

An alternative typical MFC reparation MFC cryogel hasproven particularly useful in applications where biocom-patibility and biodegradability are needed e cryogels areporous materials of interconnected nanostructures madefrom precursor hydrogels after replacing the liquid by thegas phase [14] e unique properties associated with cry-ogels have led to a wide range of applications such as in

HindawiAdvances in Polymer TechnologyVolume 2020 Article ID 9261378 8 pageshttpsdoiorg10115520209261378

catalysts [15] and as a reaction support [16] as super thermaland sound insulators [17 19] and as electronics filters andstorage media for example gases in fuel cells [20] Fornanoparticle stabilization and size control MFC porousmaterials are very effective as hosts [21 22] In the reductionreaction of metal ions the small pores have been used as sitesfor nucleation and growth thus restricting the particle sizeMoreover the resultant hybrid materials have some ad-vantages if given functionalities of the matrix are transferredto the nanoparticles [14] Here we proposeMFC cryogels fordirect use as templates for the preparation of magneticnanoparticles

We firstly report a facile method to prepare magneticnanoparticles and their loading in MFC cryogels followed bya demonstration of their application e wet strength of thecryogels was improved with the addition of chitosan andmagnetic nanoparticles were successfully synthesized insuch a bicomponent system e hybrid cryogels wereshown to be effective in heavy metal ion separation in-cluding Cr(VI) Pb(II) Cd(II) and Zn(II)

2 Experimental

21MFC Preparation Fully bleached eucalyptus fibers wereprocessed with a microgrinder (x6 passes) at a concentrationof 23 producing an MFC suspension which was keptunder refrigeration until further use e acidic groupcontent of MFC was measured by conductive titration using001M NaOH which was added dropwise until the con-ductivity of the system displayed no further drop eamount of NaOH consumed was used to calculate the acidicgroup content [23] calculated to be 70 μmolg

22 Chitosan and MFC Cryogel Synthesis Chitosan (MW10253) was purchased from Aldrich (degree of deacetylationsim85) Chitosan solutions were prepared by dissolvingchitosan (2 by weight) in 1 (by volume) aqueous aceticacid solution [24] e solution was sonicated for 30minbefore use e MFC suspension was mixed with chitosan atdifferent weight loading ratios 1000 9010 and 8020(MFCchitosan) as a 05 suspension in DI water High-shear mixing (5min) was used for this purpose followed bymagnetic bar stirring (3 h) and sonication for another30min en the mixture was centrifuged (10times104 rpm05 h) to remove excess water A hydrogel with 3 solidcontent was thus formed and was frozen with liquid ni-trogen Following this it was placed in a freeze-dryer(Labconco) for at least 48 h After water sublimation theobtained cryogel was characterized (density strength andBET surface area) e wet strength was determined qual-itatively by immersion and stirring in water for a given timee BETarea of the MFC cryogels was measured before andafter MNP loading after 4 h degassing at 105degC (Gemini VIISeries Surface Area Analyzer Micromeritics InstrumentCorporation)

221 Nanoparticle Loading e in situ loading of magneticnanoparticles (MNPs) in the cryogels was carried out

through the coprecipitation of iron salts of ferrous chloride(Fe2+ 005M) and ferric chloride (Fe3+ 01M) by addingalkaline aqueous solution (02N NaOH) at 60degC Firstly theiron solution was prepared by mixing a given volume of005M Fe2+ and 01M Fe3+ solutionse cryogel was loadedwith the iron solution dropwise and left undisturbed for30min e iron solution was saturated in the porouscryogel After air-drying (sim1 h) a partially dehydratedmatrix was obtained It was then immersed in 02N NaOHsolution at 60degC for 1 h so that the coprecipitation wascompleted as indicated by no changes in color e hybridmaterial was rinsed with Milli-Q water for 1 h to removewater-soluble substances and loosely bound iron particlesFinally the hybridmaterial was frozen in liquid nitrogen andfreeze-dried e obtained magnetic MFC cryogel isthereafter referred to as the MMFC cryogel

23 Cryogel Morphology e porous structures of the MFCcryogels were examined using a field-emission scanningelectron microscope (FESEM) at an accelerating voltage of20 kV (a JEOL 6400F high-resolution cold field-emissionSEM) e MMFC was characterized using a VPSEM(variable-pressure scanning electron microscope (HitachiS3200N)) with an energy dispersive X-ray spectrometer

A JEOL 2000FX transmission electron microscope(TEM) operating at 200 kV was further utilized for MMFCcharacterization For this purpose a specimen was preparedby cutting the sample into thin slices using a diamond sawthen cutting 3mm diameter disks from the slice thinningthe disk on a grinding wheel dimpling the thinned disk andthen ion milling it to achieve electron transparency

24 0ermal Behavior In order to determine the thermaldecomposition temperature of the hybrid cryogels a ther-mogravimetric analysis (TGA) apparatus was used (Perki-nElmer TGA Q500) operating with a heating rate of 10degCmin to 500degC in a nitrogen atmosphere In order to obtainthe MNP loading in the cryogel TGA was performed underoxygen in the T range between 500 and 575degC e iso-thermal time at 575degC was 25min

25 X-Ray Diffraction MMFC samples were subjected toXRD analysis following 2 theta signals at both small andwide angles to identify iron crystallites For this purpose aPANalytical Empyrean X-ray diffractometer was used escan range was in 5ndash40 for small angles and 10ndash80 for wideangles

26 HeavyMetal Ion Separation A stock solution of Cr(VI)(100mgL) was prepared by dissolving a certain amount ofK2Cr2O7 (from Sigma-Aldrich) in 100mL water obtainedfrom a Milliporetrade purification unit A series of standardmetal solutions were prepared by diluting the stock metalsolution A typical adsorption experiment was conducted asfollows 5mg cryogel was added to a 100mL Erlenmeyerflask containing 25mL 100mgL Cr(VI) solution andmagnetically stirred at 120 rpm for the predetermined time

2 Advances in Polymer Technology

epH of the working solution wasmaintained at a specifiedvalue using 001M NaOH and HCl solutions (both fromSigma-Aldrich) e concentrations of Cr(VI) during ad-sorption tests were analyzed by spectrophotometry (Agilent8453 UV-Vis dissolution testing system Agilent USA)Pb(II) Cd(II) and Zn(II) solutions were prepared followingsimilar protocols using Cd(NO3)2 Pb(NO3)2 andZn(NO3)2middot6H2O (Sigma-Aldrich) e uptake capacity ofMFC cryogel adsorption Qe(mgg) was defined according tothe following equation

Qe C0 minus Ce( 1113857lowastVm (1)

where C0 is the metal ion concentration in the initial so-lution Ce is the equilibrium concentration (mgL) V is thevolume of metal ion solution (L) and m is the mass of theabsorbent material (g)

3 Results and Discussion

31 Physical Properties ofMMFCCryogels e density of theneat MFC cryogel was 00258 00505 and 00807 gcm3depending on the concentration of the hydrogel precursor of2 5 and 8 respectively e MFC density was 00390 and00395 gcm3 upon chitosan loadings of 10 and 20 re-spectively indicating the densification of the system in thepresence of the cationic polymer e MFC and MMFCsurface area was measured after 4 h degassing at 105degC(Table 1)

e MFC cryogel with 10 CH loading displayed ahigher BET area than that with 20 CH ie chitosan actedas a binder for MFC In the absence of chitosan the MFCcryogels were redispersed in water after immersion undermagnetic stirring at 610 rpm for 4 h e cryogels loadedwith 10 and 20 chitosan remained intact after immer-sion under the same conditions (Figure 1) indicating thereinforcing effect of chitosan

32 MFC andMMFCMorphology e presence of chitosanproduced a denser MFC structure (Figure 2) In the absenceof chitosan the cryogel structure was open with pores beingeasily observed (Figure 2(a)) At low chitosan addition(Figure 2(b)) thin ldquowallsrdquo formed between the pores Withthe increasing chitosan content to 20 (Figure 2(c)) thethickness of such walls increased is is because of thecharacteristic properties of chitosan and its primary aminogroups Besides hydrogen bonding the reaction betweenamino and carboxyl groups took place is reaction hasbeen applied in several cellulosechitosan hybrid prepara-tions [25ndash27] Such chitosan-reinforced MFC cryogels werestable in water

After MNP loading the MMFC cryogels exhibited asimilar SEM morphology to that before loading A densercryogel was relatively tighter and less capillaries werepresent which reduced fluid penetration resulting in thegeneration of lower amounts of MNPs e MNP loading inthe MMFC cryogels as determined by TGA at 575degC in theoxygen atmosphere following 25min isothermal timecorresponded to 16 and 18 for MFC cryogels the chitosan

concentration was 10 and 20 (note that an MFC filmsample and filter paper yielded 28 and 18 respectively)

MMFC samples were subjected to SEM at high mag-nification (Figure 3) Iron particles were observed on thesurface of the fibrils is was also observed for two othertypes of cellulose substrates after the same coprecipitationmethod namely a filter paper and MFC films (see Figure 4)ese two substrates showed scattered monodispersedmetal particles but low loadings (Table 2) MFC cryogelscomprised abundant open pores and large BETsurface areaoffering a good opportunity as a template for iron nano-particle loading

Based on the homogeneous particle distribution ob-served in the SEM images in Figure 3 the MFC cryogel with20 CH was selected for particle observation under TEM(Figure 4) Both the filter paper and MFC film samplesloaded with particles were also observed as a referenceFrom the TEM images the particles were determined to bemonodispersed and their size was in the nanoscale MMFCretained more iron than both the paper and MFC films theiron particles in such a case were larger and clustered

33 XRD Analysis An X-ray diffractometer was used tocharacterize the microstructural and crystallographic fea-tures of the iron particles inMMFC (see the XRD pattern at asmall angle in Figure 5(a)) MMFC displayed an intensesignal at 2θ 3528deg corresponding to pure Fe3O4 crystals(Fe3O4 is identified at 35deg) confirming their presence Wide-angle scanning showed similar results to that at small angles(Figure 5(b)) e observed broadness and lower intensity ofthe profiles indicate a lower degree of crystallinity of Fe3O4particles imbedded in the cellulose matrix

34 0ermal Gravimetric Analysis In view of the impor-tance of thermal stability in many MMFC applications weexamined the thermal decomposition of the MMFC cryogelsby thermogravimetry in the nitrogen atmosphere until 500degC(Figure 6) All TGA curves showed small weight losses below150degC from evaporation of the adsorbed moisture Undernitrogen the decomposition behavior ofMFCwas nearly thesame at different chitosan loadings e TGA for MMFCindicated a decomposition temperature from 264 to 318degCMNPs weakened the substrate thermal stability e iso-thermal run (25min at 575degC) was used to determine theresidual mass (MNP amount) in MMFC (TGA under ox-ygen was run in the 500ndash575degC range Table 2)

35 Heavy Metal Ion Separation MFC cryogels were ex-pected to result in partial degradation in acidic solutions atlong contact time and high temperature If the pH of theadsorption solution is lowered the metal ion separation ismaximized e metal adsorption experiments were con-ducted under the near-neutral condition at pH 6 Differentcontact time and initial concentrations were tested for fourmetal ions Cr(VI) Pb(II) Cd(II) and Zn(II) Figure 7 showsthe removal rate as a function of the contact time and initialion concentration

Advances in Polymer Technology 3

In Figure 7(a) the four ion types showed a similar trendDuring the first 20min contact time the removal ratereached a maximum adsorption At longer contact times theremoval rate remained the same e MMFC could quickly

absorb the metal ions Cr(VI) Pb(II) Cd(II) and Zn(II)presented different removal extent (Figures 7 and 8) Cd(II)and Zn(II) adsorbed more readily than Cr(VI) and Pb(II)e most effective separation corresponded to Cd(II) for a

Table 1 BET data for MMFC

Cryogel BET (m2g) CH 10 (iron loaded) CH 20 (iron loaded) CH 10 CH 20 CH 30MFCCH 54 323 244 235 97

(a) (b) (c)

Figure 1 Cryogels produced from MFC and chitosan and their stability in water at loadings of chitosan (CH) of 0 (a) 10 (b) and 20 (c)

200μm

(a)

200μm

(b)

200μm

(c)

Figure 2 SEM images of MFC cryogels loaded with chitosan (CH) of 0 (a) 10 (b) and 20 (c)

Iron particles

(a)

Iron particles

(b)

Figure 3 Iron nanoparticles in MMFC cryogels


removal gt95 (Cr(VI) and Pb(II) showed removal closeto 52)

e initial concentration is an important factor in metalion separation e 50ndash1000mgL concentration range wasadsorbed by MMFC at 60min contact time which is longenough for adsorption e removal is shown inFigure 7(b) MMFC maintained a high adsorption capacityfor all initial concentration with linear profiles except forPd2+ and Cd(II) e Pd2+ removal rate was lowered from57 to 43 and Cd(II) lowered from 95 to 55 eresults indicate that MMFC is a suitable material to removeheavy metal ions from aqueous solution

In order to express MMFC adsorption capacity theequilibrium absorption amount Qe was calculated using

equation (1) Figure 8 shows the results for different initialconcentrations of the respective metal ion Four near linearprofiles are presented and indicate a high capacity for metalion removal e adsorbents were not saturated in solutionCr(VI) Pd2+ Cd(II) and Zn(II) equilibrium removalamounts were 2755 2155 3015 and 4100mgg respectivelye values exceed those reported previously [28ndash34] emaximum adsorption capacity of Cr(VI) by the quaternaryammonium-modified NFC cryogel was 18mgg showing16 removal rate increase compared with nonmodified NFCcryogels [28] An amino-functionalized magnetic cellulosenanocomposite used as a Cr(VI) adsorbent indicated a1715mgg adsorption amount for 50 magnetic particleratio to cellulose at pH 2 which decreased rapidly to 600mgg at pH 6 [29] Ethylenediamine- and methyl methacrylate-modified NFC cryogels achieved 377mgg Cr(VI) adsorp-tion at pH 2 which decreased below 200mgg at pH 6[30]

Using cellulose nanocrystals (CNCs) and Fe2O3 com-posite as a Pd2+ absorbent the maximum capacity wasmeasured to be 36mgg but 33mgg for Fe2O3 CNC [31]

MFCC cryogel

(a)

MFCC cryogel

(b)

Filter paper

(c)

MFCC film

(d)

Figure 4 TEM images of theMMFC cryogel and filter paperMFC filmwithMNPs (note that the filter paper was treated three times for ironcoprecipitation)

Table 2 MNP loading in MFC cryogels (10 and 20 chitosan(CH)) filter paper andMFC films calculated based on residuemass(TGA 575degC) per dry sample mass

CH 10 CH 20 Filter paper MFC film16 182 18 28


400

500

600

700

800

900

1000

5 15 25 35

Inte

nsity

2θ

MFC-MNP cryogel with 20CHMFC-MNP cryogel with 10CH

(a)

150

250

350

450

550

650

10 20 30 40 50 60 70 80

Inte

nsity

2θ


(b)

Figure 5 XRD patterns of MMFC cryogels at small (a) and wide (b) angles

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Wei

ght (

)

Temperature (degC)

MFCCH 9010MFCCH 9010 Fe


Figure 6 TGAprofiles ofMFC cryogels with andwithoutMNP loading (under theN2 atmosphere until 500degC and then under oxygen until 575degC)

0

25

50

75

100

0 25 50 75 100

Met

al io

n re

mov

al (

)

Contact time (min)

Cr6+

Zn2+Cd2+

Pd2+

(a)

Cr6+

Zn2+Cd2+

Pd2+

30

40

50

60

70

80

90

100

50 200 350 500 650 800 950

Met

al io

n re

mov

al (

)

Initial ion concentration (mgL)

(b)

Figure 7 Metal ion removal () as a function of the (a) contact time (initial concentration 100mgL pH 6 room temperature 25mLsolution 5mg MMFC) and (b) initial ion concentration (contact time 60min pH 6 room temperature 25mL solution 5mg MMFC) elines are added as guides to the eye


Aldehyde-functionalized NFC cryogels showed an improvedPb(II) adsorption of 156mgg [32] Chitosan-based mag-netic hydrogel beads reached 171mgg Pd2+ adsorptioncapacity with Fe2O3 and NFC addition but only 118mggwith no addition [33] Yu et al [34] reported that carbox-ylation of CNCwith succinic anhydride resulted in a sorbentwith a very high maximum adsorption uptake for Pb(II)(458mgg) and Cd(II) (335mgg) A Cd(II) adsorption of32mgg was reported for CNC and Fe2O3 composite ad-sorbents [31] Grafting carboxylic groups to chitosan im-proved the Zn(II) removal from 168mgg to 290mgg [35]Amino-functionalized microfibrillated cellulose with themaximum uptake capacity of 388mgg was measured forCd(II) [36] According to the recent review of nanocellulose-based materials for water purification [37] the MFCNFCabsorbent exhibited a high uptake amount as high as that ofMMFC used in this study

4 Conclusions

We successfully utilized chitosan to reinforce MFC pro-ducing relatively dense cryogels MNPs were loaded in situ tothe reinforced MFC cryogels e metal-loaded cryogels(MMFC cryogels) displayed monodispersed nanoparticles(TEM and XRD) MMFC cryogels had a good thermalstability (TGA) MMFC cryogels were tested for heavy metalion separation and separation capacity e Cr(VI) Pd2+Cd(II) and Zn(II) equilibrium removal amount corre-sponded to 2755 2155 3015 and 4100mgg respectivelyese values for MFC cryogels as metal ion separators in-dicate an excellent potential for nanoparticle-loaded ad-sorbents from aqueous solution

Data Availability

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

Conflicts of Interest

e authors declare no conflicts of interest

Acknowledgments

Xijiang Innovation Team Plan 2016 is greatly acknowledgedfor support

References

[1] A-H Lu W Schmidt N Matoussevitch et al ldquoNano-engineering of a magnetically separable hydrogenation cat-alystrdquo Angewandte Chemie International Edition vol 43no 33 pp 4303ndash4306 2004

[2] S C Tsang V r Caps I Paraskevas D Chadwick andD ompsett ldquoMagnetically separable carbon-supportednanocatalysts for the manufacture of fine chemicalsrdquo Ange-wandte Chemie International Edition vol 43 no 42pp 5645ndash5649 2004

[3] A K Gupta andM Gupta ldquoSynthesis and surface engineeringof iron oxide nanoparticles for biomedical applicationsrdquoBiomaterials vol 26 no 18 pp 3995ndash4021 2005

[4] DW Elliott andW-X Zhang ldquoField assessment of nanoscalebimetallic particles for groundwater treatmentrdquo Environ-mental Science amp Technology vol 35 no 24 pp 4922ndash49262001

[5] M Takafuji S Ide H Ihara and Z Xu ldquoPreparation ofpoly(1-vinylimidazole)-grafted magnetic nanoparticles andtheir application for removal of metal ionsrdquo Chemistry ofMaterials vol 16 no 10 pp 1977ndash1983 2004

[6] A-H Lu E L Salabas and F Schuth ldquoMagnetic nano-particles synthesis protection functionalization and appli-cationrdquo Angewandte Chemie International Edition vol 46no 8 pp 1222ndash1244 2007

[7] A Ditsch P E Laibinis D I C Wang and T A HattonldquoControlled clustering and enhanced stability of polymer-coated magnetic nanoparticlesrdquo Langmuir vol 21 no 13pp 6006ndash6018 2005

[8] F Hoeng A Denneulin and J Bras ldquoUse of nanocellulose inprinted electronics a reviewrdquo Nanoscale vol 8 no 27pp 13131ndash13154 2016

[9] H Zhang J Liu M Guan et al ldquoNanofibrillated cellulose(NFC) as a pore size mediator in the preparation of thermallyresistant separators for lithium ion batteriesrdquoACS SustainableChemistry amp Engineering vol 6 no 4 pp 4838ndash4844 2018

[10] X An Y Wen A Almujil et al ldquoNano-fibrillated cellulose(NFC) as versatile carriers of TiO2 nanoparticles (TNPs) forphotocatalytic hydrogen generationrdquo RSC Advances vol 6no 92 pp 89457ndash89466 2016

[11] H Dong J F Snyder D T Tran and J L Leadore ldquoHydrogelaerogel and film of cellulose nanofibrils functionalized withsilver nanoparticlesrdquo Carbohydrate Polymers vol 95 no 2pp 760ndash767 2013

[12] T Nypelo H Pynnonen M Osterberg J Paltakari andJ Laine ldquoInteractions between inorganic nanoparticles andcellulose nanofibrilsrdquo Cellulose vol 19 no 3 pp 779ndash7922012

[13] R Kolakovic L Peltonen A Laukkanen J Hirvonen andT Laaksonen ldquoNanofibrillar cellulose films for controlleddrug deliveryrdquo European Journal of Pharmaceutics and Bio-pharmaceutics vol 82 no 2 pp 308ndash315 2012

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+

Figure 8 Removal amount (mgg) relative to the initial ionconcentration of Cr(VI) Pd(II) Cd(II) and Zn(II)


[14] K J De France T Hoare and E D Cranston ldquoReview ofhydrogels and aerogels containing nanocelluloserdquo Chemistryof Materials vol 29 no 11 pp 4609ndash4631 2017

[15] M Mukhopadhyay and B S Rao ldquoModeling of supercriticaldrying of ethanol-soaked silica aerogels with carbon dioxiderdquoJournal of Chemical Technology amp Biotechnology vol 83 no 8pp 1101ndash1109 2008

[16] J Gu C Hu W Zhang and A B Dichiara ldquoReagentlesspreparation of shape memory cellulose nanofibril aerogelsdecorated with Pd nanoparticles and their application in dyediscolorationrdquo Applied Catalysis B Environmental vol 237pp 482ndash490 2018

[17] C Jimenez-Saelices B Seantier B Cathala and Y GrohensldquoSpray freeze-dried nanofibrillated cellulose aerogels withthermal superinsulating propertiesrdquo Carbohydrate Polymersvol 157 pp 105ndash113 2017

[18] G Zu K Kanamori T Shimizu et al ldquoVersatile double-cross-linking approach to transparent machinable super-compressible highly bendable aerogel thermal super-insulatorsrdquo Chemistry of Materials vol 30 no 8pp 2759ndash2770 2018

[19] R Baetens B P Jelle and A Gustavsen ldquoAerogel insulationfor building applications a state-of-the-art reviewrdquo Energyand Buildings vol 43 no 4 pp 761ndash769 2011

[20] G Nystrom A Marais E Karabulut L Wagberg Y Cui andM M Hamedi ldquoSelf-assembled three-dimensional andcompressible interdigitated thin-film supercapacitors andbatteriesrdquo Nature Communications vol 6 p 7259 2015

[21] J Cai S Kimura M Wada and S Kuga ldquoNanoporouscellulose as metal nanoparticles supportrdquo Biomacromoleculesvol 10 no 1 pp 87ndash94 2009

[22] S Liu Q Yan D Tao T Yu and X Liu ldquoHighly flexiblemagnetic composite aerogels prepared by using cellulosenanofibril networks as templatesrdquo Carbohydrate Polymersvol 89 no 2 pp 551ndash557 2012

[23] SCAN-CM 6502 Pulp Total acidic group content Con-ductometric titration method

[24] C M F Susana L Oliveira C S R Freire et al ldquoNoveltransparent nanocomposite films based on chitosan andbacterial celluloserdquo Green Chemistry vol 11 pp 2023ndash20292009

[25] Z Li L Shao W Hu et al ldquoExcellent reusable chitosancellulose aerogel as an oil and organic solvent absorbentrdquoCarbohydrate Polymers vol 191 pp 183ndash190 2018

[26] H Yang A Sheikhi and T GM van de Ven ldquoReusable greenaerogels from cross-linked hairy nanocrystalline cellulose andmodified chitosan for dye removalrdquo Langmuir vol 32 no 45pp 11771ndash11779 2016

[27] G Meng H Peng J Wu et al ldquoFabrication of super-hydrophobic cellulosechitosan composite aerogel for oilwater separationrdquo Fibers and Polymers vol 18 no 4pp 706ndash712 2017

[28] X He L Cheng Y Wang J Zhao W Zhang and C LuldquoAerogels from quaternary ammonium-functionalized cel-lulose nanofibers for rapid removal of Cr(VI) from waterrdquoCarbohydrate Polymers vol 111 pp 683ndash687 2014

[29] X Sun L Yang Q Li et al ldquoAmino-functionalized magneticcellulose nanocomposite as adsorbent for removal of Cr(VI)synthesis and adsorption studiesrdquo Chemical EngineeringJournal vol 241 pp 175ndash183 2014

[30] J Q Zhao X F Zhang X He M J Xiao W Zhang andC H Lu ldquoA super biosorbent from dendrimer poly(amido-amine)-grafted cellulose nanofibril aerogels for effective

removal of Cr(VI)rdquo Journal of Materials Chemistry Avol 3 no 28 pp 14703ndash14711 2015

[31] H Liu Synthesis and Application of Cellulose Nanocrystalsand Its Nano-Composites Chinese Forestry Institute BeijngChina 2011

[32] C Yao F Wang Z Cai and X Wang ldquoAldehyde-func-tionalized porous nanocellulose for effective removal of heavymetal ions from aqueous solutionsrdquo RSC Advances vol 6no 95 pp 92648ndash92654 2016

[33] Y Zhou S Fu L Zhang H Zhan and M V Levit ldquoUse ofcarboxylated cellulose nanofibrils-filled magnetic chitosanhydrogel beads as adsorbents for Pb(II)rdquo CarbohydratePolymers vol 101 pp 75ndash82 2014

[34] X Yu S Tong M Ge et al ldquoAdsorption of heavy metal ionsfrom aqueous solution by carboxylated cellulose nano-crystalsrdquo Journal of Environmental Sciences vol 25 no 5pp 933ndash943 2013

[35] G Z Kyzas P I Siafaka E G Pavlidou K J Chrissafis andD N Bikiaris ldquoSynthesis and adsorption application ofsuccinyl-grafted chitosan for the simultaneous removal ofzinc and cationic dye from binary hazardous mixturesrdquoChemical Engineering Journal vol 259 pp 438ndash448 2015

[36] S Hokkanen E Repo T Suopajarvi H LiimatainenJ Niinimaa and M Sillanpaa ldquoAdsorption of Ni(II) Cu(II)and Cd(II) from aqueous solutions by amino modifiednanostructured microfibrillated celluloserdquo Cellulose vol 21no 3 pp 1471ndash1487 2014

[37] H Voisin L Bergstrom P Liu and A P Mathew ldquoNano-cellulose-based materials for water purificationrdquo Nano-materials vol 7 p 57 2017


Research ArticleLoading of Iron (II III) Oxide Nanoparticles in Cryogels Based onMicrofibrillar Cellulose for Heavy Metal Ion Separation

Jinhua Yan 1 Huanlei Yang1 Juliana C da Silva2 and Orlando J Rojas 3

1Guangdong Industry Polytechnic Guangzhou 510300 China2Department of Forest Sciences Universidade Federal de Viccedilosa Viccedilosa Brazil3Bio-Based Colloids and Materials Department of Bioproducts and Biosystems Aalto University Vuorimiehentie 1Espoo 02150 Finland

Correspondence should be addressed to Jinhua Yan jhyan2013163com

Received 30 May 2019 Accepted 28 July 2019 Published 3 March 2020

Academic Editor Mingzhi Huang

Copyright copy 2020 Jinhua Yan et al 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

Cryogels based on microfibrillar cellulose (MFC) and reinforced with chitosan to endow water resistance were loaded withmagnetite nanoparticles (MNPs) and characterized by TEM XRD and TGA e MNP-loaded cryogels were tested for heavymetal ion removal from aqueous matrices e adsorption capacity under equilibrium conditions for Cr(VI) Pd(II) Cd(II) andZn(II) was measured to be 2755 2155 3015 and 4100mgg respectively e results indicate the potential of the introducedbicomponent cryogels for nanoparticle loading leading to a remarkably high metal ion sorption capacity

1 Introduction

Magnetic nanoparticles have been a topic of interest in awide range of applications including catalysis [1 2] bio-technologybiomedicine [3] and environmental remedia-tion [4 5] In most of the envisaged applications theparticles perform best when their sizes are below a criticalvalue typically around 10ndash20 nm In such a case thenanoparticles are a single magnetic domain and showsuperparamagnetic behavior at temperatures above the so-called blocking temperature [6]

Among the wide variety of magnetic materials that canbe prepared in the form of nanoparticles iron oxides havebeen considered the most intensive one while being safe Inaddition iron oxide (magnetite) nanoparticles can be easilyprepared through coprecipitation of iron salts in alkalineaqueous solutions in the presence of stabilizers [7] Suchcoprecipitation is also a convenient way to synthesize ironoxides (either Fe3O4 or c-Fe2O3) from aqueous Fe2+Fe3+

salt solutions by the addition of a base under the inert at-mosphere at room or elevated temperatures Using properstabilizing agents with carboxylate or hydroxyl carboxylategroups it is possible to produce monodispersed iron oxide

magnetic nanoparticles Moreover surface complexesreadily form between Fe2+Fe3+ and the stabilizing agentundergoing nucleation and crystal growth favoring theformation of small units and preventing aggregation

Micronanofibrillar cellulose (MFC) is isolated fromnatural cellulose fibers by mechanical action after optionalenzymatic or chemical pretreatment MFCrsquos high aspectratio biocompatibility and abundant active hydroxyl andcarboxyl groups make it attractive for applications as a hostfor particles [8 9] such as silica [10] silver [11] magnetic[12] and drug [13] nanoparticlese respective preparationcan be carried out in the slurry form which implies a rel-atively large usage of water to remove loosely bound reac-tants and particles Moreover since associated reactionsoccur in the system with typical high surface areas largereactant amounts are consumed

An alternative typical MFC reparation MFC cryogel hasproven particularly useful in applications where biocom-patibility and biodegradability are needed e cryogels areporous materials of interconnected nanostructures madefrom precursor hydrogels after replacing the liquid by thegas phase [14] e unique properties associated with cry-ogels have led to a wide range of applications such as in

HindawiAdvances in Polymer TechnologyVolume 2020 Article ID 9261378 8 pageshttpsdoiorg10115520209261378



2 Experimental






























(a) (b) (c)


200μm

(a)

200μm

(b)

200μm

(c)


Iron particles

(a)

Iron particles

(b)








MFCC cryogel

(a)

MFCC cryogel

(b)

Filter paper

(c)

MFCC film

(d)





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Inte

nsity

2θ


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nsity

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0 25 50 75 100

Met

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mov

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Cr6+

Zn2+Cd2+

Pd2+

(a)

Cr6+

Zn2+Cd2+

Pd2+

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4 Conclusions


Data Availability




Acknowledgments


References














0

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0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+































2 Experimental






























(a) (b) (c)


200μm

(a)

200μm

(b)

200μm

(c)


Iron particles

(a)

Iron particles

(b)








MFCC cryogel

(a)

MFCC cryogel

(b)

Filter paper

(c)

MFCC film

(d)





400

500

600

700

800

900

1000

5 15 25 35

Inte

nsity

2θ


(a)

150

250

350

450

550

650

10 20 30 40 50 60 70 80

Inte

nsity

2θ


(b)


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Wei

ght (

)

Temperature (degC)




0

25

50

75

100

0 25 50 75 100

Met

al io

n re

mov

al (

)

Contact time (min)

Cr6+

Zn2+Cd2+

Pd2+

(a)

Cr6+

Zn2+Cd2+

Pd2+

30

40

50

60

70

80

90

100

50 200 350 500 650 800 950

Met

al io

n re

mov

al (

)


(b)




4 Conclusions


Data Availability




Acknowledgments


References














0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+
















































(a) (b) (c)


200μm

(a)

200μm

(b)

200μm

(c)


Iron particles

(a)

Iron particles

(b)








MFCC cryogel

(a)

MFCC cryogel

(b)

Filter paper

(c)

MFCC film

(d)





400

500

600

700

800

900

1000

5 15 25 35

Inte

nsity

2θ


(a)

150

250

350

450

550

650

10 20 30 40 50 60 70 80

Inte

nsity

2θ


(b)


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Wei

ght (

)

Temperature (degC)




0

25

50

75

100

0 25 50 75 100

Met

al io

n re

mov

al (

)

Contact time (min)

Cr6+

Zn2+Cd2+

Pd2+

(a)

Cr6+

Zn2+Cd2+

Pd2+

30

40

50

60

70

80

90

100

50 200 350 500 650 800 950

Met

al io

n re

mov

al (

)


(b)




4 Conclusions


Data Availability




Acknowledgments


References














0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+


































MFCC cryogel

(a)

MFCC cryogel

(b)

Filter paper

(c)

MFCC film

(d)





400

500

600

700

800

900

1000

5 15 25 35

Inte

nsity

2θ


(a)

150

250

350

450

550

650

10 20 30 40 50 60 70 80

Inte

nsity

2θ


(b)


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Wei

ght (

)

Temperature (degC)




0

25

50

75

100

0 25 50 75 100

Met

al io

n re

mov

al (

)

Contact time (min)

Cr6+

Zn2+Cd2+

Pd2+

(a)

Cr6+

Zn2+Cd2+

Pd2+

30

40

50

60

70

80

90

100

50 200 350 500 650 800 950

Met

al io

n re

mov

al (

)


(b)




4 Conclusions


Data Availability




Acknowledgments


References














0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+





























400

500

600

700

800

900

1000

5 15 25 35

Inte

nsity

2θ


(a)

150

250

350

450

550

650

10 20 30 40 50 60 70 80

Inte

nsity

2θ


(b)


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Wei

ght (

)

Temperature (degC)




0

25

50

75

100

0 25 50 75 100

Met

al io

n re

mov

al (

)

Contact time (min)

Cr6+

Zn2+Cd2+

Pd2+

(a)

Cr6+

Zn2+Cd2+

Pd2+

30

40

50

60

70

80

90

100

50 200 350 500 650 800 950

Met

al io

n re

mov

al (

)


(b)




4 Conclusions


Data Availability




Acknowledgments


References














0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+






























4 Conclusions


Data Availability




Acknowledgments


References














0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000

Rem

oval

amou

nt (m

gg)


Cr6+

Zn2+Cd2+

Pd2+





























yan, jinhua; yang, huanlei; da silva, juliana c.; rojas

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