PTELECTICS AD ADVACED MATEIALS APID CMMUICATIS Vol. 4, o. 8, August 2010, p. 1118-1123 Modified Fe 3 4 colloidl dispersed mgnetic prticles s crrier in liquid memrnes A. C. ECHIF,, M. G. STIA, S. I. VICU *, G. ECHIF University Politehnic from Buchrest, Fculty of Applied Chemistry nd Mterils Sciences, 1-7 Gheorghe Polizu, Buchrest, 011061, omni tionl Institute for reserch nd Development in Microtechnologies (IMT-Buchrest) 126A, Erou Incu icole Street, Buchrest 077190, omni In this pper we present the results relted to mgnetic prticles synthesis (otined y vrint of Mssrt method, which consists in ferric ions co-precipittion into potssium hydroxide solution) nd their stiliztion with SAP 230 (consisting of mixture of two modified polyisoutene derivtives in minerl se oil). The otined stilized mgnetic prticles were functionlized with crown ether derivtive (minoenzo-18-crown ether) nd used for liquid memrnes preprtion in dioxn. The colloidl mgnetic prticles were chrcterized y FT-I spectroscopy, therml nlysis nd Scnning Electron Microscopy nd + nd K + from different inorgnic slts were seprted in order to test nd evlute the liquid memrne performnces. (eceived June 29, 2010; ccepted August 12, 2010) Keywords: Colloids, Mgnetic prticles, Crown ethers, Liquid memrne 1. Introduction In the lst 20 yers the memrne mterils studies re continuously incresing with new polymer types, composite mterils nd nnosystems or ultr micro dispersed systems. ecognized selectivity of the liquid memrnes is insufficient explored due to operting difficulties such s: phses mixing, contct surfce, memrne stility. An importnt step ws the preprtion of mgnetic liquids s memrne phses, ut the performnces of these mterils re limited from se solvent nture nd from mgnetic prticles type [1-3]. The synthesis nd investigtion of mgnetic properties of nnostructured mgnetic mterils present interest from oth fundmentl nd technologicl point of view [4]. noprticles hve received considerle ttention in the pst two decdes due to the interesting properties relted to their size [5]. Ferrofluids represent specil ctegory of smrt nd memrne nnomterils, consisting of stle dispersion of mgnetic nnoprticles in different liquid crriers [6]. Ferrofluids re widely used in industril pplictions, ut re lso importnt s model system for dipolr fluids. In scientific reserch, mgnetite (Fe 3 4 ) prticles hve een investigted extensively, ecuse their synthesis is convenient nd well known [7]. Pthmmnohrn et l. [8] pulished preliminry results on the synthesis nd chrcteriztion of iron prticles stilized with modified polyisoutene (PIB) nd oleic cid in declin. They found tht the size of prticles grfted with polyisoutene could e controlled well, wheres this ws not possile for oleic-cid-coted prticles [9]. K. Butter et l [9] presented n extensive study on iron dispersions, synthesized y therml decomposition of ironcronyl, in which they systemticlly vried the rdius of prticles nd studied the effect of size on the physicl ehvior of mgnetic fluids in rod size rnge. To stilize the prticles they used two different surfctnts, i.e., PIB or oleic cid [10, 11]. In this pper we present the results relted to mgnetic nnoprticles synthesis sed on ferric oxides nd their stiliztion with SAP 230 (consisting of mixture of two modified polyisoutene derivtives in minerl se oil). The otined stilized mgnetic prticles were functionlized with crown ether derivtive (minoenzo- 18-crown ether) nd used for liquid mgnetic memrnes preprtion. The colloidl mgnetic prticles nd synthesis intermedites were chrcterized y FT-I spectroscopy, M spectrometry nd Scnning Electron Microscopy nd + nd K + from different inorgnic slts were seprted in order to test nd evlute the liquid memrne performnces. 2. Experimentl 2.1 Mterils For mgnetic prticles preprtion, Mohr slt (Fe 2 (H 4 ) 3 (H 4 ) 2 S 4 ) nd ferri sulfuric lum slt (FeS 4 (H 4 ) 2 S 4 ) from Merk were used. Potssium hydroxide (KH) ws purchsed from Fluk. As solvents, dioxn, cetone, nd deionized wter from Merk were used. For liquid memrne test performnces, ntrium chloride (), potssium chloride (K), potssium perchlorte (K 4 ), potssium phenoxide (C 6 H 5 - K + ),
Modified Fe 3 4 colloidl dispersed mgnetic prticles s crrier in liquid memrnes 1119 potssium 1, 3, 5-trinitro phenoxide (C 6 H 2 ( 2 ) 3 - K + ), sodium perchlorte ( 4 ), sodium phenoxide (C 6 H 5 - + ) nd sodium 1, 3, 5-trinitro phenoxide (C 6 H 2 ( 2 ) 3 - + ) from Merk were used. In experiments minoenzo- 15-crown ether (Fluk) nd cynuric chloride (Merck) were lso used. 2.2. Methods Colloidl dispersed mgnetic prticles preprtion. Mgnetic nnoprticles re otined y vrint of Mssrt method [4], which consists in ferric ions coprecipittion into potssium hydroxide solution. 250 cm 3 of Mohr slt solution 0,1 M nd 250 cm 3 of ferrimmonium sulfuricum (ferri lum) re mixed under stirring. 1,5 L of potssium hydroxide 1M re dded in three portions. After 4 hours, the lck suspension is seprted in mgnetic field. The entire quntity of suspension is dilyzed until ph 9 vlue is chieved. The mgnetic prticles re wshed with methnol, ethnol nd then with cetone. After mgnetic seprtion the prticles re covered nd engrftment. The synthesized mgnetic prticles were stilized using SAP 230 (consisting of mixture of two modified polyisoutene derivtives in minerl se oil) with structurl formul presented in Fig. 1. The process ws performed in dioxn, y mixing quntity of 5 g of mgnetic prticles nd 2 ml of SAP 230 in 10 ml of solvent. = H 3 C CH 2 CH 2 (HCH 2 CH 2 )n H 2 CH 2 (HCH 2 CH 2 )n CH 3 C CH 3 CH 2 C CH 2 CH 3 CH 3 m Fig. 1. Structurl formul of modified PIB SAP 230, m=17, n=4. c C CH 3 CH 2 Amino enzo-18-crown ether functionliztion with cynuric chloride. The functionliztion of crown ethers with cynuric chloride is performed in dioxn, under stirring t 40 o C, in dioxn. The rection product is isolted y solvent evportion t 80 o C. The rection is presented in Fig. 2. H 2 + Dioxn H Fig. 2. Functionliztion rection of Amino enzo 18 crown 6 ether functionliztion with cynuric chloride. Amino enzo-18-crown ether grfting on colloidl mgnetic prticles. The lighted colored dispersion is reintroduced in the cermic tnk of the mill with 3g cynuric chloride nd is mixed for 3 hours nd fter this the minoenzo-18-crown ether nd is mixed for nother 3 hours. Finlly, the rown dispersion is wshed with three portions of deionised wter. H H H H H H Fe 3 4 Fe 3 4 H H H H H H H H H H H CH 2 CH 2 (HCH 2 CH 2 )n H 2 + CH 2 CH 2 (HCH 2 CH 2 )n Dioxn Fig. 3. ection scheme for mgnetic nnoprticles functionlistion. The trnsport of + nd K + ions through dioxnfunctionlized mgnetic prticles liquid memrne. Into liquid memrne system schemticlly represented in Fig. 1 the following solutions re introduced: ) source phsepotssium or sodium slts 10-5 M, ph 4,8 relized with CH 3 C - Li + / CH 3 CH; ) liquid memrne sed on functionlized Fe 3 4 mgnetic prticles in dioxn nd c) receptor phse-lkline solution, ph=8-10 relized with LiH 10-6 -10-4 M. The memrne system is represented in Fig. 4 with illustrted trnsport mechnism for +. For comprison, liquid memrne with crown ethers dissolved in ferrophse ws synthesized without H H
1120 A. C. echifor, M. G. Stoin, S. I. Voicu, G. echifor covlent interction etween mgnetic prticles nd crown ethers. + nd K + were nlyzed y flmphotometry using Phlpho 4 Crl Zeiss Jen Photometer. The experiments were performed t 25 C. min dvntge of using cynuric chloride s spcer is given y the romtic chrcteristic of the ring. After the first rection of chloride tom t 40 o C, the romtic ring is dectivted nd the formtion of dimmers is less prole. The rection t second chloride tom must e performed t more then 60 o C. The synthesized compound ws chrcterized y FT-I spectroscopy (Bruker Tensor 27 with dimond AT nnex) nd 1 H-M spectrometry (Bruker M AM 300, 300 MHz, in CD 3 ) nd the spectrum re presented in Fig. 5. In FT-I spectrum the sorption peks from 880 cm -1 nd 1650 cm -1 re ttriuted to =C- respectively =- onds in the romtic ring plne. The 1580 cm -1 sorption nd is ttriuted to H formtion ond fter the intermedite synthesis. The sorption nd t 1270 cm -1 is specific for ond from crown ether molecule. The M spectrometry ws performed in CD 3 nd the dt re: H M (CD 3 d 6 ) δ H : 1.13 (1H, s), 2.93 (1H, s), 7,89 (1H, q, J=4.35) with chemicl shift for H ond formtion t δ H 2.93 ppm. Asornce Units 0.00 0.05 0.10 0.15 0.20 0.25 0.30 3500 3000 2500 2000 Wvenumer cm-1 1500 1000 Fig. 4 Mgnetic liquid memrne device: Schemtic representtion of permetion cell (); Disperse mgnetic memrne detil (). 3. esults nd discussion In this pper we propose simple nd ccessile onding method etween mino-enzo-crown ether nd mgnetic nnoprticle for mgnetic liquid memrnes. Chemicl coprecipittion ws selected s the method to synthesize nnoprticles for this study. This method produces nnoprticles in lrge quntities (order of grms) in reltively short mount of time nd utilizes inexpensive nd redily ville chemicls s precursors. These two dvntges re importnt in the friction of nnocomposites whose potentil pplictions will require specimen mss of tens of grms. A smple with filler loding of pproximtely 5% volume requires few grms of nnoprticles. Since smples with higher volume frctions were desired, the demnd for nnoprticles incresed very quickly [12]. The first chrcterized compound ws the intermedite resulted in rection etween crown ether derivtive nd cynuric chloride. The Fig. 5. FT-I spectrum () nd M spectrum () of mino enzo crown-18-etherfunctionlized with cynuric chloride. After the covering of mgnetic prticles, respectively the functionliztion with crown ether derivtive the otined colloidl dispersed mgnetic prticles (Fe 3 4 - SAP-CE) were chrcterized y FT-I spectroscopy (Fig. 6) nd SEM microscopy (FESEM Hitchi S 4900) (Fig. 7).
Modified Fe 3 4 colloidl dispersed mgnetic prticles s crrier in liquid memrnes 1121 Fig. 6. FT-I spectrum of mgnetite prticles (), mgnetite prticles covered with SAP () nd crown ethers functionlized mgnetite prticles covered with SAP (c). Asorption chrcteristic nds for Fe- ond from Fe 3 4 re situted in rnge 375-570 cm -1, ut these two nds re shifted higher vlues respectively 440 cm -1 nd 600 cm -1 (Fig. 3). After the coting of mgnetic prticles with SAP specific sorption nds for H 2 group t 3300-3600 cm -1, C= t 1650 cm -1 nd C-C t 720 cm -1 cn e oserved (Fig. 3). The functionliztion rection is demonstrted y the specific sorption nd for C H t 1568 cm -1 shifted with 12 cm -1 in comprison with the sme group from intermedite crown ether derivtive due to the electronic effect of the liphtic cron chin. Mgnetic nnoprticles preprtion y modified Mssrt method [2] strting from Mohr slt nd lum direct to system with their chrcteristics presented in Scheme I. FT-I spectroscopy indictes tht nnoprticles re covered with hydroxyl coting (3000-3600 cm -1 ). The therml nlysis indictes the dehydrtion (mss lost efect TG nd endothermic effect DTA t 107 o C) nd TEM imges (x100000) show tht nnoprticles re qusinno-dispersed with medium dimension out 20 nm. In comprison with crude mgnetic prticles ggregted in ciculr formtions, the covered ones re well dispersed nd pprently re not ggregted which is good proof of their cover. Mgnetic liquid preprtion ws performed y mixing the chosen solvent (dioxn) with otined composite mgnetic prticles (Fe 3 4 -SAP-CE) for four hours in the etsch colloidl mill. The stilized mgnetic liquid dispersion ws plced into the well known liquid memrne system [3], schemticlly presented in Fig. 5. Fig. 7. SEM imges of Fe 3 4 mgnetic prticles () nd SAP covered Fe 3 4 mgnetic prticles (). Into this verticl system source phse ws continuously recycled nd the receiving phse ws mintined under stirring t the top prt of the system. For diffusion trnsport nd concentrtion resons the source phse nd the receiving phse were dded in 10:1 volume reports. The dt for + nd K + ions trnsport results through liquid memrne re presented in Tle 1. Ction trnsport ws coupled with hydronium ction s driving force (Fig. 5). The functionlized Fe 3 4 -SAP-CE mgnetic prticles used s crriers presents etter results for sodium nd less trnsport properties for potssium ecuse the sodium ionic rdius is more comptile with the chosen crown ether. n the other hnd, the dissolved crriers without covlent interction etween mgnetic prticle nd crown ether (in similr memrne concentrtion) present lower results in comprison with composite prticles used s crrier (Tle 1).
1122 A. C. echifor, M. G. Stoin, S. I. Voicu, G. echifor Fig. 8. epresenttion of liquid memrne system; PM-CE represent the functionlized mgnetic prticles, PM-CE +, the complex etween crown ether functionlized Fe 3 4 mgnetic prticle nd sodium ion nd X - the counter ion (chloride, perchlorte, phenoxide or 1, 3, 5-trinitro phenoxide). Tle 1. + nd K + ions trnsport through liquid memrne. Source Phse ph=12, 10-3 M J (J 10 6 mol /cm 2 h ) With crown ether dissolved in ferrophse With crown ether grfted on nnoprticles 2.7 3.2 4 4.8 4.5 C 6 H 5 - + 5.5 6.1 C 6 H 5 ( 2 ) 3 - + 5.8 7.3 K 1.0 1.2 K 4 1.8 2.3 C 6 H 5 - K + 3.6 4.3 C 6 H 5 ( 2 ) 3 - K + 3.6 4.5 The Brownin trnsport of prticles mplifies the diffusion coefficient with convective component ccording to Eq. 1. D t D t = D Fick D conv (1) represents the diffusion coefficient into the liquid memrne, D Fick represents the Fick diffusion coefficient nd D conv the contriution of convection. This oservtion is necessrily in oth trnsport cses ( + nd K + ) nd the vlue is out 21±3% from Fick vlue. 4. Conclusions The prepred composite Fe 3 4 -SAP-CE mgnetic prticles y rection etween stilized mgnetic prticles (using SAP 230) with crown ether derivtive (minoenzo-15-crown ether), is n interesting crrier for mgnetic liquid memrnes. The + nd K + trnsport using prepred mgnetic liquid memrnes offer the following results: - + trnsport is fvoured y the crown ether type (minoenzo-15-crown ether). - The nion lipophilicity mplify the ction trnsport in order: - - < 4 < C 6 H 5 - < C 6 H 5 ( 2 ) 3 -. - Using crown ethers grfted on mgnetic prticles presents etter results in comprison with dissolved crown ethers used s crriers. The diffusion coefficient enhnced with convective vlue D conv = 21±3% D Fick. Acknowledgements The uthors grtefully cknowledge the finncil support of this reserch y the Postdoctorl progrm for dvnced reserch in nnomterils domin ID-54785 nd Humn resources development y postdoctorl reserch in micro nd nnotechnology domin ID-63700 projects
Modified Fe 3 4 colloidl dispersed mgnetic prticles s crrier in liquid memrnes 1123 eferences [1] G. echifor, S. I. Voicu, A. C. echifor, G. echifor, Deslintion 241, 342 (2009). [2] S. Yu, G.M. Chow, J. Mter. Chem. 14, 2781 (2004). [3] B. Şern, E. use, M. C. Mincă, I. Psăre, G. echifor, ev. Chim. Buchrest 51(4), 349 (2000). [4] M. cuciu, D. E. Creng,. Apetroie, E. Brsn, J. ptoelectron. Adv. Mter. 10(2), 280-283 (2008). [5]. Turcu, A. n, I. Crciunescu, J. Liesher,. Pn, D. Bic, L. Veks, C. Mijngos, J. ptoelectron. Adv. Mter. 10(9), 2237-2243 (2008). [6] A. C. echifor, E. Andronescu, G. echifor, ev. Chim. Buchrest 54(8), 455 (2003). [7] F. D. Blcinu, A. C. echifor,. Brtos, S. I. Voicu, G. echifor, ptoelectron. Adv. Mter. pid Comm. 3(3), 219 (2009). [8] C. Pthmmnohrn,. L. Zuiverloon, A. P. Philipse, Prog. Colloid Polym. Sci. 115, 141 (2000). [9] K. Butter, K. Ksspidou, G. J. Vroege, A. P. Philipse, J. of Colloid nd Interfce Science 287, 485 (2005). [10] K. Butter, P. H. Bomns, P. M. Frederik, G. J. Vroege, A.P. Philipse, ture Mter. 2, 88 (2003). [11] K. Butter, P. H. Bomns, P. M. Frederik, G. J. Vroege, A. P. Philipse, J. Phys. Condens. Mtter 15, S1451 (2003). [12] S. Liong, Ph.D. Thesis, Georgi Instiute of Technology (Georgi, United Sttes, 2005). * Corresponding uthor: svoicu@gmil.com