Popovici, Eveline

English

Popovici Eveline

Burtica Georgeta

Singurel G. H.

Hanu A. M.

University of Szeged

Acta Mineralogica-Petrographica, Abstract Series 4, Szeged, 2004 ADSORPTION OF SOME MONOSACCHARIDES ON PILLARED CLAYS: PRELIMINARY RESULTS POPOVICI. E..' BURTICA, G.,1 SINGUREL, GH.,2 HANU, A. M.2 1 Department of Chemical Engineering, "Politehnica" University [Catedra Inginerie Chimicä, Universitatea Politehnica], pta. Victoriei 2, Timi$oara, 1900, Romania 2 Faculty o f Chemistry, „AI. I. Cuza" University [Facultatea de Chimie, Universitatea "Alexandru loan Cuza"], bd. Carol 111 , Ia§i, 700506, Romania E-mail: evelinepopovici@yahoo.com Pillared clays are a special class of microporous materials that can be obtained by interlayering expandable clay minerals with polymeric oxide, as pillars. The Si-PILCs and Al-PILCs have attracted considerable attention in many organic reac-tions, adsorption processes, and environmental protection. The paper shows the preliminary results of the adsorption behavi-our in the monosaccharide-water-pillared bentonite systems. Separation factors, adsorption excess isotherms of monosac-charide-water mixtures, and adsorption equilibrium diagrams show the complex interaction inside of pillaring bentonites. The bentonite from Valea Chioarului used in our experi-ment has a complex composition and contains particularly smectite (64%), illite-smectite interstratifications and nume-rous traces of feldspar and quartz with cation exchange capa-city 92 meq/lOOg bentonite was used clays, a mixture of swelling agent and pillar precursor. The swelling agent is incorporated within the interlayer species of the clay, serving to prop open the layers in such a way as to allow incorpora-tion of the organometallic compound (tetraethylorthosilicate, TEOS) as polymeric oxide precursor. The pillared clay is ob-tained after calcination at 673°K. The samples were characte-rised by XRD patterns, FTIR spectra and adsorption iso-therms. The D-glucose (Fluka) and D-fructose (Merck) solu-tions were used. The equilibrium state was checked by mea-suring the concentration in the interval 8 to 72 hours. In our experiments because of the adsorption equilibrium between water and clay is determined only by measuring the change of the bulk concentration, the calculated amount of adsorbed saccharide reflects a global isomeric mixture ad-sorption. The measure of the adsorption of a liquid mixture is the adsorption excess r 2 ' : r 2 ' = n° (x2° - x2 ' )/m; where: n° is the total number of moles in the original solution; (x2° - x2 ' ) is the change in the mole fraction of the monosaccharide solution caused by ad-sorption; m is the mass of the sample (g). It is evidently that the raw bentonite prefers the adsorp-tion of water, while pillared clays, both the calcined and not calcined samples, adsorb D-fructose preferentially. As a con-sequence of the limited solubility of the monosaccharides in water only a small portion of the adsorption excess isotherms could be determined. Fig. 1: Adsorption excess isotherms of D-fructose water mixtures on: a) raw bentonite; b) sample not calcined; c) sample calcined. The obtained data show the ability of the bentonite from Valea Chioarului (Romania), for pillaring processes. The pillaring process was developed the bentonite capacity for monosaccharides separation. Separation factors, adsorption ex-cess isotherms and adsorption equilibrium diagrams show the formation of some strong interaction between monosaccharide and clay surface. References ESPINOSA, J . , GOMEZ, S . , FRUENTES, G . ( 1 9 9 4 ) : S t u d i e s in Surface Science and Catalysis, 84C, 283-291. KOMADEL, P. (1999): Applied Sciences - Serie E, 362, 2-19. LANDIS, N . E. , AUFDEMBRINK, B . A . , CHU, P . , JOHNSON, I. D., RUBIN, M . K. (1991): Journal of the Amer ican Che-mical Society, 113, 3189. POPOVICI, E. et al. (2000): Journal of Balkan Physics, 3C, 206. 62 www. sei. u-szeged. hu/asvanytar>/acta. htm 84 

Adsorption of some monosaccharides on pillared clays : preliminary results

http://acta.bibl.u-szeged.hu/31629/1/mineralogica_as_004_084.pdf

Adsorption of some monosacchardies on pillared clays: : Preliminary results

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