Prepration And Application Of Silica-Supported Chitosan Organic-Inorganic Hybrid Materials By Molecular Imprinting Technique

The organic-inorganic hybrid materials is a new field of the composite, becausethis kind material can show good properties of organic and inorganic components, Thechitosan-based organic-inorganic hybrid materials have extensive potential applicationin separation, purification, liquid chromatography, enzyme immobilization, membraneseparation and other fields. Sol-gel chemistry offers simple and convenient methodology forthe synthesis of molecular-recognized advanced materials. In this paper, two kindsilica-supported chitosan organic-inorganic hybrid materials are prepared, silica gel ofgood mechanical property as a support by imprinting coating technique and molecularlyimprinting sol-gel process.In the prepared matrix, silica-supported chitosan macroporous organic-inorganichybrid material was achieved by using sol-gel process of inorganic precursor,γ-glycidoxypropyltrimethoxysiloxane (GPTMS), and a functional biopolymer, chitosan(CS), at atmosphere of template molecular PEG. Self-hydrolysis of GPTMS,self-condensation and co-condensation of silanol groups (Si-OH) from siloxane andsilica gel surface, and in situ covalent cross-linking of CS created a self-assemblingcoating with structural ordering on the surface of silica gel. The hybrid matrixexhibited improved thermal stability. After loading copper ion, the immobilized metal affinityadsorbent was obtained with porous surface. Protein adsorption performance of the newimmobilized metal affinity adsorbent was evaluated by batch adsorption experimentsusing bovine serum albumin (BSA). The macroporous surface prepared usingoptimized coating condition translated into a fast kinetics and high capability forprotein adsorption. The adsorption of the material was fitted with the linear form of theLangmuir equation. The maximum adsorption of BSA was 227.3 mg/L wet bead. In the prepared porous composite sorbent, covalently surface coating on thesupporting silica gel was achieved by using a Cd(Ⅱ)-imprinting sol-gel process startingfrom an inorganic precursor, -glycidoxypropyltrimethoxysiloxane (GPTMS),and a functional biopolymer, chitosan (CS) elf-condensation and co-condensation ofsilanol groups (Si-OH) from siloxane and silica gel surface, and in situ covalentcross-linking of CS created a self-assembling coating with structural ordering on thesurface of silica gel. Batch experiments were conducted to study the sorptionperformance by removal of Cd(Ⅱ) when present single or in binary system, an aqueousCd(Ⅱ) and Zn(Ⅱ) mixture. The ion-imprinted composite sorbent offered a fast kineticsfor the sorption of Cd(Ⅱ) and the maximum capacity was 1.14 mmol g^-1. The largestselectivity coefficient for Cd(Ⅱ) in the presence of Zn(Ⅱ) resulting from thecompetitive ion-binding was found to be over 100; and the largest relative selectivitycoefficient between Cd(Ⅱ) and Zn(Ⅱ), was 120. The uptake capacity of the imprintedsorbent and the selectivity coefficient were much higher than that of the non-imprintedsorbent. The imprinted sorbent exhibited high reusability.