An ion-imprinted silica-supported organic-inorganic hybrid sorbent prepared by a surface imprinting technique combined with a polysaccharide incorporated sol-gel process for selective separation of cadmium(II)from aqueous solution

摘要

Ion-imprinting concept and polysaccharide incorporated sol-gel process were applied to the preparation of a new silica-supported organic-inorganic hybrid sorbent for selective separation of Cd(II)from aqueous solution.In the prepared shell/core composite sorbent,covalently surface coating on the supporting silica gel was achieved by using a Cd(II)-imprinting sol-gel process starting from an inorganic precursor,gamma-glycidoxypropyltrimethoxysiloxane(GPTMS),and a functional biopolymer,chitosan(CS).The sorbent was prepared through self-hydrolysis of GPTMS,self-condensation and co-condensation of silanol groups(Si-OH)from siloxane and silica gel surface,in combination with in situ covalent cross-linking of CS with partial amine shielded by Cd(II)complexation.Extraction of the imprinting molecules left a predetermined arrangement of ligands and tailored binding pockets for Cd(II).The prepared sorbent was characterized by using X-ray energy dispersion spectroscopy(EDX),X-ray diffraction(XRD),and scanning electron microscopy(SEM).Batch experiments were conducted to study the sorption performance by removal of Cd(II)when present singly or in binary system,an aqueous Cd(II)and Zn(II)mixture.The ion-imprinted composite sorbent offered a fast kinetics for the sorption of Cd(II)and the maximum capacity was 1.14mmolg~(-1).The uptake capacity of the imprinted sorbent and the selectivity coefficient were much higher than that of the non-imprinted sorbent.The imprinted sorbent exhibited high reusability.The prepared functional sorbent was shown to be promising for the preconcentration of cadmium in environmental and biological samples.