Silica-Based Ion-Exchange Supports: Preparation And Application In Environment And Food

Silica-based support is ideal for separating because of the advantages of the high specific surface area, good mechanical strength, stable physical and chemical properties, easy surface modification and good biocompatibility,. Silica-based support is widely used in field of chromatography, environmental science and catalytic technology.The synthesis and functionalization of silica are important steps of preparation of silica-based support. Nowadays synthesis of silica spheres has been studied deeply. The most popular methods include sol-gel method, spray drying method and polymerization induced colloid aggregation (PICA) method. However, the irregular shape, the poor mechanical stability and low productivity of products are the deficiency of these methods. The most popular modification method of silica gel surface is the reaction of organic silane reagents and Si-OH. Due to the lack of suitable organic silane reagents, some ion-exchange supports with high exchange capacity cannot be obtained easily.The objective of this thesis is to establish a novel method to prepare silica spheres with good spherical degree, high mechanical strength, high yield rate, and short ageing time. In order to get silica-based ion exchange support with high exchange capacity, carboxyl and quarternary ammonium group silanes are prepared to modify silica.Composite spheres is prepared by inverse-suspension polymerization in an aqueous phase of silica sol, using acrylamide and N, N-Methylenebisacrylamide as monomer and cross linker, respectively. The polyacrylamide obtained is used as structure direct agent of silica spheres. The preparation method of silica spheres has been invented successfully. The advantages of this method include good sphericity, high mechanical strength, high productivity and short preparation time. Surface of silica spheres is modified by carboxyl group silane synthesized by y-glycidoxypropyltrimethoxy silane and iminodiacetic acid, and weak cation exchange support is obtained. The adsorption of Cu2+in water has been investigated.Surface of silica spheres is modified by quarternary ammonium group silanes synthesized by y-glycidoxypropyltrimethoxy silane and triethylamine hydrochloride, and strong anion exchange support is obtained. The quaternary ammonium bonded amorphous silica is used as solid phase extraction support. The most suitable pH and eluent are examined. High recovery rate has been found by the examination of benzoic and sorbic acid in jelly. The chromatographic column is filled with5μm quaternary ammonium bonded silica spheres. The column efficiency and the separation ability of substances with similar structure are examined by different compounds. The chromatographic conditions of salting strength, pH, ratio of organic phase are examined for separation of glucose and gluconic acid sodium salt. Compared with reversed-phase chromatography, the separation of glucose and gluconic acid sodium salt using ion-exchange chromatography has higher resolution, shorter analysis time.In recent years, the application prospect of ion exchange support won the favor of chromatographic workers, and plays more and more important role in the field of environment and food analysis.