Preparation of Organic-Inorganic Hybrid Porous Materials and Adsorption Characteristics for (-)-Epigallocatechin Gallate and Caffeine From the Extract of Discarded Tea

A series of novel organic-inorganic hybrid porous materials were synthesized using the method of suspension polymerization. As content of oleic acid-coated TiO2 introduced increased, the surface area, pore volume, and average pore diameter increased, and meantime macropores appeared. The adsorption efficiencies of the porous materials for (-)-epigallocatechin gallate (EGCG) and caffeine (CAF) were enhanced, due to synergistic effect of surface area, pore volume, average pore diameter, and several driving forces such as charge induced force, pi-pi stacking, and hydrogen bond. Adsorption kinetic analysis indicated that pseudo-second-order kinetics can reasonably depict the adsorption process, and intraparticle diffusion became more obvious after a contact time of 30 min. Adsorption isotherm analysis indicated Freundlich isotherm could be used to describe the adsorption process. Charge induced force, pi-pi stacking, hydrogen bond, and sieving effect of pores were the main driving forces for the adsorption of EGCG and CAF by the organic-inorganic hybrid porous materials. This study will open possibility of expanding number and types of porous materials and provide assistance in tailoring corresponding physical-chemical properties, according to specific analytes. (C) 2015 Society of Plastics Engineers