Synthesis And Application Of Environmental Restoration Materials With Hierarchically Porous Structure

Hybrid hierarchically porous silica adsorbents were simply fabricated by sol-gel method and modified by thiol or sulfonic groups. These materials with pores on both micrometer and nanometer scales exhibit satisfactorily adsorptive property to various pollutants in water, including heavy metal ions and organic compounds. The thiol functionalized hierarchically porous silicas micro-foam (SH-HSM), which has a low thiol content (0.66mmol g-1). shows significantly high adsorption capability to Hg2+(140.1mg g-1) in particular. Then sulfonic acid-functionalized adsorbent (SO3H-HSM) was got via direct oxidization of SH-HSM by H2O2. It was found that SO3H-HSM could effectively remove organic compounds with positive charge in solution through electrostatic interactions. The adsorption capability of SO3H-HSM for some basic dyes, such as fuchsin basic, could reach approximate1145.2mg g-1. The mixture of SH-HSM and SO3H-HSM showed good purifying capacity to simulate multicomponent wastewater. containing different inorganic and organic chemicals. The removal rate for any of the pollutants was more than90%. and could even reach100%for metal ions and dyes. The strong adsorption ability of these porous adsorbents may be owed to the interwoven meso-and macroporous structures which can increase mass transport and easier accessibility for pollutants to the active sites.In addition, a high performance photocatalyst was prepared by loading tungstophosphoric acid (H3PW12O40) in hierarchically porous silica. Using this catalyst, a variety of dye pollutants were efficiently degraded under visible light irradiation. The photocatalyst had a relative large surface area, pore diameter and pore volume. The degradation kinetics, degradation products, and the effect of pro-oxidant were also investigated to clarify the degradation process and the reaction pathway. The dyes can be facilely and quickly bleached and mineralized (ca.97.80%of removal for fuchsin basic in80min), and there were no small organics detected in the main degradation products of fuchsin basic. Comparing with catalysts using other porous silica as carriers (MCM-41and SB A-15), the hierarchically porous structure was considered to be an important factor to improve the molecular diffusion in the heterocatalysis process and enhance the degradation efficiency. Additionally, this hierarchically porous catalyst was very stable and very easily separated from the reaction solution for reuse.