Surface Properties and Microstructures of Al-SBA-15 under Different Temperature Calcinations in Relation to Adsorption Performance

Abstract

In this study, the calcination temperature was adjusted to influence the properties, including surface alumina types, microstructure, and surface acidity, and then to explore their association with the performance of As(V) adsorption after preparing aluminum-modified SBA-15 (Al-SBA-15x) by the incipient wetness impregnation method. The results showed that calcination promoted the formation of aluminum oxides with different coordination environments on SBA-15 carriers, resulting in different kinds of acid sites and Al–OH groups, which were the adsorption sites for As(V). However, with the increase in the calcination temperature, the total surface acidity on the Al-SBA-15x samples gradually decreased, and the dehydration and dehydroxylation reactions of aluminum oxides occurred, which reduced the Al–OH groups and changed the acid–base environment on the samples. Besides, high-temperature calcination caused a partial collapse of mesoporous channels, which was not conducive to dispersing the active adsorption centers on the surface and further reduced the effective utilization of active adsorption centers. Therefore, the adsorption capacity of an Al-SBA-15x adsorbent for As(V) decreased with the increase of the calcination temperature. Furthermore, kinetic models were used to investigate the relationship between the microstructure and adsorption processes. Finally, recycling tests were performed to demonstrate the reusability of Al-SBA-15x samples.