Acid Treatment of a Geopolymer Synthesized via the Dispersant Template Method for Enhanced Acetone Adsorption Performance

Abstract

Powdered aluminosilicate materials were synthesized directly from metakaolin by the dispersant template (DT) method to address the difficulty of grinding monolithic geopolymers for adsorption applications. The resulting powder was subjected to nitric acid treatment at various concentrations to examine the effects on composition, structure, texture, and acetone vapor adsorption. Comprehensive characterization indicated that the DT-derived parent material consisted of partially geopolymerized aluminosilicate together with residual metakaolin, and that acid treatment induced dealumination and partial breakdown of the aluminosilicate framework, leading to silica-rich structures. Nitrogen adsorption–desorption measurements showed that the specific surface area increased markedly with acid concentration, reaching the highest value for the sample treated with 5 mol L^–1 nitric acid, which exhibited a surface area more than four times that of the untreated material. Acetone adsorption experiments demonstrated that the 5 mol L^–1 nitric acid-treated sample adsorbed 16.0 µmol/g within 30 min and reached 26.2 µmol/g after 3 h, approximately 1.5 times greater than the untreated sample. The enhanced performance is attributed to the increased surface area and the development of a more favorable pore structure in the acid-treated, silica-rich aluminosilicate framework.