Adsorption/Desorption Behaviors of Acetone over Micro-/Mesoporous SBA-16 Silicas Prepared from Rice Husk Agricultural Waste

Abstract

The preparation of micro-/mesoporous SBA-16 adsorbent by rice husk derived sodium silicate as the silica source and its acetone adsorption/desorption behaviors were reported for the first time. The pore structural properties of waste-derived SBA-16 materials were controlled and optimized by adjusting the surfactant/silica molar ratios from 0.002 to 0.01 for achieving the best acetone adsorption performance. And the relationship between structural properties and acetone adsorption performances of SBA-16 adsorbents was investigated. The resultant waste-derived SBA-16 materials, denoted as RSBA-16, had specific surface areas of 575–1001 m2 g–1, pore sizes of 3.3–3.7 nm and pore volumes of 0.41–0.72 cm3 g–1. Among the studied adsorbents, RSBA-16(0.004) exhibited the highest saturated acetone adsorption capacity of 179 mg g–1. It also showed excellent regeneration stability during 20 consecutive cycles. The results indicated that specific surface areas in both micro- and meso-pore ranges were the main factor that determined the superiority of acetone adsorption capacity of RSBA-16(0.004) over other adsorbents such as mesoporous RMCM-41 and micro-/mesoporous RSBA-15. The acetone adsorption experiments at 500–5000 ppmv demonstrated that the adsorption isotherm was well fitted with the Langmuir model, thus the adsorption of acetone on RSBA-16 might be a monolayer physisorption process. The results demonstrated the high adsorption capacity and cyclic stability of waste-derived RSBA-16(0.004) can be considered as a potential adsorbent for VOCs removals.