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.