Synthesis of mesoporous silica from coal slag and CO2 for phenol removal

Abstract

Utilization of coal slag, a waste generated from coal combustion, is an attractive, renewable, and environmentally friendly approach to helps ease energy shortage and stop environmental deterioration. Coal slag was used to synthesize mesoporous silica (MS) by reacting with CO2 released from a CO2-storage material (CO2SM) in a hydrothermal process. Five key conditions including initial pH, synthesis temperature and time, cetyltrimethyl ammonium bromide (CTAB) concentration, and CO2SM dosage were systematically investigated to optimize the synthesis of MS. Additionally, kinetic models and thermodynamic analyses for phenol adsorption by MS were systemically explored. Results showed that the MS exhibited a phenol adsorption amount of 106.2 mg/g. The MS could be recycled and reused, showing a good phenol adsorption after eight cycles. The current study opens a new approach to optimize the utilization of coal slag and provides a promising way to mitigate the greenhouse effect by substantially capturing CO2. In addition, the synthesized MS is promising to be used as a substitute commercially available.