Effect analysis of initial water content and temperature on the adsorption of VOCs by activated carbon based on molecular simulation

Abstract

To analyse the effects of initial water content (IWC) and temperature on the adsorption behaviour of VOCs on activated carbon (AC), the grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) methods were used. Benzene and acetone are regarded as two representative components of VOCs, and their adsorption properties in AC models with four different IWC at 298.15 K were investigated. Their adsorption properties at four different temperatures (278.15, 288.15, 298.15, and 308.15 K) were also investigated. The simulated pressures were set in the range of 3 × 10−4 to 3 kPa (benzene) and 10 × 10−4 to 10 kPa (acetone). The results show that water molecules can impede the adsorption of benzene and acetone, decreasing the saturated adsorption capacity, the isosteric heat, and monomolecular interaction energy. However, the pre-loaded water molecules can enhance the electrostatic interaction at low pressure, which affects the isosteric heat and monomolecular interaction energy, but the pore volume is still the main influencing factor. Before reaching the saturated adsorption capacity, the higher the temperature, the lower the adsorption capacity, and the monomolecular interaction energy follows the same trend. The results provide mechanistic insights into how the IWC and temperature affect the adsorption properties of AC for VOCs.