Adsorption behavior of benzene on clay mineral surfaces at different temperatures and air humidity based on molecular simulation

Abstract

Benzene poses a severe threat to human health due to its prevalence and carcinogenicity. The adsorption behavior of benzene on clay mineral surfaces is significant to its migration and retention in soils. Therefore, it is crucial to understand the mechanism of benzene adsorption behavior under different environmental conditions. In this study, a series of Grand Monte Carlo (GCMC) simulations were performed to obtain benzene isotherms on clay under various temperatures and air humidity. The adsorption mechanisms were investigated via analysis of the distribution of interaction energy, density, and orientation of adsorbed benzene and water. Results show that benzene form multiple layers on mineral surfaces, and surfaces have a great impact on the first layer of adsorbed benzene. The impedance effect of temperature on benzene adsorption is attributed to the temperature-dependent chemical potential of benzene, but not the interaction between benzene and surfaces, which is slightly temperature-reliant. Humidity shows different inhibition effects on benzene adsorption due to different surface hydration behavior and competitive adsorption between water and benzene. Benzene tends to be adsorbed on hollow sites on kaolinite surfaces, which is the same as water. The surface cations on montmorillonite and mica are significant to benzene and water adsorption, and their density distribution causes different competitive adsorption behavior.