The characteristic of competitive adsorption of HCHO and C₆H₆ on activated carbon by molecular simulation

To explore the characteristic of competitive adsorption of formaldehyde (HCHO) and benzene(C₆H₆) on activated carbon, the slit models of activated carbon with different pore sizes of 1 nm, 2 nm and 4 nm were constructed by using the Visualizer module of Materials Studio molecular simulation software. The adsorption of single-component C₆H₆ and HCHO at three different temperatures of 288.15K,293.15K and 323.15K were conducted by the method of grand canonical Monte Carlo. Experiments were carried out to verify the accuracy of simulation results. For the single-compound adsorption, the adsorption amount of C₆H₆ varied little at different temperature conditions, while the pore size had a significant effect on the adsorption amount of C₆H₆, and the adsorption capability increased as the pore size goes up. The adsorption capacity of HCHO decreased as the temperature goes up, and the adsorption capacity of both 1 nm and 4 nm pore size activated carbon was less than that of 2 nm pore size. As for the competitive adsorption, HCHO has a better adsorption effect by activated carbon when the pore is in small size like 1 nm, while the competitive adsorption ability of C₆H₆ is much better than HCHO as the pore size goes up to 2 nm or 4 nm.Implications: (1) Understanding the equilibrium process of activated carbon adsorption at the molecular level based on the co-existence of multi-component VOCs. (2) The effects of concentration, temperature and humidity factors on the coupling of the dynamic equilibrium of competing adsorption of benzene and formaldehyde were analyzed. (3) The accuracy of the molecular simulations was verified using an experimental approach.