Molecular simulation studies on the adsorption of mercuric chloride

Abstract

Environmental context. The Clean Air Act amendments of 1990 identified mercury and associated compounds as hazardous air pollutants of particular concern to human health and the environment. Coal-fired power plants and municipal solid waste incinerators are significant sources of mercury-containing emissions. Adsorption represents a common technique used to alleviate mercury contamination. The present study uses molecular simulations to study the correlation between key surface characteristics of the adsorbent and its mercury capturing ability with a view to the selection and design of novel adsorbents. Abstract. In the present study, Monte Carlo simulations were used to model the physical adsorption of oxidised mercury (mercuric chloride) by zeolite NaX and activated carbon in the temperature range of 400–500 K. In particular, we considered zeolite NaX with spherical cavities and sodium cations, as well as activated carbon with slit carbon pores and hydroxyl, carboxyl and carbonyl sites, and layers of calcium hydroxide. The adsorption capacity and affinity of zeolite NaX were compared with those displayed by activated carbon with different acid sites and calcium hydroxide by assessing the impact on mercuric chloride adsorption within a practical range of magnitudes of the electrostatic interactions considered, namely charge-induced dipole and charge-quadrupole interactions, as well as dispersion interactions.