Insights into the mechanism of elemental mercury removal via ferric chloride modified carbon Aerogel: An experimental and theoretical research

Abstract

Removal of elemental mercury (Hg0) has been widely investigated, because of its high toxicity and removal difficulty. The carbon aerogel (CA) modified by transition metal chloride has great prospects in dealing with the mercury pollution problem in coal-fired power plants. Here, the ferric chloride (FeCl3) modified carbon aerogel by impregnation method was implemented for capturing and removing mercury (Hg), and the corresponding mechanism was analyzed in detail by density functional theory (DFT) and molecule dynamics (MD) method. The as-prepared samples maintained the large specific surface area and superior pore structure of carbon aerogel, and FeCl3 is evenly dispersed. The improvement of elemental mercury capture performance can be attributed to the interaction between Hg0 and surface active chlorine, and the synergistic effect of transition metal atoms on carbon surface and oxygen. It has been discovered that doping iron did ameliorate the electron transfer mechanism of oxygen and mercury on the surface of carbon, which results in a considerably stronger connection to mercury atoms and in turn improvement of Hg0 removal. In this work, based on the proposed scheme of FeCl3 impregnation modified carbon aerogel for mercury removal, a novel synergistic mechanism is creatively proposed, which is expected to provide some inspiration to the study of the role of free oxygen atoms on the adsorbent surface.