Revealing the influence of oxygen-containing functional groups on mercury adsorption via density functional theory and multiple linear regression analysis

Oxygen-containing functional groups (OFGs) are important species on activated carbons, which have received extensive attention due to the predominant chemisorption activity towards elemental mercury. Based on density functional theory (DFT) and multiple linear regression (MLR) studies, this work is focused on the following five aspects: (1) The Gibbs free energy-temperature dependences of OFGs are compared, and CO2 -1, CO3 -7, C2O -2, C2O2 -9, C2O3 -24 are proved as the most dominant candidates among their respective species. (2) The adsorption of OFGs on carbonaceous surface is studied, among which C, O and C2 species belong to chemisorption, on the contrary, the adsorption of CO and CO2 is weak. (3) The mechanism of mercury adsorption by OFGs is sorted into three categories, and the strongest adsorption can be obtained when mercury is co-adsorbed by OFGs and substrate. (4) Six descriptors are extracted from the binary relationships to provide data source for MLR analysis. (5) A regression equation is successfully established, which can effectively predict mercury adsorption energy. This theoretical work estimating mercury adsorption will provide new insights for the development of mercury adsorbents with OFG synergy.