Hg0 removal performance and mechanism of Cu-BTC/FeCu-BC composite adsorbent

HE Ling; FENG Youxiang; YU Jingxiang; CHENG Peng; NIE Haotian; WU Yawen; YAN Qizhen; ZHANG Zhen; JIA Li

doi:10.13225/j.cnki.jccs.2024.0227

Abstract：Composite adsorbents were prepared using a combination of modified biochar and MOFs through an in-situ growth method.The modified biochar was doped with Fe/Cu polymetallic and Cu-BTC,both containing unsaturated met-al centers and oxygen-containing functional groups.The study focused on identifying the Hg0 removal characteristics,in-vestigating the coupling and synergistic mechanisms between Cu-BTC and modified biochar,and examining the various types of active centers present.A molecular structure model of the composite adsorbent was developed based on micro-scopic properties,and theoretical calculations of the Hg0 adsorption process were conducted using density functional the-ory,and fractional-wave state density function to uncover the underlying mechanisms of mercury removal and key actions.The study revealed that the Cu-BTC material exhibited better mercury removal performance compared to modified biochar.Furthermore,the mercury removal efficiency of Cu-BTC-based modified biochar samples,resulting from a com-bination of the two materials,was significantly enhanced.The optimal loading ratio was found to be 50％,leading to a re-markable mercury removal performance of 239.18 μg/g.The molecular model of the composite adsorbent primarily con-sisted of aromatic structures,including two pyridinium azobenzenes,one anthracene benzene,and one anthracene benzene.The synergistic effect of polymetallic clusters,oxygen vacancies,and carbon skeleton facilitated the exposure of active centers.Moreover,the modified biochar acted as a substrate carrier,providing additional metal centers and carbon skelet-ons within the crosslinked MOFs structure,thereby enhancing electron acceptor and transfer capacities of the reaction sys-tem.By improving the electron acceptor capacity and mass transfer ability of the system,the formation of highly dis-persed metal centers was promoted during heat treatment,preventing self-aggregation of metal oxide particles and syner-gistically enhancing Hg0 removal.