Removal of heavy metal ions in coal gasification ash leachate:A molecular dynamics study

LIU Qianru; HUANG Zibo; ZHOU Wenjing; HAO Nanjing; WEI Jinjia; ZHANG Hao; TIAN Baiqi

doi:10.13247/j.cnki.jcumt.20240604

Abstract：Heavy metal ions in coal gasification ash pose significant risks to the environment and human health,necessitating the urgent development of efficient remediation methods.Carbon nanotubes(CNTs)exhibit advantageous properties such as large specific surface area,high stability,and superior adsorption performance,which can be further enhanced through modification with specific functional groups.In this study,molecular dynamics simulations were employed to investigate the adsorption behaviors of carboxyl-functionalized single-walled carbon nanotubes(CNT-COO-)toward heavy metal ions(Cu2+and Cd2+)present in water contaminated by coal gasification ash.Simulation results indicated that adding a sufficient a-mount of CNTs simultaneously provided favorable overall removal efficiency for heavy metal i-ons in mixed-ion systems.To better understand the adsorption mechanisms,the effects of var-ying functionalization coverage and solution temperature on parameters such as radial distribu-tion number density and mean square displacement were analyzed.It was found that CNTs functionalized with 25％carboxyl groups demonstrated stable adsorption performance for heav-y metal ions at an ionic concentration of 0.1 mol/L,exhibiting superior adsorption affinity to-ward Cu2+ons in mixed solutions.Additionally,the adsorption capacity of CNT-COO-in-creased with higher initial ion concentrations,though the relative proportion of adsorbed ions gradually decreased.The findings from this study provide valuable insights into the application of functionalized CNTs for the adsorption and removal of heavy metal ions,laying a theoretical foundation for further modifications of carbon-based adsorbents.