Enhanced dual synergistic mechanism of adsorption and ozone triggering via biochar-derived zero-valent bimetal sites for water purification

Novel zero-valent iron (ZVI) and zero-valent zinc (ZVZ) bimetal-supported biochar (ZF@BC) was developed for heterogeneous catalytic ozonation (HCO), which demonstrated the unique dual synergistic adsorption and catalysis-induced effective O3 triggering and interfacial decontamination. ZF@BC exhibited impressive catalytic and structure stabilities for 2-methyl-4-chlorophenoxyacetic acid (MCPA) degradation during long-lasting HCO, which can resist interference from a complex water quality background. Abundant electron-rich oxygen-containing functional groups and defects on BC contributed to the adsorption of MCPA and O3, respectively, while the introduced ZVZ was anticipated to expedite O3 decomposition by facilitating single-electron transfer reduction of O2 and establishing a robust connection with ZVI. Continuous efficacy of bimetal in three stages enhanced the efficiency of O3 utilization and hydroxyl radicals (•OH) yield, thereby safely mitigating the associated toxicity of MCPA after treatment. The development of O3/ZF@BC introduced a sustainable, long-term decontamination strategy and provided valuable insights for the advancement of HCO. [Display omitted] •Novel bimetal-supported biochar (ZF@BC) was developed.•Electron-rich functional groups and defects contributed to the adsorption of MCPA and O3, respectively.•Continuous efficacy of ZVI/ZVZ in two stages enhanced the O3 utilization and •OH yield.•Concerned toxicity of MCPA was safely altered.