Complexation and degradation of tetracycline by activation of molecular oxygen with biochar-supported...

Nano-zero-valent copper (nZVC) is a superior molecular oxygen (O₂) activator for the abatement of organic pollutants due to its high electron utilization rate. However, the activation efficiency of O₂ is compromised by the agglomeration tendency of nZVC particles and the concomitant reduction of the available active sites. To address this problem, the biochar (BC) with porous structure and abundant surface functional groups is utilized to disperse and stabilize nZVC for O₂ activation (simplified as the nZVC/BC/O₂ system) for efficient removal of tetracycline (TC). The nZVC/BC composite possesses a high specific area with well-distributed nZVC particles on the BC surface, which guarantees the superior dispersion and high reactivity in the activation of O₂. The efficacy of the nZVC/BC/O₂ system for TC abatement is evaluated and the underlying mechanism is elucidated. The results show that nZVC/BC/O₂ system can achieve excellent removal of TC with the efficiencies of more than 85% in the pH range of 4.0-9.0, which originated from the combined action of complexation and degradation. The degradation is dominated by reactive oxygen species (ROS) including •OH, •O₂^- and ¹O₂ generated by Cu⁰/Cu⁺ activated O₂ while the generation of Cu²⁺ via oxygen oxidation on the surface of nZVC/BC can remove TC by complexation adsorption. This study highlights the complexation and degradation in the removal of TC and can be expected to exhibit application prospects in the water and wastewater treatment.