Efficient elimination of Microcystis aeruginosa by catalytic ozonation with CuCe-LDO/modified porous carbon composites: Performance, mechanisms and ecotoxicological consequences.

Abstract

To address harmful algal blooms (HABs) and mitigate their threats to ecological security and human health, developing advanced treatment technologies is imperative. In this study, a novel metal-carbon composite (CuCe/NCS), which couples CuCe-layered double oxides with modified porous carbons, was synthesized and applied for the catalytic ozonation of Microcystis aeruginosa. The synthesized CuCe/NCS featured a well-developed porous structure and abundant active sites, thereby enabling excellent catalytic performance. The CuCe/NCS-catalyzed ozonation process achieved nearly 100% algae removal within 40 min, with a reaction rate constant of 0.096 min-1, which is approximately 6.4-fold higher than that of the sole O3 process. The practical efficacy of CuCe/NCS-catalyzed ozonation was further validated through the treatment of real algae-laden waters. Mechanistically, the algae inactivation and removal were attributed to irreversible oxidative damage to cell membranes, intracellular/extracellular components as well as photosynthetic and antioxidant systems, induced by the substantial attack of reactive oxygen species (ROS) formed during the catalytic ozonation process. A series of experimental measurements and theoretical calculations clarified the catalytic ozonation mechanisms over CuCe/NCS, specifically involving the synergistic interaction between metal sites and the carbon matrix in promoting O3 adsorption-activation and ROS formation. Additionally, the ecotoxicity assessment using zebrafish as the indicator species confirmed the improved safety profile of the treated effluent. Overall, this study presents a promising ozonation catalyst and offers a highly efficient strategy for HABs remediation.