Highly reduced ecotoxicity of ZnO-based microanostructures on aquatic biota: Influence of architecture, chemical composition, fixation, and photocatalytic efficiency

摘要

Developing efficient sunlight photocatalysts with enhanced photocorrosion resistance and minimal ecotoxicological effects on aquatic biota is critical to combat water contamination. Here, the role of chemical composition, architecture, and fixation on the ecotoxicological effects on microalgae of different ZnO and ZnO@ZnS based water decontamination photocatalysts was analyzed in depth. In particular, the ecotoxicological effects of films, nanoparticles and biomimetic microanoferns were carefully assessed by correlating the algae's viability to the Zn(II) release, the photocatalyst-microalgae interaction, and the production of reactive oxygen species (ROS). The results showed a drastic improvement in algal viability for supported ZnO@ZnS core@shell microanoferns, as their ecotoxicity after 96 h light exposure was significantly lower (3.7-10.0% viability loss) compared to the ZnO films (18.4-35.5% loss), ZnO microanoferns (28.5-53.5% loss), ZnO nanoparticles (48.3-91.7% loss) or ZnO@ZnS nanoparticles (8.6-19.2% loss) for catalysts concentrations ranging from 25 mg L-1 to 400 mg L-1. In particular, the ZnO@ZnS microanoferns with a concentration of 400 mg L-1 exhibited excellent photocatalytic efficiency to mineralize a multi-pollutant solution (81.4 +/- 0.3% mineralization efficiency after 210 min under UV-filtered visible light irradiation) and minimal photocorrosion (<5% of photocatalyst dissolution after 96 h of UV-filtered visible light irradiation). Remarkably, the ZnO@ZnS microanoferns showed lower loss of algal viability (9.8 +/- 1.1%) after 96 h of light exposure, with minimal reduction in microalgal biomass (9.1 +/- 1.0%), as well as in the quantity of chlorophyll-a (9.5 +/- 1.0%), carotenoids (8.6 +/- 0.9%) and phycocyanin (5.6 +/- 0.6%). Altogether, the optimized ZnO@ZnS core@shell microanoferns represent excellent ecofriendly photocatalysts for water remediation in complex media, as they combine enhanced sunlight remediation efficiency, minimal adverse effects on biological microorganisms, high reusability and easy recyclability. (C) 2019 Elsevier Ltd. All rights reserved.