Reusable porous chromium- zinc oxide nano-sheets for efficient detoxification of xenobiotics through integrated advanced oxidation water clean-up process

Abstract

An integrated approach of acoustic, ultraviolet, and sunlight-driven Advanced Oxidation Process (AOP) is an excellent choice in the quest for a water-cleaning process. This research delves into the realization of chromium-doped zinc oxide (Cr/ZnO) nanopores as a low energy, eco-friendly, efficient, and exhibiting stable photocatalysis for the AOP process. Ultrasonic-aided co-precipitation technique was used for the synthesis of porous Cr-ZnO nanostructures. X-ray diffraction patterns and FTIR spectra of the synthesized samples revealed that chromium ions were effectively intruded into the ZnO lattice. Tauc's equation and Kubella Munk plots have explored that the incorporation of Cr dopants in ZnO reduces the optical band energy. The formation of porous structures was evinced in SEM, TEM, HRTEM, and BET studies. The presence of abundant mesoporous structures was confirmed by the adsorption/desorption isotherms of type IV hysteresis. The antimicrobial efficacy of Cr-ZnO against aqueous bacteria, Staphylococcus aureus, and Escherichia coli was comparatively as effective as the control. The integrated AOP approach enhances the electron trapping characteristics of nanoporous Cr-ZnO catalysts to generate self-sustained in-situ reactive oxygen species on the aqueous matrix. In the current research, methylene orange and nitro phenol were detoxified up to 99 % and 98.2 %, and their half-life degradation rate constant was 22 min and 26 min, respectively. The total organic contaminants (TOC) test on the resultant treated water has confirmed the effective detoxification of xenobiotic molecules and the possibility of reusing the treated water. The ecotoxicology research using treated water on flora and primary aquatic microfauna has supported the possibility of practical utilization of Cr-ZnO in harmless environmental adaptation in the foreseeable future.