ABSTRACT The heavy metal adsorption capacity of ZnO thin films was tested using photocatalytic process to removed Cr(VI). ZnO thin films were deposited via the sol‐gel method after 24, 48, and 72 h of aging and were annealed at 500°C. The films achieving adsorption capacities of 411.6, 208.68, and 608.23 mg/g, and removal efficiencies of 96.6%, 91.9%, and 97.6% of Cr(VI), respectively. The adsorption capacity of the films was influenced by the synergy between their structural and optical properties. The highest adsorption coefficient (α) of the films enhances their light‐harvesting capability, which is further supported by largest crystallite sizes and the presence of dislocations, as confirmed by XRD results. According to EPR and PL analyses, when the film is irradiated the ZnO defects, such as zinc vacancies ( V Zn ) and interstitial zinc acting as donors, interacting with the negatively charged Cr(VI) species. These findings highlighted the role of defects and optical optimization in enhancing the photocatalytic performance of ZnO thin film for heavy metals removal.
Gutiérrez‐Abarca et al. (Sun,) studied this question.