Effective removal of atrazine pesticide residue from wastewater using transition metal-doped zinc oxide photocatalyst

Frequent use of pesticides results in the release of large quantities of their residues in the environment, raising various concerns for humans and the ecosystem. This work introduces a simple and cost-effective method for removal atrazine pesticide residue (APR) from agricultural wastewater using Cu doped-ZnO photocatalyst (Cu-ZnO). The modification of ZnO with Cu significantly improved its optical and photoelectrochemical properties, with the band gap narrowing from 3.3 to 2.64 eV. The photodegradation of APR was 93.6 and 91.7% in aqueous solution and agricultural wastewater, respectively. After being reused four times, Cu-ZnO did not display a notable drop in degradation performance, with the rates of 93.6, 91.2, 86.8, and 83.1% during the first, second, third, and fourth recycles, respectively. Also, the release of Cu from Cu-ZnO after six cycles was <2%, suggesting the excellent stability of the modified photocatalyst without any issues related to secondary pollution. Under natural sunlight, 83.9% of APR was removed, confirming the benefit of Cu-ZnO in reducing the treatment costs of pesticides by utilizing renewable energy. In addition, the degradation mechanism of APR by Cu-ZnO was proposed based on the outcomes of radical quenching and TOC removal tests.