The exploitation of plant wastes in ZnO photocatalyst electrosynthesis for 2,4-dichlorophenol degradation application

Abstract

Listen

Translate article

ZnO is established as an efficient photocatalyst for pollutant degradation but, its synthesis process that involves hazardous chemicals becomes a limitation. This work, therefore, proposed a green ZnO electrosynthesis strategy utilizing banana peel (BP) and tea leaf residue (TLR) extract. The generated ZnO photocatalysts were characterized via FTIR, SEM, XRD, BET, PSA, XPS, HRTEM and UV-DRS analysis and subjected to 2,4-dichlorophenol degradation for photocatalytic activity evaluations. The findings revealed that the ZnO-TLR sample contributed to the highest 2,4-dichlorophenol degradation (88.5%) followed by ZnO-BP (76.2%) and ZnO commercial (62.1%). This can be associated with the narrower band gap (3.20 eV), intense FTIR band of Zn-O bonds, larger surface area (9.576 m²/g), uniform surface morphology, and oxygen vacancies existence of ZnO-TLR. The highest amount of phenolic content, flavonoid content, and reducing power capacity of TLR extract as obtained by preliminary phytochemical assays was believed to contribute to such properties. The optimum reaction conditions were then found to be pH 3, 30 ppm 2,4-DCP, and 0.01 g catalyst with maximum 91.2% degradation. The ZnO-TLR catalyst was reusable for up to 3 cycles with a final 79.0% degradation. The kinetic study revealed that the photodegradation reaction that occurred in this work obeyed the pseudo-first-order kinetic model. It was found that the photogenerated hole was the main oxidation species in the 2,4-dichlorophenol mineralization process in this work.