Characterization of $\text{SO}_{4}^{{2 - }}$/ZnO and Photodegradation Kinetics of 2,4-Dichlorophenoxyacetic Acid (2,4-D)

Abstract

This work is a theoretical and practical study on the synthesis and characterization of a ZnO photocatalyst doped with ${\text{SO}}_{4}^{{2 - }}.$ X-ray diffraction analysis, band gap energy ranges and BET surface area measurements demonstrated that ${\text{SO}}_{4}^{{2 - }}$ had an impact on the photocatalyst properties of ZnO, when this material was used for the production of oxidizing agents by the action of ultraviolet radiation. Significant changes in the band gap energy were observed for ZnO doped with 3 mol of ${\text{SO}}_{4}^{{2 - }}.$ The photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was evaluated, a toxic pesticide found in agricultural effluents in Sinaloa (Mexico). Degradation process was monitored in photoreactors of 500 mL, in which the maximum degradation efficiency was achieved after 6 h. A removal efficiency of 38.4% (1.55 mmol/L) was found with an undoped ZnO, while an efficiency of 82.3% (3.4 mmol/L) was observed with ${\text{SO}}_{4}^{{2 - }}$ doped ZnO. Based on the results obtained, the photocatalysts used in this study can be considered as promising materials to mitigate pollution problems coming from agricultural activities in these regions.