Increasing use of pesticides along with an inadequate discharging of agricultural effluents has polluted water resources and severely affected the environment. 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the herbicides which is widely used all over the world. The aim of this study was to evaluate the efficiency of an electro-photo catalytic process for the removal of the 2,4-D from aqueous media. In this regard, Zn-doped Ni anode was stabilized on FTO surface by sputtering method.
Materials and methods: In the present study, the effects of different variables on the efficiency of the electro-photo catalytic process such as pH (3, 5, 7, 9, and 11), electricity current (1-2 mA/cm²), electrode surface area (16-32 cm²), initial concentration of 2,4-D (10-50 mg/L) and retention time (0-90 min) were investigated in a batch model and on a laboratory scale. Besides, mineralization and kinetics of the process under the optimal conditions were studied. The residual concentration of 2,4-D was measured by HPLC at 283 nm.
Results: The results showed that the highest removal efficiency of 2,4-D was obtained under the following conditions: pH=7, electricity current=2 mA/cm², electrode surface area=32 cm², initial concentration=10 mg/L and retention time=90 min. Under the optimal conditions, the maximum removal efficiency (i.e., 100%) and TOC of 79.5% were achieved. In addition, the kinetic studies revealed that the current process followed the first-kinetic-order model.
Conclusion: According to the obtained results, the applied electro-photo catalytic process can be considered as a suitable method for the removal of 2,4-D in aqueous solutions.