Background and purpose: Diazinon is one of the most widely used organophosphate pesticides classified by the World Health Organization (WHO) as “moderately hazardous” Class II. This work aimed at optimizing the electrocoagulation process in removal of diazinon from aqueous environments using response surface methodology.

Materials and methods: In an experimental-laboratory study using the D-optimal method, the effects of independent variables including initial concentration of diazinon (10-100 mg/l), applied voltage (20-40 V), reaction time (10-60 min) and pH (3-10) were investigated on removal of diazinon in 30 runs. Process optimization was done by response surface methodology. Analysis of proposed model was also performed using analysis of variance.

Results: Diazinon removal in proposed model was statistically significant at 95% confidence level. The model had insignificant lack-of-fit at 95% confidence level (P=0.614). Diazinon removal efficiency was dependent on initial concentration of diazinon, applied voltage, and reaction time. The removal efficiency of diazinon was 84.6% at optimum condition (voltage= 20 V and diazinon concentration= 100 mg/L).

Conclusion: Electrocoagulation process applying current experimental conditions was found to be efficient in removal of diazinon from aqueous solutions. Designing experiments by D-optimal method can optimize the removal of the process and prepare the best conditions for pollutant removal by reducing the number of experiments.