The presence of organophosphorus pesticides and their residues in both aquatic and terrestrial ecosystems can cause many problems in the environment and human health. Therefore, it is necessary to intensify research into efective and efcient processes for removing pesticides from the environment. In the present study, an electrocoagulation process was used to remove diazinon (DZ) in the presence of a magnetic guar gum (MGG) as aid coagulant. In the frst stage, guar gum was modifed by three methods and the structural properties of MGG by Fourier transform infrared spectroscopy (FTIR), X-ray difraction (XRD), Scanning Electron Microscopy (SEM) were characterized. It was then optimized in the process of electrocoagulation using magnetic guar gum as the aid coagulant. Response surface methodology (RSM) was used to evaluate the operating parameters to achieve the optimum condition for the treatment process. The model was well ftted to the actual data, and the correlation coefcients of R2 , adjusted R2 , and predicted R2 were found as 0.9903, 0.9883, and 0.9826, respectively. Results showed that the removal efciency of DZ by using the combination of FeCl3 and NH4Cl as adsorbents was lower than that of the single modifcation. Under the constant value center point of DZ concentration (17.5 mg.L−1), pH (7.0) and current density (5.25 mA cm−2), the removal efciency of DZ was increased from 59.4 to 79.8% by increasing the dosage of MGG from 0.5 to 3 g L−1. However, the maximum removal efciency (98.8%) of DZ was achieved under optimal conditions including initial DZ dosage of 11.25 mg L−1, pH of 8.5, current density of 11.75 mA cm−2, and MGG concentration of 2.38 mg L−1 upon 20 min reaction time.
