
Photo-electro Fenton process for removal of malathion: Insights into degradation mechanisms and hydroxyl radical effects
Amir Amirkhani 1 ℗, Saeid Ahmadzadeh 2 ©, Maryam Dolatabadi 3
Abstract
Introduction: Pesticides are widely used in agriculture and industry to control pests, with malathion being a typical example of an organophosphate. However, excessive pesticide use raises significant concerns regarding food safety and environmental health, presenting a major public health challenge. Malathion poses severe ecological risks in aquatic environments due to its high toxicity to fish and invertebrates. For humans, exposure can lead to significant health concerns, including neurotoxicity, respiratory problems, and endocrine disruption, with chronic exposure potentially linked to cancer and reproductive issues. therefore. Effective removal of malathion from aqueous solutions is essential to reduce human exposure and safeguard public health. Methods and Materials: The experimental study was conducted using a plexiglass reactor in a laboratory scale. Response surface methodology (RSM) with center composite design (CCD) was used to achieve the highest removal efficiency for malathion. The effect of various variables including; pH solution, light intensity, H2O2 dosage current density, initial malathion concentration on removal efficiency was investigated. The significance of the independent variables and their interactions are evaluated applying analysis of variance (ANOVA) with a 95% confidence level. Results: The results obtained from the regression analysis determined that the experimental data exhibited the highest level of conformity with the second-order polynomial model. The determination coefficient (R2) was determined to be 0.9967. Furthermore, the adjusted R2 (Adj.R2) value was found to be 0.9936; the predicted R2 (pred. R2) value was calculated as 0.9886. photo-electro Fenton process was applied successfully with removal efficiency of 99.8 % under the optimal operating condition of 3.0 pH, 18 W cm-2 of light intensity 15.0 mA cm-2 current density, 10.0 mg L-1 initial malathion concentration, and reaction time of 90 min. Under the optimal conditions of the photo-electro Fenton process, electrode consumption and electrical energy consumption were found to be 0.184 g during a single run and 0.294 kWh m-3, respectively. Conclusion and Discussion: The photo-electro Fenton process is highly effective in removing pollutants, especially pesticides, from contaminated water. This advanced oxidation technique integrates photocatalysis and electrochemical methods, resulting in improved degradation rates. By generating hydroxyl radicals through light and Fenton's reagents, it efficiently transforms complex organic compounds into less harmful substances. Moreover, its adaptability to different operational conditions positions photo-electro Fenton process as a promising technology for remediating pesticide-contaminated water, significantly aiding environmental protection.
Keywords: Malathion, Photo-electro Fenton process, Mineralization, Response surface methodology