Assessment of the efficiency of electro-Fenton process in degradation of formaldehyde from a highly concentrated aqueous solution by aluminum and iron electrodes

Due to its high reactivity، colorlessness، stability، purity in different commercial forms and low price، formaldehyde is increasingly used in industries. According to the CERCLA list، formaldehyde is toxic and dangerous to the humans and environment. The aim of this study was to investigate the efficiency of electro-Fenton process for pretreatment of industrial wastewater containing high concentrations of formaldehyde. This was an experimental laboratory study. First of all a reactor was designed and built. Then optimal reaction time was determined and kept constant to determine optimal pH. Finding optimal pH and reaction time، the influence of initial hydrogen peroxide concentration and arrangement of iron and aluminum electrodes as anode and cathode material in constant density، with 1 L/min aeration was investigated for treatment of synthetic wastewater containing initial concentration of 7500 mg/L of formaldehyde. MS Excel 2010 and relative standard deviation were used for data analysis and interpretation. Our findings demonstrated that the increase of pH and initial hydrogen peroxide concentration resulted in an increase of formaldehyde removal by Electro-Fenton Process. Increasing the reaction time up to 10 min resulted in an increase in formaldehyde removal، but increase of the reaction time more than 10 min led to a decrease in formaldehyde removal by the above mentioned process. Use of iron as anode and cathode electrodes led to more removal of formaldehyde in comparison to other possible arrangements between iron and aluminum. The results indicated that the maximum formaldehyde removal was 71. 54 percent which was achieved at operational conditions of pH=10، current intensity of 8. 5 mA/cm2، primary H2O2 concentration of 50 mM/L after 10 minutes by using iron for anode and cathode electrodes.