Advanced oxidation of high concentrations of formaldehyde in aqueous solution under fluorescent and UV light

Background: Formaldehyde (FA) is a carcinogen compound, which is soluble in water. FA can be removed from aqueous solution using advanced oxidation methods. Methods: In this study, the oxidation of FA was studied under fluorescent and UV light. Hydrogen peroxide (H_2O_2) was used as an oxidant. The pH value and H_2O_2 amount of samples were optimized. The chemical oxygen demand (COD), FA concentration, and H_2O_2 consumption were followed. Results: It was observed that the pH value of the sample was more significant under fluorescent light than UV light at oxidation of FA. The highest COD removal and H_2O_2 reduction were 18.57 and 30.90%, respectively, at pH 12.00, with a 1:1 ratio of FA:H_2O_2 under fluorescent light. 86.41% FA and 62.12% COD removal were achieved at pH 7.00, with a 1:2 ratio of FA:H_2O_2, under UV light. It was observed that H_2O_2 was consumed at all pH values under UV light. On the other hand, under fluorescent light, the concentration of H_2O_2 decreased only at pH 12. In control samples containing only H_2O_2, the H_2O_2 reduction was 92.09% at pH 11.91, while it was 26% at other pH levels under fluorescent light. The H_2O_2 reduction changed between 33 and 44% at different pH values under UV light. The oxidation of FA was found to be suitable for the pseudofirstorder kinetic model and Langmuir isotherm model. Conclusion: The most effective oxidation was obtained at the original pH value (7.00) and 1:2 ratio of FA:H_2O_2 under UV light.