Evaluation of the Fenton process using a residue as alternative iron source to degradation of methylene blue dye

ABSTRACT

In the last decades, the environmental pollution has become more and more intense, due to the considerable increase in the disposal of residues (solids and liquids) in the soil and in watercourses. To minimize this impact, technological development takes on the role of presenting increasingly effective techniques for the degradation of contaminants. In this context, the Advanced Oxidative Processes (AOP) stand out due to their high oxidizing power and, consequently, high performance in the recalcitrant organic matter degradation. Therefore, the aim of the research was to verify the use of an industrial residue (IR), as a source of iron in reactions of the Fenton type, to reduce organic matter and color in aqueous medium. The research was carried out with the methylene blue dye (MB) as a model molecule in the concentrations of 1,500 and 50 mg/L. Three preliminary studies (PS) of the Fenton reaction were conducted, resulting in 11 different experiments. Based on the best conditions of the PS, factorial planning (FP) was carried out. As a result, initially, the characterization of the IR presented a high amount of organic matter and iron. Subsequently, the PS allowed achieving the satisfactory condition for the Fenton reaction with concentrations of MB = 1,500 mg/L, IR = 20,70 mg/L, H₂O₂ = 1,75 mg/L; and 180 minutes of reaction time. In FP, this same condition stood out, reaching an efficiency of 91.8% and 49% of COD removal at MB concentrations of 1,500 and 50 mg/L, respectively. Furthermore, at the MB concentration of 50 mg/L, in this same condition, the color removal at the wavelength of 605 nm was 100%. Preliminary studies have shown that the treatment of MB with the use of IR as a catalyst in the Fenton reaction, has shown promise in removing organic matter and color.

Keywords
Advanced Oxidative Processes; wastewater treatment; degradation; reuse