Efficient degradation of organic pollutants in aqueous solution with bicarbonate-activated hydrogen peroxide

Abstract

Bicarbonate anion is an efficient activator for hydrogen peroxide to generate many active oxygen species including peroxymonocarbonate ( HCO 4 - ), superoxide ion ( O 2 - ) and singlet oxygen ( 1O 2). This study aims to understand the oxidative degradation of organic pollutants including methyl blue, methyl orange, rhodamine B, and 4-chlorophenol, with H 2O 2 activated by sodium bicarbonate at room temperature. The obtained results indicate that such a method is apparently efficient in versatile pollutant degradation. Compared with using H 2O 2 alone under similar pH conditions, the degradation rates of the pollutants were greatly enhanced through adding NaHCO 3. Through LC–MS, FT-IR and the TOC analysis, the degradation of methylene blue was revealed to proceed by the transformation of dimethylamino group in methylene blue to methylamino, aldehyde and nitro group, and the opening of phenyl ring into small molecular compounds and CO 2. The studies using the 1O 2 scavenger sodium azide and the O 2 - indicator nitro blue tetrazolium suggest that the active O 2 - intermediate, generated from HCO 4 - decomposition, rather than 1O 2 was involved in the pollutant degradation.