Electro-assisted heterogeneous activation of persulfate by Fe/SBA-15 for the degradation of Orange II

• Fe/SBA-15 was fabricated and used in a EC enhanced heterogeneous PS process.
• The effect of reaction parameters and the stability of Fe/SBA-15 were investigated.
• Primary reactive species were identified and the degradation mechanism was elucidated.
• Main intermediates were determined and a possible degradation pathway was proposed.
• The toxicity of treated solution was decreased to almost zero.

The removal of Orange II by activation of persulfate (S2O82−, PS) using synthesized Fe/SBA-15 in the electrochemical (EC) enhanced process was reported in this study. The reaction rate constants, degradation mechanism, catalyst stability, and evolution of mineralization and toxicity were detailed investigated. On the basis of radical scavenger results, both the sulfate radicals (SO4−) and hydroxyl radicals (OH) were responsible for the degradation of Orange II. A possible pathway is suggested to describe the degradation of Orange II according to the degradation intermediates identified. The results showed that the Fe/SBA-15 catalyst maintained strong reusability and stability with a low level of iron leaching. In addition, favorable mineralization efficiency in terms of COD removal efficiency (75.4%) and TOC removal efficiency (46.3%) was obtained when the reaction time was prolonged to 24 h. The toxicity experiments implied that the toxicity of the treated solution ascended at the first 30 min but then dropped to almost zero eventually. This study provides a proof-of-concept that can be applied widely for the PS remediation of contaminated water.

Figure optionsDownload as PowerPoint slide