[Kinetics for Degradation of Orange G with Peroxymonosulfate Activated by Carbon Nanotubes]

Carbon nanotube (CNT) was used as an activator to activate peroxymonosulfate (PMS) to degrade azo dye orange G (OG) in aqueous solution. The results indicated that CNT exhibited a much better performance in activating PMS to decolorize OG than activated carbon (GAC), with 99% decolorization of OG achieved within 45 min. Afterwards, the degradation mechanism of OG in CNT activated PMS system was explored, and SO₄^-·was found to be dominantly responsible for OG degradation, which mainly took place on the surface of CNT. Effects of various factors, including temperatures, initial concentration of OG, CNT loadings, PMS dosage, and initial pH, on degradation of OG were then investigated, and OG degradation in these cases well conformed to first-order kinetics. From the analysis of UV-vis spectra of OG during the reaction, the peaks at 479 nm and 330 nm were found to be significantly decreased, suggesting that the azo band and naphthaline ring were destructed, respectively. Finally, TOC analysis indicated that a certain degree of OG mineralization was obtained in CNT activated PMS system.