Mineralization of C.I. Reactive Yellow 84 in aqueous solution by sonolytic ozonation

• Published in: Chemosphere (Oxford) 2007-09, Vol.69 (2), p.191-199
• Main Authors: He, Zhiqiao, Song, Shuang, Xia, Min, Qiu, Jianping, Ying, Haiping, Lü, Bosheng, Jiang, Yifeng, Chen, Jianmeng
• Format: Article
• Language: English
• Subjects: Applied sciences; C.I. Reactive Yellow 84; Coloring Agents - chemistry; Exact sciences and technology; Gas Chromatography-Mass Spectrometry; Industrial wastewaters; Mineralization; Minerals - chemistry; Ozonation; Ozone - chemistry; Pollution; Pseudo-first-order kinetics; Solutions; Sonolysis; Wastewaters; Water - chemistry; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.04.045

The operational parameters and mechanism of mineralization of C.I. Reactive Yellow 84 (RY84), one of the azo dyes, in aqueous solution were investigated using sonolytic ozonation (US/O 3 oxidation). Of the pseudo-first-order degradation rate constants of TOC reduction, 9.0 × 10 −4, 7.3 × 10 −3 and 1.8 × 10 −2 min −1 were observed with US, O 3, and a combination of US and O 3, respectively. These results illustrate that ozonation combined with sonolysis for removal of TOC is more efficient than ozonation alone or ultrasonic irradiation alone without considering the operating costs. With the initial pH value at 10.0, the ozone dose at 4.5 g h −1, the energy density of ultrasound at 176 W l −1, and the initial concentration of RY84 at 100 mg l −1, the extent of mineralization measured as TOC loss was maximized. The variation of the concentrations of related ions (oxalate, formate, acetate, NO 3 - , NO 2 - , NH 4 + , Cl −, and SO 4 2 - ) during the reaction process was monitored. Other organic intermediates detected by GC/MS were N-methyleneaniline, phthalic acid, 4-hydroxyphthalic acid, isocyanatobenzene, aniline, 4-iminocyclohexa-2,5-dien-1-one, butene diacid and urea. Based on these findings, a tentative degradation pathway was proposed.