Microwave-Assisted Rapid Photocatalytic Degradation of Malachite Green in TiO2 Suspensions: Mechanism and Pathways

详细信息    查看全文

• 作者：Yongming Ju ; Shaogui Yang ; Youchao Ding ; Cheng Sun ; Aiqian Zhang ; Lianhong Wang
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：November 6, 2008
• 年：2008
• 卷：112
• 期：44
• 页码：11172-11177
• 全文大小：230K
• 年卷期：v.112,no.44(November 6, 2008)
• ISSN：1520-5215

文摘

Microwave-assisted photocatalytic (MPC) degradation of malachite green (MG) in aqueous TiO₂ suspensions was investigated. A 20 mg/L sample of MG was rapidly and completely decomposed in 3 min with the corresponding TOC removal efficiency of about 85%. To gain insight into the degradation mechanism, both GC-MS and LC-ESI-MS/MS techniques were employed to identify the major intermediates of MG degradation, including N-demethylation intermediates [(p-dimethylaminophenyl)(p-methylaminophenyl)phenylmethylium (DM-PM), (p-methylaminophenyl)(p-methylaminophenyl)phenylmethylium (MM-PM), (p-methylaminophenyl)(p-aminophenyl)phenylmethylium (M-PM)]; a decomposition compound of the conjugated structure (4-dimethylaminobenzophenone (DLBP)); products resulting from the adduct reaction of hydroxyl radical; products of benzene removal; and other open-ring intermediates such as phenol, terephthalic acid, adipic acid, benzoic acid, etc. The possible degradation mechanism of MG included five processes: the N-demethylation process, adduct products of the hydroxyl radical, the breakdown of chromophores such as destruction of the conjugated structure intermediate, removal of benzene, and an open-ring reaction. To the best of our knowledge, it is the first time the whole MG photodegradation processes have been reported.