Thermal Degradation of Octachloronaphthalene over As-Prepared Fe3O4 Micro/Nanomaterial and Its Hypothesized Mechanism

详细信息    查看全文

• 作者：Guijin Su ; Huijie Lu ; Lixia Zhang ; Aiqian Zhang ; Linyan Huang ; Sha Liu ; Liewu Li ; Minghui Zheng
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：June 17, 2014
• 年：2014
• 卷：48
• 期：12
• 页码：6899-6908
• 全文大小：510K
• 年卷期：v.48,no.12(June 17, 2014)
• ISSN：1520-5851

文摘

Decomposition of octachloronaphthalene (CN-75) featuring fully substituted chlorines was investigated over as-prepared Fe₃O₄ micro/nanomaterial at 300 掳C. It conforms to pseudo-first-order kinetics with k_obs = 0.10 min^鈥? as comparable to that of hexachlorobenzene and decachlorobiphenyl. Analysis of the products indicates that the degradation of CN-75 proceeds via two competitive hydrodechlorination and oxidation pathways. The onset of hydrodechlorination producing lower chlorinated naphthalenes (CNs) is more favored on 伪-position than 尾-position. Higher amounts of CN-73, CN-66/67, CN-52/60, and CN-8/11 isomers were found, while small content difference was detected within the tetrachloronaphthalene and trichloronaphthalene homologues, which might be attributed to lower energy principle and steric effects. The important hydrodechlorination steps, leading to CN-73 CN-74 in two heptachloronaphthalene isomers contrary to that in technical PCN-mixtures, were specified by calculating the charge of natural bond orbitals in CN-75 and the energy of two heptachloronaphthalene radicals. On the basis of the molecular electrostatic potential of CN-75, the nucleophilic O^{2鈥?/sup>, and eletrophilic O₂鈥?/sup> and O鈥?/sup>, present on the Fe₃O₄ surface, might attack the carbon atom and 蟺 electron cloud of naphthalene ring, producing naphthol species with Mars鈥搗an Krevelen mechanism, and formic and acetic acids.}