Thermal degradation of octachloronaphthalene over as-prepared Fe(3)O(4) micro/nanomaterial and its hypothesized mechanism.
Decomposition of octachloronaphthalene (CN-75) featuring fully substituted chlorines was investigated over as-prepared Fe3O4 micro/nanomaterial at 300 °C. It conforms to pseudo-first-order kinetics with kobs = 0.10 min(-1) 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 α-position than β-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-), and eletrophilic O2(-) and O(-), present on the Fe3O4 surface, might attack the carbon atom and π electron cloud of naphthalene ring, producing naphthol species with Mars-van Krevelen mechanism, and formic and acetic acids.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , P.O. Box 2871, Beijing 100085, China.
Guijin
G
Su
Huijie
H
Lu
Lixia
L
Zhang
Aiqian
A
Zhang
Linyan
L
Huang
Sha
S
Liu
Liewu
L
Li
Minghui
M
Zheng
D002851:Chromatography, High Pressure Liquid; D005290:Ferric Compounds / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D007536:Isomerism; D007700:Kinetics; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D055672:Static Electricity; D013696:Temperature; D013997:Time Factors
D005290:Ferric Compounds; D006843:Hydrocarbons, Chlorinated; C000499:ferric oxide; C032730:octachloronaphthalene