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PHOTOLYTIC DEGRADATION OF ENVIRONMENTALLY IMPORTANT ORGANIC CONTAMINANTS IN NOVEL ROOM TEMPERATURE IONIC LIQUIDS

YANG, QIAOLIN
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1078454909

Abstract Details

2004, MS, University of Cincinnati, Engineering : Environmental Engineering.
The photodegradation of 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,5-tetrachlorophenol, pentachlorophenol, naphthalene, anthracene, pyrene and atrazine, in 1-butyl-3-methylimidazolium hexafluorophosphate and 1-ethyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide room temperature ionic liquids (RTILs) has been investigated using 253.7, 313 and 365 nm UV radiation. These RTILs are relatively resistant to phototransformation when used as pure phases. At low concentrations (<1.57 mM), chlorophenols could be degraded in these RTILs following pseudo-first order kinetics under 253.7 nm UV radiation. Increase of UV wavelength resulted in a decrease of the degradation rate of 2-chlorophenol. Addition of hydrogen peroxide in the presence of 253.7, 313 or 365 nm UV radiation inhibited the 2-chlorophenol degradation rate. Electrospray TOF MS, GC-MS and HPLC analysis revealed the formation of phenol among the stable phototransformation intermediates of 2-chlorophenol. Two possible pathways, via formation of phenoxyl radical or carbene, could lead to phenol generation. The increase of the chlorine atoms in the phenolic ring generally resulted in a decrease in the phototransformation rates, with exception of 2,4,6-trichlorophenol. The PAHs tested could also be photodegradated under 253.7 nm UV radiation. Although the initial degradation rate followed the order: anthracene>naphthalene>pyrene, when starting from the same initial concentration of 1.11 mM, the overall removal of the PAHs was: anthracene>pyrene>naphthalene. The addition of oxygen to the naphthalene ring and the rupture of the ring due to direct photolysis are discussed as possible reaction pathways. Intermediate identification revealed the formation of bicycle[4,2,0]octa-1,3,5-triene, 2’-hydroxyacetophenone, and phenol among the stable intermediates. UV absorbing impurities present in the ionic liquids had a negative effect on the phototransformation rates of the target compounds. Purification of RTILs using activated carbon enhanced the photodegradation rates. These impurities could, at some extent, protect the ionic liquid from photolysis. In-situ degradation of pentachlorophenol and atrazine extracted from soils, namely, montmorillonite and glacial till, using 1-butyl-3-methylimidazolium hexafluorophosphate showed enhanced reaction rates compared to those of the samples prepared by dissolving the compounds in the ionic liquid. The recycling of the solvents was hindered at some extend by the presence of impurities or by the generation of byproducts that were resistant to photolysis and competed with the chlorophenol for photon absorption.
Dr. Dionysios Dionysiou (Advisor)
79 p.
chlorophenols; PAHs; atrazine; environmental; ionic liquids; photolysis; photodegradation; UV; hydrogen peroxide; purification; recycling

Recommended Citations

Citations

  • YANG, Q. (2004). PHOTOLYTIC DEGRADATION OF ENVIRONMENTALLY IMPORTANT ORGANIC CONTAMINANTS IN NOVEL ROOM TEMPERATURE IONIC LIQUIDS [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1078454909

    APA Style (7th edition)

  • YANG, QIAOLIN. PHOTOLYTIC DEGRADATION OF ENVIRONMENTALLY IMPORTANT ORGANIC CONTAMINANTS IN NOVEL ROOM TEMPERATURE IONIC LIQUIDS. 2004. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1078454909.

    MLA Style (8th edition)

  • YANG, QIAOLIN. "PHOTOLYTIC DEGRADATION OF ENVIRONMENTALLY IMPORTANT ORGANIC CONTAMINANTS IN NOVEL ROOM TEMPERATURE IONIC LIQUIDS." Master's thesis, University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1078454909

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.