The effects of humic substances for polycyclic aromatic hydrocarbons photooxidation
| Autor: | Hung, LinShung, 洪凌翔 |
|---|---|
| Rok vydání: | 1996 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 84 Humic substances can absorb the energy of solar radiation and transfer it to produce singlet oxygen in aqueous system. Singlet oxygen has higher reactivities to oxidize many organic compounds than the ground state triplet oxygen. In this research, the photooxidization of 4 different kinds of polycyclic aromatic hydrocarbons (PAHs), including naphthalene, anthracene, phenathrene and pyrene were studied. Humic substances can act as photosensitizer in the photoreaction of PAHs. The photooxidization rate of PAHs in humic water was faster than that without the existance of humic substances. The effects of soil humic substances are higher than those of the marine ones. The more rings the PAHs have, the slower photooxidization is. Changes in salinity and pH do not alter the photooxidization rates of PAHs, however, the higher concentration of humic substances or higher temperature can speed up the sensitized photoreaction. The addition of Ni2+ or Cu2+ can retard the indirect photoreaction rate, but the addition of Zn2+ makes no difference. Comparing the photoreaction rates irradiated with light sources of 546nm or 435nm wavelength, faster reaction rate was observed for the light with shorter wavelength. The PAHs themselves can also produce singlet oxygen under irradiation even without humic substances. The reactivities of PAHs to 3O2 are in the following order : naphthalene > anthracene > phenanthrene > pyrene. For 1O2, the reactivities are : naphthalene > anthracene > phenanthrene > pyrene. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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