Degradation Of Aromatic Compounds By UV/US Coupling Process In Aqueous Solution

The regularity of aromatic compounds degradation with different type, position and number of the substitute group by ultraviolet (UV,150W,365nm), ultrasonic (US,100W,160K) and UV/US processes under same experimental conditions was studied respectively in this thesis. Phenol and chlorobenzene were selected as the representatives of hydrophilic and hydrophobic organic compounds and the effects of experimental conditions, such as initial concentration, initial pH and degradation manner, on their degradation were investigated. The results indicated that, the degradation of aromatic compounds by UV,US and UV/US processes followed the apparent first order reaction kinetics. The degradation efficiencies for each series of aromatic compounds by US in decline order were chlorobenzene> nitrobenzene> benzoic acid> aniline> phenol,3-chlorophenol> 4-chlorophenol> 2-chlorophenol,2,4,6-Trichlorophenol> 2,4-Dichlorophenol> 2-chlorophenol. The degradation efficiencies by UV in decline order were phenol> aniline> benzoic acid> nitrobenzene> chlorobenzene,4-chlorophenol> 2-chlorophenol> 3-chlorophenol, 2-chlorophenol> 2,4-Dichlorophenol> 2,4,6-Trichlorophenol. The degradation efficiencies by UV/US coupling process in decline order were phenol> aniline> benzoic acid> nitrobenzene> chlorobenzene,3-chlorophenol> 4-chlorophenol> 2-chlorophenol, 2-chlorophenol> 2,4-Dichlorophenol> 2,4,6-Trichlorophenol. The degradation efficiency of UV/US coupling process was better than those of UV and US processes individually, which demonstrated good synergetic effect. UV process played a significant role in degradating hydrophilic organic compounds by UV/US coupling process, while US had a dominant contribution in degrading hydrophobic organic compounds. The degradation efficiencies and the reaction rate constants of phenol and aniline decreased with the increasing of initial concentrations. Neutral condition was favorable for phenol degradation, and initial pH had little effect on chlorobenzene degradation.