Study On Degradation Of Phenols Pollutants By γ-Irradiation

Application of irradiation technology in environmental protection is a novel and promising research field, and has been received increasing attention in recent year. At the same time, irradiation technology is a main research direction of the21st century for the peaceful uses of atomic energy by the International Atomic Energy Agency (IAEA). In recent years, the control and prevention of the phenolic organic pollutants is a new challenge in the field of water pollution control. This paper investigated the degradation of CPs and phenol in aqueous solution by y-irradiation.(1) The irradiation-induced degradation of4-chlorophenol in aqueous solution by60Co-γ irradiation technology was investigated in different systems. The experimental results show that the efficiency of degradation and dechlorination of4-chlorophenol met the following laws:·OH oxidation system> mixed system>e-aq reduction system> H-reduction system;4-chlorophenol showed higher degradation rate than dechlorination in·OH oxidation and the mixed system. This proves that it includes a considerable number of chlorinated organics during the irradiation reaction. However, the efficiency of4-chlorophenol degradation equal to dechlorination in e-aq reduction system. At the same time, the degradation product is only a phenol and e-aq which has a strong selectivity in e-aq reduction system.(2) The irradiation-induced reductive degradation of2-chlorophenol,4-chlorophenol,2,4-dichlorophenol,2,4,6-trichlorophenol in aqueous solution by60Co-yirradiation technology were investigated. The results showed that the order of degradation and dechlorination of four chlorophenol was:2,4,6-trichlorophenol>2,4-dichlorophenol>2-chlorophenol>4-chlorophenol,2,4,6-trichlorophenol and2,4-dichlorophenol degraded more faster than mono-chlorophenols and hydrated electrons preferentially attack the ortho-position of chlorine atom rather than the para-position of chlorine atom. In the early irradiation response, some reaction intermediates and2,4-dichlorophenol will cause competitive reaction leading to2,4-dichlorophenol degradation efficiency declining. In this intermediates, the concentration of4-chlorophenol was higher than2-chlorophenol.(3) The irradiation-induced degradation of phenol in aqueous solution was investigated. The experimental results showed that: the lower the initial concentration of phenol, the higher the phenol removal efficiency. The initial pH value of phenol solution will affect phenol solution, and low pH is conducive to the degradation of phenol. Removal of phenol met the back law in the different saturated gases:oxygen> air> nitrogen. Hydroquinone,resorcinol and catechol were the main intermediates, at the same time, the concentrations of catechol and hydroquinone were significantly higher than resorcinol.(4) Combined treatment of irradiation oxidation technology and zero valent iron had a synergistic effect. Because of Fenton reaction with zero valent iron and H2O2, more OH radicals were produce, which promoted the degradation of4-chlorophenol and increased the reaction rate.