Carbofuran Degradation By Biogenic Mn Oxides And Active Carbon Doped With Biogenic Mn Oxides

As a highly effective carbamate insecticide, Carbofuran was widely used in agricultural. However, the large residues and hige toxicity of carbofuran posed a threat to the human health and the environment. Therefore it was important to seek a method to control the pollution which is efficient and can not cause additional pollution.The main objectives of this thesis were to study the effect of biogenic manganese oxides(Bio-MnOx) on carbofuran degradation. The results showed that 90.63% carbofuran was degraded by Bio-MnOx in 4 days at initial pH 4.80. The degradation rate consistent with first-order kinetics, the half-lives of carbofuran degradation were 1.1 d at pH 4.80. In the same reaction with sodium azide, only 21.5% carbofuran was degraded, whereas carbofuran was hardly degraded by chemical manganese oxides in the same period and at the same initial pH. Carbofuran phenol was the major transformation product in carbofuran degradation and was further oxidized into small organic molecules as monitored by a GC/MS analyzer. Based on this analysis, a complete pathway of carbofuran degradation was considered. Bio-MnOx promoted carbofuran hydrolysis by changing the pH of the environment and encouraged carbofuran phenol cleavage by its oxidization. The reoxidation of the released Mn(II) by Mn(II)-oxidizing microorganisms ensured the continuous reactivity of Bio-MnOx and avoided the secondary pollution of Mn(II).In addition, this work used the carbonized product of Bio-MnOx(active caebon doped with biogenic Mn oxides to degrade carbofuran and carbofuran phenol. It was found that the carbonized product had no effect on carbofuran degradat ion but promoted an rapid and complete degradation of carbofuran phenol. The influence of initial p H conditions, initial concentration of carbofuran phenol, the amount of carbonation was analyzed in the degradation of carbofuran phenol. According to the characteristics of these reactions, it can be inferred that the reaction of carbonized product of Bio-MnOx and carbofuran phenol was a redox reaction. With excess carbonized product in the reaction, the degradation of carbofuran phenol was in line with second-order kinetic models, the half-lives of carbofuran phenol degradation were 0.68 h.This paper offers an efficient, feasible, and no-secondary-pollution approach to control carbofuran pollution. Carbofuran phenol was the main degradation product of carbofuran, which also could pose health hazards to human and enviroment. But little papers fouced on the removal of carbofuran phenol. This study used the carbonation of biological manganses oxides to remove the carbofuran phenol, which provides a new idea for the removal of carbofuran phenol.