Study On Degradation Efficiency Of Benzene And Toluene By Chlorine Dioxide

As one of the major pollutants in indoor space environment,benzene gas is extremely harmful to human body and environment.As a green oxidant,chlorine dioxide（ClO₂）has the characteristics of strong oxidation,wide range of action,and does not produce carcinogenic,teratogenic and mutagenic substances,etc.It is widely used in the purification of semi-enclosed space environment.The paper investigated the possibility of degradation of benzene and toluene by ClO₂ in gas phase and liquid phase,and the preliminary characterization of degradation products,aiming to provide basic theoretical and data support for the degradation of benzene series by ClO₂.The main results of the study are as follows:（1）The study on the removal of 10 mg/L benzene or toluene from aqueous solution by liquid ClO₂ showed that:a.10～50 mg/L ClO₂ was selected for the degradation of benzene,and the best removal of benzene was achieved when the concentration of ClO₂ was 45 mg/L.The removal rate of benzene increased with the increase of reaction time and then leveled off.The removal rate reached the maximum at 24 h and was 62.56%.b.The best toluene removal effect was achieved when the ClO₂ concentration was 30 mg/L.The removal rate of toluene showed an increasing trend with the increase of reaction time,and the reaction rate decreased significantly until 9 h.The removal rate reached the maximum of 73.38%at 24 h.（2）The study on the removal of benzene or toluene single gas and the mixture of benzene and toluene in the gas phase by ClO₂ showed that:a.10～50 mg/m~3 ClO₂ was selected to degrade3 mg/m~3 benzene,and the best removal of benzene was achieved when the concentration of ClO₂ was 25 mg/m~3,and the reaction rate decreased significantly until 2 h.The increase of benzene removal rate from 2 to 10 h was not obvious,and the highest removal rate of benzene was achieved until 10 h.The highest removal rate was 81.75%;b.The degradation of 3 mg/m~3toluene was carried out by selecting 10～50 mg/m~3 ClO₂,and the best removal effect on toluene was achieved when the concentration of ClO₂ was 20 mg/m~3,the reaction rate decreased significantly until 2 h,and the removal rate increased insignificantly from 2 to 10 h.The removal rate of toluene reached the maximum of 72.04%until 10 h;c.5～25 mg/m~3 ClO₂ was selected to degrade the gas mixture with both benzene and toluene concentrations of 1.5 mg/m~3.The overall removal rate of benzene by ClO₂ was higher than that of toluene.The best removal effect was achieved when the ClO₂ concentration was 10 mg/m~3 for the gas mixture,and the highest removal rates of benzene and toluene were achieved up to 24 h with 82.63%and 71.49%,respectively.（3）The possible degradation products of gas ClO₂ with benzene or toluene in the gas phase were analyzed by gas chromatography-mass spectrometry（GC-MS）with the following results:a.When gas ClO₂ degrades benzene,the main possible products are n-hexadecane,n-heptadecane,methyl hexadecanoate or methyl 14-methyl pentadecanoate,dibutyl phthalate and n-heptadecanoic acid,and the toxicity of the treated products are all less than that of benzene When gas ClO₂ degrades toluene.The main products produced may be n-hexadecane,n-heptadecane,dibutyl phthalate and n-heptadecyl acetate,which are similar to the products of ClO₂ degradation of benzene,and the products produced are all less toxic than toluene.