Catalytic Degradation Of Crylonitrile By An Bacteria And Acf

Effective treatment of acrylonitrile wastewater is difficult to study at present for widely used, high toxicity and refractory. In the paper a strain of Arthrobacter nitroguajacolicus ZJUTB06-99bacteria, or AN bacteria for short, was used to study the effect of catalytic degradation of acrylonitrile by AN bacteria, the physical adsorption of acrylonitrile by activated carbon fibre and catalytic degradation of acrylonitrile wastewater by AN bacteria and ACF.Firstly, comparing the headspace gas chromatography, HP-FFAP capillary column gas chromatography can separate acrylonitrile and acrylic acid completely within three minutes and have good linearity, accuracy and precision.Influences of reaction conditions on AN bacteria catalytic degradation of acrylonitrile were also evaluated. It was indicated that when the initial acrylonitrile concentration was high, it would cause the inhibition of nitrilase enzyme activity and reduction of the reaction rate. Increasing the cell concentration could improve the degradation rate and reduce the specific enzyme activity. The optimum temperature and pH value was35℃and pH8-9, respectively. The accumulation of acrylic acid made the degradation rate lower and the cell viability could be suppressed when its concentration was higher than200mg/L. It fit the Arrhenuish equation between25-35℃, the apparent activation energy Ea was30.78kJ/mol. By study the kinetics of substrate concentration on the degradation of acrylonitrile the Michaelis constant Km was5.18g/L and the maximum reaction velocity of Vm was5.376mg/(L·min).In the experiment, the adsorption of acrylonitrile by the activated carbon fiber could be completed within60minutes. The adsorption capacity increase but the adsorption rate decreased with acrylonitrile concentration. As pH increases the adsorption capacity decreased and the acidic environment was good for adsorption. The adsorption capacity of activated carbon fiber was better at room-temperature. While in the AN bacteria-ACF coupled system, the capacity of adsorption and the degradation by AN bacteria had improved with the acrylonitrile concentration, but the total removal rate decreased. When the cell concentration increased the degradation by AN bacteria play a leading role so that the total removal rate increased. The optimum temperature and pH was40℃and7, respectively. ACF adsorption acrylonitrile was the physical process and AN bacteria catalytic degradation of acrylonitrile to acrylic acid by the role of nitrilase.