UV/PS降解水中2,4-二氯苯酚及毒性评价研究

Degradation of 2, 4-dichlorophenol in aqueous solution using UV/PS and toxicity evaluation investigation

比较采用PS,UV/PS 2种工艺降解2,4-DCP的去除效果、一级反应动力学;考察不同氧化剂(PS)剂量、不同初始浓度的2,4-DCP、腐殖酸条件对该光解反应速率常数的影响以及采用发光菌青海弧菌-Q67来评价2,4-DCP和光解过程中间产物溶液对生态环境的毒性评价.实验结果表明,单独PS工艺光解2,4-DCP去除率仅有4%,而UV/PS光解2,4-DCP去除率高达96.4%,充分说明UV/PS工艺可高效去除2,4-DCP,且其反应基本遵循拟一级反应动力学,一级反应动力学常数为35.1×10^(-3)min^(-1).UV/PS降解2,4-DCP的降解率和反应速率常数随着氧化剂(PS)的增加而增大,随着2,4-DCP初始浓度增大而降低.随着腐殖酸初始浓度的增大,有先增大后变小的过程.毒性评价实验中,随着2,4-DCP光解45min,发光菌抑制率降低,溶液对环境毒性在降低,且从长期时间规律来看,同一氧化时间溶液对发光菌相对抑制率与发光菌接触时间没有关系.

The removal effects and the first order reaction kinetics of2,4-DCP with PS and UV/PS were compared,respectively.The effect of oxidant(PS)dosage,different initial2,4-DCP concentration and humic acid on the photolysisreaction were investigated.The vibrio-qinghaiensis sp.–Q67was applied to evaluate the environmental toxicity of2,4-DCP solution and successive transformation products during UV/PS process.The results showed that the removalpercentage of2,4-DCP was only4%for the only PS process,while the degradation percentage reached higher96.4%withUV/PS process,which showed the2,4-DCP was effectively degraded by UV/PS process compared with the PS alone.Meanwhile the pseudo-first-order reaction equation could well describe the2,4-DCP degradation behavior and the kobs(reaction rate constant)was35.1×10-3min-1in UV/PS process.The degradation efficiency and rate constant rate increasedwith the increasing of the oxidant(PS)dosage,decreased with the increase of initial2,4-DCP concentration.Thecoexisting HA promoted the2,4-DCP degradation at the beginning and then gradually inhibited the degradation.Fortoxicity evaluation experiment,Luminescent bacteria inhibition rate decreased with the decrease of concentration of2,4-DCP and the increase of intermediate products,which indicated the reduction of environmental toxicity of the reactionsystem.According to the multiple experimental results,the relative inhibition rate of luminescent bacteria had no relationwith exposure time of luminescent bacteria under the same oxidation time.