高压脉冲放电水处理技术的理论研究

为了探讨高压脉冲放电水处理技术的机理及模型,归纳、概括了高压脉冲放电过程中物理效应的形成及其作用、液体介质的击穿机理及击穿模型,还分析了高压脉冲放电过程中发生的化学过程。所得结论为:弧光放电发射的光辐射最强,火花放电次之,流光放电较弱;紫外辐射可把臭氧和过氧化氢分解为氧化性更强的羟基;冲击波可间接引起热解和自由基反应;液体介质的击穿主要可分为电击穿理论、热力(气泡)击穿理论,建立的模型在一定的范围内能准确地预言实验结果;气、液界面发生苯酚降解的化学反应是羟基进攻和臭氧氧化,氧气和氩气导致形成不同的降解副产品,而溶液中的化学过程则主要是羟基进攻。

Theoretical Study on High Voltage Pulse Discharge Technology in Wastewater Treatment

To apply high-voltage electrical discharges to alleviate environmental problems,it is necessary to consider the types of chemical reactions initiated by the discharge and the effects of the physical processes.So the physical effects and functions are induced,the breakdown mechanism and breakdown model of liquid dielectric are summarized and the chemical process in high voltage pulse discharge are analyzed.Luminous radiation of arc discharge is most strong,spark discharge takes the second place and streamer discharge is weak.Ultraviolet radiation can transform ozone and hydrogen peroxide into hydroxide radical.Shock wave can induce pyrolytic reactions and free-radical reactions indirectly.The two general classes of theories are the electrical theories and the theory of thermal bubble formation.These theories are directed mainly toward describing the breakdown mechanisms in the liquid.A thermodynamic model has been developed to account for 13 components in a NaCl water solution at a high temperature and high pressure for a 160J/pulse plasma discharge.The structures of discharge channels formed in the dielectric breakdown of gases,liquids,and at the gas/liquid interface have also been studied using fractal models and Monte Carlo simulations of fractal-type breakdown.These models provide simulations of the branch or treelike structures formed in breakdown processes.In gas-liquid discharge environments,the nature of the gas phase affects the formation of gas-phase species,which,in turn,transfer into the liquid.The major mechanisms for degradation are electrophilic attack by hydroxyl radicals and ozonization on organic contaminants under argon and oxygen atmospheres,respectively.The bulk phase corona-induced chemical reaction for direct pulsed electrical discharge in water is achieved through reaction with hydroxyl radicals.Direct reactions with hydroxyl radicals are usually very fast and not highly specific,in comparison to reactions with ozone.