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OH Radical Generation and Reaction in Water Enhanced by Gas-Liquid-Plasma Three Phase Flow

气-液-等离子体三相流增强水中·OH自由基的产生和反应

基本信息

批准号：
18360133
负责人：
YASUOKA KOICHI
金额：
$ 10.27万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18360133/
关键词：
Gas-Liquid Two-Phase Flow OH Radical Dielectric barrier discharge Plasma in Water 難分解物質 LDV

项目摘要

Many types of pulsed electrical discharges in water have been extensively studied for environmental applications, especially for use in the decomposition of persistent materials in drinking water and wastewater treatments. In this study, the plasma-water interactions were enhanced in the mixture phase of gas, liquid and plasma phases. Two types of plasma reactors were developed and the efficient decomposition of persistent material was studied.In reactor (A), pulsed dielectric barrier plasmas are generated in argon, neon or oxygen bubbles of gas-liquid two-phase flow. The flow classified as the Churn flow enabled to enhance the reaction between the pulsed dielectric barrier plasmas and persistent materials especially at the gas-liquid boundaries. The plasma initiated at the center of the bubbles then concentrated at the gas-liquid boundaries. 10-ppm acetic acid as a persistent material was successfully decomposed by repetitive operations up to 10 kHz. The decomposition rate and efficiency of the acetic acid were measured by evaluating the total organic carbon (TOC) concentration of the solution. In reactor (B), bubbles are formed by feeding a small amount of oxygen or argon gases through the tiny hole in the center of a dielectric spacer. The pulsed plasmas were initiated at the tiny hole then extended along the inner surface of argon or oxygen bubbles. The radical formation efficiency depends on the plasma shapes that changed from uniform one to constricted one during the duration of 150 ns. 20 plasmas were generated simultaneously using one exiting circuit and evaluated on the OH generation efficiency by changing the plasma energy densities. Time varying OH radical densities were measured by LIF method using small pulsed streamer plasmas instead. The life time and special distribution of OH revealed the optimum conditions on the surface plasmas generation for efficient production of OH radicals.

许多类型的水中脉冲放电已被广泛研究用于环境应用，特别是用于饮用水和废水处理中持久性物质的分解。在本研究中，等离子体与水的相互作用在气相、液相和等离子体相的混合相中得到增强。开发了两种类型的等离子体反应器，并对持久性物质的高效分解进行了研究。在反应器(A)中，脉冲介质阻挡等离子体在气液两相流的氩气、氖气或氧气泡中产生。搅拌流能够增强脉冲介质阻挡等离子体与持久性物质之间的反应，特别是在气液边界处。等离子体起源于气泡的中心，然后集中在气液边界。10-ppm醋酸作为持久性物质，通过高达10 kHz的重复操作成功分解。通过测定溶液中总有机碳（TOC）浓度来测定乙酸的分解速率和效率。在反应器(B)中，通过电介质间隔器中心的小孔，注入少量氧气或氩气形成气泡。脉冲等离子体从小孔开始，然后沿着氩气或氧气气泡的内表面延伸。自由基形成效率取决于在150ns的时间内等离子体的形状由均匀形状变为收缩形状。利用一个出射电路同时产生20个等离子体，并通过改变等离子体能量密度来评估OH的产生效率。用LIF法代替小脉冲流等离子体测量随时间变化的OH自由基密度。OH的寿命和特殊分布揭示了表面等离子体产生OH自由基的最佳条件。