提高液体阴极放电光谱对水体重金属检测性能新方法研究

Liquid cathode glow discharge plasma is a small, low cost and on-line emission spectrum excitation source which has attracted much attention in recent years. However, the detection ability for the heavy metal ions in aqueous solution for liquid cathode glow discharge spectroscopy is relativlye low. Therefore, this project intends to develop the technology of liquid cathode millisecond pulse discharge - atomic emission spectroscopy. The millisecond pulse high voltage power supply will be employed to actuate liquid cathode- metal anode discharge system, and produce millisecond pulse discharge plasma, "electronic heating effect" in the pulse discharge will be used to raise the electron excited temperature of plasma, and promote the efficiencies of atomization and excitation of heavy metal ions, and obtain the high sensitivity detection for heavy metal ions in aqueous solutions. This project will explore the basic characteristics (such as plasma temperature and electron density) and its temporal evolution process of liquid cathode millisecond pulse discharge plasma, and study the dependence between the spectral intensity and the experimental parameters. High-speed imaging technology will be employed to study the time evolution characteristics of millisecond pulse discharge plasma, and reveal migration and excitation mechanism of metal ions, and obtain the method to improve spectral intensity, signal-to-noise ratio and detection sensitivity. The research results will provide experimental basis, technical route and important instrument parameters for developing of metal ion measuring equipment based on liquid cathode discharge spectroscopy.

液体阴极辉光放电等离子体是近几年备受人们关注的小型化、低成本和在线检测的原子发射光谱激发源，然而直流高压驱动的液体阴极放电光谱对重金属的检测性能偏低。为此，本项目拟开展液体阴极毫秒脉冲放电-原子发射光谱技术研究：采用毫秒脉冲高压驱动液体阴极-金属阳极放电系统，产生大气压毫秒脉冲放电等离子体，利用脉冲放电独特的“电子加热效应”提高电子激发温度，促进重金属离子的原子化和激发效率，实现水体重金属离子的高灵敏度检测。本项目将探索液体阴极毫秒脉冲放电等离子体的温度、电子密度等基本特性及其时间演化过程，获得光谱强度与实验参数的关系，采用高速成像技术研究液体阴极毫秒脉冲放电等离子体的时间演化规律，揭示重金属离子的迁移和复合激发机理，获得提高光谱辐射强度、信噪比和检测灵敏度的途径。研究成果将为研发基于液体阴极放电光谱原理的水体金属离子测量设备提供实验依据、技术路线和重要的仪器参数。

液体阴极辉光放电等离子体是近几年备受人们关注的小型化、低成本和在线检测的原子发射光谱激发源，然而直流高压驱动的液体阴极放电光谱对重金属的检测性能偏低。为此，本项目组构建了液体阴极毫秒脉冲放电-原子发射光谱技术级装置，采用毫秒脉冲高压驱动液体阴极-金属阳极放电系统，产生大气压毫秒脉冲放电等离子体，利用脉冲放电独特的“电子加热效应”，激励等离子体对重金属离子的激发，促进重金属离子的原子化和激发效率。实验研究了影响脉冲放电等离子体的因素，获得了稳定放电的电极结构；实验研究了液体阴极毫秒脉冲放电等离子体的电学特征，研究样品流速、电解质种类和浓度等参数以及放电电压、电流和频率对对金属元素发射光谱强度的影响，获得了最佳的光谱探测条件，实现了水体金属离子的痕量检测。研究了液体阴极毫秒脉冲放电等离子体的温度、电子密度等基本特性及其时间演化过程，获得等离子体参数与实验参数的关系，获得了提高光谱辐射强度、信噪比和检测灵敏度的途径。研究成果将为研发基于液体阴极放电光谱原理的水体金属离子测量设备提供实验依据、技术路线和重要的仪器参数。项目执行期间，在国内外期刊上发表学术论文16篇，申请专利12项，参加国内外学术会议3次，培养研究生11名。