载氧环境下脉冲放电等离子体修复污染土壤体系中自由基的发射光谱

Study on Emission Spectrum of Radicals in Remediation System of Polluted Soil with Pulsed Discharge Plasma in Oxygen

基于发射光谱检测方法的优越性以及在高级氧化降解体系中·OH和·O的重要作用,本研究采用发射光谱检测技术测定载氧环境下脉冲放电等离子体(pulsed discharge plasma,PDP)修复污染土壤体系中·OH和·O相对发射光谱强度的变化。研究建立了针-网式PDP修复污染土壤体系,利用光谱仪检测该PDP体系在载氧环境下所生成的·OH和·O的相对发射光谱强度。通过对比实验分别考察了不添加土壤、添加原土、添加有机污染土壤和添加有机-重金属复合污染土壤的PDP体系中·OH和·O的相对发射光谱强度变化,同时考察了脉冲峰值电压、电极间距和O2体积流量变化对·OH和·O的相对发射光谱强度的影响。研究结果表明:添加土壤有利于放电的发生,进而提高了PDP体系中·OH和·O的生成;添加有机污染土壤的PDP体系中·OH和·O发射光谱强度较原土体系中低,证明了PDP体系中·OH和·O对有机物的氧化作用;重金属离子的加入对于PDP体系中有机物的降解有积极的促进作用。同时,脉冲峰值电压和O_2体积流量的增加有利于PDP体系中·OH和·O的产生,而电极间距的增加不利于PDP修复污染土壤体系中·OH和·O的生成。本研究在说明PDP用于污染土壤修复体系中·OH和·O的关键作用的基础上,分析了PDP用于污染土壤修复过程中体系主要因素变化对体系中主要自由基含量的影响规律。

Based on the advantage of spectroscopy method and the significant effect of · OH and · O in advanced oxidation degradation system,the change of relative emission spectra intensities of the · OH and the · O in a pulsed discharge plasma（PDP）system bubbled with oxygen were tested by using the spectrum detecting technique in this research.The PDP system with needle-to-net electrode was set up in the paper to remediate the polluted soil.The relative emission spectra intensities of the · OH and the · O formed in the PDP system with oxygen（O_2） bubbling were detected with the spectrograph to illustrate the critical effect of the · OH and the · O on the organic compound degradation in the PDP system.The changes of the relative emission spectra intensities of the · OH and the · O under the conditions of without soil addition,with the original soil addition,with the organic compound polluted soil addition and with the organic compound-heavy metal polluted soil addition were firstly investigated in the paper.The effect of peak pulse voltage,electrode gap and O_2 flow rate on the relative emission spectra intensities of the · OH and the · O were also studied to explain the changing rule of the active species in the PDP system.The obtained results show that the addition of soil are beneficial to the formation of the · OH and the · O in PDP system for the soil remediation.The relative emission spectra intensities of the · OH and the · O in the PDP system with organic compounds polluted soil addition were lower than those in the PDP system with the original soil addition,which proved the oxidation of the · OH and the· O on the organic compounds degradation in the remediation system,and the addition of heavy metal ions were favorable to the degradation of the organic compounds in the PDP system.Furthermore,the increase of the peak pulse voltage as well as the O_2flow rate was in favor of the formation of the · OH and the · O,while the relative emission spectra intensities of the · OH and the · O were lower under the condition of the higher electrode gap,which demonstrated that the higher electrode gap were not in favor of the active species formation.In the study,based on the description of the pivotal role of · OH and the · O in the PDP system for the polluted soil remediation,the influence rule of the main factors during the process of polluted soil remediation in the PDP system on the content of · OH and the · O were analyzed.This research will provide some basic experimental evidence for the application of PDP technology on the polluted soil remediation.