新型液滴喷雾质谱法对醌类化合物活化过硫酸盐机理的研究

Persulfate oxidation technology as a novel advanced oxidation process developed rapidly in recent years and it shows a good application prospect in pollution control and environmental restoration. Natural organic compounds (i.e. quinone moieties in humic acid) activation persulfate has attracted much attention because of its low cost, low contamination and good application potential for in situ chemical oxidation. However，the activation reaction paths and mechanism by quinones are still unclear. The primary goal of this project is to utilize Droplet Spray Ionization (DSI) as an ion source to establish an ion dissociation mass spectral method (DSI-MS) and, based on this method, the mechanism of persulfate activation by quinones will be investigated in depth. By DSI-MS, the in situ analysis and real-time monitoring of chemical reaction could be conducted to detect various reaction intermediates, confirm active species and their role, and research the mechanism of persulfate activation by quinones and degradation mechanism of the organic contaminatants in the system. In a DSI source, a high voltage is applied directly to the droplet containing the analyte of interest, which creats strong electric fields within the interface of the mass spectrometer, and then an electrospray is generated to achieve ionization of the analyte. In conventional methods, the reaction solution usually is transported by capillary to an ESI source and this leads to a delay between the start of a reaction and when that reaction can be analysed. Fortunately, DSI overcomes the drawback. In this project, a novel and powerful technology is developed for the mechanism research of persulfate activation. This project aim to clarify the mechanism of the activation of persulfate by quinones. This research will provide useful information for the improvement of reaction efficiency and persulfate activation path. This project will further promote the development and application of persulfate oxidation technology in situ chemical oxidation of organic contaminants in soils, sediments, and groundwater, and the treatment of special waste water.

过硫酸盐高级氧化技术近年来在污染物控制和环境修复中展现了广阔的应用前景。天然有机质（如腐殖酸中含醌结构有机物）活化过硫酸盐具有成本低、环境污染小以及原位修复潜力大等优势，而备受关注，但目前醌类化合物活化过硫酸盐的反应机理尚不明确。本项目拟采用新型液滴喷雾离子源，建立液滴喷雾质谱分析法，并采用该方法对醌类化合物活化过硫酸盐的反应过程进行实时、原位监测，深入研究该反应的反应机理及其降解污染物的机制。新型液滴喷雾离子源是在待测物液滴上直接施加高压，与质谱接口形成强电场，直接实现液滴的电喷雾电离，避免了常规质谱法因需液体传输导致的反应监测延迟问题。本项目提出了研究过硫酸盐活化机理的新技术手段，旨在解决醌类化合物/过硫酸盐反应机理不明确的问题，为建立高效环保的过硫酸盐活化方式、提高反应效率和技术改进提供理论依据，为拓展过硫酸盐在原位修复土壤和水处理中的应用奠定基础。

过硫酸盐高级氧化技术近年来在污染物控制和环境修复中展现了广阔的应用前景。天然有机质（如腐殖酸中含醌结构有机物）活化过硫酸盐具有成本低、环境污染小以及原位修复潜力大等优势，而备受关注，但目前醌类化合物活化过硫酸盐的反应机理尚不明确。针对上述问题，本项目基于新型液滴喷雾离子源（Droplet Spray Ionization, DSI），建立液滴喷雾质谱分析法（DSI-MS），并采用该方法对醌类化合物活化过硫酸盐的反应过程进行实时、原位监测，捕获和解析了关键反应中间体，研究了醌类化合物活化过硫酸盐的反应机理以及该体系降解污染物的机制。DSI是在待测物液滴上直接施加高压，与质谱接口形成强电场，直接实现液滴的电喷雾电离，避免了常规质谱法因需液体传输导致的反应监测延迟问题。基于DSI-MS，实时分析了不同醌类化合物活化过一硫酸盐（PMS）机制，研究发现不同醌类化合物活化PMS均形成了单线态氧（1O2）。捕获了活化PMS形成的中间体，结合MS/MS、同位素和高精度质量数解析了中间体结构, 结果表明，不同醌类化合物活化PMS机理一致，即醌类化合物的C=O可视为酮类结构，PMS与醌类化合物羧基碳原子发生亲核加成形成加合中间体，在碱性条件下转化为共轭碱，经分子内亲核取代形成类双环氧乙烷结构中间体。该中间体在SO52-的亲核攻击下重新形成醌类，并释放出1O2用于污染物降解。本项目的开展为高级氧化技术机理的研究提供了新的技术手段，解决了醌类化合物/过硫酸盐的反应机理不明确的问题，为建立高效环保的过硫酸盐活化方式、提高反应效率和技术改进提供理论依据，为拓展基于过硫酸盐的高级氧化技术在原位修复土壤和水处理中的应用奠定基础。