电催化臭氧技术去除高盐废液中有机物

Enhanced removal of refractory organic pollutants from high-salinity mining wastewater by E-peroxone process

  • 摘要: 矿井水高盐废液产生于废水零排放过程,由于其成分复杂,有机物含量高,其处理已成为世界性难题,研发高盐废液中有机物高效脱除技术迫在眉睫。电催化臭氧技术作为一项新型高级氧化技术,具有高效、灵活、环境友好的特点,为高盐废液中有机物深度脱除提供了一种颇具前景的技术选择。基于此,首先采用气相色谱−质谱联用仪(GC-MS)对西部某矿区矿井水高盐废液中的有机物进行了解析,共检测到15种有机物,可分为大环硅氧烷、酯类、腈类和酰胺类,其中邻苯二甲酸二甲酯(DMP)这种酯类化合物显示出很强的峰信号,峰面积占比20.38%。因此,DMP被选作矿井水高盐废液中的特征污染物,用于电催化臭氧技术的去除动力学和反应机理研究,在此基础上进一步探究电催化臭氧技术处理实际高盐废液的技术和经济可行性。结果表明:DMP由于其较低的臭氧反应活性,很难被常规臭氧技术高效去除。而电催化臭氧技术通过将电化学原位产过氧化氢与臭氧技术耦合,可以将反应体系中的羟基自由基(OH)浓度提升1个数量级,因此可以明显加速和强化废水中特征污染物DMP的去除。理论计算显示:OH进攻DMP的优势活性位点是苯环上的C4和C8点位,与检测出的降解产物结果一致。在实际矿井水高盐废液处理方面,电催化臭氧技术相较传统电化学和臭氧技术,显示出最高的有机物矿化效率和最低的能量消耗,初步论证了该技术在高盐废水有机物深度脱除方面的技术和经济可行性,展示出良好的应用前景。

     

    Abstract: High-salinity mining wastewater is produced in the process of zero discharge. Due to its complex composition and high organic concentration, its treatment has become a worldwide problem. Hence, it is urgent to develop efficient technologies to remove refractory organics from high-salinity wastewater. E-peroxone process is a novel advanced oxidation process, and its advantages of high efficiency, good flexibility, and environmental friendliness make it a promising technical option for deep removal of organics from high-salinity wastewater. In term of this, this study firstly analyzed organic compounds in a high-salinity mining wastewater from western China with gas chromatography-mass spectrometry (GC-MS). A total of 15 organic compounds were detected, and they can be divided into three species, that is, macrocyclic siloxanes, esters, and nitriles and amides. Among them, dimethyl phthalate (DMP), an ester compound, showed a high peak signal, with its peak area accounting for 20.38%. Hence, DMP was selected as the characteristic compound of the high-salinity mining wastewater to investigate its removal kinetics and reaction mechanism in the E-peroxone process, based on which the technical and economic feasibility of E-peroxone process for the treatment of practical high-salinity wastewater was further explored. Results show that DMP was difficult to be efficiently removed by conventional ozonation due to its relatively low ozone reactivity. In contrast, by electrochemically in-situ generating hydrogen peroxide in conventional ozonation, the E-peroxone process obviously increased the hydroxyl radical (OH) concentration in the reaction system by 1 order of magnitude, and thus significantly accelerated and enhanced the removal of DMP in the solution. Further theoretical calculations show that the C4 and C8 sites on the benzene ring of DMP are the dominant reaction sites for OH attack, and transformation products of this reaction pathway were also detected. For the treatment of practical high-salinity mining wastewater, the E-peroxone process also exhibited the highest organic mineralization efficiency and the lowest energy consumption compared with conventional electrolysis and ozonation. Therefore, the results of this study demonstrated the technical and economic feasibility of the E-peroxone process for deep removal of organics from high-salinity wastewater, showing a promising application potential.

     

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