Abstract:

The mechanism of catalytic oxidation degradation of organics in high salt wastewater of coal chemical industry by ozone was studied. Firstly, the high-salt wastewater of a typical coal chemical enterprises in China was collected, and the composition and content of various salt ions in the water were determined. Secondly, the effects of different active components on the efficiency of ozone catalytic oxidation were studied to screen the best ozone catalyst. Characterization analysis was carried out on the ozone catalyst to determine the apparent morphology, element composition and active component loading of the catalyst. Finally, the simulated water sample with formic acid was used to study the action mode of ozone catalytic oxidation, the change of ozone attenuation rate, the change of hydroxyl radical(·OH), H₂O₂ and superoxide radical (·O₂^-) to reveal the action mechanism and reaction process of ozone catalytic oxidation. The results showed that the cations of the high-salt wastewater from coal chemical industry were mainly sodium ions, followed by potassium ion, calcium ion, and magnesium ion. The anions were mainly chloride ions and sulfate ions, followed by nitrate ions. By studying the effect of different active components on the ozone catalytic oxidation efficiency, we found the best catalyst was SiO₂/Al₂O₃-Fe₂O₃. The characterization analysis of the catalyst showed that the catalyst's support was SiO₂/Al₂O₃, and iron was loaded on the support as the active component. Through the degradation mechanism study, it was found that the process of ozone catalytic oxidation followed the action mechanism of hydroxyl radical. i.e. O₃ produced hydroxyl radical through attenuation, and the addition of the catalyst promoted the formation of ·OH. The amount of H₂O₂ produced during the reaction was related to·OH. The more·OH, the more H₂O₂ was produced, but the production of·O₂^- was not related to·OH.

Key words: high salt wastewater of coal chemical industry, ozone catalytic oxidation, catalyst, characterization analysis, degradation mechanism

摘要：

研究了臭氧催化氧化降解煤化工高盐废水有机物的机理。实验采集了国内典型煤化工企业高盐废水，明确了水中盐离子的组成及含量；制备高盐性臭氧催化剂，研究了不同活性组分对臭氧催化氧化效率的影响，确定了最佳的臭氧催化剂；对臭氧催化剂开展表征分析，明确催化剂表观形貌、元素组成及负载情况；最后采用甲酸模拟水样，研究臭氧催化氧化作用方式、臭氧衰减率变化、羟基自由基（·OH）变化、H₂O₂变化及超氧自由基（·O₂^-）变化，明确臭氧催化氧化作用机理及反应历程。结果表明：煤化工高盐废水阳离子主要为钠离子，其次是钾离子、钙离子、镁离子；阴离子主要为氯离子、硫酸根，其次是硝酸根离子；通过研究不同活性组分对臭氧催化氧化效率确定最佳催化剂为SiO₂/Al₂O₃-Fe₂O₃。对催化剂开展表征分析发现：催化剂载体为硅铝复合氧化物，铁作为活性组分均匀负载于载体上。臭氧催化氧化降解机理研究发现：臭氧催化氧化过程遵从羟基自由基作用机理，O₃通过衰减产生羟基自由基，而催化剂的加入促进了·OH生成；反应过程中产生的H₂O₂量与·?OH有关，·?OH越多，H₂O₂产生量越多，但·O₂^-的产生与·OH没关系。

关键词: 煤化工高盐废水, 臭氧催化氧化, 催化剂, 表征分析, 降解机理