热活化过硫酸盐高级氧化机理研究及其在造纸废水深度处理中的应用

Study on the Mechanism of Advanced Oxidation of Thermally Activated Persulfate and Its Application in the Advanced of Papermaking Wastewater

关键词:  热活化过硫酸盐  造纸废水  深度处理  COD  自由基

Key Words:TAP  papermaking wastewater  advanced treatment  COD  radicals

摘要:本研究主要探究了热活化过硫酸盐（TAP）氧化法对造纸废水处理的可行性。首先研究温度和初始Na₂S₂O₈浓度对TAP体系的影响得出最优体系；接着讨论无机阳离子和阴离子的存在对TAP体系的影响；随后深入分析TAP体系的氧化机理以及污染物可能的降解途径；最后将TAP体系用于处理实际造纸废水。结果表明，在温度70 ℃和Na₂S₂O₈ 摩尔浓度16 mmol/L的优化条件下，模拟有机造纸废水的COD_Cr在360 min内降解率达84.2%。而基于SO4-·自由基的TAP体系受无机离子影响较小。另外，TAP体系中主要活性物质是∙OH和SO4-·自由基，二者在模拟有机污染物的降解中发挥着主要作用。此外，其他活性自由基在污染物的降解过程中起到辅助作用，如·O2-、¹O₂和有机自由基。通过推测可能的降解途径，模拟有机污染物转化为小分子化合物后，最终被矿化为CO₂和H₂O。将TAP体系应用于实际造纸废水的生化处理出水中，发现在70 ℃和酸性条件下，处理出水的COD_Cr和色度均达到GB 3544—2008排放标准。

Abstract:In this research， the feasibility of thermally activated persulfate （TAP） oxidation for the papermaking wastewater was investigated. The effect of temperature and initial Na₂S₂O₈ concentration on the TAP system was first investigated to achieve the optimal system. This was followed by a discussion of the effect of inorganic cations and anions presence in the system on the TAP system. Then an elaborate analysis of the oxidation mechanism of the TAP system and the possible degradation pathways of the pollutants was carried out. Finally application of the TAP system was used to the actual wastewater. The results showed that the COD_Cr of the simulated wastewater was degraded by 84.2% within 360 min under the optimized conditions of 70 ℃ and Na₂S₂O₈ 16 mmol/L. The efficiency of SO4-· radical based TAP system was less affected by inorganic ions. In addition， the main active substances in the TAP system were the ∙OH and SO4-· radicals， both of which plaied a major role in the degradation of organic pollutants in simulated wastewater. Besides， other reactive radicals plaied a supporting role in the degradation of pollutants， such as ·O2-， ¹O₂ and organic radicals. Then， the simulated organic pollutants were converted into small molecule compounds that ere eventually mineralised into CO₂ and H₂O by speculating on the possible degradation pathway. The TAP system was applied to the treatment of biochemical treatment effluent of actual wastewater and it was found that the COD_Cr and colority of the treated effluent met the GB 3544—2008 discharge standard at 70 ℃ and under acidic conditions.