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炼油行业是我国的支柱产业,据统计,我国每加工1 t原油会产生0.7~3.5 t污水[1]。炼油污水中有机污染物种类多,浓度高,且多为难降解有机物。污水中的溶解性有机物(dissolved organic matters, DOM)的组成及其在水处理过程中的迁移转化一直是水处理研究过程中的重点和难点。DOM成分复杂,其会对体系中金属、胶体等物质在体系中的形成和变化产生影响[2],排入天然水体的DOM会对自然生态产生影响[3]。因此,了解炼化污水中DOM的组成和性质对污水处理和水资源保护有重要的作用[4-5]。
大孔树脂吸附和固相萃取是2种最常用的DOM化学分级分离方法[6]。大孔树脂吸附法一般使用XAD树脂根据DOM的极性和酸碱性将DOM分成不同组分[7-8],但XAD树脂自身有机碳杂质溶出较高,使用前需要进行清洗预处理,操作繁琐耗时长。固相萃取法采用商品化的固相萃取柱对DOM进行分离富集,是近年来快速发展的DOM分离富集方法。与XAD树脂吸附法相比,固相萃取法采用高纯度商品化萃取填料,萃取柱背景溶出低,操作简单,耗时短,同时可供选择的萃取填料种类多,可将DOM分级分离成不同性质的组分。WANG等[9]比较了不同固相萃取填料对城市生活污水处理厂二沉出水中DOM分离的效果,发现不同固相萃取填料对DOM组分选择性不同。单独使用1种SPE材料能分离富集特定性质的DOM组分,但不适于对DOM中不同性质的组分进行全面表征。FANG等[10]将利用Waters Oasis MCX和MAX固相萃取柱串联,将炼油厂污水中DOM分为疏水酸性组分(HOA)、疏水碱性组分(HOB)、疏水中性组分(HON)和亲水物质(HIS)4个组分,该方法所需样品量少,操作简单快捷,可以对DOM中不同性质组分进行全面表征,适合于对DOM组成分离分析。三维荧光光谱(EEM)和傅里叶离子回旋共振质谱(FTICR MS)是DOM组成分析常用的2种高分辨分析方法,三维荧光光谱(EEM)可将水中有机物的进行光谱和组成性质的整体分析,并根据水样特征峰区域将DOM分为不同组分,已经广泛用于水中DOM的组成分析[11];傅里叶离子回旋共振质谱(FT-ICR MS)具有超高质量分辨率和超高质量精确度,可明确DOM的分子式,是分析DOM分子组成的重要手段[12-13],常用于炼油污水中DOM分子组成和转化的表征[14-15]。
本研究利用MCX和MAX固相萃取柱串联的分离提取方法将炼油污水处理厂二沉出水中的DOM分为疏水酸性组分 (hydrophobic acid, HOA) 、疏水碱性组分(hydrophobic base, HOB)、疏水中性组分(hydrophobic neutral, HON)和亲水物质(hydrophilic substance, HIS)4种亚组分,并应用EEM和FT-ICR MS对其进行了组成分析,为炼油污水处理工艺优化和外排水环境影响评估提供科学支撑。
炼油污水处理厂二沉出水中溶解性有机物组分分析
Characterization of four fractions of dissolved organic matters in secondary effluent of refinery wastewater treatment plant
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摘要: 使用MCX/MAX萃取柱对炼油污水处理厂二沉池出水中的溶解性有机物(DOM)进行分离,获得疏水酸性组分(HOA)、疏水碱性组分(HOB)、疏水中性组分(HON)和亲水物质(HIS)4种亚组分。使用三维荧光光谱和电喷雾-傅里叶变换离子回旋共振质谱对各组分进行了组成表征,结果表明:二沉出水中存在酚类物质和石油类物质的特征荧光峰;HOA组分中化合物类型较多,主要为CHOS类物质;HOB组分中检测到的物质较少,主要为O3S1物质;HON组分中有较多的CHOS、CHON和CHO类物质。以上研究结果可为炼油污水处理工艺优化和外排水环境影响评估提供参考。Abstract: The dissolved organic matter (DOM) in the effluent from the secondary effluent of a refinery wastewater treatment plant was separated by MCX/MAX extraction column, and four sub-components including hydrophobic acidic component (HOA), hydrophobic alkaline component (HOB), hydrophobic neutral component (HON) and hydrophilic substance (HIS) were obtained. 3D-EEM and ESI FT-ICR MS were used to analyze each component. The results showed that specific fluorescence peaks of phenolic substances and petroleum substances existed in the refined wastewater, there were more compounds in HOA component, which mainly was CHOS substances; less substances were detected in HOB component, which mainly was O3S1 substances, and more CHOS, CHON and CHO substances were observed in HON component. This study makes an in-depth analysis of DOM in the effluent of refined wastewater, providing a reference for treatment process optimization and environmental impact assessment of external drainage of refinery wastewater.
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Key words:
- refinery wastewater /
- secondary effluent /
- 3D-EEM /
- molecular composition
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表 1 二沉出水中4种DOM组分占比
Table 1. The proportion of four components of DOM in the secondary effluent
组分 TOC/(mg·L−1) 组分占比/% HOA 5.02 17.8 HOB 4.78 16.95 HON 9.21 32.65 HIS 4.86 17.23 -
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