摘要
有效去除水溶性有机质(DOM)是废水处理的一项重要内容,但DOM分子组成及其在处理过程中的变化规律并不明确。本文以一整套煤焦化废水为研究对象,通过液-液萃取和固相萃取分离得到不同极性的水相有机质组分,使用傅里叶变换离子回旋共振质谱(FT-ICR MS)对所得的有机质进行分子层次表征。油相和水相有机质的水溶性总有机碳(TOC)比例基本一致,随着处理过程的进行,废水的“油性”越来越弱,能溶解在二氯甲烷中的有机质越来越少,最后所剩的主要是一些难以降解的腐殖质类物质;而水相有机质具有极其复杂的分子组成,在单一质谱图中共鉴定出70余种不同种类的化合物,这些化合物,尤其是O_(4)S_(1)类化合物,虽然在废水处理过程中有很好的去除效果,但在最终出水中仍有残留。
Efficient removal of dissolved organic matter(DOM) is an important task for wastewater treatment.However,the molecular composition of DOM and its transformation during the treatment are still unclear.In this paper,the organic components in the stream of a coal coking wastewater treatment process were studied.The wastewater was extracted by dichloromethane(CH_(2)Cl_(2)),the extract was named as 'oil phase'.Then the raffinate was extracted by solid-phase extraction,the extract was named as 'water phase'.The ratios of total organic carbon contents(TOC) in the oil and water phase samples were generally consistent during the treatment process.The extracted DOM was characterized by Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS).Eight class species were as assigned from the mass spectra,namely N_(1)O_(1-7),N_(2)O_(1-6),N_(1)O_5,N_(1)O_(2-6)S_(1),N_(2)O_(3-5)S_(1),O_(2-8),O_(2-6)S_(1),O_(4-5)S_(2).The class categories which contain multiple oxygen atoms(O_(x)) and both multiple oxygen and sulfur atoms(O_(x)S_(y)) were dominant in the oil phase.The relative abundance of each species was decreased sharply after the first aerobic biological process,which was consistent with the TOC rapid decline in the sample.O_(2-8) compounds existed in all wastewater samples and dominated in the final sample,indicating that these compounds were the most stubborn pollutants which were difficult to remove in all treatment processes.It is speculated that these compounds may come from some humic-acids which have complex structure and multiple oxygen atoms naturally existing in natural water.The composition of O_(3) class species showed two patterns among the wastewater treatment process,compounds with high double bond equivalent(DBE) were dominant in the first four processes,while a proliferation of low DBE components was observed in the last three samples.It indicated that those low DBE components were generated by the oxidation of other substances,such as O_(1) and O_(2) species.The water phase organic matter had an extremely complex molecular composition and a total of 27 different compound class species were identified in a single mass spectrum.O_(x),O_(x)S_(1-2) and N_(x)O_(y)S_(1-2) were the major class categories in water phase.On the whole,O_(x)S_(1-2) was much easier than the other two categories to be removed during the wastewater treatment process.In the O_(x)S_(1-2) class category,O_(4)S_(1) had a much higher relative abundance than other species.It decreased sharply among the process,but it still accounted for a large proportion in the final process,which implied the O_(4)S_(1) species had strong resistance to removal.The relative abundances of each species in N_(x)O_(y)S_(1-2) had consistent composition and transformation,and could be effectively removed after the wastewater treatment process.The composition transformation trend of O_(6)S_(1) was similar to N_(1)O_(6)S_(1),those compounds with low DBE value(5-12) and low carbon number(10-20) were dominated after the aerobic biological process section and remained in the final process.The study of DOM in coal coking wastewater treatment from the molecular level by FT-ICR MS will contribute to understand the transformation law of pollutant compounds.However,limited by the mass spectrometry,only the molecular composition information can be obtained.The molecular structure information,especially for the functional groups,is hard to be obtained.In order to research the transformations law of pollutant compounds for further,the structural information needs to be deduced combining the molecular composition,the precursor and the polarity of wastewater pollutants.Developing more efficient and advanced separation and enrichment methods is another way to research the molecular structure information.By the further work,a fully understand of the pollutant composition will be obtained,and a more effective wastewater treatment process will be developed.
作者
马超
吴建勋
倪洪星
房治
王威
高源
史权
MA Chao;WU Jian-xun;NI Hong-xing;FANG Zhi;WANG Wei;GAO Yuan;SHI Quan(School of Earth System Science,Tianjin University,Tianjin 300072,China;State Key Laboratory of Heavy Oil,China University of Petroleum,Beijing 102249,China;Sinochem Asset Management Co.,Ltd.,Beijing 100045,China;State Key Laboratory of Environmental and Biological Analysis,Hong Kong Baptist University,Hong Kong 999077,China)
出处
《质谱学报》
EI
CAS
CSCD
北大核心
2023年第3期387-396,I0003,共11页
Journal of Chinese Mass Spectrometry Society
