Occurrence of nine nitrosamines and secondary amines in source water and drinking water: Potential of secondary amines as nitrosamine precursors

Due to their high carcinogenicity, the control of nitrosamines, a group of disinfection by-products (DBPs), is an important issue for drinking water supplies. In this study, a method using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry was improved for simultaneously analyzing nine nitrosamines in source water and finished water samples of twelve drinking water treatment plants (DWTPs) in China. The method detection limits of the nine target analytes were 0.2-0.9 ng/L for the source water samples and 0.1-0.7 ng/L for the finished water samples. Of the nine nitrosamines, six (N-nitrosodimethylamine (NDMA), nitrosodiethylamine (NDEA), N-nitrosomorpholine (NMor), N-nitrosodi-n-butylamine (NDBA), N-nitrosomethylethylamine (NMEA), and N-nitrosodiphenylamine (NDPhA)) were detected. The total nitrosamine concentrations in source water and finished water samples were no detection-42.4 ng/L and no detection-26.3 ng/L, respectively, and NDMA (no detection-13.9 ng/L and no detection-20.5 ng/L, respectively) and NDEA (no detection-16.3 ng/L and no detection-14.0 ng/L, respectively) were the most abundant. Meanwhile, the occurrence of nine secondary amines corresponding to the nine nitrosamines was also investigated. All of them except for di-n-propylamine were detected in some source water and finished water samples, and dimethylamine (no detection-3.9 μg/L and no detection-4.0 μg/L, respectively) and diethylamine (no detection-2.4 μg/L and no detection-1.8 μg/L, respectively) were the most abundant ones. Controlled experiments involving chloramination of four secondary amines confirmed that dimethylamine, diethylamine, morpholine and di-n-butylamine in water can form the corresponding nitrosamines, with diethylamine and morpholine showing significantly higher yields than dimethylamine which has already been identified as a precursor of NDMA. This study proved that diethylamine, morpholine and di-n-butylamine detected in raw water would be one of the important the precursors of NDEA, NMOR and NDBA, respectively, in drinking water.     

H_2O_2/O_3体系处理反渗透浓缩垃圾渗滤液

采用H2O2/O3体系处理经反渗透膜处理后的浓缩垃圾渗滤液,比较了H2O2/O3体系和单独H2O2和单独O3处理浓缩液;并考察了体系初始pH值、O3投量、H2O2投量对H2O2/O3体系降解浓缩液的色度、腐殖酸以及COD的去除的影响;以及考察了H2O2/O3体系对浓缩液中大分子的胡敏酸（HA）以及中等分子量的富里酸（FA）的去除,并通过E250/E365（E2/E3）和E240/E420（E2/E4）的变化表征腐殖酸的腐殖度的变化。结果表明：H2O2/O3体系的处理效果远好于单独H2O2和单独O3处理;在pH值为8.0、O3投量为5.02 g/h、H2O2投量为90 mmol/L、反应时间为30 min时,H2O2/O3体系处理浓缩液的色度、腐殖酸和COD的去除率分别达到97.72%、88.85%和74.54%;O3/H2O2氧化体系对HA的去除率高于FA,且经过O3/H2O2氧化体系处理后浓缩液中腐殖酸分子量降低,腐殖化程度降低。     

用有机物分子量分布变化评价不同处理方法去除有机物的效果

本文就不同的净水处理引起的水中有机物分子量分布的变化进行了探讨。混凝处理去除大分子有机物，粉末活性发不仅能有效地去除小分子有机物，对大分子量的有机物也有很好的去除效果。臭氧主要氧化大分子有机物，生物预处理由于微生物新陈代谢产物的影响，没有分子量变化的规律性。根据水源有机物分子量分布和净水处理去除不同分子量有机物的特点，可达到净水处理工艺的最佳组合。     

吗啉副产物的开发利用

以吗啉工业生产中的副产物为原料,采用加压水解法,经分离后,可得到吗啉及混合醇。在210℃,2．0MPa下,水与副产物的质量比为1：1,采用氢氧化钠为催化剂,用量为副产物的1．5％,反应时间为4小时,吗啉的收率可达35％,混合醇的收率可达42％。混合醇可替代乙二醇作为防冻液的主要原料,60％的混合醇水溶液凝固点能达到-40℃以下。     

臭氧预氧化强化煤气废水生化处理研究

煤气废水生物处理出水存在着色度、NH3-N和COD等指标超标的问题,需要进行深度处理。臭氧氧化是一种比较常用的深度处理方法,然而单独依靠臭氧氧化去除废水中的COD和NH3-N需要较高的臭氧投加量,处理成本很高。探讨了臭氧对煤气废水生物处理出水的预氧化效果及其对后续生物处理过程的强化作用。实验表明,臭氧对废水的色度去除很有效,投加<160mg/L的臭氧就可去除90%的色度,废水pH较低时色度去除效果较好;臭氧氧化对废水残留COD有一定的去除作用,不同的pH条件下去除率有差异,总体每mg臭氧可去除0.44～0.64mg的COD;臭氧有效投加质量浓度为240mg/L时,废水COD去除率降低,氧化后出水BOD上升,有利于后续生物处理;臭氧氧化对废水NH3-N的去除效果不明显。对比原水与臭氧氧化出水的分子质量分布特征,发现废水经臭氧氧化后其成分有两种变化趋势,既有一定量的小分子物质产生,又有大分子物质聚合生成,因此臭氧预氧化后续处理工艺应以生物处理为主,同时配合混凝处理工艺。     

金属及其氧化物催化臭氧化反应的研究进展

介绍了金属及其氧化物催化臭氧化降解水中有机物的应用及其反应机理的研究进展；探讨了影响催化剂催化活性和催化臭氧化效率的因素及金属及其氧化物的催化性能；分析了催化臭氧化过程的反应途径。     

柑桔加工下脚料提取类胡萝卜素、橙皮苷、果胶和柠檬苦素

介绍了从柑桔加工下脚料提取类胡萝卜素、橙皮苷、果胶和柠檬苦素类产品的工艺方法 ,并简述了这些产品在医药、食品、日化等方面的应用     

催化臭氧氧化处理渗滤液RO浓液的氧化特性及光谱分析

腐殖质的去除效率是催化臭氧氧化降解垃圾渗滤液RO浓液中有机物的关键,活性炭负载金属铈催化剂（Ce-AC）催化臭氧氧化可有效提高腐殖质的去除效率。本文通过XRD、SEM和EDS等手段对Ce-AC催化剂进行表征,对比不同催化剂催化臭氧氧化对RO浓液COD去除及可生化性的影响,通过降解产物光谱分析明晰腐殖质的降解机制。结果表明,铈氧化物是以CeO₂萤石晶型的形式负载在AC上,负载后的AC比表面积和孔容积减少,平均孔径增加。催化剂Ce-AC对COD和UV₂₅₄的去除效果最好,为44.7%和67.3%,出水可生化性显著提升,B/C比从0.06提升到0.47。紫外-可见光谱表明,体系代表腐殖质的芳香类化合物降解效率明显;三维荧光光谱表明体系中腐殖质类物质被极大程度地降解,荧光区域积分的结果表明腐殖质类物质的去除效率达到了66.7%;傅里叶红外光谱表明腐殖质类物质被氧化分解成了相对小分子的碳水化合物和有机胺、硫和醇等。     

Gallic acid water ozonation using activated carbon

The ozonation of gallic acid in water in the presence of activated carbon has been studied at pH 5. Hydrogen peroxide, ketomalonic and oxalic acids were identified as by-products. The process involves two main periods of reaction. The first period, up to complete disappearance of gallic acid, during which ozonation rates are slightly improved by the presence of activated carbon. The second one, during which activated carbon plays an important role as promoter, and total mineralization of the organic content of the water is achieved. The organic matter removal is due to the sum of contributions of ozone direct reactions and adsorption during the first period and to a free radical mechanism likely involving surface reactions of ozone and hydrogen peroxide on the carbon surface during the second period. There is a third transition period where by-products concentration reach maximum values and ozonation is likely due to both direct and free radical mechanisms involving ozone and adsorption. Discussion on the mechanism and kinetics of the process is also presented both for single ozonation and activated carbon ozonation.     

有机硅低沸物研究进展

概述了有机硅低沸物的特点,介绍了国内外处理有机硅低沸物的主要方法：精馏法和再分配法,试图总结出适合工业化运用的处理有机硅低沸物的方法。