氧化剂去除藻毒素BMAA的效能及其影响因素研究
发布时间：2018-08-06 19:57
【摘要】：β-N-甲氨基-L-丙氨酸(BMAA)是一种新近发现的藻毒素,可能是肌萎缩性脊髓侧索硬化症(ALS)和帕金森症的重要诱因。有报道称绝大多数蓝藻能够分泌该种毒素,并且在世界各地的水体及水产品中均有检出。当前我国很多地区水源面临着严重的富营养化问题,其伴生的BMAA问题可能对城镇居民饮用水安全和身心健康构成严重的威胁。然而目前有关BMAA的水处理研究尚鲜见报道,现有水处理工艺能否去除BMAA以及如何安全有效去除BMAA是当前亟待解决的问题,对于提高供水水质、保障供水安全有着十分重要的意义。针对上述问题,本研究以净水厂常规氧化技术为基础,研究了典型氧化剂次氯酸钠和臭氧对于BMAA的氧化效果,考察了氧化剂初始浓度、温度、pH值等不同条件对BMAA去除效果的影响,同时对次氯酸钠和臭氧氧化BMAA的氧化产物和氧化路径进行探究。次氯酸钠氧化BMAA的研究表明,次氯酸钠氧化BMAA的反应符合二级反应动力学模型,二级反应动力学常数为697.6 L·mol-1min-1。温度越高,次氯酸钠氧化BMAA反应速率常数越大,进行Arrhenius和Eyring方程拟合得到反应活化能为16.639kJ/mol,?H*为14.106kJ/mol,?S*为142.250 J/molK。pH值对次氯酸钠氧化BMAA影响显著,酸性条件下,次氯酸钠氧化BMAA的效果最好。臭氧对BMAA的去除主要是臭氧直接氧化作用,反应2分钟去除率即可达到95%以上。臭氧初始浓度越高,臭氧氧化去除BMAA反应越快,臭氧浓度足够高时BMAA去除率可达99%,同时一定的臭氧剩余量可保证BMAA的完全去除。不同pH值条件下,臭氧氧化BMAA主要与BMAA在pH值条件下存在形式有关,中性条件下氧化效果最好,反应1分钟去除率即可达97%。低温条件有利于臭氧氧化去除BMAA,反应30s低温条件BMAA去除率比高温条件高7.3%,侧面验证臭氧对BMAA的去除主要是臭氧直接氧化作用。次氯酸钠氧化BMAA过程中,发现7种氧化产物。他们的质核比分别为88(Ⅰ)、153(Ⅰ)、153(Ⅰ)、187(Ⅳ)、187(Ⅴ)、108(Ⅵ)和71(Ⅶ)。次氯酸钠对BMAA的氧化路径主要包括(1)氯的取代,产生质核比为153(Ⅰ)、153(Ⅰ)、187(Ⅳ)和187(Ⅴ)的氯代物;(2)脱羧基,产生质核比为108(Ⅵ)和71(Ⅶ)的产物;(3)N-C键氧化断裂,产生质核比为88(Ⅰ)的产物。臭氧氧化BMAA过程中发现3种产物。他们的质核比分别为105(Ⅰ)、91(Ⅱ)、88(Ⅲ),臭氧对BMAA的氧化路径主要是C-N键的氧化断裂,产生质核比为105(Ⅰ)、91(Ⅱ)、88(Ⅲ)的氧化产物。本研究考察了两种氧化剂在不同条件下对BMAA的去除效能,为饮用水中BMAA的去除提供了理论基础。综合对比发现臭氧对BMAA氧化去除效果明显优于次氯酸钠,反应迅速、去除效果好且矿化度高,更适用于去除BMAA。
[Abstract]:尾 -N-methylamino-L-alanine (BMAA) is a newly discovered alga toxin, which may be an important cause of (ALS) and Parkinson's disease in amyotrophic lateral sclerosis. Most cyanobacteria are reported to secrete the toxin and are detected in water and aquatic products around the world. At present, many water sources in China are facing serious eutrophication problems, and the associated BMAA problem may pose a serious threat to the safety of drinking water and the physical and mental health of urban residents. However, there are few reports on water treatment of BMAA. Whether the existing water treatment process can remove BMAA and how to remove BMAA safely and effectively is an urgent problem to be solved, and it is necessary to improve the quality of water supply. It is of great significance to ensure the safety of water supply. To solve the above problems, the oxidation effect of typical oxidant sodium hypochlorite and ozone on BMAA was studied on the basis of conventional oxidation technology in water purification plant, and the initial concentration of oxidant was investigated. The effects of temperature and pH value on the removal efficiency of BMAA were investigated. The oxidation products and oxidation paths of BMAA by sodium hypochlorite and ozone oxidation were investigated. The study on the oxidation of BMAA by sodium hypochlorite shows that the reaction of BMAA oxidized by sodium hypochlorite accords with the second-order reaction kinetic model, and the kinetic constant of the second-order reaction is 697.6 L mol -1 min -1. The higher the temperature, the greater the rate constant of BMAA oxidation of sodium hypochlorite. By fitting the Arrhenius and Eyring equation, the activation energy of the reaction is 16.639kJ / mol 路mol ~ (-1) H * = 14.106kJ / mol ~ (-1) S *, and the value of 142.250 J/molK.pH has a significant effect on the oxidation of BMAA by sodium hypochlorite, and the effect of BMAA oxidation by sodium hypochlorite is the best under acidic conditions. The removal of BMAA by ozone was mainly caused by direct ozonation, and the removal rate of BMAA in 2 minutes was over 95%. The higher the initial concentration of ozone, the faster the reaction of BMAA removal by ozone oxidation. When the ozone concentration is high enough, the removal rate of BMAA can reach 99%, and a certain amount of ozone surplus can ensure the complete removal of BMAA. Under different pH conditions, ozone oxidation of BMAA was mainly related to the existence of BMAA at pH value. The oxidation effect was best under neutral conditions, and the removal rate of BMAA reached 97% in 1 minute reaction. The removal rate of BMAA at low temperature for 30s was higher than that at high temperature. It was verified that the removal of BMAA by ozone was mainly direct ozonation. Seven oxidation products were found during the oxidation of BMAA by sodium hypochlorite. Their ratio of plasma to nucleus is 88 (鈪，
本文编号：2168829
[Abstract]:尾 -N-methylamino-L-alanine (BMAA) is a newly discovered alga toxin, which may be an important cause of (ALS) and Parkinson's disease in amyotrophic lateral sclerosis. Most cyanobacteria are reported to secrete the toxin and are detected in water and aquatic products around the world. At present, many water sources in China are facing serious eutrophication problems, and the associated BMAA problem may pose a serious threat to the safety of drinking water and the physical and mental health of urban residents. However, there are few reports on water treatment of BMAA. Whether the existing water treatment process can remove BMAA and how to remove BMAA safely and effectively is an urgent problem to be solved, and it is necessary to improve the quality of water supply. It is of great significance to ensure the safety of water supply. To solve the above problems, the oxidation effect of typical oxidant sodium hypochlorite and ozone on BMAA was studied on the basis of conventional oxidation technology in water purification plant, and the initial concentration of oxidant was investigated. The effects of temperature and pH value on the removal efficiency of BMAA were investigated. The oxidation products and oxidation paths of BMAA by sodium hypochlorite and ozone oxidation were investigated. The study on the oxidation of BMAA by sodium hypochlorite shows that the reaction of BMAA oxidized by sodium hypochlorite accords with the second-order reaction kinetic model, and the kinetic constant of the second-order reaction is 697.6 L mol -1 min -1. The higher the temperature, the greater the rate constant of BMAA oxidation of sodium hypochlorite. By fitting the Arrhenius and Eyring equation, the activation energy of the reaction is 16.639kJ / mol 路mol ~ (-1) H * = 14.106kJ / mol ~ (-1) S *, and the value of 142.250 J/molK.pH has a significant effect on the oxidation of BMAA by sodium hypochlorite, and the effect of BMAA oxidation by sodium hypochlorite is the best under acidic conditions. The removal of BMAA by ozone was mainly caused by direct ozonation, and the removal rate of BMAA in 2 minutes was over 95%. The higher the initial concentration of ozone, the faster the reaction of BMAA removal by ozone oxidation. When the ozone concentration is high enough, the removal rate of BMAA can reach 99%, and a certain amount of ozone surplus can ensure the complete removal of BMAA. Under different pH conditions, ozone oxidation of BMAA was mainly related to the existence of BMAA at pH value. The oxidation effect was best under neutral conditions, and the removal rate of BMAA reached 97% in 1 minute reaction. The removal rate of BMAA at low temperature for 30s was higher than that at high temperature. It was verified that the removal of BMAA by ozone was mainly direct ozonation. Seven oxidation products were found during the oxidation of BMAA by sodium hypochlorite. Their ratio of plasma to nucleus is 88 (鈪，
本文编号：2168829
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