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Method for removing N-nitrosodimethylamine from water
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A dimethylnitrosamine and water removal technology, applied in chemical instruments and methods, water/sewage treatment, reduced water/sewage treatment, etc., can solve problems such as easy oxidation, easy agglomeration, and poor chemical stability of nano-iron particles , to achieve the effects of outstanding safety, high reactivity, and reduced toxicity
Inactive Publication Date: 2012-03-21
TONGJI UNIV
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Problems solved by technology
However, in practical applications, there are also practical problems such as poor chemical stability, easy oxidation, and easy agglomeration of nano-iron particles. Therefore, how to overcome the above problems, improve technical practicability, and enhance the effect of pollutant removal has always been a difficulty in its application. focus
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Embodiment 1
[0031] The concentration of NDMA in deionized water is 1 mg / L, the pH is 5.5, and the catalyst materials of nano-iron and aluminum sulfate are added to carry out the NDMA degradation test. Calculated according to the concentration of substances in water, the dosage of commercial nano-iron is 5g / L, while the dosage of aluminum sulfate is 0mg / L, 50mg / L, 150mg / L, 300mg / L, 450mg / L, 900mg / L Under the condition, the curve of NDMA concentration changing with time is as follows figure 1 shown.
[0032] from figure 1 It can be seen that under the condition of different catalyst dosage, the removal rate of nano-iron to NDMA is different. When the dosage of catalyst aluminum sulfate was 50mg / L, the removal rate of NDMA was 36% in 10h and 81% in 24h. And when the dosage of aluminum sulfate increased to 900mg / L, the removal rate of NDMA was close to 100% after 10h. It can be seen that adding a certain amount of aluminum sulfate catalyst to pure nano-iron can effectively improve the rem...
Embodiment 2
[0034] When the initial concentration of NDMA is 1mg / L and the pH is 5.5, the dosage of aluminum sulfate is 300mg / L, and the dosage of nano-iron after 24 hours of reaction is 0g / L, 1g / L, 2.5g / L, 4g / L NDMA removal rates are 0, 54%, 78%, 81%, 94%, and 98% at L, 6g / L, and 7.5g / L, see figure 2 .
[0035] On the one hand, the increase in the dosage of composite nano-iron increases the concentration of matrix reactants and increases the driving force of the reaction; Under the joint action, the rate of reduction reaction and the removal rate of NDMA are effectively improved.
Embodiment 3
[0037] When the initial concentration of NDMA is 1mg / L, and under normal temperature conditions, the dosage of composite nano iron is 5g / L, and the pH values are 3.03, 4.15, 5.12, 6.23, 7.17, 8.02, 8.95, respectively, the removal of NDMA The rates were 90%, 78%, 93%, 40%, 20%, 3%, and 2%, respectively.
[0038] from image 3 It can be found that adjusting the pH has a decisive impact on improving the removal efficiency of NDMA. Generally, the removal rate of NDMA is very good at low pH, but the removal rate of NDMA at high pH is very low. When the pH is controlled at about 3, 4 or 5, the removal rate of NDMA within 21 hours reaches over 78%, and the reaction effect is the best when the pH is about 5, reaching over 90%.
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Abstract
The invention provides a method for removing a trace amount of a highly-carcinogenic disinfection byproduct N-nitrosodimethylamine (NDMA) from drinking water by catalytic reduction, which is simultaneously applied to the treatment of NDMA-containing industrial wastewater and contaminated ground water and belongs to the field of water treatment application. Specifically, in the method provided by the invention, commercial nano iron is adopted as a reducing agent, a certain amount of water treatment aluminum sulfate is added into reaction solution, a reaction pH range is controlled to be 4 to 7, and the reaction is performed for 10 to 24 hours under oscillation or stirring to fulfill the aim of removing the trace amount of NDMA from the water. The trace amount of NDMA in the water is treated by the method without controlling the dissolved oxygen of the reaction solution, the removal rate can reach over 80 percent and difficulties in effectively degrading the NDMA by oxidization, absorption and membrane filtration are effectively overcome. Products produced by the reaction mainly comprise ammonia nitrogen, ferrous ions and the like, and can be removed by simple aeration, precipitation or the membrane filtration. The method for treating the drinking water is safe.
Description
technical field [0001] The invention relates to a method for removing toxic and harmful organic substances in water, which is suitable for rapid removal of NDMA in drinking water, ground water, surface water and industrial waste water. Background technique [0002] In recent years, a new chlorinated disinfection by-product, Nitrosodimethylamine (NDMA), has been widely detected in drinking water in the United States and Canada, especially in water plants that use combined chlorine disinfection. , even detected in water plants using ion exchange processes. The International Institute of Cancer Research (IARC) has fully proved the carcinogenicity of this substance to the human body through animal experiments, and rated the carcinogenicity level as 2B. The U.S. EPA also lists it as one of the 200 carcinogens, and its carcinogenicity level is 2. Under the condition of exposure concentration of only 0.7ng / L, the theoretical carcinogenic risk coefficient can reach 10-6. Compared ...
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