The Nitrogenous Disinfection By-Products Formation Of Amino Acids In Water Environment

Along with economic development and the increasing population of our country, the handunds of thousands pollutants produced by human and life emissions have continued into the environment. Kinds of pollutants enter into water environment in different ways, pollutants and its disinfection by-products generated in the treatment process have a potential impact. Disinfection by-products is one of the most important pollutant, and the study of halohydrocarbons. On the basis of nitrogenous disinfection by-products, this paper presents study on the chlorination by-products of the organic nitrogen pollutants(amino acids) as precursors, because some have unpleasant smell. It can deteriorated quality of drinking water severely in many aspects.Solid phase extraction combined with high-performance liquid chromatography were used to quanlify five amino acids in water. The linearity and precision of this method was well, the recoveries of His, Pro, Ile, Leu and Lys reached 85.2%, 95.1%, 70.2%, 79.6% and 97.1%, respectively. Amino acids in raw water were determined with SPE-HPLC for water treatment plant in Hangzhou. Results showed that three amino acid Pro, Ile, Leu were detected as concentration of 5.17, 1.23 and 6.45μg/L, respectively in three raw water of waterworks drawed from Qiantang River. For Xiangfu waterworks, the concentrations were 5.17, 1.23 and 6.45μg/L, respectively.Amino acids, in water enviroment, can produce some kinds of disinfection by products in the process of chlorination disinfection. Using GC-MS and HPLC-MS, chlorination of Lys can induce chloropyridine and dichloropyridine. Lys reacts with chlorine to produce intermediate products glutaraldehyde and imine through a series of reactions, such as replacing, decarboxylation, hydrolyzation, both of which can react with each other to produce chloropyridine and dichloropyridine. Chloronation of Phe can induce chlorophenylacetaldimine, phenylacetaldehyde, 2,6-diphenylpyridine. Amongthem, N-chlorophenylacetaldimine suspected the odor substance is a smelling disinfection by-products. Phe reacts with chlorine to produce N-chlorophenylalanine and N-dichlorophenylalanine, which can decompose and transform to phenylacetaldehyde. N-dichlorophenylalanine can also produce N-chlorophenylacetaldimine. While when phenylacetaldehyde and N-chlorophenylacetaldimine exist simutenously, they react with each other by a series of complex reaction, like condensation reaction, to form 2,6-diphenylpyridine. Chlorination of amino aicid will produce corresponding nitrile, aldehye and imine byproducts. The imine is to be suspected the smelling disinfection by-products.Taking Lys for example, the influence on production of the disinfection by-products such as pH, reaction time, chlorine concentration, amino acid concentration, UV light were investigation. The results shows that with the increase of concentration of available chloropyridine, the formation of dichloropyridine increased firstly and then decreased. pH, reaction time, amino acid concentration, UV illumination had great effect on the formation of two disinfection by-products. As the the four factors varied, their production showed variation along with.