Study On The Formation And Influencing Factors Of Chlorophenylacetonitrile As Precursor During Chlor(am)ine Disinfection

Chlorophenylacetonitrile（CPANs）is a new type of nitrogen-containing aromatic disinfection byproducts（DBPs）,which has become a new focus in the field of water treatment and environmental engineering due to its high toxicity and potential biological accumulation.However,at present,the corresponding precursors of CPANs in water bodies are not clear and the detection methods still have problems of poor separation.In this paper,GC-MS is used as the main detection method to optimize the CPANs sample detection method,meanwhile,aromatic amino acids and humic acids in water were used as precursors to study the main precursors of CPANs and the influencing factors of CPANs formation in the process of chlor（am）ination disinfection,so as to provide theoretical and technical support for the development of CPANs control technology.The main work contents and results are as follows:（1）Optimization of GC-MS detection and analysis methods for 2-chlorophenylacetonitrile（2-CPAN）,4-chlorophenylacetonitrile（4-CPAN）,and 3,4-dichlorophenylacetonitrile（3,4-DCPAN）:the detection limit of the method is 0.21ng/L、0.33ng/L and 0.41ng/L,respectively,and the linearity is good in the range of 1～40μg/L（R²>0.999）.The water samples are concentrated by CPANs through blank spiking,solid phase extraction was used for enrichment and GC-MS for detection and analysis,the average recoveries of three kinds of CPANs were 88%～117%,which can meet the requirements of trace CPANs in water samples.（2）Humic acid,Phenylalanine,Tryptophan and Tyrosine were used as precursors to react with chlor（am）ine and test the formation potential of CPANs:the reaction activity of aromatic amino acids with chlor（am）ine is greater than that of humic acid,and the CPANs formation potential is higher than that of humic acid,and the CPANs formation potential of phenylalanine and tryptophan is higher than that of humic acid and tyrosine.Phenylalanine and Tryptophan are important precursors of CPANs.（3）The influencing factors of CPANs formation from four precursors（Humic acid,Phenylalanine,Tryptophan and Tyrosine）during chlor（am）ination disinfection were investigated.The total CPANs generation potential of the four precursors showed a trend of first increasing and then decreasing with the increase of molar ratio.In the chlorination process,the total CPANs formation potential of the four precursors reached the maximum when the molar ratio was 1:2、1:10、1:5 and 1:5,respectively;in the chloramination process,the total CPANs formation potential of the four precursors reached the maximum at the molar ratio of 1:2、1:5、1:2 and 1:5,respectively.In the process of chlor（am）ination disinfection,with the increase of p H value,the total CPANs of the four precursors showed a trend of first increasing and then decreasing,and reached the maximum formation potential under near neutral conditions（p H=7 or 8）.With the extension of chlor（am）ination time,the total CPANs formation potential of the three aromatic amino acids reached the maximum formation potential in 1d,and then decreased gradually.The total CPANs formation of humic acid decreased gradually with the extension of chlorination time,but increased first and then decreased with the extension of chloramination time,the maximum CPANs formation potential was reached at the chloramination time for 3d,and the maximum value was 86.5ng/L.In the process of chlor（am）ination disinfection,pipeline corrosion products Cu O and Fe OOH treatment can inhibit the total CPANs of four precursors;30mg/L SO₄^2-treatment increased the total CPANs formation potential of the four precursors,while 30mg/L NO₃^-treatment had no significant effect on the total CPANs formation of the four precursors.During the disinfection process,neutral conditions,low chlor（am）ine dose and short disinfection time were risk factors for total CPANs production,while Cu O and Fe OOH treatments decreased the potential for total CPANs production.