Impact of chitosan and polyacrylamide on formation of carbonaceous and nitrogenous disinfection by-products. (July 2017)

• Record Type: Journal Article
• Authors: Li, Zhao; Chen, Ting; Cui, Fuyi; Xie, Yuefeng; Xu, Wenqing
• Is Part Of: Chemosphere. Volume 178(2017)
• Page Start: 26
• Page End: 33
• Publication Date: 2017-07
• Subjects: Disinfection by-products -- NDMA -- Chitosan -- Polyacrylamide -- Quaternary ammonium groups -- Coagulation; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.02.140
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Coagulation is one of the most commonly used practices in water treatment to remove natural organic matter, which can serve as precursors for disinfection by-products (DBPs). Furthermore, some coagulant aids, particularly amine-based polymers, could foster the formation of both carbonaceous and nitrogenous DBPs (C-DBPs and N-DBPs, respectively). In this study, we evaluated the formation potentials of 11 C-DBPs and N-DBPs during chloramination when two coagulant aids, chitosan and polyacrylamide (PAM), were used under typical water treatment conditions. Our results suggest that both chitosan and PAM promote the formation of N-DBPs, while neither affects the formation of C-DBPs. We further investigated a potential method to mitigate the formation of N-DBPs. Methyl iodide (MeI), an alkylating agent, was effective at reducing the formation of N-DBPs by converting amine to quaternary ammonium groups in chitosan. 1 H-NMR results confirmed that the quaternarization reaction did take place. This study reports that chitosan, a natural coagulant, and PAM contribute to the formation of toxic DBPs. More importantly, it provides a preventative strategy for curbing the formation of DBPs through chemical structural modification. Graphical abstract: Highlights: Demonstrated chitosan and PAM promote the formation of N-DBPs as coagulant aids. Modified the chemical structure of chitosan to mitigate the formation of N-DBPs. Suggested a method for reducing DBPs formation, while enhancing coagulation. Advanced our understanding of polymers on DBPs formation in water treatment.