TY - JOUR
T1 - Novel Ion-Exchange Coagulants Remove More Low Molecular Weight Organics than Traditional Coagulants
AU - Zhao, Huazhang
AU - Wang, Lei
AU - Hanigan, David
AU - Westerhoff, Paul
AU - Ni, Jinren
N1 - Funding Information:
The authors are grateful for the financial support from the Major Program of the National Natural Science Foundation of China (Grant No. 91434132), National Natural Science Foundation of China (Grant No. 51378020 and 21077001), the Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-10-0208), and the Collaborative Innovation Center for Regional Environmental Quality. Partial funding was provided from the US Environmental Protection Agency through the STAR program (RD83558001), the Water Research Foundation (Project #4499), and US National Science Foundation (EEC-1449500).
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/4/5
Y1 - 2016/4/5
N2 - Low molecular weight (MW) charged organic matter is poorly removed by conventional coagulants but contributes to disinfection byproduct formation during chlorination of drinking waters. We hypothesized that CIEX, a new Al-based hybrid coagulant with ion-exchange functional groups, would be new mechanistic approach to remove low MW organic matter during coagulation and would perform better than polyaluminum chloride (PACl) or metal-salt based coagulants. We measured coagulation performance using dissolved organic carbon (DOC) in a high hardness surface water. CIEX achieved excellent turbidity removal and removed 20% to 46% more DOC than FeCl3, Al2(SO4)3, or PACl, depending on dose. The improved DOC removal was attributable to better removal of low MW organic matter (<2 kDa). We further studied removal mechanisms in a model water containing a low MW organic acid (salicylic acid (SA)). CIEX achieved high removal of organic acids (>90% of SA) independent of pH, whereas removal by metal salts was lower (<15%) and was strongly pH dependent. CIEX ion-exchange capability is facilitated by its covalently bound quaternary ammonium group, which conventional coagulants lack. Plus, unlike other cationic polymers that react with chloramines to form N-nitrosodimethylamine (NDMA), CIEX has a low molar yield (9.3 × 10-7 mol NDMA per mol CIEX-N). (Chemical Equation Presented).
AB - Low molecular weight (MW) charged organic matter is poorly removed by conventional coagulants but contributes to disinfection byproduct formation during chlorination of drinking waters. We hypothesized that CIEX, a new Al-based hybrid coagulant with ion-exchange functional groups, would be new mechanistic approach to remove low MW organic matter during coagulation and would perform better than polyaluminum chloride (PACl) or metal-salt based coagulants. We measured coagulation performance using dissolved organic carbon (DOC) in a high hardness surface water. CIEX achieved excellent turbidity removal and removed 20% to 46% more DOC than FeCl3, Al2(SO4)3, or PACl, depending on dose. The improved DOC removal was attributable to better removal of low MW organic matter (<2 kDa). We further studied removal mechanisms in a model water containing a low MW organic acid (salicylic acid (SA)). CIEX achieved high removal of organic acids (>90% of SA) independent of pH, whereas removal by metal salts was lower (<15%) and was strongly pH dependent. CIEX ion-exchange capability is facilitated by its covalently bound quaternary ammonium group, which conventional coagulants lack. Plus, unlike other cationic polymers that react with chloramines to form N-nitrosodimethylamine (NDMA), CIEX has a low molar yield (9.3 × 10-7 mol NDMA per mol CIEX-N). (Chemical Equation Presented).
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U2 - 10.1021/acs.est.6b00635
DO - 10.1021/acs.est.6b00635
M3 - Article
C2 - 26974542
AN - SCOPUS:84964220557
SN - 0013-936X
VL - 50
SP - 3897
EP - 3904
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 7
ER -