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Novel Ion-Exchange Coagulants Remove More Low Molecular Weight Organics than Traditional Coagulants.
- Source :
-
Environmental Science & Technology . 4/5/2016, Vol. 50 Issue 7, p3897-3904. 8p. - Publication Year :
- 2016
-
Abstract
- 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 x 10-7 mol NDMA per mol CIEX-N). [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0013936X
- Volume :
- 50
- Issue :
- 7
- Database :
- Academic Search Index
- Journal :
- Environmental Science & Technology
- Publication Type :
- Academic Journal
- Accession number :
- 114698534
- Full Text :
- https://doi.org/10.1021/acs.est.6b00635