Journal
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
Volume 62, Issue -, Pages 4-12Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ijbiomac.2013.08.009
Keywords
Chitosan; Bentonite suspension; Flocculation; Coagulation; Turbidity; Molecular parameter
Funding
- National Natural Science Foundation of China [41106067]
- Shandong Natural Science Foundation, P.R. China [ZR2010BQ013]
- Fundamental Research Funds for the Central Universities (Ocean University of China) [201013032]
- special Grand National Science & Technology Project of China [2008ZX07106-003-2]
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Chitosans with different degrees of deacetylation (DD) and Molecular weights (M-w) were tested for the flocculation of bentonite suspensions prepared with demineralized water (DW) and tap water (TW), respectively. Flocculation kinetics model of particles collisions combining zeta potential and turbidity measurements was employed to investigate the effects of the DD and M-w of the chitosans on the flocculation properties. The results indicated that the chitosan (M-w 232 kDa) dosages required for maximum flocculation are 20 mg/L in DW and 5 mg/L in TW, respectively, regardless of DD from 54.6% to 95.2% and pH of bentonite suspension. Chitooligomers (M-w 1.5 kDa, DD 95.2%) failed to reach the required residual turbidity (i.e., 10 NTU) in DW under all investigated conditions, whereas good results were obtained using 5-20 mg/L in TW. The polymer-induced flocculation processed obeyed Von Smoluchowski's bimolecular rate equation. The flocculation performance in TW was very different from that in DW due to the presence of salts in TW. The results were consistent with the destabilization of bentonite by the combined mechanisms of charge neutralization and bridging. (C) 2013 Elsevier B.V. All rights reserved.
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