کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4486951 | 1317006 | 2005 | 12 صفحه PDF | دانلود رایگان |
Ten chitosan preparations with different molecular weights (MW) and degrees of deacetylation (DD) were tested for coagulation of 5 g L−1 bentonite suspensions at pH 5 and 7 in demineralized water (DW) and in tap water (TW). Coagulation was better in TW than in DW for every condition and lower doses of chitosan were required at pH 5 than at pH 7. More than 95% of residual turbidity (after sedimentation in the absence of chitosan) was removed using less than 0.10 mg L−1 chitosan in either TW or DW at pH 5 or in TW at pH 7. Higher doses were required for removal of turbidity in DW at pH 7, but in all cases the effective concentrations of chitosan were much lower than required for complete neutralization of the negative charge on the bentonite particles. Removal of turbidity was best for the higher MW chitosans in either the B series (89.5% DD) or the C series (95% DD) of chitosans. Overall, the results were consistent with destabilization of bentonite by the combined mechanisms of electrostatic patch and bridging. The improved performance of chitosan in TW could have been due to improved attachment to bentonite due to the presence of sulfate and other counter-ions in TW.
Journal: Water Research - Volume 39, Issue 14, September 2005, Pages 3247–3258