壳聚糖接枝三元共聚阳离子絮凝剂对高岭土悬浊液的絮凝特性

采用烧杯混凝实验研究了壳聚糖(CTS)、CTS与丙烯酰胺和丙烯酸乙酯季铵盐三元接枝共聚阳离子絮凝剂(CAS)对高岭土悬浊液的絮凝特性.结果表明,CAS具有比CTS絮凝效果好、用量少、pH值适用范围广等优点.CAS絮凝效能受胶体颗粒性质的影响小,对自来水和蒸馏水配置的高岭土悬浊液均具有较好的絮凝效能.中性条件下,CAS的最佳投加量仅为CTS的1/10.在pH值2.0-11.0范围内,CAA对浊度的去除率在95%左右.CAS投加量与原水浊度的关系为:投加量低于0.5nag·L-1时,絮凝效果随原水浊度的升高降低;投加量大于0.5 mg·L-1,浊度去除率随原水浊度的增大而提高;投加量超过1.0 mg·L-1后,对浊度(10～160 NTU)的悬浊;液浊度去除率均在85%以上.悬浮颗粒聚集状态的变化分析、颗粒ξ电位测定、絮体粒径分布测定及其形态结构的观察结果表明,电性中和、吸附架桥是CAS的主要絮凝作用机理,絮凝过程是多种机制共同起作用的动态变化过程.

Flocculation of Kaolin Suspensions by Chitosan Grafted Ternary Polymerization Flocculant

Flocculation of kaolin suspensions using ternary polymerization flocculant (CAS) synthesized by chitosan (CTS), acrylamide and ethyl acrylate quaternary ammonium salt was investigated in lab-scale. It was found that CAS had more advantages such as higher flocculation efficiency, lesser dosage and wider pH flocculation range than CTS. CAS was insignificantly exposed to the properties of suspended particles, so preferable flocculation efficiency by it could be obtained both with distilled water and tap water kaolin suspensions. The optimal dosage for CAS was only one-tenth of that of CTS in neutral condition. Good flocculation performance was observed in the pH range of 2.0-11.0 at the dosage of 0.5 mg x L(-1) CAS, and the turbidity removal rates were about 95%. It was also shown that flocculation efficiency was very sensitive to the raw turbidity of kaolin suspensions. At less than 0.5 mg x L(-1) of CAS dose, the higher raw turbidity of the suspension contrarily yielded a lower removing rate. However, when the dosage of CAS was more than 0.5 mg x L(-1), the flocculation efficiency increased with increasing the raw turbidity of kaolin. When the dosage was more than 1.0 mg x L(-1), turbidity removal efficiencies exceeding 85% could be achieved in overall experimental turbidities from 10 to 160 NTU. iPDA-100 device was used to follow the particle aggregation process. And also zeta potential values of particles,floc sizes, shape analyses were presented. It is presumed that the flocculation induced by CAS is dominated by charge patch mechanism and bond bridging. The flocculation reactivity of kaolin suspensions exhibits a dynamic changing, which is simultaneously responsible for several kinds of driving forces.