BioPRIA, Australian Pulp & Paper Institute, Department of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia.
Langmuir. 2010 Nov 16;26(22):16949-57. doi: 10.1021/la103410j. Epub 2010 Oct 7.
The effect of polymer adsorption kinetics and ionic strength on the dynamics of particle flocculation was quantified using a model system consisting of precipitated calcium carbonate (PCC) and cationic polyacrylamide (CPAM) at a low shear rate. All early flocculations detectable by a photodispersion analyzer (PDA) happened in nonequilibrium polymer adsorption regimes. We observed discrepancies in flocculation rates with the surface coverage theory, which is based on a simple monolayer adsorption model, in both early and late flocculation stages. For instance, the same amount of adsorbed CPAM reached at different polymer doses demonstrated different flocculating capabilities. This highlighted the importance of polymer adsorption kinetics upon flocculation. The transient conformation of the adsorbed CPAM during the kinetic process sometimes even superceded the adsorbed amount in the determination of PCC flocculation. Both antagonistic and synergetic effects of increased ionic strength on the CPAM-induced PCC aggregation were observed during early flocculation. However, late-stage PCC flocculation shared some similarities, irrespective of polymer dose and ionic strength. Despite the decreased amount of adsorbed polymer from the increased ionic strength, the combination of CPAM and salt, at certain concentrations, demonstrated a synergy to promote PCC aggregation more efficiently than the same amount of the respective components.
采用低剪切速率的沉淀碳酸钙（PCC）和阳离子聚丙烯酰胺（CPAM）模型体系，定量研究了聚合物吸附动力学和离子强度对颗粒絮凝聚动力学的影响。光散射分析仪（PDA）可检测到的所有早期絮凝聚都是在非平衡聚合物吸附区发生的。我们观察到在早期和后期絮凝聚阶段，基于简单单层吸附模型的表面覆盖理论与絮凝聚率存在差异。例如，在不同的聚合物剂量下达到相同的吸附 CPAM 量表现出不同的絮凝能力。这强调了聚合物吸附动力学对絮凝聚的重要性。在动力学过程中，吸附 CPAM 的瞬态构象有时甚至超过了在确定 PCC 絮凝聚时的吸附量。在早期絮凝聚过程中，增加离子强度对 CPAM 诱导的 PCC 聚集表现出拮抗和协同作用。然而，无论聚合物剂量和离子强度如何，后期 PCC 絮凝聚都具有一些相似之处。尽管增加离子强度会导致吸附聚合物的量减少，但 CPAM 和盐的组合在某些浓度下表现出协同作用，可更有效地促进 PCC 聚集，其效果优于相同量的各组分。
