【摘要】 考察了相同剂量下不同浓度阴离子型聚丙烯酰胺絮凝剂(PAM)母液对三氧化二铁悬浮液的絮凝效果.通过电导率和流变行为测试,阐明了随母液浓度增大絮凝效果先变好后变差的原因.研究结果表明,母液浓度为0.3 g/L时PAM絮凝效果最佳.根据聚电解质标度理论及流变测试结果,认为此最佳母液浓度(cop)接近临界缠结浓度.母液电导率及加入絮凝剂后的搅拌过程中水体电导率变化表明,絮凝剂浓度高于最佳母液浓度时出现的电荷屏蔽现象使得有效电荷减少,导致高母液浓度下絮凝效果变差.向低浓度母液中添加适量β-环糊精后,环糊精分子通过氢键作用搭桥使PAM分子间距变小,发生协同絮凝形成足够大的絮体,从而使絮凝效果得到改善.这一结果表明,低于最佳母液浓度时由于PAM分子相对孤立形成的絮体不足以沉降,是导致絮凝效果较差的原因.更多还原

【Abstract】 The flocculation performance of isodose anionic polyacrylamide(PAM) with different parent solution concentrations(cp) for ferric oxide suspension was investigated.It is found that the flocculation performance of PAM could be improved and impaired with the increase of cp.Moreover,the concentration of 0.3 g/L is the optimal parent solution concentration(cop) of PAM.Through scaling theory analysis and rheological measurements,cop is proved to approach the critical entanglement concentration(ce).Conductivity test results of PAM parent solution and the conductivity varieties of stirring water added PAM reveal that there exits a charge shielding phenomenon when cp is above cop.The number of PAM effective charges decreases due to the charge shielding,which deteriorates PAM flocculation performance.On the other hand,the flocculation performance of dilute PAM solutions can be enhanced in case of mixing dilute PAM solutions with appropriate amount of β-cyclodextrin(CD).There exists intermolecular hydrogen bond between PAM and β-CD,which makes several PAM molecules bridged by one β-CD molecule.The observed variations of flock sizes and flocculation performance after PAM being bridged can explain the reason of the poor performance for dilute parent solutions,that is,PAM could hardly form flock with ample size and sedimentate sufficiently because the molecules are relatively isolated when the parent solution concentration is below cop.更多还原