聚合氯化铝中Al_b形态去除腐殖酸的效果及机制研究

Coagulation Performance and Mechanism of Al_b Species in Polyaluminum Chloride in Removing Humic Acid

Alb形态[Al12AlO4（OH）247^＋]是聚合氯化铝（polyaluminium chloride,PAC）水解-聚合作用中形成的一种粒度小、所带正电荷多、聚集程度高及分子量大的多核羟基配合物.本试验采用乙醇-丙酮混合沉淀法分离PAC溶液中各种铝形态,提纯出Alb形态（Alb絮凝剂）.研究投加量、pH及无机离子对Alb絮凝剂处理腐殖酸模拟水样絮凝效果的影响,并利用光散射颗粒分析仪（PDA2000）测定Alb絮凝剂对腐殖酸絮凝过程中絮体的形成与增长过程的动态变化,结合絮体的Zeta电位,对Alb絮凝剂的絮凝机制进行了初步探讨.结果表明,当投加量为4.3-6.3 mg/L、pH值为3.0-6.0时,Alb絮凝剂处理腐殖酸模拟水样达到最佳絮凝效果;NH4^＋、SiO3^2-、H2PO4^-的存在明显抑制其絮凝性能.絮凝动力学过程和絮体Zeta电位表明,Alb絮凝剂在水处理中主要是通过电中和作用和吸附网捕卷扫作用共同起絮凝作用的.

Alb species [Al12 AlO4 （OH）24^7＋ is multinuclear hydroxyl compound formed in PAC hydrolysis-polymerization process, with properties of small particle sizes, much positive charge, high aggregation degree and large molecular weight. Alb species was purified from PAC containing high concentration of Alb species using ethanol-acetone mixed precipitation method. The influence of dosage, pH and inorganic ions on humic acid removal from simulative water was studied by measuring zeta potential and UV254 The PDA output （FI curve） was analyzed and the relationship between the parameters （ S1,S2, H1, H2 ） of FI curve and coagulation mechanism were studied at different Alb dosage and pH. When the dosage was 4.3 to 6.3 mg· L^- 1 and pH was 3.0 to 6.0, the highest humic acid removal efficiency was obtained. The existence of NH4^＋, SiO3^2- and H2 PO4^- inhibits the coagulation performance. The results of coagulation kinetics and Zeta potential studies revealed that Alb acted mainly by charge neutralization as well as adsorption bridge building in water treatment.