Coagulation of submicron colloids in water treatment by incorporation into aluminum hydroxide floc
Coagulation of submicron colloids in water treatment by incorporation into aluminum hydroxide floc
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DOI：
10.1021/es00022a014
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发表时间：
1991-10
影响因子：
11.4
通讯作者：
Z. Chowdhury;G. Amy;R. Bales
中科院分区：
文献类型：
--
作者：
Z. Chowdhury;G. Amy;R. Bales
在一系列实验室实验中，观察到氢氧化铝沉淀的速率和化学计量取决于pH和Al剂量，以及HCO{sub 3}{sup {minus}}、SO{sub 4}{sup 2{minus}}和天然有机物浓度。含水氧化铝胶体进入沉淀物的合并遵循两种途径之一。在pH 7.5时，形成松散的絮凝物;胶体去除涉及随后的胶体与絮凝物的聚集。在pH 6.5时，沉淀物覆盖在种子颗粒表面;去除涉及胶体的快速自凝聚。在两种pH下的去除率均为99.9%。在pH 5.5时，胶体去除不显著。结果表明，在pH 6.5的沉淀物的异相成核和生长得到不稳定的颗粒和更小，紧凑的絮凝物。涉及沉淀和随后的颗粒聚集的均相途径效率较低。非均相途径具有较低的沉淀OH/Al比和较低的电泳迁移率。
In a series of laboratory experiments it was observed that the rate and stoichiometry of aluminum hydroxide precipitation depended on pH and Al dose, and on HCO{sub 3}{sup {minus}}, SO{sub 4}{sup 2{minus}}, and natural organic matter concentrations. Incorporation of hydrous aluminum oxide colloids into the precipitate followed either of two paths. At pH 7.5 a loose floc formed; colloid removal involved subsequent aggregation of the colloids with the floc. At pH 6.5, the precipitate coated the seed particle surface; removal involved rapid self-coagulation of the colloids. Removal was {ge} 99.9% at both pH's. At pH 5.5, colloid removals were insignificant. Results suggest that heterogeneous nucleation and growth of precipitate at pH 6.5 gives destabilized particles and smaller, compact floc. The homogeneous pathway involving precipitation and subsequent particle aggregation was less efficient. The heterogeneous pathway had a lower precipitate OH/Al ratio and a lower electrophoretic mobility.