Université de Limoges-Groupement de Recherche Eau Sol Environnement (GRESE), ENSIL, Parc d'Ester Technopôle, 16 rue Atlantis, 87068 Limoges, France.
J Colloid Interface Sci. 2010 Feb 1;342(1):26-32. doi: 10.1016/j.jcis.2009.09.068. Epub 2009 Oct 4.
The aim of this study is to evaluate the influence of organic matter on arsenic removal by coagulation/flocculation on both a model water with low mineral content and a natural water sample. Ferric chloride was used as coagulant at concentrations avoiding the preoxidation step usually required to oxidize As(III) and increase its removal. Arsenic removal was accomplished by combining evaluation of arsenic residual concentrations and speciation analysis with zeta potential measurements. A preliminary study evaluated the influence of coagulant dose, coagulation pH, and organic matter on As(III) and As(V) removal. The main conclusions were: (i) As(III) removal depended on coagulant dose and on the number of sites available on hydroxide surfaces rather than on coagulation pH; (ii) As(V) removal depended on the zeta potential of colloidal suspension and was more influenced than As(III) by coagulation pH and the presence of organic matter; (iii) organic matter removal followed As(V) removal. This allowed determination of adsorption as the main mechanism occurring during As(V) and organic matter removal and supposing precipitation/coprecipitation as an important As(III) removal mechanism. Adsorption on preformed ferric hydroxide flocs experiments allowed then confirmation of these hypotheses.
本研究旨在评估有机物对混凝/絮凝去除砷的影响，分别针对低矿物质含量模型水和天然水样进行研究。采用氯化铁作为混凝剂，其浓度可避免通常需要进行的预氧化步骤，以氧化 As(III)并提高其去除率。通过评估砷残留浓度和形态分析以及zeta 电位测量来实现砷的去除。初步研究评估了混凝剂剂量、混凝 pH 值和有机物对 As(III)和 As(V)去除的影响。主要结论如下：(i) As(III)的去除取决于混凝剂剂量和氢氧化物表面上的可用位点数量，而不是混凝 pH 值；(ii) As(V)的去除取决于胶体悬浮液的 zeta 电位，并且比 As(III)更受混凝 pH 值和有机物存在的影响；(iii)有机物的去除遵循 As(V)的去除。这允许确定吸附是在 As(V)和有机物去除过程中发生的主要机制，并假设沉淀/共沉淀是 As(III)去除的重要机制。然后通过预形成的氢氧化铁絮体吸附实验验证了这些假设。
