Separation of Aquatic Humic Substances by Flotation and Sorption

天然存在的腐殖物质，即，腐殖酸和富里酸是河流、湖泊、池塘和海水的主要和普遍存在的有机成分。它们与各种重金属离子相互作用，形成带负电荷的腐殖酸络合物。它们也被认为是在用氯处理水的过程中形成的三卤甲烷的前体。因此，腐殖酸和富里酸的表征一直是地球化学、环境科学和水处理领域的研究热点。然而，在大多数情况下，腐殖物质的浓度太低，无法直接研究它们。因此，应处理大量样品以收集可观量的腐殖酸和富里酸。在我们实验室开发的流动系统中浮选是一种简单而有效的方法，其中低ppm或ppb水平的水生腐殖物质与金属氢氧化物载体（例如，氢氧化铟）并通过在溶液表面上浮选分离。该技术可从10-100 μ l样品中半自动地富集毫克量的腐殖酸和富里酸。与肟酸镁共沉淀或收集在热可逆聚合物上。结果表明，这些配合物与金属离子一起被完全分离和富集。采用大孔阴离子交换剂SephadexA-25吸附和电感耦合等离子体质谱（ICP-MS）研究了金属-腐殖酸络合物在弱酸性溶液中的解离行为。用阳极溶出伏安法研究了金属-腐殖酸络合物的稳定性。

Naturally occurring humic substances, i, e., humic and fulvic acids, are the major and ubiquitous organic constituents of river, lake, pond and sea water. They interact with various heavy metal ions to form negatively charged humic complexes. They are also said to be precursors of trihalomethanes formed during water treatment with chlorine. Therefore, the characterization of humic and fulvic acids has been a topic of increasing research interest in geochemistry, environmental sciences and water treatment. In most cascs, however, the concentrations of humic substances are too low to study them directly. Therefore, large sample volumes should be treated for the collection of appreciable amounts of humic and fulvic acids.Flotation in a flow system developed in our laboratory was a simple and powerful method, where aquatic humic substances at low ppm or ppb levels were continuously coprecipitated with metal hydroxide carrier (e.g., indium hydroxide) and separated by flotation on the solution surface. The proposed technique allows to concentrate semiautomatically milligram quantities of humic and fulvic acids from 10-100 1 of samples.Further, the separation behavior of metal-humic complexes was studied in some preconcentra-tion steps, e.g., in coprecipitation with magnesium oxinale or collection on thermally reversible polymers. It was foumd that these complexes were completely separated and concentrated, together with metal ions. The dissociations of metal-humic complexes in slightly acidic solutions were examined by using sorption on a macroreticular anion exchanger Sephadex A-25 and inductively coupled plasma-mass spectrometry. The stability of metal-humic complexes were also discussed by using anodic stripping voltammetry.