基于金属离子配位调控分子组装的淀粉废水磁分离净化技术基础研究

Fundamental Research on Magnetic Separation and Purification of Starch Wastewater Based on Coordination-Driven Assembly of Metal Ions

针对淀粉废水有机物含量高、难降解等特点,提出了金属离子调控淀粉大分子结构-磁絮凝高效沉淀分离净化技术路线,研究了不同金属离子与淀粉的配位组装行为及磁分离技术对淀粉废水的净化作用机制。结果表明:金属离子与淀粉作用可形成金属离子-淀粉高分子络合沉淀物,当铁离子、铝离子或铅离子用量分别为4.2 g/L、5.65 g/L和2.5 g/L时,COD去除率均可达90%;不同金属离子调控淀粉分离净化效率的顺序为:Fe^3+=Pb^2+>Al^3+>Ca^2+。沉降试验和粒度分析结果表明,金属离子-淀粉颗粒粒度极细、部分呈胶态结构,沉降分离效率很低;金属离子-淀粉颗粒可与磁性晶核发生异相凝聚形成具有磁性的核壳状包裹体,在磁场中实现快速沉降分离。金属离子的配位调控分子组装和磁分离技术为高浓度淀粉废水的高效净化提供了新的解决方案。

As the starch wastewater contains high content of organic matter and is difficult to be degraded, a separation approach including regulation of starch macromolecules with metal ions and precipitation with magnetic flocculation was proposed. The coordination-driven assembly behavior of different metal ions and starch, as well as the function of magnetic separation on the purification performance of starch wastewater were all explored. The results show that metal ions and starch could react with each other, generating complex precipitates, and the COD removal rate can attain 90% by adding respectively 4.2 g/L Fe3+, 5.65 g/L Al3+ or 2.5 g/L Pb2+, and the capacities of different metal ions to enhance the purification efficiency follow the order: Fe3+= Pb2+>Al3+>Ca2+. However, the metal ion-starch particulates are superfine, partially of colloidosome, leading to the low efficiency in the separation by sedimentation. Fe3+-starch granules can be condensed onto magnetic nuclei and form a magnetic core-shell structure, which actualizes the rapid separation in magnetic field. The combination of cation-starch coordination-driven assembly and magnetic separation technique can provide a solution for efficient purification of high concentrated starch wastewater.