含硫高分子螯合-絮凝剂的制备及其捕集重金属性能差异性研究

Sulphur-containing groups (e.g., mercaptoacetyl group, dithiocarbamate group and xanthogenate group) will be introduced to macromolecular flocculants such as polyacrylamide, chitosan and their modified products by chemical process. A series of novel macromolecule chelating-flocculants synthesized in this way have the function of trapping heavy metals. On the one hand, these novel flocculants can turn dissolved heavy metal ions into insoluble precipitate because of the chelation between sulfur atom and heavy metal ions. On the other hand, the insoluble precipitate would settle rapidly through the bridge and flocculation of original flocculants. Because these novel flocculants have two functions: chelating precipitation and flocculating precipitation, it is possible to reduce the amount of heavy metal ions in wastewater, and the discharge concentration for heavy metals can reach the national discharge standard. The preparation condition, the property in the aqueous solution, and the trapping performance of heavy metals for these novel chelating-flocculants will be studied in the project. The difference and mechanism of their performance to trap heavy metal will be also investigated. The above-mentioned research provides a theoretical guide for the development of heavy metal treating agents.

本项目拟采用化学合成方法将含硫原子的配位基团（巯基乙酰基、二硫代氨基甲酸基、黄原酸基）引入到现有的有机高分子絮凝剂聚丙烯酰胺、壳聚糖及其改性产物中，制备出系列含硫高分子螯合-絮凝剂，赋予其对重金属离子的捕集功能。一方面，该系列新型絮凝剂可通过硫原子与重金属离子形成稳定的螯合沉淀物，使溶解态重金属离子转化成不溶态沉淀物；另一方面，可通过原高分子絮凝剂的"架桥絮凝"作用使形成的螯合沉淀物加速聚集和沉降。因而该系列新型絮凝剂具有螯合沉淀和絮凝沉淀双重作用，利用其有望降低废水中重金属离子的含量，做到重金属废水达标排放。本项目通过对该系列新型絮凝剂的制备条件、溶液特性及其捕集重金属离子性能等方面的研究，揭示出不同含硫配位基团对重金属离子捕集能力差异性的规律和机理，有望为今后制备其他新型重金属处理剂的研究起到一定的理论指导作用。

本项目以现有的有机高分子絮凝剂（聚丙烯酰胺、壳聚糖）作为母体，通过化学合成方法将含硫原子配位基团（巯基乙酰基、二硫代氨基甲酸基、黄原酸基）引入到其高分子链上，制备出对重金属离子具有螯合沉淀和絮凝沉淀双重作用的11种新型高分子螯合-絮凝剂。项目主要研究各种高分子螯合-絮凝剂的最优制备条件、溶液性质、捕集重金属离子性能及机理，揭示不同含硫配位基团对重金属离子捕集能力差异性的规律。实验结果表明，各种高分子螯合-絮凝剂对水样中重金属离子均具有较好的捕集能力，重金属去除率均在90%以上，其有望成为重金属废水的新型处理剂，具有一定的应用前景。