淀粉基重金属捕集材料的微观结构及捕集效能

Microstructure and Trapping Efficiency of Starch Based Heavy Metal Trapping Materials

摘要:

天然淀粉具有低毒、易降解、可循环利用等优点，经多元修饰后，具备捕集重金属的能力。使用季铵型醚化剂，磷酸盐及尿素对淀粉分子进行多元修饰，最终获得了多种电荷分布的淀粉分子修饰产品。通过红外光谱、固体核磁共振、扫描电镜及捕集效能评价等手段研究了淀粉基捕集剂的微观结构、特性及捕集机理。结果表明：淀粉分子成功引入阳离子季铵基团、阴离子磷酸基团及非离子的酰胺基团；比表面积增大，分子量增大，有利于对重金属离子进行捕集；0.06g淀粉基捕集剂对30mg/L混合溶液中铜、铅、镉、镍离子的去除率分别为97.80%、99.83%、99.23%、99.53%，均优于国家排放标准；其捕集吸附过程符合伪二级吸附模型，且由电性中和反应和微孔吸附联合共同控制。

Abstract:

The natural starch has the advantages of low toxicity, easy to be degraded, and can be recycled. It has the ability of capturing heavy metal after multi modification.Using quaternary ammonium type etherification agent, phosphate and urea were used to modify starch molecules, and finally, a variety of charge distribution of starch molecular modified products were obtained.The microstructure, properties and mechanism of starch based collector were studied by means of infrared spectroscopy, solid state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and trapping efficiency.The results show that: the starch molecules into the cationic quaternary ammonium groups, anionic phosphate groups and nonionic amide groups; the specific surface area increasesis conducive to trapping heavy metal ions. The removal rate of copper, lead, cadmium and nickel ions in 30mg/L mixed solution was 97.80%, 99.83%, 99.23%, 99.53%, respectively, which were up to the national emission standard. The trapping process is in accordance with the pseudo two stage adsorption model, which is controlled by the combination of electric neutralization reaction and micropore adsorption.