交联改性对木薯淀粉絮凝剂絮凝性能的影响

Effect of cross-linking modification on the flocculation performance of cassava starch flocculant

以木薯淀粉及丙烯酰胺单体为原料,用水溶液聚合法制备淀粉接枝丙烯酰胺絮凝剂(St-PAM);用交联剂(KPS)交联改性木薯淀粉,制备交联淀粉接枝丙烯酰胺絮凝剂(CL-St-PAM)。采用正交试验,考察交联剂、反应温度、反应时间以及淀粉与丙烯酰胺单体比对单体转化率的影响,得出CL-St-PAM的最优制备条件,并对交联前后的淀粉絮凝剂进行结构表征和性能测试。结果表明,CL-St-PAM的最佳制备条件为KPS 6mmol·L^(-1),反应温度50℃,反应时间5h,单体比1∶3;结构表征分析表明,CL-St-PAM与St-PAM均成功接枝,且CL-St-PAM的表面更为粗糙,无定型结构更加明显,分子量更大,有利于絮凝性能的发挥;模拟废水絮凝实验表明在絮凝剂用量为250mg·L^(-1)、常温、pH值为8的最佳条件下,CL-St-PAM絮凝率可达到93.4%,明显高于相同条件下St-PAM的絮凝率,且pH值适用范围更宽,有利于实际应用。

Using tapioca starch and acrylamide monomers as raw materials,starch grafted acrylamide flocculant(St-PAM)is prepared by aqueous solution polymerization;modified tapioca starch is cross-linked with cross-linking agent(KPS)to prepare cross-linked starch grafted with propylene Amide flocculant(CL-St-PAM).Orthogonal experiments were used to investigate the effects of cross-linking agent,reaction temperature,reaction time,and the ratio of starch to acrylamide monomer on the monomer conversion rate,and the optimal preparation conditions for CL-St-PAM were obtained,and the structure characterization and performance test of starch flocculant are carried out.The results showed that the best preparation conditions for CL-St-PAM were KPS 6mmol·L^(-1),reaction temperature 50℃,reaction time 5h,monomer ratio 1∶3;structural characterization analysis showed that the grafting of both CL-St-PAM and St-PAM are successful,and the surface of CL-St-PAM is rougher,the amorphous structure is more obvious,and the molecular weight is larger,which is conducive to the performance of flocculation;the simulated wastewater flocculation experiment shows that the amount of flocculant is 250mg·L^(-1),under the optimal conditions of normal temperature and pH=8,the flocculation rate of CL-St-PAM can reach 93.4%,which is significantly higher than the flocculation rate of St-PAM under the same conditions,and the pH range is wider,which is beneficial to practical applications.