Wang Xiaoqi, Gao Weijue, Kong Fangong, Fatehi Pedram
Department of Chemical Engineering and Green Processes Research Centre, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B5E1, Canada.
State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
ACS Omega. 2024 Oct 15;9(43):43864-43874. doi: 10.1021/acsomega.4c06904. eCollection 2024 Oct 29.
Purification is an essential step in many polymerization processes for fabricating highly pure polymers. This study considered various purification methods for purifying the product of lignin, acrylamide (AM), and diallyl dimethylammonium chloride (DADMAC) copolymerization reactions at a laboratory scale. The charge density, yield, molecular weight, and solubility analyses confirmed that ethanol extraction and membrane filtration were the most effective processes for producing lignin-p(AM)-p(DADMAC). The H NMR analysis revealed that the membrane dialysis effectively removed unreacted AM and DADMAC monomers from the reaction medium. The produced samples of the ethanol-extraction and dialysis processes had higher solubility and yield compared to the product of the acidification process. Thermogravimetric studies confirmed that the ethanol-extracted and dialyzed samples had a degradation temperature (220 °C) higher than that of the acidified samples (160 °C). The rheological studies confirmed that the viscosities of the polymer solutions were influenced more by the solubility than by the molecular weight of the generated polymers within the molecular weight range examined in this study. The flocculation studies confirmed that the ethanol-extracted and dialyzed polymers were more effective flocculants than the acidified samples for the particles of a kaolinite suspension. Based on the above results, membrane filtration with a larger pore size could be an environmentally friendly method for effectively purifying lignin-p(AM)-p(DADMAC).
纯化是许多用于制造高纯度聚合物的聚合过程中的关键步骤。本研究在实验室规模下考虑了多种用于纯化木质素、丙烯酰胺（AM）和二烯丙基二甲基氯化铵（DADMAC）共聚反应产物的纯化方法。电荷密度、产率、分子量和溶解性分析证实，乙醇萃取和膜过滤是生产木质素-p(AM)-p(DADMAC)最有效的方法。核磁共振氢谱（H NMR）分析表明，膜透析能有效去除反应介质中未反应的AM和DADMAC单体。与酸化过程的产物相比，乙醇萃取和透析过程产生的样品具有更高的溶解度和产率。热重分析证实，乙醇萃取和透析后的样品的降解温度（220℃）高于酸化样品（160℃）。流变学研究证实，在本研究考察的分子量范围内，聚合物溶液的粘度受溶解度的影响大于受生成聚合物分子量的影响。絮凝研究证实，对于高岭土悬浮液中的颗粒，乙醇萃取和透析后的聚合物比酸化样品是更有效的絮凝剂。基于上述结果，孔径较大的膜过滤可能是一种有效纯化木质素-p(AM)-p(DADMAC)的环保方法。
