离子液体辅助纳米纤维素吸附剂的制备及其吸附性能

以脱脂棉纤维素(Cellulose,Ce)为原料，以丙烯酸(AA)和丙烯酰胺(AM)为单体，使用酸性离子液体1-丁基-3-甲基咪唑硫酸氢盐(Bmim]HSO₄)为溶剂和水解催化剂对纤维素进行水解和改性，然后对改性纤维素进行高压均质处理制备出纳米纤维素吸附剂(AA/AM-g-NC)。对AA/AM-g-NC的结构和性能进行表征，并以亚甲基蓝为吸附质研究了对AA/AM-g-NC的吸附性能。结果表明，离子液体辅助高压均质处理脱脂棉后得到纤丝交联网状结构的AA/AM-g-NC吸附剂。这种吸附剂的晶型保持了纤维素Ⅰ型结构，结晶度略有提高；AA/AM-g-NC吸附剂表面接有丙烯酸和丙烯酰胺官能团，对亚甲基蓝的吸附受pH值的影响且为自发放热过程，并符合Langmuir吸附等温式；吸附过程接近准二级动力学方程，由颗粒的内扩散和表面扩散共同控制。

Ionic Liquid-assisted Synthesis of Nanocellulose Adsorbent and Its Adsorption Properties

Nanocellulose adsorbent (AA/AM-g-NC) from cotton linter was successfully prepared by high pressure homogenization with the assistance of an ionic liquid. The cotton linter was first swelled, hydrolyzed and grafted with acrylic acid and acrylamide in an ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate (Bmim]HSO₄)), and then further treated by high pressure homogenization and finally AA/AM-g-NC was obtained. The AA/AM-g-NC adsorbent was characterized and used as adsorbent to adsorb methylene blue. The results show that after the treatment of high pressure homogenization assisted with hydrolysis and graft in ionic liquid AA/AM-g-NC illustrated as crosslinked net with fibril. The crystalline of AA/AM-g-NC remained as cellulose Ⅰ type, with a little increase in the crystallinity. The appearance of functional group from acrylic acid and acrylamide on the AA/AM-g-NC surface was proved. The sorption process towards methylene blue was pH value dependent, spontaneous, exothermic and followed the Langmuir adsorption isotherm. And the adsorption kinetic is closer to the quasi-second order kinetic equation and controlled by both intraparticle diffusion and surface diffusion.