纤维素纳米纤丝气凝胶制备及其对亚甲基蓝的吸附性能

针对印染废水中的亚甲基蓝(MB)吸附问题,以水稻秸秆纤维素纳米纤丝(CNF)悬浮液为原料,通过冻融凝胶、叔丁醇溶剂置换、液氮冷冻干燥制得CNF气凝胶,对其形态结构进行表征,并研究其对MB的吸附性能;考察了吸附剂用量、溶液pH值的影响,并利用吸附动力学和吸附等温线模型对吸附机制进行探讨分析。结果表明:叔丁醇冷冻干燥得到的CNF气凝胶内分布着大量由直径6~26 nm的蛛丝状纤丝构成的三维网络结构,其比表面积为52.25 m²/g,平均孔径为28.82 nm,是多孔材料;准二级动力学模型和Freundlich吸附等温线模型能更好地描述CNF气凝胶对MB的吸附过程,计算得到理论最大吸附量为196.08 mg/g。

Preparation of cellulose nanofibrils aerogel and its adsorption of methylene blue

In order to solve the adsorption problem of methylene blue (MB) in dyeing wastewater, a cellulose nanofiber(CNF) aerogel was prepared from rice straw CNF suspension by freezing and thawing gel, displacing with tert-butanol solvent and freeze drying with liquid nitrogen. The morphology structure of the aerogel as well as its adsorption capacity to MB was characterized. The influences of adsorbent quality and solution pH value on the adsorption performance were also investigated. The adsorption mechanism was discussed by adsorption kinetics and adsorption isotherm model. The results show that the CNF aerogel obtained by freeze-drying of tert-butanol has a three-dimensional network structure which contains a large number of spider-like fibers with a diameter of 6-26 nm. The aerogel exhibits a porous structure with a specific surface area of 52.25 m²/g, and an average pore size of 28.82 nm. The pseudo-second-order adsorption kinetic and Freundlich adsorption isothermal model are more suitable for describing the adsorption process of methylene blue on CNF aerogel, with the theoretical maximum adsorption of 196.08 mg/g.