One-step preparation of porous cellulose/chitosan macro-spheres from ionic liquid-based solutions

摘要

Environmentally friendly and easily biodegradable porous adsorbents for water purification based on cellulose and chitosan blends have been prepared by a green technology utilizing room temperature ionic liquids as main solvent component. The dissolution and re-precipitation mechanisms for the two biopolymers and of their mixtures have been studied in detail, targeting to optimize the composition of the casting solutions and make them adequate for preparation of porous polymer spheres by the "dropping cum phase separation" technique. With the increase of the chitosan content in the sample the time required for the polymer dissolution was increasing and the amount of water necessary to destabilize the formed casting solution was decreasing. Further on, the viscosities of the casting solutions had a strong impact on the formation of the porous structure during the non-solvent induced phase separation process. For the blend spheres prepared from 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) based solutions materials with higher specific surface areas and improved Cu2+ adsorption capacity were obtained at the increase of the chitosan fraction in the polymer blend. For the samples prepared from 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) based solutions no such a trend has been observed.