Влияние осадителя на нанофильтрационные свойства целлюлозных мембран, формуемых из растворов в ионных средах
The influence of the nature of the precipitant on the nanofiltration characteristics of cellulose membranes obtained from solutions in 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) or a mixture of this ionic liquid with dimethyl sulfoxide (DMSO) was studied. Precipitation in water led to the formation of the densest cellulose membrane, characterized by low dimethylformamide permeability (PDMF = 0.25 kg/m2 h atm.) and high retention coefficients of the model substances Orange II (350 g/mol) and Remazol Brilliant Blue R (626 g/mol ) – 65 and 82%, respectively. To reduce the rate of cellulose sedimentation in order to reduce the density of membranes, various compounds were introduced into the water, partially imitating the solvent medium, until their 30% solutions were obtained: acetic acid to increase the content of acetate anions, N-methylmorpholine N-oxide (MMO) to increase the concentration of ammonium fragments, and DMSO. In all cases, the modification of the precipitant led to an increase in membrane permeability by 2–2.5 times, while maintaining high values of retention coefficients. The best nanofiltration characteristics were demonstrated by a cellulose membrane obtained by precipitation in a 30% aqueous solution of acetic acid: PDMF = 0.67 kg/m2 h atm., ROrangeII = 66%, and RRemazol = 78%.