Abstract

The effect of the nature of a coagulant on the nanofiltration characteristics of the cellulose membranes obtained from solutions in 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) or a mixture of this ionic liquid with dimethylsulfoxide (DMSO) is studied in this work. Precipitation in water leads to the formation of the densest cellulose membrane characterized by the low permeability of dimethylformamide (P_DMF = 0.25 kg m⁻² h⁻¹ atm⁻¹) and high rejection coefficients of the model substances, Orange II (350 g/mol) and Remazol Brilliant Blue R (626 g/mol), of 65 and 82%, respectively. To reduce the rate of precipitation of cellulose for the purpose of decreasing the density of the membranes, various compounds that partially mimic the medium of the solvent are introduced to water to obtain their 30% solutions: acetic acid to increase the concentration of acetate anions, N-methylmorpholine N-oxide to increase the concentration of ammonium fragments, and DMSO. In all the cases, the modification of the coagulant leads to a 2–2.5-fold increase in the permeability of the membranes without sacrificing the high values of the rejection coefficients. A cellulose membrane obtained by precipitation in a 30% aqueous solution of acetic acid demonstrates the best nanofiltration characteristics, namely, P_DMF = 0.67 kg m⁻² h⁻¹ atm⁻¹, R_OrangeII = 66%, and R_Remazol = 78%.

中文翻译：

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混凝剂的性质对离子介质中溶液形成的纤维素膜的纳滤特性的影响

摘要

在此研究了混凝剂的性质对从醋酸1-乙基-3-甲基咪唑鎓盐（[Emim] Ac）或该离子液体与二甲基亚砜（DMSO）的混合物中获得的纤维素膜的纳滤特性的影响。工作。水中的沉淀导致形成最致密的纤维素膜，其特征在于二甲基甲酰胺的低渗透性（P _DMF = 0.25 kg m ^-2 h ^-1 atm ^-1）和模型物质橘子II（350 g / mol）和Remazol亮蓝R（626 g / mol）的高排斥系数分别为65％和82％。为了降低纤维素的沉淀速率（以降低膜的密度为目的），将部分模拟溶剂介质的各种化合物引入水中以获得其30％的溶液：乙酸以增加乙酸根阴离子的浓度，ñ甲基吗啉ñ氧化以增加铵碎片和DMSO的浓度。在所有情况下，凝结剂的改性都会使膜的渗透率提高2–2.5倍，而不会牺牲高的排斥系数。通过在30％的乙酸水溶液中沉淀而获得的纤维素膜表现出最佳的纳滤特性，即P _DMF = 0.67 kg m ^-2 h ^-1 atm ^-1，R _OrangeII = 66％，R _Remazol = 78％ 。