Abstract:

The novel technology of membrane separation, especially the two-dimensional lamellar membrane, holds broad application prospects in the separation field. However, the complex chemical environment and high cost of membrane nanomaterials currently limit their industrialization. Natural vermiculite has the advantages of cheap and easy to obtain, simple to exfoliationl, and only contains silica hydroxyl on the surface which is easy to adjust. Thus, the hydrophilicity and hydrophobicity of the as-prepared lamellar membrane can be precisely controlled to achieve efficient permeation of organic solvents and high separation of polar and non-polar solvents. The results indicated that the vermiculite lamellar membrane showed excellent molecular transport ability for polar solvents, while relatively low ability for non-polar solvents. The permeance of acetonitrile was up to 1650L/(m²·h·bar), while that of toluene was only 37.8L/(m²·h·bar). The separation factor of acetonitrile to toluene could be as high as 43.6, showing excellent molecular separation performance. The prepared vermiculite lamellar membrane with the interlayer spacing of 1.36nm held outstanding size sieving ability due to its regular and straight interlayer channels. The rejection of crystal violet (1.5nm), bright blue (1.6nm), acid yellow 14 (1.9nm) and other dye molecules with larger dynamics diameter than interlayer spacing were over 90%. Moreover, the vermiculite lamellar membrane displayed excellent pressure cycling stability and anti-pollution ability, showing great potential in separation applications.

Key words: vermiculite, two-dimensional nanosheets, lamellar membrane, organic solvent nanofiltration, molecular separation

摘要：

受全球能源形势与环境问题影响，新型膜分离技术尤其是二维层状膜在分离领域展现出广阔的应用前景。然而，目前使用的二维纳米材料化学环境相对复杂，且膜制备成本高昂，限制了其工业化推广。天然蛭石廉价易得，剥离简单，表面只含有硅羟基且其含量易于调控，可精确调控所制备层状膜层间亲疏水性，实现有机溶剂的高效渗透和极性与非极性溶剂的高效分离。研究发现：蛭石层状膜展现出优异的极性溶剂分子传递能力，而非极性溶剂则相对较低，其中乙腈分子渗透性高达1650L/（m²·h·bar)（1bar=0.1MPa），甲苯分子渗透性仅为37.8L/（m²·h·bar)，乙腈与甲苯的分离因子高达43.6，展现出优异的分子分离性能。本文所制备蛭石层状膜具有1.36nm的规则平直层间传递通道，对分子动力学直径大于层间距的结晶紫（1.5nm）、亮蓝（1.6nm）、酸性黄14（1.9nm）等染料分子的截留率均大于90%，截留性能优良。同时，蛭石层状膜具有良好的压力循环稳定性及抗污染能力， 展现出巨大的分离应用潜力。

关键词: 蛭石, 二维纳米片, 层状膜, 有机溶剂纳滤, 分子分离