Abstract Al2O3 nanoporous membranes for nanofiltration were successfully prepared from nanofiber sols (4 nm in diameter and 1400 nm in length) by controlling the number of sol coats and the firing temperature of the membrane. The effects of the number of sol coats and the firing temperature were characterized via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption, scanning electron microscope (SEM), transmission electron microscopy (TEM), nanopermporometry, and nanofiltration. A crack-free and continuous separation layer of the membranes, which is composed of Al2O3 nanofibers overlapping in the same direction on the membrane surface, was achieved. A greater number of sol coats greatly reduced the N2 permeance and water permeability of the membrane, but had no significant effect on either the average pore size or the molecular weight cut-off (MWCO). Meanwhile, firing temperature greatly affected the structure and separation performance of the membranes due to a transformation of the crystalline phase from boehmite to γ-Al2O3 under high temperatures. Al2O3 nanofiber-derived membranes had an average pore size and a MWCO that tended to be constant at 1.0 nm and 870–990 g/mol via firing at 200 °C, irrespective of the number of sol coats. Those values were increased, however, with increases in the firing temperature.

中文翻译：

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由纳米纤维溶胶制成的 Al2O3 纳滤膜：制备、表征和性能

摘要 以纳米纤维溶胶（直径4 nm，长度1 400 nm）为原料，通过控制溶胶层数和膜的焙烧温度，成功制备了用于纳滤的Al2O3纳米多孔膜。通过 X 射线衍射 (XRD)、傅里叶变换红外光谱 (FTIR)、N2 吸附-解吸、扫描电子显微镜 (SEM)、透射电子显微镜 (TEM)、纳米渗透法和纳米过滤。实现了无裂纹且连续的膜分离层，该层由 Al2O3 纳米纤维在膜表面以相同方向重叠组成。更多的溶胶涂层大大降低了膜的 N2 渗透性和水渗透性，但对平均孔径或截留分子量 (MWCO) 没有显着影响。同时，由于在高温下结晶相从勃姆石转变为γ-Al2O3，焙烧温度极大地影响了膜的结构和分离性能。Al2O3 纳米纤维衍生膜的平均孔径和 MWCO 通过在 200°C 下烧制而趋于恒定在 1.0 nm 和 870-990 g/mol，与溶胶涂层的数量无关。然而，这些值随着烧制温度的增加而增加。Al2O3 纳米纤维衍生膜的平均孔径和 MWCO 通过在 200°C 下烧制而趋于恒定在 1.0 nm 和 870-990 g/mol，与溶胶涂层的数量无关。然而，这些值随着烧制温度的增加而增加。Al2O3 纳米纤维衍生膜的平均孔径和 MWCO 通过在 200°C 下烧制而趋于恒定在 1.0 nm 和 870-990 g/mol，与溶胶涂层的数量无关。然而，这些值随着烧制温度的增加而增加。