Institute for Advanced Membrane Technology (IAMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344Eggenstein-Leopoldshafen, Germany.
Environ Sci Technol. 2022 Dec 6;56(23):16811-16821. doi: 10.1021/acs.est.2c04658. Epub 2022 Nov 11.
Nanofiltration (NF) membranes can retain micropollutants (MPs) to a large extent, even though adsorption into the membrane and gradual permeation result in breakthrough and incomplete removal. The permeation of MPs is investigated by examining the energy barriers (determined using the Arrhenius concept) for adsorption, intrapore diffusion, and permeation encountered by four different steroid hormones in tight and loose NF membranes. Results show that the energy barriers for steroid hormone transport in tight membrane are entropically dominated and underestimated because of the high steric exclusion at the pore entrance. In contrast, the loose NF membrane enables steroid hormones partitioning at the pore entrance, with a permeation energy barrier (from feed toward the permeate side) ranging between 96 and 116 kJ/mol. The contribution of adsorption and intrapore diffusion to the energy barrier for steroid hormone permeation reveals a significant role of intrapore diffusive transport on the obtained permeation energy barrier. Overall, the breakthrough phenomenon observed during the NF of MPs is facilitated by the low energy barrier for adsorption. Experimental evidence of such principles is relevant for understanding mechanisms and ultimately improving the selectivity of NF.
纳滤（NF）膜可以在很大程度上保留微量污染物（MPs），尽管吸附到膜中和逐渐渗透会导致穿透和不完全去除。通过研究四种不同的甾体激素在紧密和松散 NF 膜中遇到的吸附、孔内扩散和渗透的能垒（使用阿累尼乌斯概念确定）来研究 MPs 的渗透。结果表明，由于孔入口处的高空间排斥，紧密膜中甾体激素传输的能垒主要受熵控制且被低估。相比之下，松散的 NF 膜允许甾体激素在孔入口处进行分配，渗透能垒（从进料侧到渗透侧）在 96 到 116 kJ/mol 之间。吸附和孔内扩散对甾体激素渗透能垒的贡献揭示了孔内扩散传输在获得的渗透能垒中起着重要作用。总的来说，在 NF 处理 MPs 时观察到的穿透现象是由吸附的低能垒促进的。这些原则的实验证据对于理解机制并最终提高 NF 的选择性具有重要意义。
