Bilayer nanofiltration (NF) membranes tend to delaminate and have poor stability when applied in organic solvents due to their bi-layered structure. In this study we prepared two types of polydopamine (PDOPA) modified NF membranes including PDOPA-TMC (trimesoyl chloride)/PSF and PDOPA/PIP(Piperazine)-TMC/PSF NF membranes on polysulfone (PSF) ultrafiltration membranes via interfacial polymerization based on PDOPA’s specialized molecular structure and high adhesion property. The separation performance and stability of the NF membranes were investigated. Both the polyester bonds of the PDOPA bilayer membranes and the bioadhesion of the PDOPA were simultaneously beneficial to improving the structure and chemical stabilities of the bilayer membranes. After soaking both the PDOPA-TMC/PSF and PDOPA/PIP-TMC/PSF NF membranes in ethanol solvent for 12 days, the rejection of Congo red only decreased by 1.8% (original, 99.9%) and 1.2% (original, 99.9%), respectively. For the PDOPA/PIP-TMC/PSF NF membrane, the rejection of Na₂SO₄ was only reduced by 1.6% (original, 98.5%). Moreover, the separation performances of both the PDOPA-TMC/PSF and PDOPA/PIP-TMC/PSF NF membranes were still excellent after soaking in a sodium hypochlorite solution (50 ppm) for 240 h (12,000 ppm·hours). The NF membranes thus exhibited long-term structural stability in ethanol and excellent chemical stability in the sodium hypochlorite solution. In particular, no delamination was observed in the above experiments, which is significant for their use in the wastewater treatment field.

双层纳滤（NF）膜由于其双层结构，在有机溶剂中使用时往往会分层并具有较差的稳定性。在这项研究中，我们通过基于界面聚合的聚砜（PSF）超滤膜，制备了两种类型的聚多巴胺（PDOPA）改性的NF膜，包括PDOPA-TMC（三甲酰氯）/ PSF和PDOPA / PIP（哌嗪）-TMC / PSF NF膜。 PDOPA的特殊分子结构和高粘附性。研究了NF膜的分离性能和稳定性。PDOPA双层膜的聚酯键和PDOPA的生物粘附力同时有利于改善双层膜的结构和化学稳定性。将PDOPA-TMC / PSF和PDOPA / PIP-TMC / PSF NF膜在乙醇溶剂中浸泡12天后，刚果红的拒收率仅分别下降了1.8％（原价99.9％）和1.2％（原价99.9％）。对于PDOPA / PIP-TMC / PSF NF膜，Na的排斥₂ SO ₄仅减少了1.6％（原为98.5％）。此外，PDPOA-TMC / PSF和PDOPA / PIP-TMC / PSF NF膜的分离性能在次氯酸钠溶液（50 ppm）中浸泡240 h（12,000 ppm·小时）后仍然很出色。因此，NF膜在乙醇中表现出长期的结构稳定性，在次氯酸钠溶液中表现出优异的化学稳定性。特别地，在上述实验中未观察到分层，这对于它们在废水处理领域中的使用是重要的。