Nano-striped polyamide membranes enabled by vacuum-assisted incorporation of hierarchical flower-like MoS2 for enhanced nanofiltration performance

Introducing nanomaterials into the polyamide layer of thin-film composite (TFC) membranes during interfacial polymerization process can customize the physicochemical properties of membranes and further enhance the membrane permeability without sacrificing selectivity. In this study, we prepared novel thin-film nanocomposite (TFN) nanofiltration membranes by varying the deposition density of hierarchical flower-like structured molybdenum disulfide (HF–MoS2) with the assistance of vacuum filtration. Ascribed to the unique 3D hierarchical structure of HF–MoS2, a nano-sized striped polyamide film with a decreased thickness of 30–40 nm was formed, which increased the membrane effective filtration area and reduced the mass transfer resistance for water permeation. In addition, compared to the control TFC membrane, the TFN membranes possessed relatively looser polyamide layers with higher surface hydrophilicity and more negative surface charges. When the deposition density of HF–MoS2 was 10 μg/cm2, the optimal performance of the TFN membranes was obtained, i.e., a water permeability of 18.4 L m−2 h−1 bar−1 and rejections above 98% for Na2SO4 and MgSO4. Moreover, the optimal TFN membrane demonstrated an excellent separation performance and structure stability in the mixed salt solution and the long-term filtration test of 120 h, respectively. This work provides a novel approach to design high-performance TFN membranes applied for water/wastewater treatment.