Development of Thin-Film Nanocomposite Membranes Incorporated with CuAl LDH-Zeolite X for Enhanced Forward Osmosis Performance

Forward osmosis (FO) technology for desalination and wastewater treatment has been widely researched because of its significant advantages over traditional pressure-driven membrane processes. However, this process encounters several challenges like low water flux, high reverse solute flux, and inadequate fouling resistance, which necessitate careful consideration in membrane design. This research focuses on improving the desalination, antifouling, and heavy metal rejection efficiency of thin-film nanocomposite (TFN) FO membranes by integrating a CuAl LDH-zeolite X (LDH-Z) into the polyamide active layer. To synergistically exploit the structural characteristics of both LDH and zeolite, the LDH-Z composite was synthesized via a simple in situ coprecipitation method, enabling LDH growth on the external surface and within the pores of zeolite. The intrapore growth of LDH modulated Z internal pore size and enhanced its ion rejection abilities, while the formation of textural mesoporous nanochannels facilitated water transport. FO performance evaluations revealed that the optimized TFN-LZ2 membrane achieved a 64.3% increase in water flux relative to the unmodified TFC membrane. Meanwhile, it maintains reverse solute flux comparable to that of the TFC membrane while exhibiting a 1.35-fold higher selectivity. Moreover, antifouling tests show that water flux decline decreased from 41.9% (TFC) to 26.3% for the optimized membrane due to enhanced surface hydrophilicity and smoothness imparted by LDH-Z. The TFN-LZ2 membrane also performs more effectively at rejecting Cd2+ and Cu2+ heavy metal ions (>97%). These results underscore the capability of LDH-Z-modified membranes to improve FO performance, presenting a promising avenue for FO membrane modification using 2D/3D structured materials.