Abstract
Membrane fouling, especially the composite pollution caused by inorganic scaling and biological fouling, is a key challenge in the treatment of underground karst water with high salinity and high hardness. This study reports a polyethersulfone (PES) ultrafiltration (UF) membrane modified by molybdenum disulfide-tannic acid@copper ions (MoS2-TA@Cu2+) bionanomaterial. By blending MoS2-TA@Cu2+ nanoparticles into the PES matrix, the membrane's structure and comprehensive properties were systematically controlled. Scanning electron microscopy (SEM) and static water contact angle measurements were employed to characterize the morphology and surface properties of the membranes. Characterization analysis confirmed that the hydrophilicity of the modified membrane was enhanced (the water contact angle [WCA] was reduced from 69° to 56°), and it showed high antibacterial properties (the antibacterial rate against Escherichia coli [E. coli] reached 95%). The core contribution of this study is to systematically elucidate the tunable trade-off mechanism between key membrane properties dominated by nanoparticle loading. Specifically, a loading capacity of 10 g/m2 achieved optimal anti-fouling stability, with a flux recovery rate (FRR) as high as 81.5% (40.5% higher than that of the original membrane). In contrast, a loading capacity of 15 g/m2 showed the superior permeation and separation performance, with a turbidity removal rate of 92.9% in actual karst water and a silt density index (SDI) reduction value of 5.3, fully meeting the stringent requirements of reverse osmosis pretreatment. Both static and dynamic anti-fouling experiments confirmed its excellent performance, with the CaCO3 scaling amount reduced by up to 65.2%. This study provides an effective strategy for the development of multifunctional UF membranes that can cope with complex water quality challenges by revealing the inherent trade-off between separation efficiency and anti-fouling stability. This paper provides the key theoretical basis and practical guidance for the precise design of high-performance multifunctional membranes.