Development and Performance of Natural Wax-Modified ABS/PU Electrospun Membranes: Sustainable Oil–Water Separation and Secondary Heavy-Metal Adsorption Capability

At present, numerous oil–water separation membranes have been developed for the purification of oily wastewater. However, such wastewater often contains heavy metals, which are difficult to remove during the separation process. In this study, acrylonitrile-butadiene-styrene/polyurethane (ABS/PU) membranes were fabricated using the electrospinning technique. The ABS/PU blend electrospun membrane was modified with natural waxes, including beeswax (BW), soy wax (SY), candelilla wax (CD), and carnauba wax (CR), to achieve effective oil–water separation along with enhanced thermal and mechanical properties. The incorporation of natural waxes significantly improved the membrane hydrophobicity, achieving superhydrophobicity with a water contact angle (WCA) of 156 ± 2° for the soy wax (SY)-modified ABS/PU membrane (ABS/PU–SY). The natural wax-modified membranes exhibited high oil sorption capacity and significant performance under gravity-driven conditions without the application of external pressure. Among them, the ABS/PU–SY membrane achieved the highest flux of 1202 ± 10.52 L m –2 h –1 and a separation efficiency of 99.52% for diesel–water mixtures. The membranes also exhibited preliminary interactions with heavy metal ions, with the CR-modified ABS/PU membrane (ABS/PU-CR) showing an apparent uptake capacity of 32 mg g –1 for Cu 2+ and Fe 3+ ions from aqueous solutions with an initial concentration of 500 mg L –1 . Additionally, TGA and UTM analyses clearly demonstrated that the incorporation of natural wax enhances the thermal and mechanical properties of the ABS/PU membrane, particularly by improving its elongation and elasticity. Durability assessments demonstrated superior UV resistance, pH stability, and reusability. These findings highlight the potential of natural wax-modified ABS/PU electrospun polymer membranes as sustainable, reusable, and multifunctional materials for oil–water separation, with additional potential for heavy-metal ion removal in wastewater treatment applications.