Enhanced anti-wetting and anti-fouling performance of superhydrophobic supported liquid membrane contactors for selective short-chain fatty acid recovery from food waste leachate

Food waste leachate (FWL) contains high concentrations of short-chain fatty acids (SCFAs), such as acetic, propionic, butyric, and valeric acids, offering significant potential for resource recovery using membrane-based separation frameworks. Among these, supported liquid membrane contactors (SLMCs) have emerged as a promising platform for the selective recovery of SCFAs owing to their low energy requirements and tunable selectivity. This study was aimed at systematically examining the recovery efficiency and transport behavior of SCFAs from FWL were using hydrophobic polyvinylidene fluoride (PVDF) membranes, superhydrophobic membranes modified with 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane (PFDTMS), and membranes impregnated with organic extractants including trioctylamine (TOA) and tridodecylamine (TDDA). Among these configurations, the TDDA-impregnated superhydrophobic membrane (PVDF@P_TMS@TDDA) exhibited exceptional selectivity toward n-valeric acid, achieving a recovery efficiency of 93.9 %, whereas acetic acid recovery remained low (2.87 %). These results indicated a strong molecular affinity and ion-pair complexation between TDDA and longer-chain SCFAs. Additionally, the anti-wetting and anti-fouling properties of these membranes were assessed under long-term (50-h) operation. Water contact angle measurements and optical coherence tomography (OCT) revealed that the virgin PVDF membrane experienced severe wetting and structural degradation. Conversely, the PVDF@P_TMS@TDDA membrane maintained high surface hydrophobicity and exhibited minimal changes in porosity, demonstrating excellent mechanical stability and durability. These findings highlight the potential of integrating superhydrophobic membranes with tertiary amine extractants for the selective, energy-efficient recovery of high-value SCFAs from organic waste streams. The proposed approach can support waste-to-resource valorization and contribute to the development of sustainable bio-based production systems aligned with circular economy principles.