Relative selectivity of short- and medium-chain fatty acids in hydrophobic membrane for resource recovery in wastewater: Effects of supported liquid, feed pH, and membrane pores

The recovery of fatty acids from waste resources has attracted attention in terms of reducing the use of fossil fuels and minimizing the influence of climate change. Recently, interest in the recovery of medium-chain fatty acids has increased because medium-chain fatty acids are high-value chemicals and require lower separation costs to produce than short-chain fatty acids. Recently, a supported liquid membrane contactor was studied, and filling the membrane pores with the extractant is very economical and environmentally friendly because very small amounts of extractant are used. However, there are no studies on the transport behavior difference between virgin and supported liquid membrane contactors and the selectivity of medium-chain fatty acids for high-purity separation in supported liquid membrane contactors. In this study, virgin and supported liquid membrane contactors were used, and the behavior of fatty acids was evaluated based on factors such as supported liquid, feed pH, and membrane pore size. Each mass flux was correlated with the log K-ow values of fatty acids. The results showed that the mass transfer of medium-chain fatty acids was higher in supported liquid PVDF membrane than virgin membrane, up to 4.4 times in the case of hexanoic acids, and the relative selectivity of medium chain fatty acids was also increased up to 13.4 times.