Effect of Methanol Concentration on the Morphology and Wettability of Electrospun Nanofibrous Membranes Based on Polycaprolactone for Oil-water Separation

Nowadays, a cost-effective and energy-efficient separation technology is mandatory for the removal of oil contaminants from industrial wastewater. In this study, nanofibrous electrospun membranes based on polycaprolactone (PCL) with superhydrophobic and superoleophilic properties were fabricated with the aim of separating oil-water emulsions. The best solvent for PCL is chloroform; however, due to its low conductivity, no nanofibrous structure could be attained. Methanol was added to the electrospinning solution to increase the conductivity and thus decrease the fiber diameter. Effect of methanol concentration on the morphology and fiber diameter of the membranes was investigated, and as a result, 30 (vol/vol%) was determined as the optimum content for the added methanol. Wettability results revealed that the addition of methanol did not solely lead to superhydrophobicity; however, introducing silica nanoparticles turned the membrane superhydrophobic. Despite the similar oil absorption capacity of methanol-added and nanocomposite membranes, it was found that the nanofibrous structure of methanol-added membrane could not guarantee a high separation efficiency; however, the attained superhydrophobic property for the nanocomposite membrane resulted in a very high separation efficiency (98 %). All in all, the addition of methanol could highly increase the application window of biodegradable PCL-based membranes, especially in oil/water separation.