Enhancing the oil/water separation efficiency of polylactic acid fiber membrane via polydimethylsiloxane-polycaprolactone copolymer

Membrane technology is one of the important methods of treating oily wastewater due to low energy consumption. How to design the membrane with high efficiency, biodegradable, reusable and good mechanical properties has attracted increasing interest. In this work, a polydimethylsiloxane-polycaprolactone (PDMS-PCL) was synthesized to endow polylactic acid (PLA) fiber membrane with superhydrophobicity and superoleophilicity via electrospinning without secondary processing. When the blend ratio of PDMS-PCL/PLA is 15 wt %, the water contact angle of the fiber membrane is 155.1 +/- 3 degrees, and the oil contact angle is almost zero. The tensile strength and elongation at break are 2.05 +/- 0.16 MPa and 37.9 +/- 2.3 %, respectively. The fiber membrane exhibited high oil/water separation performance and quick adsorption of oil drop underwater. The permeate flux and separation efficiency for n-hexane are 3550 +/- 50 L center dot m(-2 center dot)h(-1) and 99.3 +/- 0.2 %, separately. It also has excellent self-cleaning and durable properties. The fiber membrane maintains high oil flux, separation efficiency, and mechanical properties after more than 10 rounds of separation. The fiber membrane can resist the external environment variation such as to some extent. The water contact angle of the fiber membrane undergoing friction and heating at 100 degrees C stably remains at about 150 degrees. The weight loss is little in salt solution. Then this simple efficient method is suitable large-scale production and will promote membrane technologies in application of oil/water separation.