2022 Annual Meeting
Chlorine Stability of Bio-Inspired Liquid Infused Membranes
Ultrafiltration membranes are widely used because of their effectiveness in removing contaminants while also operating at a low pressure in water treatment and wastewater reuse. However, fouling or the accumulation of particles within or on the membraneâs surface can lead to a decrease in the overall efficiency of water filtration. This can lead to a decrease in the overall flux and increase the cost of operation. Sodium hypochlorite (NaClO) or chlorine bleach is a disinfectant commonly used to remove microbial fouling, but the use of disinfectants can also lead to the deterioration of the membrane itself. We have recently developed liquid-infused membranes (LIMs) that take inspiration from the Nepenthes pitcher plant to combine a porous polymer membrane with a lubricating oil to form a membrane that shows resistance to fouling. A chemically inert, omniphobic perfluoropolyether oil Krytox, was added to polyvinylidene chloride (PVDF) membranes with a 0.45 μm pore size. Two Krytox oils with varying viscosity; Krytox grade 103 having a low viscosity and Krytox grade 107 having a higher viscosity; were used to form the LIMs. In this study, the chlorine stability of LIMs was tested. The membranes were soaked in a 400 ppm NaClO solution for 1 day, 3 days, and 7 days. The solution was kept at a pH of 4.5 to have the hypochlorite ion (OCl-) as the dominate species because of its effective disinfecting properties. A dead-end filtration unit was used to measure the flux before and after chlorination. The LIMs membranes compared to the bare membranes show potential to withstand chemical cleaning based on the flux before and after chlorination, but further chemical analysis is needed to fully understand the effects of chemical cleaning on LIMs. Namely, the perfluoropolyether oil used in the LIMs has the potential to break down into per- and poly-fluoroalkyl substances (PFAS); a group of chemicals connected to a variety of health risks with exposure limits in the parts per trillion.