Passive flux recovery in protein-fouled liquid-gated membranes

Removing biofouling is a significant challenge in membrane filtration. Here, the presence of a surface-immobilized layer of lubricant is shown to result in flux recovery in protein-fouled polytetrafluoroethylene (PTFE) membranes. Recovery of these liquid-gated membranes (LGMs) occurs during a 15- or 30-min cessation of flow, or rest, and results in up to 60% recovery of clean-membrane flux compared to 10% in membranes with no lubricant layer. Repeated filtration of a 2.5 g L−1 solution of whey protein and subsequent resting continues to result in recovery of flow over 12 cycles. Resting does not result in flux recovery in LGMs fouled with bacterial biofilms. Nevertheless, it is found that flow can be recovered in biofilm-fouled membranes through exposure to an air-water interface. This work demonstrates the potential for liquid gating to facilitate passive flux recovery in biofouled membranes, with promising applications in industry processes.