Thin-film nanocomposite membranes incorporated with water stable metal-organic framework CuBTTri for mitigating biofouling

Thin-film composite (TFC) polyamide membranes are the most commonly used membrane materials for reverse osmosis (RO) processes; however, the high biofouling propensity is one of major limitations to the widespread application of TFC membranes. In this study, we developed an antibiofouling thin-film nanocomposite (TFN) membrane by incorporating a copper-based water-stable metal-organic framework (MOF), CuBTTri, in the active layer. Results showed that the presence of MOFs in the TFN active layer significantly increased membrane water permeability without compromising selectivity. Furthermore, the incorporation of CuBTTri imparted the TFN membrane with efficient antibacterial properties. After 24 h contact, the colony forming units (CFU) of Pseudomonas aeruginosa on the TFN membrane (with a dosage of 0.1% MOF) was 3.4% of that on the pristine membrane, demonstrating a strong antibiofouling behavior. The cross-flow filtration tests further confirmed the antibiofouling performance of the TFN membrane, with a significantly lower flux decline (similar to 36%) compared to the control (similar to 70% flux decline). The TFN membranes also had a thinner biofouling layer and less quantity of biofoulants on their surface compared to the TFC membrane. The antibiofouling properties of the TFN membrane were associated with bacterial membrane potential depolarization and cell damage due to the contact with MOF. These results highlight the potential of water-stable MOFs to be used as functional materials to fabricate antibiofouling TFN membranes for advanced water and wastewater treatment.