Recycling End-of-Life RO Membranes for NF Membranes via Layer-by-Layer Assembly and Interfacial Polymerization

To solve the problem of environmental pollution caused by waste reverse osmosis (RO) membranes, we recycled the end-of-life (EoL) RO membrane by a cleaning-healing-interfacial polymerization (IP) method and reused it as a nanofiltration (NF) membrane. In this work, the influence of the regenerated ultrafiltration (UF) membrane repaired in different ways on the subsequent IP process and the performance of the NF membrane were discussed. The NF membrane prepared with 2.0 layers of LbL self-assembled healed membranes had a pure water permeability (PWP) of 7.25 L·m–2·h–1·bar–1, which also showed excellent long-term working stability and fouling resistance. The rejection rates were all above 99.5% for Na2SO4 solutions with different concentrations, disclosing that the regenerated membranes can be considered as tight nanofiltration membranes. This works provided an economic and environmental protection management method for the future treatment of waste RO membrane modules.