Braid-reinforced thin film composite hollow fiber nanofiltration membranes

We report on a new thin film composite (TFC) hollow fiber membrane that uses a braid-reinforced hollow fiber ultrafiltration membrane as a support. This reinforced support offers pressure tolerance that far exceeds self-supported hollow fiber membranes with the similar chemistry, morphology and geometry. A selective layer is formed onto this support using interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) monomers. Through a systematic optimization of monomer concentrations and reaction conditions, we have created membranes with MgSO4 rejection of 92% and a pure water permeance of 12 LMH/bar. Higher productivity membranes were made with pure water permeance of 22 LMH/bar and a MgSO4 rejection of 65%. The membranes also exhibited a low NaCl rejection (below 30%) which is desirable for water softening applications.