Monofilament-reinforced hollow fiber membrane

A process for embedding a monofilament, tubular open-weave braid of monofilaments in a membrane polymer, comprising,

• weaving an open tubular braid having a recurring rhomboid pattern of synthetic resinous monofilaments in the denier range from 25-250, directly over the surface of and snugly contacting a core cable of poly vinyl alcohol plasticized with from 5-20 weight percent of plasticizer, the cable having a diameter chosen to provide a lumen of desired diameter in the range from 0.5-2.0 mm;
• coating the tubular braid with a membrane-forming dope in a coating nozzle until the dope infiltrates into an area below the surface of filaments overlying the cable to form the lumen;
• pulling the cable and braid together through the coating nozzle;
• coagulating the dope to form a semipermeable membrane embedding the braid as a monolayer which, together with polymer surrounding it, defines the lumen of the membrane;
• washing in hot water until at least 99% of the plasticized PVA is removed, and, further washing with an aqueous oxidizing agent chosen from sodium hypochlorite (NaOCl), hydrogen peroxide and potassium hypochlorite (KOCl) to make an asymmetric membrane which tests for eluted water having a total organic carbon (“TOC”) of <0.5 ppm without damaging the lumen of the membrane formed.