Abstract: A filtering membrane has a supporting structure comprising filaments and is coated with a dope to produce a polymeric membrane layer. Some or all of the filaments comprise a second polymer that is soluble or swellable in a solvent of the dope. The supporting structure may be braided with yarns. One or more yarns may comprise filaments comprising the second polymer. In one example, a braided tubular support is coated with a dope based on PVDF in NMP. Some or all of the yarns of the braid are made of bi-component core-sheath PET-PVDF filaments. With as few as 4% of the yarns in the braid made of the bicomponent filaments, peel strength and pull force of the membrane is improved relative to a braid made entirely of PET yarns. In experimental examples, unpeelable composite membranes were produced. The membrane may be used, for example, for water or wastewater filtration applications.

Abstract: A filtration membrane is coated with a polymer made from a compound comprising a benzenediol or a substituted phenol, such as catechol. The polymer deposition process comprises exposing the membrane to the compound in an aqueous alkaline solution. A membrane module may be immersed in the solution. Optionally, the solution is aerated. The polymer coating is reasonably durable in aqueous environments but may be removable. In an example, a module of PVDF based outside-in hollow fiber membranes was coated with poly(catechol). The membranes had a reduced fouling rate and could be maintenance cleaned with water or a dilute oxidant solution. The polycatechol coating could be oxidized by cleaning the membrane with a hypochlorite solution and re-coated. The modified membranes may be used, for example, in water or wastewater treatment. A filtration process includes steps of oxidizing and re-applying the coating after the membrane has been in use.

Abstract: A filtering membrane has a supporting structure comprising filaments and is coated with a dope to produce a polymeric membrane layer. Some or all of the filaments comprise a second polymer that is soluble or swellable in a solvent of the dope. The supporting structure may be braided with yarns. One or more yarns may comprise filaments comprising the second polymer. In one example, a braided tubular support is coated with a dope based on PVDF in NMP. Some or all of the yarns of the braid are made of bi-component core-sheath PET-PVDF filaments. With as few as 4% of the yarns in the braid made of the bicomponent filaments, peel strength and pull force of the membrane is improved relative to a braid made entirely of PET yarns. In experimental examples, unpeelable composite membranes were produced. The membrane may be used, for example, for water or wastewater filtration applications.

Abstract: A membrane generally comprises a tubular support, and a polymeric membrane film on the support. The polymeric membrane film comprises three zones cast simultaneously from a single dope. The three zones include an inner zone on the support comprising macro-void pores, an intermediate zone on the inner zone comprising macro-void pores smaller than the macro-void pores of the inner zone, and a skin on the intermediate zone comprising pores of less than 1 micron.