Provided are a lined hollow fiber membrane (HFM) with a sandwich structure, and a preparation method and use thereof. In the lined HFM with a sandwich structure, a membrane structure of the lined HFM includes an inner PVDF layer, a braided liner layer, and an outer PVDF layer in sequence from inside to outside.

Embodiments described herein relate generally to graphene oxide membranes for fluid filtration and more specifically to graphene oxide membranes having tunable permeability, rejection rate, and flux. Some embodiments of the graphene oxide membranes disclosed herein are characterized as having a flux of at least about 2.510.sup.4 gallons per square foot per day per psi with a 1 wt % lactose solution at room temperature, and a lactose rejection rate of at least 50% with a 1 wt % lactose solution.

Filtration apparatus including Graphene Oxide (GO) are described herein. The GO membranes include a plurality of graphene oxide sheets, each of the graphene oxide sheets covalently bound to a chemical spacer. The filtration apparatus can include a GO membrane and a sulfonated polyethersulfone (S-PES). The filtration apparatus can exhibit improved performance with respect to prior art membranes (e.g., high flux and rejection rate) in applications such as pulp and paper processing, which facilitates achieving permeate quality targets. The filtration apparatus described herein can also offer a more stable replacement for reverse osmosis membranes which are known to degrade under strongly alkaline conditions and high temperatures.

The present invention relates to a composite semipermeable membrane including a porous support layer and a separation functional layer provided on the porous support layer, in which the composite semipermeable membrane has a first surface which is a surface on a separation functional layer side and a second surface which is a surface opposite to the first surface, the separation functional layer contains a crosslinked polyamide, and an amino group density measured by a scanning transmission electron microscope (STEM) in a cross section in a thickness direction of the separation functional layer satisfies Nb/Nd0.40, provided that Nb and Nd are defined in the description.

A method for modifying a polymer membrane is disclosed and includes: pre-wetting a polymer membrane using a crosslinking agent solution, where the crosslinking agent solution includes a first crosslinking agent and a second crosslinking agent; irradiating the pre-wetted polymer membrane to initiate a crosslinking reaction; and rinsing and drying the polymer membrane after the crosslinking reaction to obtain a modified polymer membrane. The method for modifying the polymer membrane uses two cross-linking agents to modify the polymer membrane, thereby forming a 3D network on the surface and within the bulk of the polymer membrane to obtain a modified polymer membrane. The modified polymer membrane has low protein adsorption, caustic stability, autoclave sterilization stability, and gamma sterilization stability, while retaining the overall mechanical properties to meet the pleatability requirement for filter manufacturing.