The present invention relates to a composite semipermeable membrane including: a supporting membrane including a substrate and a porous supporting layer; and a separation functional layer disposed on the porous supporting layer, in which the separation functional layer includes: a crosslinked polyamide; and a hydrophilic polymer which is a polymer of a monomer having an ethylenically unsaturated group, and a surface of the separation functional layer has a ratio of the number of oxygen atoms to the number of nitrogen atoms (O/N ratio), both determined by X-ray photoelectron spectrometry, of 1.5-10, and a standard deviation of the O/N ratio of 0.15 or larger.

Provided are a hydrophilic porous membrane including a porous membrane and a hydroxyalkyl cellulose retained in the porous membrane, in which the average pore size differs between two surfaces of the porous membrane, the hydroxyalkyl cellulose distributed in the thickness direction of the hydrophilic porous membrane exhibits two or more peaks of detection intensity in GPC, and the weight-average molecular weight Mw.sub.min of the peak that is detected latest among the above-mentioned peaks is less than 100,000; and a method for producing a hydrophilic porous membrane, the method including separately preparing a hydrophilizing liquid including a hydroxyalkyl cellulose having a smaller weight-average molecular weight and a hydrophilizing liquid including a hydroxyalkyl cellulose having a larger weight-average molecular weight, and applying each of the hydrophilizing liquids on two surfaces of the porous membrane or sequentially on one surface thereof.

A substrate for a composite membrane includes a microporous polyolefin membrane for carrying a hydrophilic resin compound within the pores of the microporous membrane wherein: the average pore diameter is 1 nm to 50 nm; the porosity is 50% to 78%; the membrane thickness is 1 μm to 12 μm; and, when a mixed solution of ethanol and water (volume ratio 1/2) is dripped onto a surface of the microporous polyolefin membrane which has not undergone hydrophilization treatment, the contact angle θ1 between the droplet and the surface is 0 to 90 degrees 1 second after the dripping, and the contact angle θ2 between the droplet and the surface is 0 to 70 degrees 10 minutes after the dripping, and the rate of change of the contact angle ((θ1−θ2)/θ1×100) is 10 to 50%.

The present disclosure provides a process for producing a modified microporous membrane, comprising (i) Providing a first solution comprising at least one first polymer and at least one epoxy functional compound; (ii) Providing a second solution comprising at least one diamine compound; (iii) Bringing the first solution and the second solution into contact, thereby obtaining a modified microporous membrane comprising at least one first polymer and the crosslinked reaction product of the at least one epoxy functional compound and the at least one diamine compound; wherein the modified microporous membrane is a hollow-fiber membrane; and wherein the first solution is a dope solution, the second solution is a bore solution, and bringing the first and second solutions into contact takes place in a spinneret.

Durable asymmetric composite membranes comprising of a film of cross-linked poly(ether ether ketone) adhered to a sheet of hydrophilicitized microporous polyolefin are disclosed. The membranes are suitable for use in the recovery or removal of water from feed streams where repeated clean-in-place protocols are required such as in the processing of dairy products. The membranes are also suitable for use in the preparation of durable asymmetric composite membranes with improved rejection characteristics.

The problem is to provide a porous membrane with a reduced phenomenon in which membranes firmly adhere to one another during production of the porous membrane (membrane adhesion). The problem is solved by a porous membrane comprising a hydrophobic polymer and a hydrophilic polymer, wherein an average value T of ratios of the number of counts of ions derived from the hydrophilic polymer to the number of counts of ions derived from the hydrophobic polymer is 1.0 or more when a surface of the porous membrane is measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

The object of the present invention is to provide a porous membrane by which a useful component can be recovered while suppressing the clogging during filtration of a protein solution and from which only a small amount of an eluate is eluted even when an aqueous solution is filtered. The present invention provides a porous membrane containing a hydrophobic polymer and a water-insoluble hydrophilic polymer, the porous membrane having a dense layer in the downstream portion of filtration in the membrane, having a gradient asymmetric structure in which the average pore diameter of fine pores increases from the downstream portion of filtration toward the upstream portion of filtration, and having a gradient index of the average pore diameter from the dense layer to the coarse layer of 0.5 to 12.0.

A method of directed evolution for developing a membrane includes using a 3D protocol to simulate particle trajectories and determine the effect of intermolecular forces on particle capture performance during membrane filtration to determine the effectiveness of different candidate membranes in optimizing performance.

A method of making a filter, the resulting filter, and a method of using the filter to filter proteins from solution are described. The method includes contacting a porous, polymeric substrate with a transfer liquid comprising a solvent(s) and a charged polymeric solute. The transfer liquid and the polymeric substrate have a Hansen Solubility Parameter (“HSP”) distance of from about 10 to about 35. Contacting the polymeric substrate with the transfer solution causes the polymeric substrate to accept the charged polymeric solute by diffusion transfer, thereby yielding a functionalized filter medium. Removal of the transfer liquid from the polymeric substrate traps the charged polymeric solute on the surface of the polymeric substrate.

The present disclosure generally relates to liquid separation membranes. The present disclosure also relates to membranes comprising at least a nanoporous hydrophilic layer and a porous hydrophobic substrate. The present disclosure also relates to a process for preparing the membranes and to use of the membranes in pervaporation and/or membrane distillation processes including desalination and/or solvent dehydration.