A method for producing a hollow fiber pre-product for a dialysis membrane is disclosed. The dialysis membrane includes a distribution of the pore sizes which follows an exponential function such as an e-function. The inverse value of the exponential coefficient (K) is at least 30 nm.sup.2. The dialysis membrane includes at least 50 pores per μm.sup.2 and the share of a free flow area at a surface of the dialysis membrane amounts to at least 2.5%.

A membrane system includes a first membrane and a second membrane. At a given temperature and pressure: the first membrane has a permeation rate for a first gas and a selectivity for a gas mixture comprising the first gas a second gas different from the first gas; the second membrane has a permeation rate for the first gas and a selectivity for the gas mixture; the permeation rate of the first membrane is greater than the permeation rate of the second membrane; and the selectivity of the second membrane is greater than the selectivity of the first membrane.

A membrane system includes a first membrane and a second membrane. At a given temperature and pressure: the first membrane has a permeation rate for a first gas and a selectivity for a gas mixture comprising the first gas a second gas different from the first gas; the second membrane has a permeation rate for the first gas and a selectivity for the gas mixture; the permeation rate of the first membrane is greater than the permeation rate of the second membrane; and the selectivity of the second membrane is greater than the selectivity of the first membrane.

A filter includes a housing having an interior space, in which the housing has at least one opening end. The filter further includes a membrane disposed within the housing that has a length that extends along a length direction of the housing, and a baffle provided at least in the interior space of the housing. The baffle includes at least two baffle partitions that extend along at least a portion of the length of the membrane to divide the interior space of the housing into at least a first portion and a second portion so that when a fluid is supplied to the filter, the fluid is directed to first flow in the first portion and then to the second portion.

A fluid filtration system includes a fluid storage vessel such as a bioreactor, a filter housing including a filter element disposed therein, a pump coupled between the fluid storage vessel and the filter housing, and a flow diverter disposed between the pump and the filter housing. The pump is configured to move fluid from the fluid storage vessel through the filter element, and the flow diverter is configured for selectively directing fluid received from the pump to the first or second end of the filter housing. In a first mode of operation, the flow diverter directs flow through the filter housing in a first direction, while in a second mode of operation, the flow diverter directs flow through the filter housing in a second direction opposite the first direction.

Viral filters include a filter member featuring a first surface and a second surface and having a thickness extending between the first and second surfaces in a first direction, and a plurality of channels formed in the filter member, each of the channels having a channel axis, where during use, a solution carrying a viral load flows in a direction parallel to the first surface, and at least a portion of the viral load enters the membrane through the first surface and propagates in the first direction, and where for at least 50% of the channels in the filter member, the channel axis is oriented at an angle of between 5 degrees and 85 degrees relative to the first direction.

A pervaporation membrane may be an acid-resistant polybenzidimazole (PBI) membrane. The acid-resistant PBI membrane may be a PBI membrane chemically modified by a process selected from the group consisting of sulfonation, phosphonation, cross-linking, N-substitution, and/or combinations thereof. The membrane may be thermally stabilized. A method for the dehydration of an acid material may include the steps of: contacting an acidic aqueous solution with a membrane of an acid-resistant polybenzidimazole; taking away a permeate stream rich in water; and taking away a concentrate steam rich in the acid material. The acidic aqueous solution may be acetic acid.

A pervaporation membrane may be an acid-resistant polybenzidimazole (PBI) membrane. The acid-resistant PBI membrane may be a PBI membrane chemically modified by a process selected from the group consisting of sulfonation, phosphonation, cross-linking, N-substitution, and/or combinations thereof. The membrane may be thermally stabilized. A method for the dehydration of an acid material may include the steps of: contacting an acidic aqueous solution with a membrane of an acid-resistant polybenzidimazole; taking away a permeate stream rich in water; and taking away a concentrate steam rich in the acid material. The acidic aqueous solution may be acetic acid.

A spin dope composition produces a polymeric fiber useful in non-cryogenic gas separation. The composition includes polysulfone as the polymeric component, two solvents, in which the polymer is soluble, and a non-solvent, in which the polymer is insoluble. The solvents preferably include N-methyl-pyrrolidone (NMP) and N,N-dimethyl acetamide (DMAC), and the non-solvent preferably includes triethylene glycol (TEG). Fibers made from the present composition have been found to exhibit superior properties of gas flux and selectivity, as compared with fibers made from spin dopes having only one solvent component.

A device is disclosed for separating nitrogen and oxygen. The device includes an inlet in fluid communication with a source of a gas comprising oxygen and nitrogen, a membrane having a greater permeability to oxygen than to nitrogen. One side of the membrane is in fluid communication with the inlet, and the other side of the membrane is in fluid communication with an outlet for nitrogen-enriched gas. An outlet for oxygen-enriched gas is also in fluid communication with the first side of the membrane. A porous metal foam is disposed between the inlet and the membrane.