The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

A porous polytetrafluoroethylene (PTFE) membrane of the present disclosure is a membrane having an average fibril length of 50 μm or more, having an average node length 5 or more times larger than the average fibril length, and having an average node area ratio of 5% or less. The porous PTFE membrane of the present disclosure, when attached as a waterproof air-permeable membrane to a housing of an electrical component or electrical device, allows water vapor residing inside the housing to be quickly discharged out of the housing.

Disclosed are a method of manufacturing a polyethylene membrane comprising: stretching a polyethylene film in a first direction during a first stretching; attaching a plurality of rods on side edges of the polyethylene film; attaching a tape on the polyethylene film; stretching the polyethylene film having the rods attached thereto in a second direction during a second stretching; and annealing the polyethylene film after the second stretching. The second direction can be a transverse direction of the first direction, and the first stretching and the second stretching can be performed at the same (or higher) temperature and the same stretching speed as each other.

Hollow-fibre membrane having at least one first curl in the form of a first wave which is characterized by a first oscillation plane and a first wavelength and at least one second curl in the form of a second wave which is characterized by a second oscillation plane and a second wavelength, characterized in that the first oscillation plane and the second oscillation plane confine an angle with one another which is different from zero.

In the present invention, a water-based wetting dispersant having an acid value of 5 mg KOH/g or more and an amine value of 10 mg KOH/g or less is used to dilute and disperse black carbon and a hydrophobic fluorine resin in an organic solvent to manufacture a slurry for microporous layer formation. In this regard, the added amount of the water-based wetting dispersant is adjusted to 5 to 30 parts by weight on the basis of 100 parts by weight of black carbon. In the present invention, the slurry is applied to at least one surface of carbon fiber paper and dried to form a microporous layer in which two independent peaks appear as analyzed on a particle size graph, followed by compression and deposition thereof to fabricate a gas diffusion layer including the microporous layer in which two independent peaks appear as analyzed on a particle size graph. With the appearance of two independent peaks on a particle size analysis graph, the gas diffusion layer of the present invention has an excellent drainage function, thereby increasing in the current value of the concentration polarization curve at the equivalent voltage value.

A process is provided of making facilitated transport membrane comprising a relatively hydrophilic, very small pore, nanoporous support membrane, a hydrophilic polymer inside the very small nanopores on the skin layer surface of the support membrane, a thin, nonporous, hydrophilic polymer layer coated on the surface of the support membrane, and metal salts incorporated in the hydrophilic polymer layer coated on the surface of the support membrane and the hydrophilic polymer inside the very small nanopores. In addition, the process provides a new method of making facilitated transport membrane spiral wound elements or hollow fiber modules for olefin/paraffin separations, particularly for C3=/C3 and C2=/C2 separations.

Embodiments described herein relate generally to durable graphene oxide membranes for fluid filtration. For example, the graphene oxide membranes can be durable under high temperatures non-neutral pH, and/or high pressures. One aspect of the present disclosure relates to a filtration apparatus comprising: a support substrate, and a graphene oxide membrane disposed on the support substrate. The graphene oxide membrane has a first lactose rejection rate of at least 50% with a first 1 wt % lactose solution at room temperature. The graphene oxide membrane has a second lactose rejection rate of at least 50% with a second 1 wt % lactose solution at room temperature after the graphene oxide membrane is contacted with a solution that is at least 80° C. for a period of time.

A reverse osmosis membrane of the present invention includes a porous support substrate (2) and a separation active layer (3) formed on a surface of the porous support substrate (2) and formed of a carbon film containing organized carbon.

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 2.5×10.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.

An apparatus may include a lower chamber to contain a culture that emits volatile organic compounds, an upper chamber, a first sensor within the upper chamber, a second sensor within the upper chamber in a transport selector. The second sensor may be different than the first sensor so as to sense volatile organic compounds differently than the first sensor. The transport selector is to transport a selected portion of the volatile organic compounds emitted from the lower chamber to the first sensor and a second portion of the volatile organic compounds emitted from the lower chamber to the second sensor.