Polytetrafluoroethylene (PTFE) composite articles that have a macro textured surface. The composite articles include at least two different PTFE membranes in a layered or stacked configuration. The composite article has a macro textured surface characterized by a plurality of strands raised from the surface of the PTFE membrane. The strands may be formed of either interconnected nodes of PTFE or of at least one nodal mass of PTFE and have a length equal to or greater than about 1.5 mm. The macro textured surface provides a topography to the first PTFE membrane. The composite articles have a bubble point from about 3.0 psi to about 200 psi, a thickness from about 0.01 to about 3.0 mm, and a bulk density from about 0.01 g/cm.sup.3 to about 1.0 g/cm.sup.3.

Polytetrafluoroethylene (PTFE) composite articles that have a macro textured surface. The composite articles include at least two different PTFE membranes in a layered or stacked configuration. The composite article has a macro textured surface characterized by a plurality of strands raised from the surface of the PTFE membrane. The strands may be formed of either interconnected nodes of PTFE or of at least one nodal mass of PTFE and have a length equal to or greater than about 1.5 mm. The macro textured surface provides a topography to the first PTFE membrane. The composite articles have a bubble point from about 3.0 psi to about 200 psi, a thickness from about 0.01 to about 3.0 mm, and a bulk density from about 0.01 g/cm.sup.3 to about 1.0 g/cm.sup.3.

Provided is a porous membrane including polytetrafluoroethylene and/or modified polytetrafluoroethylene having a small pore diameter, thin film thickness, high porosity, and high strength; and a method for manufacturing the same. The porous membrane including polytetrafluoroethylene and/or modified polytetrafluoroethylenehas bubble point of isopropyl alcohol according to JIS K3832 of 600 kPa or more, and tensile strength according to JIS K6251 of 90 MPa or more.

Provided is a porous membrane including polytetrafluoroethylene and/or modified polytetrafluoroethylene having a small pore diameter, thin film thickness, high porosity, and high strength; and a method for manufacturing the same. The porous membrane including polytetrafluoroethylene and/or modified polytetrafluoroethylenehas bubble point of isopropyl alcohol according to JIS K3832 of 600 kPa or more, and tensile strength according to JIS K6251 of 90 MPa or more.

Methods and systems for recovering sulfur dioxide from a Claus unit process emissions stream are provided. The method comprises the steps of generating a process emissions stream from a thermal oxidizer or other combustion device, introducing the emissions stream to an SO.sub.2 removal system, introducing the SO.sub.2 rich stream from the SO.sub.2 removal system to a CO.sub.2 removal system, and introducing an enriched SO.sub.2 stream back to the Claus unit. The SO.sub.2 removal system can include one or more SO.sub.2 selective membranes. The CO.sub.2 removal system can include one or more CO.sub.2 selective membranes.

A filtering device is for obtaining a chemical liquid by purifying a liquid to be purified, and the filtering device has an inlet portion, an outlet portion, a filter A, at least one filter B different from the filter A, and a flow path which includes the filter A and the filter B arranged in series and extends from the inlet portion to the outlet portion, in which the filter A has a porous base material made of polyfluorocarbon and a coating layer which is disposed to cover the porous base material and contains a resin having an adsorptive group.

A filtering device is for obtaining a chemical liquid by purifying a liquid to be purified, and the filtering device has an inlet portion, an outlet portion, a filter A, at least one filter B different from the filter A, and a flow path which includes the filter A and the filter B arranged in series and extends from the inlet portion to the outlet portion, in which the filter A has a porous base material made of polyfluorocarbon and a coating layer which is disposed to cover the porous base material and contains a resin having an adsorptive group.

A method for process a chemical liquid is provided. The method includes at least providing a system having at least one filtration medium, treatment the system with a treatment liquid having a content of iron (Fe) and calcium (Ca) of about 10 ppb or less, and processing a chemical liquid using an apparatus having the system configured therein after the treatment process.

A method for process a chemical liquid is provided. The method includes at least providing a system having at least one filtration medium, treatment the system with a treatment liquid having a content of iron (Fe) and calcium (Ca) of about 10 ppb or less, and processing a chemical liquid using an apparatus having the system configured therein after the treatment process.

A chemical liquid purification apparatus includes a tank body, a return tube, a liquid sending pump, a filtration device and a piping. The tank body has a liquid passage port and a circulation port communicated to a storage space inside the tank body. The return tube has one end connected to the circulation port and another end extending to the storage space. The liquid sending pump and the filtration device are located outside the tank body in between the liquid passage port and the circulation port. The piping is connecting the liquid sending pump and the filtration device to the liquid passage port and the circulation port.