Aeration module
An aeration module capable of aerating a liquid supplied to inner portions of hollow-fiber membranes includes a housing containing a fluororesin as a main component, and a plurality of the hollow-fiber membranes containing polytetrafluoroethylene or a modified polytetrafluoroethylene as a main component. A porosity K [%], an average thickness T 1 [mm], and an average outer diameter D 2 [mm] of the hollow-fiber membranes satisfy a relation of a formula of K/(T 1 ×D 2 ×100)≥2.0.
1 . An aeration module capable of aerating a liquid supplied to inner portions of hollow-fiber membranes, comprising:
a housing containing a fluororesin as a main component; and
a plurality of the hollow-fiber membranes containing polytetrafluoroethylene or a modified polytetrafluoroethylene as a main component,
wherein a porosity K [%], an average thickness T 1 [mm], and an average outer diameter D 2 [mm] of the hollow-fiber membranes satisfy a relation of a formula (1) below:
K
/
(
T
1
×
D
2
×
100
)
≥
2.
;
(
1
)
wherein the hollow-fiber membranes have a heat of fusion of 30 J/g to 45 J/g, as measured by differential scanning calorimetry (DSC), wherein the heat of fusion is defined as an integrated endothermic heat amount from 296° C. to 343° C. obtained in a third heating step of a DSC measurement that includes a first heating step, a second heating step, and the third heating step, and
wherein the hollow-fiber membranes have an average outer diameter D 2 of 0.70 mm or less, an average inner diameter D 1 of 0.32 mm or less, and a porosity K of 30% or more.
2 . The aeration module according to claim 1 , wherein the hollow-fiber membranes have a water pressure resistance of 0.3 MPa or more.
3 . The aeration module according to claim 1 , wherein when pure water with a dissolved oxygen concentration of 0.6 ppm or less is supplied to the inner portions of the hollow-fiber membranes and air is caused to permeate at a pressure of 10 kPa, a maximum flow rate per minute at which the pure water after aeration treatment is capable of maintaining a dissolved oxygen concentration of 8 ppm or more is 0.035 mL/(cm 2 ·min) or more relative to a unit inner surface area of the hollow-fiber membranes.
4 . The aeration module according to claim 1 , wherein the main component of the housing is a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene, a tetrafluoroethylene/hexafluoropropylene copolymer, or a combination thereof.
5 . The aeration module according to claim 2 , wherein when pure water with a dissolved oxygen concentration of 0.6 ppm or less is supplied to the inner portions of the hollow-fiber membranes and air is caused to permeate at a pressure of 10 kPa, a maximum flow rate per minute at which the pure water after aeration treatment is capable of maintaining a dissolved oxygen concentration of 8 ppm or more is 0.035 mL/(cm 2 ·min) or more relative to a unit inner surface area of the hollow-fiber membranes.
6 . The aeration module according to claim 2 , wherein the main component of the housing is a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene, a tetrafluoroethylene/hexafluoropropylene copolymer, or a combination thereof.
7 . The aeration module according to claim 3 , wherein the main component of the housing is a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene, a tetrafluoroethylene/hexafluoropropylene copolymer, or a combination thereof.
8 . The aeration module according to claim 5 , wherein the main component of the housing is a tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene, a tetrafluoroethylene/hexafluoropropylene copolymer, or a combination thereof.
9 . The aeration module according to claim 1 , wherein the hollow-fiber membranes have an average pore size of 5.2 nm to 9.4 nm.