Modification of polyvinylidene fluoride membrane and method of filtering
AssigneeUniversity of Arizona
InventorsSrini Raghavan, Der'e Jan, Raghunath Chilkunda
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Abstract
There is provided a filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer containing a positively charged organic phosphonium compound grafted to the membrane in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is minimal susceptibility to the extraction of said polymer. The polymer may also contain an acrylate or methacrylate. There is also provided a method for ultrapurifying a liquid and an ultrapurifying system for water.
Claims24
A filter medium comprising a microporous polyvinylidene fluoride membrane having a polymer containing vinyltriphenyl phosphonium bromide and a member of the group consisting of an acrylate and a methacrylate grafted thereto in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is a minimal susceptibility to the extraction of said polymer.
A filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer grafted thereto, said polymer grafted to said membrane from a solution comprising from about 1.0 weight % to about 2.0 weight % of vinyl triphenyl phosphonium bromide and from about 0.1 weight % to about 0.5 weight % of a hydroxylated acrylate or methacrylate, said weight % based on total weight of said grafting solution, and the remainder of said grafting solution being water.
A method for ultrapurifying a liquid having macromolecular contaminants therein comprising passing the liquid through a microporous polyvinylidene fluoride membrane having a polymer of vinyltriphenyl phosphonium bromide and a member of the group consisting of an acrylate and a methacrylate grafted thereto in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is a minimal susceptibility to the extraction of the polymer.
An ultrapure water treatment system comprising:
- a housing;
- a water supply including a water inlet and a water outlet communicating within said housing and defining a path of travel of the water from said inlet to said outlet;
- irradiation means for irradiating water in the housing with UV light of wavelength of about 180 nm to about 190 nm, and
- a filter medium positioned within said path of travel of the water, said filter medium comprising a microporous polyvinylidene fluoride membrane having a polymer containing vinyl triphenyl phosphonium bromide and a member of the group consisting of an acrylate and a methacrylate grafted thereto in a concentration sufficient to provide a surface of said membrane with a positive charge such that there is minimal susceptibility to the extraction of said polymer.
An ultrapure water treatment system comprising:
- a housing,
- a water supply including a water inlet and a water outlet communication with said housing and defining a path of travel of the water from said inlet to said outlet,
- irradiation means for irradiating water in the housing with UV light of wavelength of about 180 nm to about 190 nm, and
- a filter medium positioned within said path of travel of the water, and between said housing and said water outlet or said water inlet or both, said filter medium comprising a microporous polyvinylidene fluoride membrane and a polymer, said polymer being grafted to said membrane from a solution containing from about 1 weight % to 2.0 weight % of a positively charged vinyl triphenyl phosphonium bromide and from about 0.1 weight % to about 0.5 weight % of a hydroxylated acrylate or methacrylate, said weight % based on the total weight of said solution, and the remainder of said solution being water.
Dependencies are inferred from the claim text.