Method for removing chromium from water using ion exchange resins including interpenetrating polymer networks
View Patent ↗The invention includes ion exchange resins and their use in the removal of chromium from water. In one embodiment, the invention comprises a method for removing chromium from a water source by contacting the water with an ion exchange resin, wherein the ion exchange resin comprises particles of a crosslinked copolymer comprising: an interpenetrating polymer network (IPN) of at least two polymer components each having a styrenic content greater than 50 molar percent, and a quaternary ammonium functionality.
1. A method for removing chromium from a water source having a chromium concentration from 10 ug/L to 5000 ug/L and a pH of at least 6.5; comprising the steps of: providing an ion exchange resin, wherein the ion exchange resin comprises particles of a crosslinked copolymer comprising: an interpenetrating polymer network (IPN) of at least two polymer components each having a styrenic content greater than 50 molar percent, and a quaternary ammonium functionality; and contacting the water source with the ion exchange resin.
2. The method of claim 1 wherein the crosslinked copolymer has a styrenic content of greater than 75 molar percent.
3. The method of claim 1 wherein the quaternary ammonium functionality comprises a nitrogen atom bonded to a benzyl carbon of the copolymer and three alkyl groups.
4. The method of claim 1 wherein the quaternary ammonium functionality comprises a nitrogen atom bonded to a benzyl carbon of the copolymer and three alkyl groups, wherein each alkyl group independently comprises from 2 to 6 carbon atoms.
5. The method of claim 1 wherein the quaternary ammonium functionality comprises a nitrogen atom bonded to a benzyl carbon of the copolymer and three alkyl groups, wherein the alkyl groups are selected from: triethyl, tripropyl, tributyl, tripentyl, trihexyl, and dimethylisopropyl.
6. The method of claim 1 wherein the crosslinked copolymer is comprises a gel-type copolymer.
7. The method of claim 1 wherein the particles of crosslinked copolymer comprise a bead structure having a median particle diameter and wherein at least 90 volume percent of the beads have a particle diameter from about 0.9 to about 1.1 times the volume average particle diameter.
8. The method of claim 1 wherein the water source has a pH of 7 or greater.
9. The method of claim 1 wherein the method excludes the step of reducing the pH of the water prior to contacting with the ion exchange resin.