Method of preparing uniform size ion exchange resin particles by partial functionalization
First Claim
1. A process for preparing improved ion-exchange resins that are derived from a plurality of cross-linked copolymer beads which are non-uniform in particle size, the process comprising:
- contacting the copolymer beads with a functionalizing agent under conditions sufficient to substitute ion-exchange groups onto the copolymer beads; and
continuing the contact until a partially functionalized ion-exchange resin is obtained having a particle size distribution characterized by a standard deviation located substantially at the minimum point on a two-dimensional curve, the curve being defined by a plot of standard deviation versus contact time for the copolymer beads wherein standard deviation is plotted in reference to the vertical axis and contact time is plotted in reference to the horizontal axis.
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Abstract
A process is provided for preparing ion-exchange resin particles of relatively uniform size by partial functionalization of non-uniform copolymer beads with ion-exchange groups. The non-uniform copolymer beads are preferably functionalized in a manner such that the ion-exchange groups are substituted at available sites which are most accessible to diffusion by functionalizing agents. Due to the size difference between individual copolymer particles, a greater proportion of available sites is functionalized in a small particle when compared to that of a large particle. Due to the greater proportion of ion-exchange groups present in a small particle, the small particle swells relatively more than a larger particle. The result is effectively a narrowing of the size distribution for the partially functionalized resin particles. The relatively uniform resin particles obtained by the process have performance advantages, such as reduced pressure drops, improved exchange kinetics, rinse efficiencies, and separation efficiencies when compared to fully functionalize ion-exchange resins that are non-uniform in particle size.
35 Citations
18 Claims
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1. A process for preparing improved ion-exchange resins that are derived from a plurality of cross-linked copolymer beads which are non-uniform in particle size, the process comprising:
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contacting the copolymer beads with a functionalizing agent under conditions sufficient to substitute ion-exchange groups onto the copolymer beads; and continuing the contact until a partially functionalized ion-exchange resin is obtained having a particle size distribution characterized by a standard deviation located substantially at the minimum point on a two-dimensional curve, the curve being defined by a plot of standard deviation versus contact time for the copolymer beads wherein standard deviation is plotted in reference to the vertical axis and contact time is plotted in reference to the horizontal axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification