Ion Exchange Characteristics

The resins prepared with the proper synthetic procedures have characteristics related to the percentage cross-linkage in the copolymers. They also have particle size ranges consistent with the 16-50 U.S. mesh size with a uniformity coefficient not exceeding 1.5. (The uniformity coefficient is the 40% size divided by the 90% size.) The effective size (90% size) should be not less than 0.35 mm as measured from a probability plot of size as a function of the accumulative percentage.

The values summarized in Table 7.36.1 are averages. The total number of functional groups per unit weight or volume of resins determines the exchange capacity, whereas the types of functional groups influence ion selectivity and equilibrium. Many specifications deal with these resins, including the whole-bead content, bead strength, attrition values, special sizes, effluent quality, and

FIG. 7.36.2 Preparation of anion exchange resins. (Reprinted, with permission, from T.V. Arden, 1968, Water purification by ion exchange, 22, New York: Plenum Press.

FIG. 7.36.2 Preparation of anion exchange resins. (Reprinted, with permission, from T.V. Arden, 1968, Water purification by ion exchange, 22, New York: Plenum Press.

Linear polystyrene CH CH2 CH CH2 CH CH2

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