Routine Exchange Capacity Determinations of Ion Exchange Resins

Abstract

1191 ber of the first column. The third member of the new column is the sum of the second member of the new column and the third member of the first column. Thus the mth member of the new column is the sum of the preceding member of the new column and the mth nember of column I.5. Summing column II gives Si.6. A third column is obtained from column II just as column II was obtained from I. The sum of column III is St. 7. Calculate xm 605i -blSi -j-12S3 245i -1852 4S3 8. The peak position is given now by Pm = Po + (xm)(A P) (5) (6)where P" is the position of the first reading, x" is calculated according to step 7, and AP is the size of the equally spaced interval in the usual units. EXAMPLEThe intensity of x-ray spectrometer lines is measured precisely by measuring automatically the time required to accumulate a fixed number of counts. The number of counts per unit of time is then the measure of intensity. Determining a peak position may be done by taking measurements at equal intervals of 26 about the expected point. (For this type of measurement, P is 26.) If the intensity is a maximum, the time is a minimum. Such times were determined for the cobalt Ka line by the follow-ing data taken with a lithium fluoride analyzing crystal. The various steps are indicated.Observations other than seven are permissible but the expression for xm is not as simple as that shown in step 7. The corresponding expressions may be derived by carrying out the standard orthogonal polynomial method. The expressions for x" when n = 5, 6, 7, 8, or 9 were all computed and that for seven points was the simplest. It must be emphasized that the peak must be symmetric in the form used. By decreasing AP and limiting the measurements to a small region around the peak, departure from symmetry may sometimes be reduced to a negligible magnitude. For the illustrative data (Table I), the orthogonal polynomial method was used to determine that the cubic and further terms beyond x2 were not statistically significant.The usefulness of the method consists in its simplicity which results in a great saving of time. For example, these data were computed in about 4 minutes. Using the same data but the more usual method involving squaring, cubing, etc., took 20 minutes. If uneven intervals had been used, the long method would probably have taken from 30 to 60 minutes. LITERATURE CITED(1) Snedecor, G. W., "Statistical Methods," 4th ed., pp. 388-97,

Thermodynamic equilibrium for the dehydration of 1-butanol to di-n-butyl ether

“…Amberlyst-70 is a low cross-linked (8 %DVB) chlorinated and sulfonated copolymer of styrene-divinybenzene. Its maximum operating temperature is 473 K. The acid capacity, determined by titration against standard base following the procedure described by Fisher and Kunnin (1955), was found to be 2.65 meq.H + /g. The catalyst was used in its commercial form (mean bead diameter = 0.59 mm).…”

Pervaporation behavior of asymmetric sulfonated polysulfones and sulfonated poly(ether sulfone) membranes

“…The degree of sulfonation was measured via the ion-exchange capacity (IEC) determined by converting the sulfonic acid group to sodium sulfonate with 0.1N NaOH and titrating with 0.1N HCl according to the procedure described by Fisher and Kunin. 13 …”

Atomistic simulations of the structure of highly crosslinked sulfonated poly(styrene-co-divinylbenzene) ion exchange resins

“…Monosulfonated resins present one sulfonic group per phenyl ring. Table 1 lists the physical properties determined [29][30][31] for Amberlyst 15 ® , which is the highly crosslinked (19-20% w/w) monosulfonated resin, used as reference in this work to model P(S-DVB).…”