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Soil Science Society of America Journal Abstract -

Backtitration Technique for Proton Isotherm Modeling of Oxide Surfaces1


This article in SSSAJ

  1. Vol. 50 No. 6, p. 1406-1411
    Received: Nov 8, 1985

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  1. C. P. Schulthess and
  2. D. L. Sparks2



Batch potentiometric titration analyses were made on a γ-Al2O3 colloidal suspension and interpreted in terms of the electroneutrality principle. Three titration methods involving a singular reference curve were compared. The first reference used was theoretical, the latter two were representative supernatant curves: an electrolyte solution, and an aliquot of the zero point of titration (ZPT) supernatant. All three methods resulted in similar charge isotherms and a zero point of charge (ZPC) = 8.60. A fourth titration method was developed involving each supernatant of the batch titration sample to act as a unique reference. This latter method is a backtitration technique which accounts for all sources that also consume H+ ions, leaving the difference to be the adsorbed proton concentration only. The NaClO4 electrolyte solution used is postulated to be adsorbed with competitive cation and anion exchange mechanisms with a point of zero salt effect (PZSE) = 7.50.

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