EVALUATION OF ADSORPTION FROM DISPERSION CHARGE PROFILE

The evaluation of adsorption behavior from the charge profile of an adsorbent dispersion determined as a function of the adsorbate concentration was investigated by the streaming current measurement, using methylene blue and erythrosine as adsorbates and activated charcoal, microcrystalline cellulose, and polyvinylpolypyrrolidone as adsorbents. Adsorption capacity was evaluated using streaming current versus solute concentration plots of dye solutions and of corresponding dye solutions equilibrated with the adsorbent. It was also determined by adsorption isotherm measurement and application of the Langmuir equation. Good agreement was obtained between the adsorption capacity values from streaming current data and adsorption isotherm measurements for microcrystalline cellulose, suggesting that adsorption here was a surface phenomenon without water‐soluble extractives affecting particle charge. Similar agreement was not obtained for charcoal adsorption, and this result was attributed to the unusual adsorption behavior of charcoal. Since polyvinylpolypyrrolidone gave a dispersion with high particle charge, the streaming current method could not be used with this system. The charge profile could be useful in characterizing powders for unusual adsorption behavior and possible water‐soluble extractives as well as for surface area estimation in the absence of these factors. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company