The adsorption of crystal violet by kaolin

Abstract
The uptake of crystal violet on kaolin was examined over a pH range of 2·5 to 9·5, adsorption showing an increase with pH. The attainment of equilibrium between adsorbate and adsorbent is shown to be a two-stage process, the first stage being synchronous with the release of magnesium from the kaolin lattice. Evidence is presented that the major mechanism of adsorption is by electrostatic charges arising from cation replacement in the clay lattice, and that charges arising from the amphoteric nature of the aluminium atom of kaolin make little contribution to the overall adsorptive process.