The zeta potential studies were conducted in a Rank Brothers
Mark II equipment with a flat cell attached to a video camera
and a rotating prism that allows the measurement of the particles’
electrophoretic mobility. A constant ionic strength based on NaCl
concentration of 103 mol/L was maintained in all tests.
A batch testwork was undertaken to investigate the effect of pH
in the range of 3.0–8.0 by shaking 10 mL of Cr(VI) solution with
0.1 g of the montmorillonite sample modified by contact with
7.5 mmol/L of CPB. In the experiments related to the adsorption
isotherms, the tests were carried out with the initial Cr(VI) concentration
varying from 10 to 150 mg/L.