Adsorption of copper ions on two clays from Tunisia: pH and temperature effects

We studied the pH and temperature effects on copper ions adsorption on green and red clays from Tejera-Esghira in Medenine, Tunisia. Acid-activation was studied to improve the adsorption capacity. X-Ray Diffraction identified kaolinite and illite as major clay minerals. At 20 °C, pH5.5 and before acid-activation, the amount adsorbed by the green and red clays was 28.3 and 13.2 mg . g− 1 respectively and increased to 40.6 and 26.8 mg . g− 1 after acid-activation, and the adsorption isotherms could be described by the Langmuir model. Thermodynamic parameters showed that the adsorption process was spontaneous and exothermic. In comparison silica gel adsorbed 27.15 mg . g− 1 copper ions.