Potential of a Tunisian Natural Clay to Remove Cationic and Anionic Dyes From Polluted Waters

The objective of this study is to show the adsorption power of Tunisian smectitic clay from Jebel Aidoudi from the region of El Hamma (southern Tunisia). A cationic dye (Methylene Blue: MB) and an anionic dye (Orange II: OII) are used to determine the maximum absorbability of clay. Physico-chemical characterization tests (XRD, XRF, SBET) on the clay sample were performed. The experimental results showed that the optimal contact time of adsorption is 40 min (91.35% and 51.87%, respectively, for MB and OII). An increase in the retention rate of the dyes was noted by varying the adsorbent rate from 0.06 g to 0.12 g. The experimental results showed that the retention was strongly influenced by the pH of the medium (a high adsorption rate of MB at basic pH and a high adsorption rate for OII at acidic pH). The adsorption capacities are well described by the Langmuir isotherm. The pseudo-second order model is the most reliable for determining the order of absorption kinetics of MM and OII by this smectitic clay.