Comparative study on adsorption of cationic and anionic dyes by smectite rich natural clays

Abstract The smectite rich natural clays of upper Cretaceous of Jebel Romana (South of Tunisia) and Lower Oligocene of Khledia area (Norh of Tunisia) were evaluated as adsorbents for anionic (Acid Brown 75) and cationic (Basic Yellow 28) dyes. XRD, XRF, FTIR, S BET , CEC and pH pzc were used to study the physico-chemical properties of clay samples. The experimental results showed that, the adsorption was pH dependent with a high adsorption capacity of BY28 in basic range and high adsorption of AB75 in acidic range. The maximum adsorption capacities, predicted by the Langmuir model, were 76.92 and 8.33 mg/g for BY28 and AB75, respectively. Smectitic clays showed to be an advantageous adsorbents in terms of price and availability, they use without purification or chemical modifications, which is beneficial for the economy of the treatment.