Lead removal from aqueous solutions by a Tunisian smectitic clay

The ability of AYDs sample to remove Pb2+ from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount, metal ion concentration and pH. Kinetic experiments showed that the sorption of lead ions on AYDs was very fast and the equilibrium was practically reached after only 20 min. The results revealed also that the adsorption of lead increases with an increase in the solution pH from 1 to 4.5 and then decreases, slightly between pH 4.5 and 6, and rapidly at pH 6.5 due to the precipitation of some Pb2+ ions. The equilibrium data were analysed using Langmuir isotherm model. The maximum adsorption capacity (Q0) increased from 25 to 25.44 mg/g with increasing temperature from 25 to 40 °C. Comparative study between sulphuric acid activated clay (AYDs) and powder activated carbon (PAC) for the adsorption of lead was also conducted. The results showed that sulphuric acid activated clay is more efficient than PAC.