Mono-/competitive adsorption of cadmium(II) and lead(II) using straw/bentonite-g-poly(acrylic acid-co-acrylamide) resin

We investigated the adsorption of Cd2+ and Pb2+ using straw/bentonite-g-poly(acrylic acid-co-acrylamide) resin as an adsorbent in single and binary-component systems. The resin was characterized by various analytical techniques. Adsorption experiments were conducted by varying the pH, adsorbent dosage, initial concentration and temperature. Adsorption data for Cd2+ and Pb2+ fitted the Langmuir isotherm in the single-component system. Kinetic data for Cd2+ and Pb2+ followed the pseudo-second-order kinetic in a single-component system. A maximum adsorption for Cd2+ occurred at pH 5, whereas for Pb2+, the maximum Cd2+ adsorption occurred at pH 3. The maximum Cd2+ and Pb2+ adsorption capacities were 315.1 mg g−1 and 355.5 mg g−1, respectively. In the binary-component system, the presence of Cd2+ could improve the adsorption capacity of Pb2+ and the presence of Pb2+ could reduce the adsorption capacity of Cd2+ when the Cd2+ concentration was high. This study provides realistic and valid data on resin use to remove heavy metal ions from aqueous solutions.