Cadmium-109 Radioisotope Adsorption onto Polypyrrole Coated Sawdust of Dryobalanops aromatic: Kinetics and Adsorption Isotherms Modelling

A radiotracer study was conducted to investigate the removal characteristics of cadmium (¹⁰⁹Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited ¹⁰⁹Cd removal from its aqueous solution. The experimental data for ¹⁰⁹Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor’s materials and the toxicity of ¹⁰⁹Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of ¹⁰⁹Cd radioisotope from radionuclide-containing effluents.