Activated carbon produced from Iris plant: Equilibrium and thermodynamical behavior in the removal of Cd (II) ions

Solid phase extraction (SPE) is an efficient technique for separation/ preconcentration of metal ions. In the present work Activated carbon was prepared from Irish plant by carbonization at 400°C in oven and activation with phosphoric acid for 1 h [1, 2]. The effect of experimental parameters including contact time, solution pH, initial concentration of analyte, ionic strength and temperature on the adsorption efficiency was investigated. From the batch experiment results it was found that the pH of the working solution played significant role in the adsorption process. The results showed that activated carbon produced from Irish plant adsorbed greater amount of Cd(II) ions than the unactivated Irish plant. The effect of pH on the extraction of cadmium was investigate in the range of 2-9. It was observed that the uptake efficiency was increased by increasing pH value up to 4 and then decreased slightly, hence, pH 4 was chosen for further experiments. The equilibration time and rate are other two important parameters in adsorption processes. Hence these parameters were studied in the ranges of 2-15 min and 50-500 rpm.Consequently 14 min and 400 rpm were selected as optimum contact time and stirring rate, respectively.