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Background & Aims of the Study: Heavy metals, such as cadmium (Cd(II)), enter into the environment and cause health hazard due to their toxicity and bioaccumulation in the human body. Therefore, they must be removed from water. In recent years, much attention has been focused on the use of material residues as low-cost adsorbents for the removal of heavy metal ions from aqueous solutions. The aim of this paper is the assessment of tea wastes efficiency on removal of Cd(II) from aqueous solutions.

Materials and Methods: The present study was conducted in experimental scale. In this paper, tea wastes were prepared and used as an adsorbent for the removal of Cd(II) ions from water. In batch tests, the effect of parameters like pH (1.0-8.0), initial metal concentration (100-800 mg L^-1), contact time (15-120 min), adsorbent dose (1.0-5.0 g) and temperature (25-55 °C) on the adsorption process was studied.

Results: The results demonstrated that the maximum percentage of Cd(II) adsorption was found at pH 6.0 and the equilibrium was achieved after 60 min with 3.0 g tea wastes. The experimental isotherm data were analyzed, using the Langmuir and Freundlich models and it was found that the removal process followed the Langmuir isotherm. In addition, the adsorption kinetics followed the pseudo-second-order kinetic model. The maximum adsorption capacity calculated by Langmuir fitting was 71.4 mg g^−1.