Abstract

Cadmium is one of the environmental toxic elements used in various industries such as electroplating, plasticization, battery making, electrically, communications, dyeing, fertilization and alloy making and its adverse health effects such as kidney and lung damage, types of cancer, hypertension Blood and anemia have been proven in humans. Therefore, its entry into the body through water, air and food causes disturbance to the body's natural activities, so it is of great ecological and biological importance. The aim of this research was to investigate the cadmium removal using eggshell and specifying the adsorption isotherms and kinetics. In this research, cadmium solutions were prepared from cadmium nitrate (Cd(NO₃)₂.4H₂O). The pH amount of the solutions was adjusted by Sodium Hydroxide and Acetic Acid at a concentration of 0.1 mol/L. The pH of the solution was adjusted in the amount of 2 to 10. To describe the data, kinetics models of Ho et al. and Lagergren were used. Isotherm models of Langmuir and Freundlich were used to describe the laboratory data in the adsorption process. The results indicated that the most capacity of eggshell in cadmium adsorption happened at pH=8 and contact time 120 minutes. Investigation of adsorption isotherms showed that Freundlich isotherm with a correlation coefficient of 0.97 is more consistent with cadmium adsorption by eggshell. Comparing the correlation coefficient between measured data and obtained amount from Ho et al model and Lagergren model showed that the Ho et al model with a correlation coefficient of 0.96 describes experimental data better.