Abstract:

Heavy metal ions can harm living organisms and the environment in which they live, due to of their toxicity values. It is necessary to improve water, soil and air contaminated with heavy metals. Among the conventional methods used to remove these ions, adsorption is one of the low cost and environmentally friendly methods. In this study, it was aimed to remove Cu (II) and Pb (II) metal ions from solutions using pumice in a batch system. In the study, the effects of variable parameters such as the effect of the amount of adsorbent (0.1-0.5g), the effect of concentration of Cu(II) and Pb(II) ion solutions(for Cu(II);3.2- 31.8 ppm for Pb(II); 10.2-103.6 ppm), the effect of pH of the solutions(for Cu(II) 3-6.1 (natural pH), Pb(II) 3-5.25(natural pH) were investigated. It was determined that the adsorption efficiency decreased by increasing the ion concentrations of the solutions, and the adsorption efficiency increased by increasing the pH value and the amount of adsorbent.While 91% copper removal efficiency was obtained under optimum conditions where adsorbent amount was 0.4g, solution ion concentration was 6.4 ppm and pH value was 6.1, 97.7% lead removal efficiency was obtained under optimum conditions where adsorbent amount was 0.4g, solution ion concentration was 20.7 ppm and pH value was 5.2. The adsorption data obtained experimentally were modeled by applying Langmuir, Freundlich, Temkin and Harkins-Jura adsorption isotherm models and the isotherm constants were calculated. In the adsorption of copper and lead ions, the Freundlich isotherm model was the most suitable model for the experimental data. The maximum adsorption capacity of pumice for copper was found to be 2.55 mg g-1, and the maximum adsorption capacity of pumice for lead was 10.28 mg g-1. It was determined that the adsorption kinetics were more compatible with the pseudo-second-order reaction kinetic model. The standard free energy change (ΔG°) at different temperatures was calculated, and accordingly the enthalpy (ΔH°) and entropy (ΔS°) values of the adsorption reaction were determined. The values obtained showed that the adsorption of copper and lead ions on pumice was exothermic between 20-50°C and was applicable. The results obtained in the study showed that pumice can be an effective, economical and alternative adsorbent material in the removal of heavy metals from aqueous solutions when compared with other commercially used adsorbents.

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