Limestone residues of sculpting factories utilization as sorbent for removing Pb(II) ion from aqueous solution

This study aims to use limestone wasted from the factory of stone carving for the adsorption of Pb(II) ion from aqueous solution. The process of adsorbing Pb(II) ion was achieved by using the patch method at conditions of (mass of adsorbent = 0.3, 0,6, 1.2 g, contact time = 15, 30, 45, 60, 120 min, particles size = 150, 250, 300 µm, pH media = 2, 3, 4, 5, 6, 7, 8, 9, temperature = 288, 298, 308, 318 K and initial concentration = 50, 70, 90, 100 mg/L) to obtain the best adsorption conditions. The atomic absorption spectroscopy was used to determine the concentration of the Pb(II) ion after the adsorption steps. Results show that the limestone was efficient for the removal of Pb(II) ion with efficiency reaching 99.5 % when 1.2 g of limestone was used. The study also revealed that the smaller particle size of limestone is, the higher percentage of removal will be. The adsorption increased almost rapidly with pH up to 5. The adsorbent uptake reaches the maximum after 15 min of contact. The Freundlich, Langmuir and Temkin isotherms plots show a good linearity, where R2 was more than 0.99, suggesting a good agreement with the experimental data.