Comparative adsorption of Pb(II) and Cd(II) ions on chestnut shell in aqueous system

In this study, high capacity Chestnut shell, a waste product from the chestnut sugar production industry, was successfully applied to remove Pb (II) and Cd (II) ions from aqueous solutions. Maximum adsorption capacities were found as 541.25 mg/g and 75.86 mg/g for Pb(II), and Cd(II) respectively. Several important parameters influencing the adsorption of Pb(II) and Cd(II) ions such as contact time, pH, temperature and effect of metal concentration were investigated systematically by batch experiments. Langmuir and Freundlich adsorption models were used to describe adsorption isotherms and constants. The thermodynamic parameters, such as standard free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°), of the adsorption process were calculated. The adsorbents were characterised by scanning electron microscopy. It has been observed from the experimental results that in case of both Cd (II) and Pb (II), pseudo 2nd order kinetic model. From the results, Chestnut Shell are considered as an effective, low cost and environmental friendly adsorbent for the removal of Pb (II) and Cd (II) from wastewater. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group

Removal of arsenic(III) ions from aqueous solutions by modified hazelnut shell

In this study, modified hazelnut shells (HS) were used to remove As(III) ions from aqueous solu­tions. For this purpose, FeCl3 and FeCl3 + NaOH were used as modifying agents. Several important parameters influencing the adsorption of As(III) ions such as contact time, pH, temperature and initial metal concentration were investigated following batch experiments. From the results, it is indicated that temperature 20°C and solution pH = 9.0 are the optimum conditions for adsorption. Maximum adsorption experimental capacities of HS that was treated with FeCl3 and FeCl3 + NaOH were 4.37 and 11.84 mg g-1 for arsenic, respectively. The adsorption data at optimum conditions were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich and Temkin isotherm models, and it was found that Freundlich isotherm model gives better fit. Thermodynamic parameters such as enthalpy change (ΔH°), entropy change (ΔS°) and free energy change (ΔG°) were also calculated. These results were indicated that the adsorption of arsenic on HS is exothermic and proceeds spontaneously. Additionally, it can be said that these adsorptions are physical because the Gibbs free energy change (ΔG°) for both adsorbents were found lower than 20 kJ mol-1. © 2017 Desalination Publications. All rights reserved

Removal of lead from aqueous solutions by low cost and waste biosorbents (lemon, bean and artichoke shells)

Simple, fast, effective, low cost and waste biosorbents, lemon, bean and artichoke shells, were used to remove lead (II) ions from aqueous solution. The influence of pH, contact time, temperature and lead (II) concentration of the removal process was investigated. The sufficient contact time was deemed 10 minutes for bean and artichoke shells and 60 minutes for lemon shells for Pb(II) ions. The thermodynamic parameters, such as standard free energy (AG), standard enthalpy (AH), and standard entropy (AS) of the adsorption process were calculated as -5.6786, -5.5758, -3.1488 kJmol- 1 for AG, -7.2791, -20.285, -9.5561 kJ mol-1 for AH, -0.00545, -0.05017, -0.02185 kJ mol-1 K-1 for AS, respectively, for lemon, artichoke and bean shells. Maximum adsorption capacities of lead (II) were observed as 61.30 m g g - 1, 88.5 mgg- 1 and 62.81 m g g - 1, respectively, for lemon, bean and artichoke shells according to the Freundlich isotherm model at 20 °C. Scanning electron microscope (SEM) and energy-dispersive X-ray detector (EDX) were used to characterize the surface morphology of the adsorbents. Consequently, Pb(II) removal using lemon, bean and artichoke shells would be an effective method for the economic treatment of wastewater. © IWA Publishing 2020 Water Science & Technolog