Copper and Lead Ions Removal from Aqueous Solutions Case Study: Fly Ash Carbon as Low-Cost Effective Sorbent

Document Type : Original Article

Authors

1 Central Laboratory for Environmental Radioactivity Measurements Inter-Comparison and Training (CLERMIT), Nuclear and Radiological Regulatory Authority, Cairo, Egypt

2 Chemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt

3 Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Egypt

Abstract

In this study, the use of fly ash carbon for removal of copper (II) and lead (II) ions from aqueous solution has been studied. The removal was conducted in batch system under various conditions of pH, contact time, initial concentration of metal ions, adsorbent dose and temperatures. Isotherms from Langmuir, Freundlich, and Dubinin-Radushkevich at different temperatures (303-333K) were evaluated and the results were compared. Both pseudo-first and pseudo-second-order adsorption kinetics were also tested. Thermodynamic parameters; ΔH°, ΔG°, and ΔS° have been calculated. SEM is used to assess morphological changed in the fly ash carbon surfaces following adsorption of copper (II) and lead (II) ions. The obtained results have been shown that equilibrium was established within 20 min from the process and the optimum adsorption was achieved at a pH 6 for copper and pH 7.0 for lead. The uptake level of copper (II) and lead (II) ions by the fly ash generally increased at higher pH values. The pseudo-second order adsorption model was found to be more suitable for describing copper and lead adsorption kinetics on fly ash carbon. Langmuir adsorption model displayed the best RL values for copper (II) ions adsorption ranged from 2.5 to 10.1 and lead (II) ions adsorption ranged from 0.23 to 1.06. The Freundlich value of 1/n was less than 1, indicating favorable adsorption process and confirming adsorbent’s heterogeneity. The thermodynamic parameters (∆G, ∆H, ∆S) were found to be ranged from -502 to -1424 kJ/mol, -4.5 kJ/mol and 16.6 kJ/mol, respectively for cooper (II). For lead (II) it was found to be be ranged from -1525 to -3236 kJ/mol, 1.052 kJ/mol and 3.675 kJ/mol, respectively which means that high percent removal of lead. In (D-R) isotherm model the adsorption of the mean free energy for the copper was 0.002 kJ/mol, while in the case of lead; it was 0.0007 kJ/mol, confirming a physical adsorption mechanism.

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  • Receive Date: 09 October 2021
  • Revise Date: 13 January 2022
  • Accept Date: 25 January 2022
  • First Publish Date: 25 January 2022