Adsorption of U(VI) ions from aqueous solutions by activated carbon prepared from Antep pistachio (Pistacia vera L.) shells

Antep pistachio (Pistacia vera L.) shells an abundant and low cost natural resource in Turkey was used to prepare activated carbon by physiochemical activation and carbon dioxide (CO2) atmosphere as the activating agents at 700°C for 2 h. The adsorption equilibrium of U(VI) from aqueous solutions on such carbon has been studied using a batch system. The parameters that affect the U(VI) adsorption, such as particle size of adsorbent, contact time, of pH of the solution, and temperature, have been investigated and conditions have also been optimized. The equilibrium data for U(VI) ions’ adsorption onto activated carbon well fitted to the Langmuir equation, with a maximum monolayer adsorption capacity of 8.68 mg/g, The Freundlich and Dubinin–Radushkevich (D–R) isotherms have been applied and the data correlated well with Freundlich model and that the adsorption is physical in nature (Ea =15.46 kJ/mol). Thermodynamic parameters [ΔHs =11.33 kJ/mol, ΔS=0.084 kJ/molK, ΔG (293.15 K)=−13.29 kJ/mol] showed the endothermic heat of adsorption and the feasibility of the process.