Theoretical studies on adsorption of Ni(II) from aqueous solution using Citrus limetta peels

The potential of an agro industrial waste Citrus limetta peels (CLP) for biosorption of Ni(II) ions from aqueous solution was explored in batch system in terms of equilibrium, kinetics and thermodynamics. The peels were characterized by FTIR spectroscopy, TGA analysis, and SEM. The effect of process parameters such as initial pH, metal ion concentration, biosorbent dosage and contact time on metal ion sorption was examined. The optimum values for pH and biosorbent dose for Ni(II) sorption were 6 and 2 g/L, with time for equilibrium adsorption 45 min. Application of the experimental data to several kinetic models and adsorption isotherms showed that the adsorption process follows a pseudo second order and Langmuir isotherm. The maximum adsorption capacity was found to be 27.78 mg/g. Elution efficiency was determined with different concentrations of HCl. Effect of various competing ions on sorption was also evaluated. The study was extended to metal sorption from synthetic wastewater. Results indicate that the CLP can be an effective and environmentally friendly adsorbent to detoxify Ni(II)-polluted wastewater. The high nickel adsorption capacity of CLP suggests its utility on industrial scale. (c) 2017 American Institute of Chemical Engineers Environ Prog, 36: 864-872, 2017