Thermodynamic Study of the Competitive Adsorption of Chromium (III) Ionsand Halides onto Sweet Orange (Citrus Sinensis) Peels as Adsorbent

摘要

The combined adsorption of Cr (III) ions and halides from aqueous solution using orange peels as adsorbent was modeled. Orange peels as adsorbent is resource-saving, and has environmental friendly behavior. The influence of initial pH, initial solution ion concentration, adsorbent dosage, halides and temperature on the adsorption efficiency was studied using batch equilibrium assays. Results showed that, adsorption of Cr (III) ions increases with decrease in initial pH (maximum at 2), increasing initial solution concentration, increasing peels dosage, absence of halides and decreasing temperature. Among the tested????isotherm????models, the Freundlich isotherm best modeled both adsorptions without and with presence of halides. Some thermodynamic parameters; ΔG, ΔH, A, ΔHr and ΔS were calculated from the experimental data, with the result showing that the adsorption process is feasible, spontaneous and follow physisorption mechanism. Thus, orange peel is effective in the sorption of chromium (III) ions from aqueous solution.