Sorption of Methylene Blue onto Orange and Lemon Peel

This study examines the sorption of methylene blue on the cheap unconventional bio sorbents, citrus fruits: oranges and lemons. Bio sorbents which was used was: orange and lemon peel, seeds and pulp. The results are compared with results of sorption to mineral sorbents, zeolite clinoptilolite, Pyrolox and Birm. Sorption kinetics and the influence of pH on the sorption of methylene blue on orange and lemon peel was examined. Sorption isotherm of methylene blue onto the orange end lemon peel was determined at 25C with the initial concentrations of methylene blue 50 – 1000 mg/dm. The sorption kinetic data were analyzed using pseudo–first–order and pseudo–second-order models. It was found that the pseudo-second-order kinetic model was the best applicable model to describe the sorption kinetics. When the pH of the solution dyes was 2-3, the sorption of methylene blue was slightly weaker than at pH 3-6. In the studied concentration range 50-1000 mg/dm sorption of methylene blue on orange and lemon peel was linear, with sorption efficiency of approximately 100%. The capacity of zeolite for methylene blue was 20 mg/g. Sorption capacity of citrus waste was significantly higher than in the mineral sorbents (zeolite, Pyrolox, Birm).