Aloe Vera waste for Methylene Blue (MB), Rhodamine B (RB) and Methyl Orange (MO) adsorption.

Aloe Vera (Aloe barbadensis miller) waste obtained from a local cosmetic production factory was used as bio-adsorbent for the removal of three different dyes: Methylene Blue (MB), Rhodamine B (RB) and Methyl Orange (MO). The material was preliminary washed with water at room temperature. Batch tests at 25°C were performed and the experimental data were fitted using the pseudo-second order kinetic model. It was found out that the rate of adsorption for the tested dyes follows the order MO>MB>RB. Results show that the Aloe Vera waste can be successfully used to remove cationic dyes in aqueous solution. More precisely, 94% removal of MB, 71% removal of RB and a 13% removal of MO was observed in separate tests in which the starting concentration of the correspondent dye was set to 210 mg/L and the bio-adsorbent dosage to 20g/L.