Adsorption of Chromium From Aqueous Solutions by Terminalia chebula- A Kinetic Approach

摘要

Terminalia chebula (Haritaki), one of the main constituent of Triphala, is widely used as an ayurvedic medicine. Batch adsorption studies reveal that the dried fruit of Terminalia chebula has a significant capacity for the removal of chromium (VI) from aqueous solutions. The effects of various parameters, such as initial metal ion concentration, dosage of adsorbent, contact time, pH of the medium, etc., have been investigated. The percentage of adsorption increased with decrease in initial concentration, decrease in pH, increase in adsorbent dosage and increase in contact time. The adsorption processes of Cr (VI) were modeled with Langmuir and Freundlich adsorption isotherms. A comparison of kinetic models are also evaluated for the pseudo first order, pseudo second order model and is found that the pseudo second order model fit the experimental data very well. IR and surface morphology analysis indicates that the adsorbent prepared from Terminalia chebula is efficient for Cr (VI) removal from aqueous solutions.