Removal of Chromium (VI) from Aqueous Environment Using Modified Parkia Biglobosa (Locust Bean) Shell

Abstract

The different metal complexing ligands containing synthetic and natural adsorbents have been described in literature for the removal of heavy metal ions from aqueous solutions. However, the removal of Chromium (IV) ion using Parkia biglobosa is yet to be reported in literature. A new method was developed to obtain adsorption capacity using modified Parkia biglobosa shells as a natural Chromium (IV) heavy metal ion adsorbent from aqueous solution at a certain pH. Agricultural waste: Carob husks (a product derived from carob beans) were modified with HNO3 and citric acid, and their effectiveness on the removal of Cr (VI) from aqueous solutions was examined in a batch experiment. The core sizes used are 150 µm and 300 µm. The effects of different parameters such as pH, Cr (VI) concentration, adsorbent loading, and contact time were determined. The optimum pH values for the two dimensions were found to be 3 and 1, respectively. The contact time for maximum adsorption is 30 minutes. The Freundlich isotherm describes the equilibrium between liquid and solid phases. Parkia biglobosa can be said to be a good adsorbent for the removal of Chromium (VI) heavy metal ion from aqueous solutions depending on the pH of the solution.