Biosorption of chromium and nickel from aqueous solution using pine cones, eucalyptus bark, and moringa pods: A comparative study

Abstract

Low-cost local plants (eucalyptus bark, moringa pods, pine cones) have been successfully used to remove heavy metals from simulated wastewater. Two types of heavy metals were chosen to study the removal capacity, nickel (Ni) and chrome (Cr), with a concentration of 400, 600, 900 ppm. The results show that moringa pods have the best removal capacity for heavy metals with percentages of 90-99% for both metals, Ni and Cr, for the eucalyptus bark the removal capacity percentages reach 50-98%, while for the pine cones revealed a lower removing capacity with percentages of 40-99%, indicating that this is the lowest removal capacity. The data has been best fitted to the Langmuir adsorption model for all plants, while the Freundlich adsorption model could not fit the obtained results at the experimental conditions. The kinetic study has revealed that the first-order kinetic model successfully describes the kinetics of Ni adsorption, while the second-order describes the kinetics of Cr adsorption. The removal of heavy metals (Ni, Cr) was obtained when moringa was used; its highest removal efficiency was reached within 20 minutes. On the other hand, other plants (eucalyptus bark, pine cone) removal efficiency was attained in more than two hours. The removal is remarkable even at a high concentration of heavy metals, especially with the moringa plant.