Adsorption Kinetics of Cr (VI) using Modified Residual Biomass in Batch and Continuous System

摘要

Background: The increasing concentration of heavy metal pollutants as hexavalent chromium ions has gained attention due to its effect on the environment. Hence, different methods have been applied for removing Cr (VI) in aqueous solution and bioadsorption seems to be a cost-effective alternative due to the use of lignocellulosic materials as biosorbents. Objectives: This paper is focused on a comparative study of adsorption capacity of Cassava Peel (CP), Lemon Peel (LP) and its chemical modification with citric acid (CP-CA and LP-CA). Methods/Analysis: The adsorption process was carried out in batch and continuous systems in order to determine the effects of biosorbent particle size and pH on Cr (VI) removal yield. Findings: It was obtained that removal yield of 54% and 56% were obtained for unmodified cassava peel and citric acid-modified cassava peel, respectively. In addition, LP-CA showed higher removal yield (48%) than LP (43%), which suggested that chemical modification, improves biosorbent performance. The Cr (VI) ions were desorbed using a solution of HCl, and then the biomass was used in three adsorption cycles to determine its reusability. The kinetic model was adjusted to the pseudo-second order model and Elovich’s model for both modified and unmodified biomasses regarding adsorption isotherms. Freundlich model is the one that best describes the adsorption process. Novelty/Improvement: The good performance of these biosorbents in aqueous solution of Cr (VI) ions make them promising candidate for removing of heavy metals water pollutants.