Open AccessLead Removal from Aqueous Solutions Using Bean Shells � Equilibrium, Kinetics, and Thermodynamic Studies
Author(s) -
Miljan Marković,
Milan Gorgievski,
Dragana S. Bozic,
Vesna Stanković,
Milorad D. Cakić,
Vesna Grekulović,
Kristina Božinović
Publication year - 2021
Publication title -
revista de chimie
Language(s) - English
Resource type - Journals
ISSN - 0034-7752
DOI - 10.37358/rc.21.4.8462
Subject(s) - adsorption , aqueous solution , chemistry , distilled water , metal ions in aqueous solution , fourier transform infrared spectroscopy , alkali metal , metal , nuclear chemistry , inorganic chemistry , chromatography , chemical engineering , organic chemistry , engineering
Lead ions removal from aqueous solutions onto bean shells is presented in this paper. The experiments were conducted in a batch system. The bean shells samples were rinsed with distilled water before the adsorption experiments. The analysis of the rinsed water showed that a significant amount of alkali and alkaline-earth metal ions are transferred from the adsorbent structure into the rinsed solution during the rinsing process. The COD analysis showed that these waters should be treated before being discharged into the surrounding watercourses. The influence of different process parameters (the pH value of the solution, the initial metal ions concentration, and the initial mass of the adsorbent) on the adsorption capacity was investigated. The adsorption capacity was higher at higher pH values of the solution. The adsorption capacity showed a decrease with the increase in the mass of the adsorbent. The increase in the initial metal ions concentration was shown to lead to an increase in the adsorption capacity until 0.8 g dm-3, after which a slight decrease was noted. Characterization of the adsorbent was performed by SEM-EDX, DTA-TGA, and FTIR analysis. The SEM-EDX analysis indicates a change in the morphology of the sample after the adsorption, as well as that K and Mg are possibly exchanged with lead ions during the adsorption process. The results obtained by the DTA-TGA analysis showed a weight loss of 77.8 % in the temperature range from 20oC to 900oC. The FTIR analysis indicated that the amide group is involved in the adsorption process. The pseudo-second order kinetic model was shown to be the best fit for the analyzed data, which led to the conclusion that chemisorption was a possible way of binding lead ions onto the surface of the bean shells. The Hill isotherm model was the best model for the analyzed adsorption equilibrium data. Obtained thermodynamic data indicated that the adsorption process was spontaneous, endothermic, and disordered, in which lead ions are bound to the surface of the bean shells by chemisorption. The maximum achieved adsorption capacity was 46.36 mg g-1.