Continuous fixed-bed column study and adsorption modeling: Removal of cadmium (II) and lead (II) ions in aqueous solution by dead calcareous skeletons

• Published in: Biochemical engineering journal 2014-06, Vol.87, p.50-61
• Main Authors: Lim, Ai Phing, Aris, Ahmad Zaharin
• Format: Article
• Language: English
• Subjects: Adsorption; Biological and medical sciences; Bioreactors; Biotechnology; Breakthrough curve; Calcareous skeletons; Dynamic modeling; Filtration; Fixed-bed bioreactor; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Various methods and equipments
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2014.03.019

•The column with 2.2cm bed height did not exhausted after 24h of adsorption.•The Cd(II) columns data fitted better in the column models than Pb(II) columns.•The Saturation Index of aragonite and calcite showed the dissolution of calcium.•Sorption of Cd(II) and Pb(II) ions were of the exchange of Ca(II) on the adsorbent.•The Adam–Bohart model was weakly fitted except for long bed height column data. The sorption of Cd(II) and Pb(II) ions was conducted in a continuous fixed-bed column by using dead calcareous skeletons (CS). The column performances were evaluated by varying the adsorbent bed height, influent flow rate and metals initial concentration. The breakthrough curve for the bed height indicated that a longer bed column prolonged the life span of the column with a maximum capacity of 26.447 and 38.460mg/g for the Cd(II) and Pb(II) column, respectively. The increased flow rate and initial concentration caused the column exhaustion time to occur earlier. The experimental column data were also expressed in column adsorption models, namely, the Thomas, Yoon–Nelson and Adam–Bohart models. The Thomas model fitted well with the Cd(II) data with the correlated curve (r2>0.9). The Yoon–Nelson model was selected to predict the 50% breakthrough time achieved by the column system and provided the estimated breakthrough time for the columns that were not exhausted during the operation. The Adam–Bohart model was applicable for the initial part of adsorption with the saturation concentration data at the equilibrium. The saturation index of aragonite and calcite depicted that dissolution of calcium occurred in the aqueous solution. The experimental and theoretical data were correlated with a significant relationship trend (p