Continuous fixed-bed adsorption of Mo(VI) from aqueous solutions by Mo(VI)-IIP: Breakthrough curves analysis and mathematical modeling

Abstract

In the search for cost-effective and highly selective adsorbents for the removal of Mo(VI) from aqueous systems, the Mo(VI)-imprinted polymer (Mo(VI)-IIP) has been identified as a potential candidate. In this study, we investigated the performance of Mo(VI)-IIP in the packed fixed-bed column, to assess its potential for industrial extension. In a laboratory-scale fixed-bed column, the effluent Mo(VI) concentration versus time span (i.e., breakthrough curves) were determined for various operational parameters, such as flow rate (5, 7 and 9 mL min−1), influent Mo(VI) concentrations (50, 70 and 90 mg L−1), bed depths (0.5, 1 and 1.5 cm) at pH 3. The breakthrough curve of various bed height demonstrated that the life span of the continuous fixed-bed column will be extended with a longer bed column. The maximum capacity and total metal removal reached 94.3 mg g−1 and 80.2% respectively, using 1.5 cm bed depth, 7 mL min−1 flow rate and 50 mg L−1 influent Mo(VI) concentration. The growth of influent Mo(VI) concentration and flow rate caused the earlier exhaustion time in the column. The experimental data were fitted with well-established mathematical models such as Yoon-Nelson, Thomas, and Adams-Bohart. The results were best-fitted with Thomas and Yoon-Nelson models (with correlation coefficient R2 ≥ 0.99) rather than the Adams-Bohart model for all conditions.