LABORATORY SCALE FIXED-BED COLUMN ADSORPTION STUDY OF METHYLENE BLUE ON GLUTARALDEHYDE CROSS-LINKED CHITOSAN BEADS

Abstract

This work focuses on the exploration of the potential of glutaraldehyde cross-linked chitosan beads (GCLCBs) to remove methylene blue (MB) from aqueous solutions using bench-scale fixed bed columns. The biosorbent, GCLCB was prepared using glutaraldehyde as the croos-linking agents and characterized by SEM and FTIR. A down-flow bench-scale fixed-bed column packed with GCLCBs were designed for column studies. The effects of adsorbent bed height (1, 2 and 3 cm), inlet flow rate (5, 10 and 15 mL/min) and initial MB concentration (10, 12 and 15 mg/L) on the column performance were analyzed using breakthrough curves. The maximum adsorption capacity (225.47 mg/g) of MB was observed at 3 cm bed height, inlet flow rate of 5 mL/min and at initial MB concentration of 12 mg/L. The breakthrough curves were further analyzed using three common kinetic models namely the Thomas, Yoon – Nelson, and Adams - Bohart models to determine the column adsorption kinetic parameters. Thomas model showed that the value of equilibrium adsorbate uptake (q°) increased with increasing all three process parameters. Yoon – Nelson model showed that the time required for achieving 50% adsorbate breakthrough, τ agreed well with the experimental data (τexp 50%) in the entire column system. The results of the kinetic models revealed that both the Thomas and Yoon – Nelson models were fitted well with the experimental data.