Fixed-bed column adsorption of methyl blue using carbon derived from axle-wood (<i>Anogeissus leiocarpus</i>) stem as adsorsent

Abstract

Axle Wood Carbon (AWC) was used to study the removal of Methyl Blue (MB) from its aqueous solution in a fixed-bed column adsorption system. The adsorbent (AWC) was characterized using SEM and pH_PZC. SEM revealed the surface morphology and from the pH_PZC determination, it was found that at pH of 8.21 the adsorbent has a net surface charge of zero. The column adsorption parameters were optimized and the maximum percentage removal was achieved by setting the level of process variables at 100 mg/L initial MB dye concentration, 28cm bed height, and 3mL/min flow rate. The fixed-bed adsorption system was found to perform well with lower initial dye concentration, higher adsorbent bed height, and lower feed flow rate. The breakthrough curve obtained from the adsorption process was fitted into Adams-Bohart and Yoon-Nelson models. Yoon–Nelson model showed the time required to achieve 50% adsorbate breakthrough, (τ) agreed closely with the experimental data (τ50% exp.) whose value is 298. While Adams-Borhat model, gave 35.7885 as the volumetric sorption capacity of the bed (N₀). This implies that the column has reached first saturation level. As such AWC is effective for the removal of MB and the selected kinetic models can be used to explain the column behaviours for the removal of MB and also to predict the large scale industrial application of the process.

Keywords: Axle wood Carbon, Breakthrough Curve, Column adsorption, Kinetic Model, Methyl Blue