Continuous Adsorption of Acid Wood Dyes onto an Activated Carbon Prepared from Pine Sawdust

Abstract

In this paper, an activated carbon obtained from Pinus radiata sawdust is applied to remove blue, red, and black wood dyes from aqueous solutions in a fixed-bed column. The flow rate (7.7–30.8 mL min−1), initial dye concentration (25–500 mg L−1), and bed height (2–4 cm) highly influence the breakthrough-curves’ features. The results indicate that the adsorption capacity increased by decreasing the flow rate and increasing the initial dye concentration, except for the black dye, and increasing bed height, except for the red dye. In addition, the breakthrough time changed by modifying the studied variables. The curves became steeper as the flow rate increased and as the bed height decreased. Also, by increasing the inlet dye concentration, the breakthrough time decreased significantly, and sharper breakthrough curves were obtained. The activated carbon with a surface area of 2826 m2 g−1 led to high values of the adsorption capacity between 150 and 1300 mg g−1. The Yoon–Nelson and Thomas models were the ones that best described the adsorption data. The activated carbon saturated with black dye could be used in three successive cycles after regeneration with H2O2.

Keywords

• pine sawdust
• wood dyes
• fixed-bed adsorption
• breakthrough curves
• kinetic models
• regeneration