Adsorption characteristics of dyes in columns of activated carbon prepared from paper mill sewage sludge

In this work, sludge-based activated carbon (SAC) was prepared from paper mill sewage sludge by physical activation with steam. The adsorption efficiency of SAC to cationic methylene blue (MB) and anionic reactive red 24 (RR 24) from aqueous solutions was investigated using fixed-bed adsorption column. The effects of influent dye concentration, particle size, adsorbent mass and flow rate on the breakthrough characteristics of the adsorption system were determined. Desorption of dyes on SAC was repeated for several cycles in HCl, NaOH and deionized water. The results showed that breakthrough time and exhaustion time increased with decreasing inlet dye concentration, particle size, flow rate and increasing adsorbent mass. The adsorption capacity of SAC in fixed-bed column was lower than that obtained from equilibrium study. However, the SAC adsorption performance was much better than commercial activated carbon, indicating the enormous potential of SAC for removing dyes. In addition, the lower desorption rate of MB than of RR 24 demonstrated that cationic dye was more stable on SAC. (C) 2011 Elsevier B.V. All rights reserved.