Methylene blue (cationic dye) adsorption onto sugar beet pulp: Equilibrium isotherm and kinetic studies

Abstract

Sugar beet pulp (SBP) is a well known adsorbent, however the use of sugar beet pulp as an adsorbent for removal of cationic dyes was not reported in the literature, so far. Batch adsorption experiments were conducted to study the effects of contact time, initial concentration (20-50mg/L) and pH (2-8) on the removal of methylene blue (MB) from aqueous solution by SBP. Freundlich and Langmuir isotherm models were found to be suitable for description of MB adsorption on SBP. The SBP was found to have a Langmuir monolayers adsorption capacity of 714.29mg/g at pH 8 and 25°C. The results showed that the pseudo-second-order kinetic model best described the absorption process (R 2≥0.9999). The extent of MB adsorption on SBP increased along with an increase of initial pH of the solution and initial MB concentration. The results demonstrated that the SBP is a promising adsorbent for removal of MB from aqueous solutions. © 2011 Taiwan Institute of Chemical Engineers.