Equilibrium and thermodynamic studies on the adsorption of the dye rhodamine-B onto mustard cake and activated carbon

Mustard cake, obtained from local oil mills, has been characterized and used as an inexpensive and effective adsorbent for the removal of rhodamine-B dye from wastewater. The influence of various factors on the adsorption capacity has been studied by batch experiments. The optimum contact time to reach equilibrium was found to be 6 h. Maximum decolorization took place at pH 2.30. The optimum adsorbent dose was 5 g•L-1 of particle size < 106 üm. The ongoing adsorption validates both the Langmuir and the Freundlich adsorption isotherms at temperatures of (40, 50, and 60) °C. Thermodynamic parameters indicate the feasibility of the process. The desorption profile revealed that a significant portion (80 %) of rhodamine-B could be desorbed by using 50 % ethanol as eluting agent. Desorption studies indicated the possibility of recycling and regeneration of both the adsorbent and the dye. © 2010 American Chemical Society.