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 center dot L-1 of particle size < 106 mu m. The ongoing adsorption validates both the Langmuir and the Freundlich adsorption isotherms at temperatures of (40, 50, and 60) degrees 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.