Adsorption of Rhodamine B Dye – Thermodynamic and Equilibrium Studies

Abstract

Calotropis gigantea bark carbon, a waste from the agricultural field, was investigated as a replacement for the current expensive methods of removing rhodamine B from aqueous solutions. Calotropis gigantea bark was collected from agricultural fields in and around Pudukkottai. It was carbonized and activated and sieved to the desired particle size. The 50 ml conical flasks containing solution and Calotropis gigantea bark carbon were shaken at room temperature (30+20C). The pH of values of solution was adjusted by addition of HNO3 and NaOH. The batch study indicated that initial pH of aqueous solution considerably affects the dye removal. While the removal efficiency decreased with increasing initial concentration, it increased with increasing adsorbent concentration. The linear forms of the Langmuir and Freundlich models result indicated that the Langmuir adsorption isotherm fitted the data better than the Freundlich adsorption isotherm. Adsorption of the dye onto Calotropis gigantea bark carbon was favorable sorption. Therefore, Calotropis gigantea bark carbon, the low-cost is suitable for use as adsorbent for rhodamine B under this investigation