Abstract

C. Theivarasu^1* and S. Chandra²

Low cost activated carbon prepared from elephant dung was used as an eco-friendly adsorbent for the removal of the textile dye Rhodamine B from an aqueous solution. The adsorbent was characterized by Scanning Electron Microscope (SEM), X-Ray Diffraction(XRD), Thermo gravimetric(TG) and Fourier Transform Infra red (FT-IR)analysis. Batch adsorption experiments were carried out by varying the initial dye concentration, adsorbent dosage, pH and temperature. Zeta potential (pH_ZPC) was found to be 3.2.The optimum dosage of the adsorbent was found to be 100 mg. The adsorption process reached equilibrium within 240 minutes. Maximum amount of dye was adsorbed at pH 3. The percentage removal of the dye was increased with increase in temperature. The adsorption followed pseudo second order kinetic model. The experimental data can be best fitted with Langmuir isotherm compared to Freundlich isotherm. The thermodynamic parameters like Gibb's Free energy change (ΔG), Entropy change (ΔS) and enthalpy change (?H) were calculated which indicated that Rhodamine B adsorption process was endothermic and spontaneous.

Elephant dung; Rhodamine B; Adsorption; kinetics; Isotherm; Thermodynamics

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