The Kinetic and Equilibrium Studies on Adsorption of Rhodamine-B Dye From Aqueous Solution onto Rice Husk Carbon

Kinetic and equilibrium studies for the adsorption of Rhodamine-B dye from aqueous solution onto activated rice husk carbon have been reported. The effect of parameters such as: contact time, dye initial concentration, temperature, adsorbent's amount and particle size on the color removing efficiency of the activated rice husk carbon has been investigated. Kinetics of adsorption of dye at adsorbent in aqueous solution was monitored spectrophotometrically. At the given initial dye concentration, its percent adsorption increases with increase in temperature as well as the adsorbate-adsorbent contact period and the equilibrium was established after 120 minutes. However, at the given temperature, % adsorption of the dye decreases with the increase in its initial concentration. The curves representing adsorption isotherms are single and continuous leading to saturation, suggesting monolayer coverage of the dye on the adsorbent surface. The observed adsorption data was analysed in the light of Langmuir and Freundlich adsorption isotherms. Dye adsorption rate constant (k_ad) follows the first order kinetics. Activation energy (E_a), intra-particle diffusion rate constant and thermodynamic quantities of dye adsorption on the rice-husk carbon have been evaluated and interpreted.