A. Rajappa1, K. Ramesh2, V. Nandhakumar3
1Department of chemistry, Sri Manakula Vinayagar Engineering College, Madagadipet, Puducherry, India.
2Department of Chemistry, Arasu Engineering college, Kumbakonam, Thanjavur, India.
3*Department of Chemistry, A.V.V.M Sri Pushpam college, Poondi, Thanjavur, India.
Received: 8 May 2014, Accepted: 29 June 2014, Published Online: 27 July 2014
The present investigation is removal of Congo red dye from aqueous solution using Activated Carbon prepared from Delonix regia pods (Flame tree) activated with Zinc chloride (DRZAC). The characteristics of the DRZAC were determined by SEM, XRD, FTIR, BET and pHZPC.Batch mode adsorption experiments were carried out. Experimental data obtained were fitted with linearised forms of Legergren and Ho kinetic models. The Sum of Error Squares Percentage (SSE %) for second order and first order kinetics were 5.14 & 8.22 respectively and hence this adsorption followed second order kinetics. Equilibrium isotherms data were fitted with Langmuir, Freundlich, Tempkin and Dubinin-Raduskevich isotherm equations. Significance of these results was discussed in detail. Thermodynamic parameters for such as ΔH°, ΔS°, and ΔG° were determined using Van’t Hoff plots. Analysis of these values inferred that the adsorption was endothermic, spontaneous with increased randomness. The FTIR and XRD studies confirmed the partial chemisorption. This study demonstrated that DRZAC was an effective and cheap adsorbent for the removal of Cango Red dye from an aqueous solution.
Keywords: Adsorption, Delonix regia zinc chloride activated carbon, Kinetic models, thermodynamic studies, Isotherms.