Kinetics of Adsorption of Methylene Blue onto Microwave Assisted Zinc Chloride Activated Carbon Prepared from Delonix regia pods

K. Ramesh¹, A. Rajappa² and V. Nandhakumar^3* 
1Department of Chemistry, Arasu Engineering College, Kumbakonam-612 501, India.
²Department of Chemistry, Sri Manakula Vinayagar Engineering College, Pondicherry–605 107, India.
³Department of Chemistry, A.V.V.M Sri Pushpam College, Poondi – 613 501, India.

Abstract
The activated carbon from Delonix regia (Flame tree) pods was prepared using orthogonal array experimental design method with the parameters such as microwave radiation power, radiation time, concentration of ZnCl₂ solution and impregnation time. Optimized conditions were found to be radiation power 850 W, radiation time 12 min, 60 % of ZnCl₂ and impregnation time 24 hours. Carbon prepared was designated as MWZAC (Microwave assisted Zinc chloride Activated Carbon). The characteristics of the MWZAC were determined by BET analysis, SEM and pH _ZPC. Batch mode adsorption experiments were carried out for the removal of Methylene Blue dye (MB dye) from aqueous solution using MWZAC. Influence of the parameters such as dose of the adsorbent, agitation time, initial dye concentration, pH of the solution on adsorption were studied. Kinetics of the system was studied with linearised forms of Legergren, Ho and Webber Morris models. The SSE % result revealed that present system followed pseudo second order kinetics equation with the intra particle diffusion as the rate determining step. The exhausted MWZAC was regenerated by desorption processes using 1 M NaOH and microwave irradiation processes. Comparison of readsorption results showed that microwave irradiation method was more effective regeneration method.
Keywords: Adsorption, ZnCl₂ activated microwave carbon, pH effect, methylene blue dye, Desorption, Kinetics, Readsorption