Kinetics and Thermodynamics of Methyl Orange Uptake from Model Effluent by Watermelon Shells and Neem Leaves

Abstract

Abstract-The adsorption kinetics and thermodynamics of methyl orange dye removal from model dyeing effluent by cheap watermelon (Citrullus lanatus) shells (WSA) and neem (Azadirachta indica) leaves (NLA) adsorbents were investigated. Kinetic parameters of pseudo-first order (PS-1), pseudo-second order (PS-2), intraparticle diffusion (IP-D) and Elovich's (EL-V) models for the dye adsorption onto the adsorbents were determined. Linear coefficients of determination (R 2 ) for all the models were in the range 0.0411-0.9224 for WSA and 0.4241-0.9979 for NLA. The goodnessof-fit of the models for the dye uptake onto both adsorbents was in the order PS-2 > PS-1 > IP-D > EL-V with the PS-2 model having the best and EL-V model having the least fitting of the experimental data in each case. Adsorption rate constants for the models also followed similar pattern with the best rate in PS-2 model (k 2 for WSA: 17.2726 g. and α for NLA: 2.87×10 -11 g.mg -1 .min -1 ). Error analyses and χ 2 -test of the data confirmed NLA to be a better adsorbent than WSA but both adsorbents are potentially effective for the dye removal from the effluent.