Abstract

Removal of methylene blue, a basic dye from aqueous solutions by adsorption using mango (Mangifera indica) leaf powder

Author(s): Satish Patil, Sameer Renukdas, Naseema Patel

Systematic batch mode studies of adsorption of methylene blue (MB) on mango leaf powder (MLP) were carried out as a function of process of parameters includes initial dye concentration, adsorbent dose, pH, agitation time, agitation speed, particle size of adsorbent and temperature.MLP was found to have good adsorption capacity. Freundlich, Langmuir and Temkin isotherm models were used to test the equilibrium data. The best fitting isotherm models was found to be Langmuir and Freundlich. The linear regression coefficient R2 was used to elucidate the best fitting isotherm model. Lagergen pseudo –first order model, Lagergen pseudo -second order model, Natrajan and Khalaf model, Bhattacharya and Venkobachar models were tested for the kinetic study. Lagergen pseudo - second order model best fits the kinetics of adsorption (R2  1). Intra particle diffusion plot showed boundary layer effect and larger intercepts indicates greater contribution of surface sorption in rate determining step. Adsorption was found to increase on increasing pH, increasing temperature and decreasing particle size. Thermodynamic analysis showed negative values of G indicating adsorption was favourable and spontaneous, positive values of H indicating endothermic physisorption and positive values of S indicating increased disorder and randomness at the solidsolution interface of MB with the adsorbents.