Abstract: Adsorption is potentially an attractive technology for treatment of waste water for retaining dyes from dilute solutions. Studies carried through environmental biotechnology have shown that many adsorbents present in the nature have great capacity for removal of dyes. The Methylene Blue dye was adsorbed on an adsorbent prepared from matured leaves of the Psidium guajava. A batch adsorption study was carried out with variable dye concentration, adsorbent amount, pH, adsorbent size and temperature. 94.9% of Methylene Blue dye was removed by 0.1 g of Psidium guajava leaf powder from 30 ml of aqueous dye solution with a concentration of 20 ppm at 333K. The adsorption followed pseudo second order kinetics with a rate constant of 0.025 mg/min .The experimental data yielded an excellent fit with Langmuir, Freundlich and Tempkin isotherm models. Langmuir monolayer capacity had a mean value of 29.913 mg/g. The best fitted model to the experimental equilibrium data for Psidium guajava was Langmuir isotherm for methylene blue dye. Free energy of adsorption (DG), enthalpy change (DH) and entropy changes (DS) were calculated to predict the nature adsorption.
Keywords: Psidium guajava leaf powder, dye removal, batch adsorption,Kinetics,Modelling.