ADSORPTION OF METHYLENE BLUE ON TO LOW COST ADSORBENTS: KINETIC AND THERMODYNAMIC ANALYSISLOKESHWARI NAVALGUND, KESHAVA JOSHI, AMRUTHA PRABHU, CHITRA HEGDE, SINDHU BHAVI AND ARCHANA DANAWADEAbstract Adsorption is as an alternative technology to remove colour from wastewater. In this study, low cost adsorbent (Rice husk and Papaya seeds) has been utilized as the adsorbent for the removal of basic dyes from aqueous solution. A basic dye, Methylene Blue (MB) has been used as the adsorbate. Effect of pH, adsorbent dose, initial concentration of dye and contact time was studied. Colour was effectively removed at all selected pH, and the increase in dosage showed an increase in the removal percentage. The adsorption equilibrium for colour was reached after 90 minutes of contact time. The adsorption followed both Langmuir and Freundlich isotherms. Gibbs free energy values obtained confirmed that the process was feasible and spontaneous (ΔG = -24.44, - 23.90, and -22.75 kJ/mol). The value of ΔH (-49.12 kJ/mol) indicated that an exothermic chemisorption had taken place. The value of ΔS (-0.084 kJ/mol) suggested that the randomness decreased after adsorption. The experimental data were fitted into Lagergren pseudo second order, the chemisorption. The colour removal efficiency for Rice husk and Papaya seeds were 85% and 70% respectively for batch studies.
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