Biosorption of acidic dyes from aqueous solution by Paenibacillus macerans: Kinetic, thermodynamic and equilibrium studies

Batch studies were conducted for thermodynamic, kinetics and equilibrium studies on the biosorption of Acid Blue 225 (AB 225) and Acid Blue 062 (AB 062) from aqueous solution by Paenibacillus macerans. The operating variables studied were initial dye concentration, biomass concentration, contact time, temperature and solution pH. Results show that the pH value of 1 is favorable for the biosorption of dyes. The biosorption data have been analysed using Langmuir, Freundlich and Tempkin isotherms. The isothermal data for biosorption followed Langmuir Model. The biosorption processes conformed to the pseudo-second-order rate kinetics. Thermodynamic parameters such as enthalpy, entropy, and Gibb's free energy changes were also calculated and it was found that the biosorption of dyes by Paenibacillus macerans was a spontaneous process. The biosorption mechanism of biomass was explained by FT-IR spectroscopy and the FT-IR spectrum confirmed the presence of -COOH, C=O, and -NH2 groups in the biomass structure. The maximum adsorption efficiency of AB 225 and AB 062 is 94.98 mgg(-1) and 95.08 mgg(-1), respectively. (C) 2009 Published by Elsevier B.V.