Determination of Adsorption of Acidic Dye from Aqueous Solutions onto Blue Green Algal Biomass: An Approach to Kinetic, Equilibrium and Thermodynamic Studies

Abstract

The adsorption of an acidic dye Methyl Orange (MO) onto non-viable blue green algal biomass, Oscillatoria sp. was investigated in aqueous solutions in a batch mode with respect to operational parameters like contact time, adsorbent dose, pH, and temperature. The characterization of the algal biomass was done by Fourier transform infrared (FTIR) spectroscopy, elemental analysis and Scanning Electron Microscope (SEM). Equilibrium isotherms were analyzed by Langmuir and Freundlich adsorption models and Langmuir isotherm was found to be the best fit exhibiting maximum adsorption capacity of 98.03 mg/g. The rate constants at different concentrations were analysed using the pseudo-first order, pseudo-second order, and intraparticle diffusion models to describe the kinetic data. Adsorption kinetics were discovered to follow the pseudo-second order rate equation. At high temperatures, thermodynamic parameters such as changes in enthalpy, entropy, and Gibbs free energy revealed that adsorption is endothermic, random, and spontaneous. The results indicated that Oscillatoria sp. could be effectively employed as adsorbent material for the removal of MO dye from effluents.