Bioremediation of Methyl Orange onto NOSTOC CARNEUM Biomass by Adsorption; Kinetics and Isotherm Studies

Abstract

The present study is concerning with the use of cyanobacterium NOSTOC CARNEUM as a model for potential biosorbent of azo dye Methyl Orange (MO) from aquatic solutions. The impacts of major variables (pH, contact time, initial dye concentration, biosorbent capacity and salt concentrations) overriding algal biosorbent and process settings on specific decolorization rate and dye biosorbtion were investigated. Michaelis–Menten kinetics model was applied to assess the decolorization kinetics factors as 2.173 mg g^-1 h^-1 and 46.435 mg L⁻¹ for maximum specific decolorization rate and k_m of dye concentration, respectively. The adsorption of MO is increasing with increasing the initial dye concentration as well as the algal biosorbent. NOSTOC CARNEUM with decolorization efficiency 50.749, 44.225, 42.934, 38.367, 36.211, 28.056, 23.754, 18.273 and 17.241 % at dye concentrations of 5, 10, 20, 30, 40, 50, 60, 70 and 80 mg L⁻¹, respectively at contact time 5 h. The maximum specific decolorization rate was found to be 2.1734 mg g^-1 h^-1. Pseudo-second order kinetic rate and Langmuir adsorption isotherm models were the best fitted with the experimental equilibrium data. The interaction of MO with the biosorbent was demonstrated on the bases of scanning electron microscopy (SEM), FT-IR and XRD spectral data that prove the efficiency of NOSTOC CARNEUM fresh biomass with respect to alternative low-cost technology for azo dyes bioremediation.