Adsorption behavior of Reactive Blue 4, a tri-azine dye on dry cells of Rhizopus oryzae in a batch system

The adsorpion behavior of Reactive Blue 4, a tri-azine dye, on dry Rhizopus oryzae biomass (ROB) has been investigated in aqueous solution with special reference to physicochemical parameters associated with the adsorption process. Adsorption of dye on the biomass is found to be a function of solution pH (optimum 3.0), while temperature has no significant effect. Adsorption rate of biomass is very fast initially and attains equilibrium within 5 h for 50 and 100 mg L-1 and 6 h for 200 mg L-1 initial dye concentrations, respectively, following pseudo-second-order rate model (R-2 = 0.99). The equilibrium adsorption isotherm can be best described by Redlich-Peterson model (R-2 = 0.95). Scanning electron micrograph demonstrates a conspicuous change in surface morphology of ROB after dye adsorption. Fourier transform infrared spectroscopic data reflect the binding of Reactive Blue 4 on the biomass through complexation reaction involving amino and carboxyl groups. Reactive Blue 4 can be desorbed from the dye loaded biomass using 1(N) NaOH solution. Results establish that ROB has the potential to pollution control management involving Reactive Blue 4.