Sorption Kinetics and Equilibrium Analysis for the Removal of Reactive Red 2 and Reactive Blue 81 Dyes from Synthetic Effluents Using Dried Soya Bean Meal

Abstract

Biosorption of Reactive Red 2 and Reactive Blue 81 dye from an aqueous solution using soya bean meal in a batch system was evaluated. The potential of the meal to act as an adsorbent was determined using Scanning Electron Micrograph and Fourier Transform Infrared Analysis. The effect of sorbent dosage (0.2 to 1.2 g/100 mL), pH (1 to 7) and initial dye concentration (20 to 120 mg/L) on the biosorption process was studied. The equilibrium dye uptake capacity was found to be more at 0.2 g/100 mL of sorbent dosage when compared to all other sorbent dosage studied in the present investigation with the initial dye concentration of 30 mg/L and pH value of 6. The equilibrium dye uptake capacity was found to be more at pH value of 2.0 when compared to all other pH levels studied in the present investigation with the sorbent dosage of 2.0 g/L at 30 mg/L initial dye concentration. The equilibrium uptake value was found to be higher for Reactive Red 2 when compared with Reactive Blue 81 dye. The rate of sorption was investigated using pseudo first and pseudo second order rate equations. The pseudo second order rate expression fit the experimental data well. The equilibrium data was analysed using Langmuir and Freundlich adsorption isotherm model. The equilibrium data for both dyes followed the Freundlich adsorption isotherm at 30°C. Intra particle diffusion model was used to determine the mechanism of the biosorption process. In this present investigation, the maximum uptake capacity of Reactive Red 2 dye was observed as 49.04 mg/g using Soya Bean Meal at 120 mg/L initial dye concentration. The adsorption capacity of Soya Bean Meal was found to be comparable with other low cost adsorbents.