Biosorption of Acid Yellow by Spent Brewery Grains in a Batch System: Equilibrium and Kinetic Modelling

Biosorption of Acid Yellow (AY17) a monoazo acid dye currently used in textile and dyeing industries was investigatedusing Spent Brewery Grains (SBG) a brewing industry waste in a batch system with respect to initial pH, temperature,initial dye concentration, biosorbent dosage, and contact time. The biomass exhibited the highest dye uptake capacity at303 K, initial pH value of 2, the initial dye concentration of 150mg/L, biosorbent dosage of 0.5 g and contact time of 40min. The extent of dye removal increased with increase in time, biosorbent dosage and decreased with increase intemperature. The equilibrium sorption capacity of the biomass increased on increasing the initial dye concentration upto 150 mg/L and then started decreasing in the studied concentration up to 600 mg/L.The experimental results hasshown that the acidic pH favours the biosorption. Langmuir and Freundlich adsorption model is used for themathematical description of the biosorption equilibrium and isotherm constants are evaluated at different temperatures.Equilibrium data fitted very well to the Freundlich model in the studied concentration (25-600 mg/L) and temperature(303-323 K) ranges. The pseudo first- and second-order kinetic models were also applied to the experimental data. Theresults indicated that the dye uptake process followed the pseudo second-order rate expression and adsorption rateconstants increased with increasing concentration.