Abstract

Biosorption of Acid Green (AG 25) was investigated using 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 at 303 K, initial pH value of 3, the initial dye concentration of
90mg/L, biosorbent dosage of 0.2 g and contact time of 75 min. The extent of dye removal increased with increase in
time, biosorbent dosage and decreased with increase in temperature. The equilibrium sorption capacity of the biomass
increased on increasing the initial dye concentration up to 90 mg/L and then started decreasing in the studied
concentration up to 300 mg/L. The experimental result has shown that the acidic pH favours the biosorption. Langmuir
and Freundlich adsorption model is used for the mathematical description of the biosorption equilibrium and isotherm
constants are evaluated. Equilibrium data fitted very well to the Langmuir model. The pseudo first- and second-order
kinetic models were also applied to the experimental data. The results indicated that the dye uptake process followed the
pseudo second-order rate expression and biosorption rate constants increased with increasing concentration.

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