Studies on the adsorption of Brilliant Green dye from aqueous solution onto low-cost NaOH treated saw dust

The present study explored the adsorptive characteristics of Brilliant Green dye from aqueous solution onto NaOH treated saw dust of Indian Eucalyptus wood, a timber industry waste. Batch studies were performed to evaluate the influence of various experimental parameters like initial pH, contact time, adsorbent dose, initial concentration and temperature on the removal of Brilliant Green. Optimum conditions were found to be initial pH = 2.9, contact time = 3 h and adsorbent dose = 4 g/l. The pseudo-second-order kinetic model represented the adsorption kinetics of Brilliant Green onto NaOH treated saw dust. Equilibrium isotherms were analyzed by Freundlich, Langmuir, Redlich–Peterson and Temkin isotherm models using non-linear regression technique. NaOH treated saw dust which was used showed surface area = 0.3742 m 2/g, pore volume = 0.00836 cm 3/g and average pore diameter = 893.6 A 0. Adsorption of Brilliant Green onto NaOH treated saw dust is favorably influenced by decrease in the temperature of the operation. Thermodynamics showed that the Brilliant Green adsorption was most favorable onto NaOH treated saw dust. ►Adsorption kinetics was found to follow a second-order rate expression. ►Isotherm data for Brilliant Green on saw dust fitted the R–P and Temkin isotherms. ►The adsorption was found to be exothermic in nature. ►The negative value of Gibbs free energy change indicates spontaneous adsorption. ►Saw dust could be employed as low-cost adsorbent for removal of Brilliant Green.