Efficient removal of acid dye from aqueous solutions via adsorption using low-cost blast-furnace slag

摘要

Acid Red 138 (AR138) and Acid Green 27 (AG27) were efficiently removed from aqueous solutions via adsorption using modified blast-furnace slag (MBFS). The surface of MBFS was investigated using scanning electron microscopy and Brunauer-Emmett-Teller method. The effects of operating parameters such as adsorbent dosage, pH, and temperature on the dye removal were studied. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to describe the kinetics data. The equilibrium isotherms were analyzed using the Langmuir and Freundlich adsorption models. The experimental data fitted well to the pseudo-second-order kinetics model for AR138 and AG27. The Freundlich isotherm described the equilibrium data of acid dyes on MBFS better than the Langmuir isotherm. Furthermore, the thermodynamic parameters (Delta G(0) 0, Delta H-0 0, and Delta S-0 0) showed that the adsorption reactions of AR138 and AG27 onto MBFS were feasible, spontaneous, and exothermic under the investigated conditions. Thus, MBFS is an effective biosorbent for the removal of acid dyes.