Removal of Textile Dyes from Aqueous Solutions by Dolochar: Equilibrium, Kinetic, and Thermodynamic Studies

Abstract

The current study explicates the feasibility of using dolochar, a solid waste generated from the sponge iron industry, for removal of color from synthetic textile dye solution containing equal amounts of the dyes Reactive Red 120 (RR 120) and Disperse Blue 3 (DB 3). The study investigated the significance of major experimental process parameters on adsorption. The experimental data were well fitted to the Langmuir isotherm model (R2 = 0.99) with a maximum adsorption capacity of 39.71 mg g−1. The adsorption kinetics were properly explained by a pseudo-second-order reaction (R2 = 0.99). The values of the separation factor 0.109 (1 > RL > 0), Freundlich exponent 3.108(n > 1), and thermodynamic parameters (ΔG, −4,371 kJ mol−l at 303 °K and ΔH, 6,124 kJ mol−1) pointed to favorable, spontaneous, and endothermic adsorption processes, respectively. Treatment of real dye-bath water with dolochar resulted in 94.4% dye removal efficiency. The viability of using dolochar as a potential adsorbent for dye removal from textile industry effluent is established in this study.