Strontium removal from aquatic solution using electric arc furnace slag: kinetic, equilibrium and thermodynamic approach

This study investigated strontium removal from aqueous solution using electric arc furnace (EAF) slag. Influence of sorbent dosage (0.5–3 g/L), pH (2.5–9.5), initial concentration of Sr 2+ (50–300 ppm) and temperature (20°C–45°C) was evaluated. Optimal sorbent dosage and initial Sr 2+ concentration were found to be 1.5 g/L and 150 ppm, respectively. Kinetics, equilibrium and thermodynamic models were used to analyse the data. Kinetics of Sr 2+ adsorption onto EAF slag was evaluated using pseudo-first-order and pseudo-second-order models and results have shown that experimental data had a better fit with the pseudo-second-order model. Langmuir and Freundlich isotherm models were used for evaluating the adsorption equilibrium and it has been shown that Langmuir model better described isotherm data. Maximal adsorption capacities of 111.11, 129.87 and 156.25 mg/g were obtained at 20°C, 30°C and 45°C, respectively. Thermodynamic investigation indicated that adsorption of Sr 2+ onto EAF slag is endothermic in nature, spontaneous and more favorable at higher temperatures.