Characterization of Phosphorus and Ground Granulated Blast-Furnace Slags as Low-Cost Adsorbents for Cu(II) Removal; Kinetic, Isotherm, and Thermodynamic Studies

Cu(II) is one of the pollutants that exist in the produced wastewater by many industries. According to the World Health Organization (WHO), its concentration should be less than 2 mg/L. In this study, Phosphorus Slag (PS) and Ground Granulated Blast-Furnace Slag (GGBFS) as industrial wastes with the properties of abundant and low cost are used to remove Cu(II). The effects of the shaker rotation rate, initial concentration of Cu(II), and amount of adsorbent on the adsorption process are investigated. The adsorption capacity was maximized at a shaking rate of 150 rpm, initial concentration of 50 mg/L, 0.2 g GGBFS per 0.03 liter, and 0.5 g PS per 0.03 liter. At various temperatures, the values of thermodynamic parameters were calculated by measuring the equilibrium data. The results showed that the adsorption process was exothermic using both GGBFS and PS adsorbents. The experimental data of Cu(II) adsorption by GGBFS and PS was fitted well by Langmuir and Freundlich isotherm models, respectively. The maximum adsorption capacity was obtained 156.30 and 151.52 mg/g for GGBFS and PS, respectively. Also, the kinetic modeling indicated that the adsorption process is achieved to the equilibrium state using both adsorbents at less than 5 min.