Adsorption characterization of Cu(II) from aqueous solution onto basic oxygen furnace slag

•BOFs adsorbent samples prepared and modification.•Copper adsorption onto BOFs and characterization was evaluated.•Grey system theory used in heavy metal removal from aqueous solution.

In this work, adsorption removal of Cu(II) from aqueous solution by basic oxygen furnace slag (BOFs) which was activated by the mechanochemistry process was investigated. BOFs adsorbents were prepared in this investigation by vertical planetary ball milling and moderate ball milling in the investigation, and characterized by SEM and XRD. Batch experiments were performed to evaluate the influences of various experimental parameters like the initial concentration of adsorbate, pH value, contact time, and temperature on the removal of Cu(II). Results showed that in a low concentration solution, the optimum condition for removal was found to be 0.5 g adsorbent on the treatment of 1000 mg/L adsorbate. The Cu(II) removal rate could reach 99.9% by the precipitation and adsorption effect. Langmuir isotherm and pseudo-second-order model were more accurate to describe adsorption isotherm and kinetics process. When the pH of solution was less than 3.5, it was thought that hydrogen bond and dipole force on the surface of adsorbents dominated the Cu(II) removal. BOFs adsorbent was more effective at removing heavy metal in acid waste water due to its excellent acid neutralization capacity. An increase in temperature showed a positive effect on Cu(II)-adsorbent system and ΔH0 > 0 indicated the reaction was endothermic. Grey system theory was used in heavy metal removal from aqueous solution. The initial concentration of solution was the most important factor to influence the Cu(II) removal, while temperature showed negligible effect due to the existence of precipitation. Hence, initial concentration and pH value should be preferentially considered for the heavy metal removal from solution by such alkaline adsorbent.