Kinetic studies of Ni(II) ions adsorption from aqueous solutions using the blast furnace slag (BF slag)

Abstract

In this work, we used the blast furnace slag for the nickel adsorption in aqueous solution. The physico-chemical characterization showed that the BF slag consists mainly of the silica, lime, and alumina. The specific surface area of the BF slag grains is of the order of 275.8 m2/g. The optimum elimination parameters are the agitation speed 200 rpm, pH 4.5, the adsorption temperature 20 °C, and particle size between 200 and 500 μm. The adsorption capacity and the efficiency of nickel removal by the BF slag after 90 min of agitation are respectively 53.58 mg/g and 92.7%. The experimental adsorption data showed that the pseudo-second-order model was the most appropriate in nickel adsorption kinetics; the adsorption isotherm could be described well by the Langmuir model indicating that the process was monolayer, and intra-particle diffusion is not the sole mechanism involved in this process. Thermodynamic study showed that the Ni(II) elimination by BF slag process is spontaneous, exothermic, and less entropic.