Removal of Cr(III), Pb(II) and Cr-Pb Mixture by Blast Furnace Slag (BFS) in Solution

Blast furnace slag (BFS) was exploited as an adsorbent for the removal of Cr (III), Pb (II), and Cr-Pb. In discontinuous mode, the influence of the contact time, stirring speed, pH, mass of the adsorbent, initial concentration, and temperature were examined. The physico-chemical tests indicated that the BFS is formed from a mixture composed mainly of silicates, aluminates, lime, and magnesium oxide. Its specific surface is ۳۲۵.۶m۲/g and the pHzpc value corresponds to ۳.۸. Experimental results have indicated that the equilibrium is obtained after ۶۰, ۵۰, and ۸۰ minutes for Cr(III), Pb(II), and the Cr-Pb mixture, respectively. Under our experimental conditions (pH ۴.۸, Vag: ۱۵۰rpm, T: ۲۰°C, Øs: ۲۰۰μm, and Ms: ۱g), the adsorption capacities of Cr(III), Pb(II), Cr-Pb, Cr(III) in the mix, and Pb(II) in the mix were ۴۳.۱۶, ۵۰.۱۲, ۳۹.۹۱, ۱۷.۰۵, and ۲۲.۶۶mg/g, respectively. Moreover, BFS has more affinity for lead in the binary mixture. The adsorption isotherms revealed that the Langmuir model was the best fit for the metal ion adsorption processes examined (R۲= ۰.۹۹). The kinetics indicated that the adsorption of the metal ions studied follows the pseudo-second order model and that their transfers from the solution to the adsorbent are controlled by external and intraparticle diffusion. The thermodynamic study has shown that all the processes applied are spontaneous, exothermic and less entropic. The desorption of the binary mixture revealed that saturated BFS can be efficiently exploited over four cycles, and it is more efficient in the presence of HCL at ۰.۱N.

Keywords:

Blast furnace slag , Cr(III) , Pb(II) , Kinetics , Adsorption Isotherm