Flotation of α‐iron(III) oxide by cetyltrimethylammonium bromide and its activation by phosphates

Abstract

AbstractThe zero point of charge, z.p.c., of chemically prepared α‐Fe2O3 was found at pH 6.9. The adsorption isotherms of cetyltrimethylammonium bromide, CTAB, had a Langmuir shape and shifted to higher adsorption density as the pH increased above the z.p.c. The variation of the adsorption plateau with pH could be correlated with the change in ζ potential accompanying the adsorption of CTAB. The graphs of the recovery of α‐Fe2O3 floated by CTAB plotted against its equilibrium concentration exhibited maxima, which became higher as the pH increased from 6 to 10. The adsorption capacity of α‐Fe2O3 for phosphate ions markedly decreased and their desorption increased as the pH increased. The drop in ζ potential of α‐Fe2O3 in phosphate solution became smaller as the pH increased. In presence of phosphate ions, the adsorption capacity of α‐Fe2O3 for CTAB markedly increased at pH 6, the enhancement becoming less marked as the pH increased. The enhancement paralleled the phosphate adsorption. In presence of phosphate ions, the recovery of α‐Fe2O3 floated by CTAB was higher, the activation decreasing as the pH increased. The maximum recovery was shifted to lower CTAB concentration compared to the recovery of unactivated α‐Fe2O3.