Adsorption of α-hydroxyoctyl phosphonic acid to ilmenite/water interface and its application in flotation

In this paper, the adsorption mechanism of alpha-hydroxyoctyl phosphonic acid (HPA) to ilmenite was evaluated by adsorption and flotation experiments, density functional theory (DFT) calculations, zeta potential, X-ray photoelectron spectroscopy (XPS) and FTIR measurements. DFT calculations inferred the three O atoms in PO(OH)(2) group were of the reactive center of the three HPA species and their chemical reactivity was followed the order as: HPA < HPA(-) < HPA(2-). The results of adsorption and flotation experiments demonstrated HPA exhibited superior affinity to ilmenite at pH around 9.0. In the presence of HPA, the zeta potentials of ilmenite particles shifted to more negative values, implying a chemisorption of HPA onto ilmenite. The FUR analyses further inferred that HPA chemisorbed on ilmenite surfaces as its HPA(2-) species. The XPS results offered clear evidence that the adsorbed HPA species react with the Fe or Ti species on ilmenite interfaces. (C) 2015 Elsevier B.V. All rights reserved.