Adsorption behavior and mechanism of Bi(III) ions on rutile-water interface in the presence of nonyl hydroxamic acid
(1. Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha 410083, China;
2. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The adsorption behavior and mechanism of Bi(III) ions on the rutile-water interface were investigated through micro-flotation, Zeta potential measurement, adsorption amount measurement and X-ray photoelectron spectroscopy (XPS). According to the results of micro-flotation, Bi(III) ions could largely improve the rutile flotation recovery (from 62% to 91%), and they could increase the activating sites and reduce the competitive adsorption between nonyl hydroxamic acid negative ions and OH- ions, which determined that Bi(III) ions were capable of activating rutile flotation. The adsorption of Bi(III) ions onto the rutile surface led to the shift of Zeta potential into the positive direction, which was good for the adsorption of nonyl hydroxamic acid anions. In addition, the results of XPS indicated that the chemical environment around Ti atom had not changed before and after the adsorption of Bi(III) ions. Based on the adsorption mechanism of Bi(III) ions, it was deduced that firstly Bi(III) ions occupied the vacancies of the original Ca2+, Mg2+ and Fe2+ ions on the rutile surface; secondly Bi(III) ions covered on the rutile surface in the form of hydroxides.
Key words: rutile; flotation; activation of Bi(III) ions; competitive adsorption; activation sites