Insights into the adsorption properties of NaOL on hydroxide mineral surfaces: experiments and DFT calculations

Abstract

Brucite, diaspore, and limonite, as typical hydroxide minerals, exhibit similar surface properties due to their high content of–OH. This study investigated the effect of traditional anionic collector sodium oleate (NaOL) on the flotation performance and surface properties of brucite, diaspore, and limonite. The flotation experiment results show that adding 40 mg/L NaOL at pH 11 can significantly increase the flotation recovery of brucite compared to diaspore and limonite. The results of contact angle, Zeta potential, and XPS indicate that NaOL can exhibit strong adsorption on the surfaces of the three minerals, but the adsorption effect on the brucite surface of is stronger than that on diaspore and limonite, resulting in differences in floatability among the three minerals. This is mainly due to the weak interlayer interaction force of brucite, which can expose more Mg²⁺ sites during the grinding process, resulting in brucite being able to adsorb more oleate ions. DFT calculations further indicate that sodium oleate has greater adsorption energy on brucite surface and can stably undergo chemical adsorption through covalent bonding between O in the carboxyl group and metal sites on the surface of hydroxides. This study provides molecular level insights into the design of highly efficient selective collectors for metal hydroxide minerals.

Keywords

hydroxide minerals / density functional theory / surface characteristics / adsorption mechanism / floatability

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