Probing the Interaction Mechanism between Benzohydroxamic Acid and Mineral Surface in the Presence of Pb2+ Ions by AFM Force Measurements and First-Principles Calculations

Wenjihao Hu; Mengjie Tian; Jian Cao; Lei Xie; Lu Gong; Wei Sun; Zhiyong Gao; Hongbo Zeng

doi:10.1021/acs.langmuir.0c01307

Probing the Interaction Mechanism between Benzohydroxamic Acid and Mineral Surface in the Presence of Pb²⁺ Ions by AFM Force Measurements and First-Principles Calculations

Langmuir. 2020 Jul 21;36(28):8199-8208. doi: 10.1021/acs.langmuir.0c01307. Epub 2020 Jul 9.

Authors

Wenjihao Hu¹, Mengjie Tian^{2

3}, Jian Cao^{2

3}, Lei Xie¹, Lu Gong¹, Wei Sun^{2

3}, Zhiyong Gao^{2

3}, Hongbo Zeng¹

Affiliations

¹ Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
² School of Minerals Processing and Bioengineering, Central South University, Changsha 410083 PR China.
³ Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083 China.

PMID: 32594745
DOI: 10.1021/acs.langmuir.0c01307

Abstract

Probing the interaction mechanism between organic molecules and material surfaces in the presence of metal ions is of great importance in many fields, such as mineral flotation. The collectability of benzohydroxamic acid (BHA) to a spodumene (LiAl(SiO₃)₂) mineral surface during mineral flotation could be enhanced with the addition of metal ion activators-Pb²⁺ ions. Pb²⁺ ions could be added as either Pb-BHA complex formed by premixing Pb²⁺ ions and BHA molecules at a given ratio or sequential addition of Pb²⁺ ions and BHA molecules. However, the complete understanding of the interaction mechanisms (e.g., adhesion) between BHA and the spodumene mineral surface in the presence of Pb²⁺ ions remains very limited. In this study, atomic force microscopy (AFM) was used to measure the intermolecular forces between BHA and the spodumene mineral surface in aqueous solutions. A BHA model molecule, that is, N-hydroxy-4-mercaptobenzamide (MBHA), was synthesized to prepare a BHA-functionalized AFM probe for force measurements. Two model systems (i.e., a Pb-BHA complex interacting with the spodumene mineral surface (model I) and BHA with a Pb²⁺-activated spodumene surface (model II)) were investigated for comparing the role of Pb²⁺ in BHA-mineral adhesion. The adhesion measured for model I (23.7 mN/m) is much higher than that of model II (12.5 mN/m), as further supported by the adsorption energies obtained from density functional theory (DFT) calculations. The calculation results showed a higher adsorption energy for model I (∼188.58 kJ/mol) than model II (∼128.16 kJ/mol), which is due to the better spodumene flotation recovery for the Pb-BHA complex as a collector than the sequential addition of Pb²⁺ and BHA. This work provides useful information on the intermolecular interactions between chemical additives and mineral surfaces in complex mineral flotation processes, and the methodology can be readily extended to other related interfacial processes such as membrane technology, water treatment, oil production, and bioengineering processes.