Abstract
The adsorption of cysteine on the pyrite (1 0 0) surface was evaluated by using first-principles-based density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) measurements. The frontier orbitals analyses indicate that the interaction of cysteine and pyrite mainly occurs between HOMO of cysteine and LUMO of pyrite. The adsorption energy calculation shows that the configuration of the -OH of -COOH adsorbed on the Fe site is the thermodynamically preferred adsorption configuration, and it is the strongest ionic bond according to the Mulliken bond populations. As for Fe site mode, the electrons are found transferred from cysteine to Fe of pyrite (1 0 0) surface, while there is little or no electron transfer for S site mode. Projected density of states (PDOS) is analyzed further in order to clarify the interaction mechanism between cysteine and the pyrite (1 0 0) surface. After that, the presence of cysteine adsorption on the pyrite (1 0 0) surface is indicated by the qualitative results of the XPS spectra. This study provides an alternative way to enhance the knowledge of microbe–mineral interactions and find a route to improve the rate of bioleaching.
Highlights
Bioleaching technology plays an important role in cost-effective recovery of valuable metals from low-grade sulfide mineral resources [1]
-NH3+, and -COOH, was systematically studied using density functional theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) measurements in this work; we obtained the interaction orbitals, the optimized adsorption configurations, the adsorption energies, the types of bonds, the direction of the electrons transfer, and the projected density of states when cysteine adsorbed on the pyrite (1 0 0)
These results provide an alternative way of understanding the interfacial interaction between microbes and sulfide mineral surface at the quantum level and give us a method that is simple and effective for evaluating the interfacial interaction
Summary
Bioleaching technology plays an important role in cost-effective recovery of valuable metals from low-grade sulfide mineral resources [1]. Research on the adsorption mechanisms of simple organic molecules on pyrite surfaces is significant for understanding microbe–mineral interface interaction. The group of Jianhua Chen [21,22,23,24] studied the interaction of O2 with pyrite (1 0 0) by DFT, and found that electron transfer from pyrite (1 0 0) to O2 simulated the process of electron transfer in sulfide flotation and found that the interaction between xanthate and pyrite is controlled by the energy of valence band They investigated the occurrence of gold in pyrite and its effects on the electronic and structural details, simulated single, mono-, and multilayer water adsorptions on the pyrite (1 0 0) surfaces by DFT. This may enhance our understanding of microbe–mineral interactions and be helpful to find a way to improve the rate of bioleaching
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