Adsorption Mechanism of 4-Amino-5-mercapto-1,2,4-triazole as Flotation Reagent on Chalcopyrite

Preparation of 4-Amino-3-hydrazino-1,2,4-triazol-5-thiol-Modified Graphene Oxide and Its Greatly Enhanced Selective Adsorption of Gallium in Aqueous Solution

Efficient recovery of gallium (Ga) from vanadium slag processing residue (VSPR) solution is of great significance for environmental protection and resource utilization, but improving its selective adsorption against the coexisting Sc3+ and In3+ is still challenging. Herein, a novel adsorbent consisting of 4-amino-3-hydrazino-1,2,4-triazol-5-thiol (AHTZT)-modified graphene oxide (GO-AHTZT) was successfully synthesized that exhibits a higher adsorption selectivity for Ga3+ in VSPR solution with coexisting Sc3+ and In3+. Under optimal conditions, the adsorption capacity of GO-AHTZT for Ga3+ can reach 23.92 mg g-1, which is 4.9 and 12.6 times higher than that for Sc3+ (4.87 mg g-1) and In3+ (1.90 mg g-1) adsorption, indicating the excellent anti-interference ability of GO-AHTZT against Sc3+ and In3+. The process and mechanism of Ga3+ adsorption onto GO-AHTZT was also studied and discussed in detail. By measuring the adsorption process and by characterizing the adsorbent before and after adsorption, we demonstrate that the selective interaction between the Ga3+- and N-containing groups in AHTZT is the main reason for the improved adsorption selectivity. This work opens up an avenue for the design and synthesis of highly selective adsorbents for Ga3+ in complex VSPR solutions.

Influence of Galvanic Interaction between the Iron Grinding Medium and Chalcopyrite on Collectorless Flotation Behavior of Chalcopyrite: Experimental and Density Functional Theory Study

The eco-friendly flotation process for chalcopyrite is economically significant and promotes sustainable development in mining. Collectorless flotation is a green and clean method for chalcopyrite utilization, but galvanic interactions during the grinding process can affect the surface structure, chemical composition, and electrochemical properties, impacting collectorless flotation recovery. This article uses a self-made device and flotation experiments to study galvanic interactions and their effects on surface oxidation and collectorless flotation behavior under different grinding conditions (including mineral particle size, slurry water content, pressure, and galvanic interaction time). The impact of galvanic interaction on the surface chemical composition and electrochemical properties of chalcopyrite is studied using high-performance liquid chromatography (HPLC), X-ray photoelectron spectroscopy (XPS), and electrochemical tests. Additionally, the effect of the galvanic interaction on the surface structure is analyzed with density functional theory. XPS and HPLC results show that iron grinding media contact with chalcopyrite, reducing elemental sulfur content of the chalcopyrite surface, improving hydrophilicity, and decreasing chalcopyrite collectorless flotation recovery. Grinding conditions, such as mineral particle size, slurry water content, and galvanic interaction time, significantly impact collectorless flotation and can be regulated to optimize results.

Adsorption Mechanism of Amidoxime Collector on the Flotation of Lepidolite: Experiment and DFT Calculation

Lepidolite is an important mineral resource of lithium. With the increase in awareness of low-carbon and green travel, the demand for lithium has increased dramatically. Therefore, how to increase the output of lithium has to turn into high precedence. In this paper, amidoxime (DPA) was synthesized and used for the efficient collection of lepidolite. Dodecylamine (DA), a commonly used collector of lepidolite ore, was used for comparison. The collecting performances of DA and DPA for lepidolite were studied by the micro-flotation experiment, and the adsorption mechanism of DPA on lepidolite was verified by contact angle, zeta potential tests, FTIR spectra, and density functional theory (DFT) calculations. The results of flotation experiments showed that at the same collector dosage (3 × 10^-4 mol/L), the recovery of lepidolite could reach 90%, while the recovery of lepidolite with DA was only 52.5%, and to achieve the maximum recovery of DA (77.5%), only half of the DPA was added. The contact angle test results showed that DPA could effectively improve the hydrophobicity of lepidolite than DA. FTIR spectra and zeta potential tests suggested that DPA molecules were adsorbed on the lepidolite surface by electrostatic attraction. DFT calculations revealed that DPA reacted with the nucleophilic reagent (lepidolite) by the reactive site of the -CH₂NH(CH₂)₂C(NOH)N⁺H₃ group and more easily absorbed on the surface of lepidolite than DA. Therefore, our new finding will provide an important prospect for the sustainable development and utilization of lithium resources.

Discovery of Electronic Structure and Interfacial Interaction Features in Catalytic Activity

The selective transformation of inert bonds (C-H, C-O, C-C, C-F, etc.) via various catalysts is one of the most challenging areas, with applications in organic synthesis, materials science, and biological and pharmaceutical chemistry. The catalytic performance of homogeneous and heterogeneous catalysts can be rationally controlled in two ways: (i) electronic structure modulation of the active site, such as the metal center, ligands, and coordination modes, to improve the catalytic activity and stability and (ii) tuning intermolecular or interfacial interactions to promoting the reaction kinetics by accelerating the transmission of electrons between the catalyst and solvents or support. The rational design of catalysts based on adjustable features, such as metal (monometallic or bimetallic) active sites, crystal phase, ligands, solvents, and supports for inert bond activation under mild conditions remains a challenge. This Perspective summarizes the features of electronic structures, interfacial interactions, and their effects on molecular catalysis, metal-organic frameworks (MOFs), and natural mineral catalysis. The discovery of efficient catalysts could be promoted using machine-learning methods with high-performance descriptors. More attention should be paid to high-throughput quantum-chemical computations and experiments, automatic searches of chemical reaction pathways, and efficient machine-learning or deep-learning methods to accelerate catalyst design and synthesis in the future.

Recent progress on research of molybdenite flotation: A review

Molybdenum is an important alloy element for metallurgical industry because of its high temperature stability. As the major mineral reserve for molybdenum, molybdenite (MoS₂) is commonly found in porphyry copper deposits. Molybdenite is naturally floatable and can be separated from copper sulfide mineral using froth flotation. Properties of molybdenite such as mineralogy, microstructure, surface wettability, zeta potential, etc. can have a great effect on its floatability. Organic and inorganic depressants and surface pre-treatment methods are applied to improve the recovery of molybdenite. Electrochemical potential measurements using different electrodes are used to monitor process conditions and enable processing parameter adjustments to improve flotation circuit performance and reduce operating costs. Cations like Ca²⁺ and Mg²⁺ are reported to have negative effects on the flotation of molybdenite in alkaline solution, and dispersants and oil collectors need to be added to restore the flotation of molybdenite. In addition, effects of gangue minerals, particle size, and oil collectors and surfactants on molybdenite recovery are also discussed in this manuscript.

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

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.

Novel Sodium O-Benzythioethyl Xanthate Surfactant: Synthesis, DFT Calculation and Adsorption Mechanism on Chalcopyrite Surface

Xanthate with low cost and strong collecting ability has great application in the recovery of sulfide mineral. Herein, a xanthate, sodium O-benzythioethyl xanthate (SBEX), with high collecting ability was prepared by introducing thioether structure, which was constructed by reactive 2-(benzylthio)ethanol, carbon disulfide, and sodium hydroxide. The flotation performance of SBEX to chalcopyrite is yet to be explored by flotation experimental, surface tension measurements, adsorption experimental, density functional theory (DFT) calculations, and X-ray photoelectron spectroscopy (XPS) analyses. It is found that the thioether structure can increase the hydrophobicity and adsorption amount of SBEX on chalcopyrite surface, and SBEX features a higher collecting recovery toward chalcopyrite than sodium isobutyl xanthate (SIBX) and sodium phenylethyl xanthate (SPEX). The adsorption mechanism analyses reveal that two S atoms in the structure of -C(═S)-S are the reactive sites that can donate their electrons to minerals, as confirmed by DFT calculations and XPS analyses.

Novel Insights into the Hydroxylation Behaviors of α-Quartz (101) Surface and its Effects on the Adsorption of Sodium Oleate

A scientific and rigorous study on the adsorption behavior and molecular mechanism of collector sodium oleate (NaOL) on a Ca2+-activated hydroxylated α-quartz surface was performed through experiments and density functional theory (DFT) simulations. The rarely reported hydroxylation behaviors of water molecules on the α-quartz (101) surface were first innovatively and systematically studied by DFT calculations. Both experimental and computational results consistently demonstrated that the adsorbed calcium species onto the hydroxylated structure can significantly enhance the adsorption of oleate ions, resulting in a higher quartz recovery. The calculated adsorption energies confirmed that the adsorbed hydrated Ca2+ in the form of Ca(H2O)3(OH)+ can greatly promote the adsorption of OL− on hydroxylated quartz (101). In addition, Mulliken population analysis together with electron density difference analysis intuitively illustrated the process of electron transfer and the Ca-bridge phenomenon between the hydroxylated surface and OL− ions. This work may offer new insights into the interaction mechanisms existing among oxidized minerals, aqueous medium, and flotation reagents.

Adsorption Structure and Mechanism of Styryl Phosphoric Acid at the Rutile–Water Interface

The microstructure and mechanism of styryl phosphoric acid (SPA) adsorbed at the rutile–water interface were investigated through zeta potential measurement, ultraviolet-visible spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results of the zeta potential measurement illustrate that SPA is mainly electrostatically adsorbed on the rutile surface, and the adsorption process and result can be well fitted by the Stern-Grahame equation. The adsorption is severely affected by pH due to different species of SPA occurring in different pH solutions. The compound of P–O–Ti, with a structure of bidentate binuclear or bidentate mononuclear complexes, is formed after SPA is adsorbed on the rutile surface. SPA can be adsorbed on the rutile surface through the coordination of self-polymerization and bidentate mononuclear, which greatly increases the hydrophobicity of the rutile surface. Based on the above analysis and discussion, we proposed the adsorption model of SPA at the rutile–water interface, which was conducive to the modification and synthesis of a highly efficient flotation collector of the primary rutile ore.