Advanced Powder Technology最新文献

In the low-rank coal flotation process, the modification and adhesion behavior of particles can be reflected by the interaction of the phase interface. Therefore, the interfacial mechanism of alkali metal ions (K⁺, Na⁺) in gas-surfactant solution (DTAC, SDS) and the coal-liquid interfaces were investigated by dynamic surface tension and contact angle measurements. The results showed that the salt ions can affect the adsorption kinetic behavior of surfactants at the gas–liquid interface as well as the wetting performance of the solution on coal. Besides, through the interfacial energy and wetting work could judge the tendency of the reactivity and flotability of a solution. In this case, the adsorption experiments, SEM, XPS, probe method and hydrophilicity test were further carried out to verify the surface information of the modified coal. The results illustrated that the DTAC molecule absorbed on coal is realized by the N⁺–OH⁻ ionic bond, which is firstly proved in the coals modification; while the SDS molecule can be absorbed by O–HO hydrogen bond, which were also proved by the surface free energy analysis. Moreover, the flotability performance of modified coal on the residue solution showed the DTAC could increase the hydrophobicity of the coal, while the SDS-modified coal should be paid attention to the occurrence of hydrophobic tail adsorption.

Photocatalysis uses semiconductor materials to solar energy effectively purify to water by eliminating pollutants. Organic Dye degradation serves as a standard to assess the photocatalytic effects of the materials. In this study Mg, Cu dual-doped ZnS nanosheets were synthesized using the coprecipitation method. The impact of the concentration on the structural, morphology, optical, and degradation efficiency was investigated with XRD, XPS, TEM with EDAX, and UV spectroscopy. The pure ZnS and Zn_0.98-xCu_0.02Mg_xS (x = 0, 0.01, 0.02) (ZCM1, ZCM2, ZCM3, and ZCM4) nanosheets, exhibited cubic structure with high phase purity. The average crystalline size was calculated as 1.66, 1.60, 1.45, and 1.47 nm for the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets, respectively. TEM analysis revealed the presence of crumpled nanosheets. The bandgap of the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets were 3.99, 3.78, 4.03, and 4.09 eV respectively. This study investigated the photocatalytic activity of crystal violet dye when exposed to natural sunlight irradiation. Notably, ZCM3 nanosheets exhibited a high degradation rate of 99 % over 120 min under sunlight. Furthermore, the proposed dye degradation mechanism, effect of dosage, effect of dye variation, reusability, scavenging activity, and hemolytic activity were comprehensively discussed. The nanosheets embedded with the Polyvinyl alcohol (PVA) polymer membrane for reusability.

Cu/TiB₂ composite combines electrical conductivity and wear resistance, leading to its wide application prospect in electrical contact. In this study, electromagnetic impact was applied to compact Cu/TiB₂ powder. The interaction between powder and die under electromagnetic impact was analyzed by observing the surface quality, density, microstructure, and hardness. The results showed that when the energy was less than 21 kJ, the increase in energy could enhance density and tensile strength of the compact. However, when the energy exceeded 21 kJ, the state of compact hardly changed and burr near the edge would be worsened. Besides, the hardness of the upper surface increased gradually from the center to the edge, while the opposite was true for the lower surface, reflecting the spatial distribution of density. With the aid of simulation, it was found that the stress wave propagation influenced the densification behavior and led to the variation of density.

In this study, FeCoNi alloy nanoparticles were combined with Nd(OH)₃ nanostructures to create unique cotton-like nanoparticles (C-NPs). These C-NPs were synthesized through an accessible, two-step reactive chemical milling process. The nanoparticles originated from a blend of metal chlorides (FeCl₂, CoCl₂, and NiCl₂) and sodium (Na), used as a precursor in the reaction, within a SPEX milling apparatus. The Fe, Co, and Ni were maintained at equal weight percentages (1:1:1). Subsequently, NdCl₃ and Na were utilized to facilitate the attachment of Nd(OH)₃ nanostructures onto the FeCoNi nanoparticles through a solid-state reaction in the same SPEX milling setup. The Nd content was varied to investigate its effect on the integration of Nd(OH)₃ onto the surface of CoNiFe nanoparticles. Electron microscopy revealed the formation of cotton-like nanoparticles, and the distribution of elements was identified using secondary ion mass spectrometry. The CoNiFe alloy and Nd(OH)₃ phases were verified by X-ray diffraction analysis. These nanoparticles were internalized into cells via endocytosis, as observed in transmission electron microscopy images after incubation with the BT20 cell line (triple-negative breast cancer), likely due to interactions between –OH groups and the cell membrane. Following this, the cells containing C-NPs underwent photoluminescence studies, revealing two distinct emission peaks at 400 nm, and 486 nm. X-ray photoelectron spectroscopy indicated the presence of various heterostructures within the FeCoNi-Nd(OH)₃ complex, which may be responsible for these emission properties.

Corn starch powder is highly flammable and explosive, presenting significant safety hazards of dust explosions when encountering obstacles during its production and processing. This study indicate that with an increase in the number of obstacles, obstacle blockage ratio, and dust concentration, both the average flame spread velocity (AFSV) and the maximum flame spread velocity (MFSV) initially rise and then decline. However, the presence of obstacles significantly enhances both MFSV and AFSV compared to the absence of obstacles. Additionally, Using the Extreme Gradient Boosting (XGBoost) algorithm, predictive models for the MFSV and AFSV of corn starch dust were developed. By employing the Particle Swarm Optimization (PSO) algorithm for hyperparameter tuning, the model achieved an coefficient of determination (R²) of 0.9821 for MFSV and 0.9687 for AFSV, enabling highly accurate flame spread velocity (FSV) predictions. Random Forest importance analysis revealed that obstacle characteristics exert a more pronounced impact on FSV.

In the wood processing industry, wood dust commonly mixes with other processing by-products to form piles, which generally have large voidage due to differences in component sizes. It is essential to understand the effect of voidage on the true ignition and smoldering behavior of wood dust layer on hot plates. In this study, wood dust and shavings were selected as experimental materials. The effects of voidage on the minimum ignition temperature of the dust layer (MITL), ignition delay time, and smoldering behaviors were investigated by means of a hot plate test. The results showed that the addition of large-sized shaving particles significantly enhanced the overall voidage of the dust layer. With the increased deposit voidage, the ignition delay time decreased, and smoldering propagation accelerated. When the shavings content was less than 50%, the MITL decreased; however, further addition of shavings significantly increased the MITL. The analysis shows that voidage affects the ignition and smoldering behavior of the dust layer mainly by influencing oxygen transport and heat transfer processes. These findings offer a new insight for the prevention and control of dust fires under real working conditions.

Flotation separation of copper-sulfur at low alkalinity has attracted soaring interest in the beneficiation of copper sulfide ore. In this work, application of calcium hypochlorite (Ca(ClO)₂) and carboxymethyl chitosan (OCMC) as combined depressants for selective flotation separation of chalcopyrite from pyrite was investigated. A maximum recovery difference of 71.35 % between both minerals is observed under the recommended conditions ([Ca(ClO)₂] = 60 mg/L, [OCMC] = 400 mg/L and 40 mg/L SBX at pH=8). Besides, the copper-sulfur flotation separation indexes were assessed by the artificial mixed-mineral tests. Results of contact angle measurement, zeta potential and adsorption amount analysis reveal that the combined depressants severely impede the collector adsorption onto pyrite surfaces, and has a light effect on the chalcopyrite. OCMC exhibits a stronger complexing ability on Ca²⁺ and Fe²⁺ ions than Cu²⁺ ions. XPS results confirm that the combined depressant interact with pyrite surfaces intensively, and prompt a deep conversion of S₂^2- and S_n^2-/S⁰ into S^2- and SO₄^2- species, as well as a deep transformation of Fe(II)-S into Fe(III)-O/OH on the pyrite surface. ToF-SIMS and thermodynamic calculation results afford the favorable evidence for the selective suppression of the pyrite with added the combined depressant. Thereby the selective oxidation and intense complexation on the pyrite stemming from the combined depressant synergy are responsible for the selective separation of chalcopyrite from pyrite.