Advanced Powder Technology最新文献

Calcite is a common gangue mineral in tin ore, which seriously affects the flotation of fine-grained cassiterite. The enhanced flotation separation of fine-grained cassiterite and calcite with cetylpyridine bromide (CPB) as a dispersant were investigated in the study. The CPB significantly improved the flotation separation efficiency of fine-grained cassiterite and calcite, and it exhibited an excellent dispersion effect and relieved the coating phenomenon of calcite particles on the surface of cassiterite particles. The CPB changed the surface potential of cassiterite from negative value to positive value when the pH was in the range of 3.4–11.5. However, regardless of treatment with CPB, the surface potential of calcite was positive when the pH was below 11.5. The O on the surface of cassiterite reacted with CPB, promoting the chemical adsorption of CPB on the surface of cassiterite. There was weak physical adsorption between CPB and calcite. The covering between cassiterite and calcite without CPB was mainly dependent on van der Waals interaction energy and electrostatic interaction energy. When CPB was in the presence, cassiterite and calcite were repelled by the hydrophobic interaction energy and electrostatic interaction energy.

Computation of blood flow containing ferrofluid would be useful for analysis of drug carrier motion for cancer therapy. A thorough understanding nanoparticles behavior is challenging and needs to be addressed by developing sophisticated theoretical methods. A hybrid modeling for analysis of blood motion containing ferrofluid was implemented via mechanistic modeling combined with artificial intelligence. The system of analysis also considered external magnetic force for control of nanoparticles motion in the blood vessel. This research focuses on the analysis of velocity field based on a dataset consisting of variables x(m), y(m), and U(m/s). The objective is to develop accurate predictive models using Gaussian Process Regression (GPR), Kernel ridge regression (KRR), and Polynomial Regression (PR). The Dragonfly Algorithm (DA) was employed for hyper-parameter optimizing. The results demonstrate the performance of these models in relation to R² score, RMSE, and MAE. The GPR model achieves the highest score of 0.99603 in terms of R², indicating excellent predictive accuracy. It also exhibits the lowest RMSE of 7.1443x10^-3 and MAE of 5.35436 x10^-3, suggesting minimal deviations between the expected and predicted velocity values. The PR model also has a significant performance with an R² test score of 0.99348, RMSE of 9.1376 x10^-3, and MAE of 7.22828 x10^-3. The aforementioned results underscore the effectiveness of these models in accurately forecasting velocity based on the provided input variables.

Due to their unique properties and suitability for a wide range of applications, nanometer-scale semiconductors such as ZnO have garnered much attention. We successfully synthesized undoped and doped ZnO (Mg/Cu/N-ZnO and Mg/Cu/N/B-ZnO) using the solid-state method and analyzed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman Spectroscopy, UV − Visible Diffuse Reflectance (UV– Vis DRS), and Photoluminescence spectra (PL). The synthesized material exhibited a hexagonal structure in the presence of additional potentially doped ZnO defects, as evidenced by the XRD and Raman spectra. The scanning electron microscopy (SEM) study showed that the undoped ZnO exhibited a rod-shaped morphology with a non-uniform size distribution. In contrast, the doped ZnO particles had an almost spherical shape. The particle sizes of undoped ZnO are 91.52 nm, while doped ZnO particles are 74.92 nm for Mg/Cu/N-ZnO and 42.28 nm for Mg/Cu/N/B-ZnO. According to BET analysis, Mg/Cu/N- ZnO exhibits the highest specific surface area, measured at 803.009 m²/g. X-ray photoelectron spectroscopy verified the presence of dopants within the ZnO lattice. The UV-DRS study results showed that doping impacts the bandgap energy. The PL spectrum shows the formation of UV emission (∼400 nm) and visible emission (513–520 nm and ∼ 649 nm) peaks, indicating the inhibition of electron-hole recombination and various types of defects, including intrinsic and extrinsic defects. The photocatalytic activities of undoped ZnO and doped ZnO for methyl violet (MV) degradation were investigated using UV–vis spectroscopy after 120 min of exposure to visible light. Triple and quadruple-doped ZnO showed excellent photocatalytic ability to degrade a 93 – 95 % solution of methyl violet. The material’s stability was assessed through five cycles of the photocatalyst, and characterization data (XRD, XPS) for the catalyst utilized are also provided. Antibacterial activity increased against S. aureus and E. coli bacteria in quadruple-doped ZnO samples. The Mg/Cu/N/B-ZnO sample had the most significant antibacterial activity, with an average zone of inhibition measuring 9.85 mm for S. aureus and 11.95 mm for E. coli.

We developed a multi-emission fluorescence sensor based on hybridizing two different fluorescent centers, which provides a built-in correction to remove environmental effects. Eu³⁺ doped Gd₂O₃ nanoparticles were embedded in the silica hollow spheres while the fluorophore naphthalene derived molecules were covalently linked to the surface of silica to form multi-emission fluorescence sensors (Eu³⁺/Gd₂O₃@HSiO₂/NCO). With a detection limit of 3.8 nM, the nanosensor offers an effective platform for reliable Cr⁶⁺ detection. The obtained accuracy is considerably lower than the maximum level of Cr⁶⁺ in drinking water permitted by the U.S. Environmental Protection Agency (EPA). The prepared Eu³⁺/Gd₂O₃@HSiO₂/NCO inherited simultaneously the excellent luminescence performance of Eu³⁺/Gd₂O₃ and the fluorophore group and exhibited interesting structural and fluorescence stability in aqueous solution. A higher enhancement of fluorescence emission stemming from an intrinsic structure of Eu³⁺/Gd₂O₃ nanoparticles was observed by adding Cr⁶⁺ ions as opposed to naphthalene molecules. There was a good linear relationship between the sum of fluorescence intensity changes (ΔI₃₃₀ + ΔI₆₁₀) and the Cr⁶⁺ concentration in the range of 0.1–1.0 ppm. The nanosensor fabricated by this method showed good reversibility, enabling the rapid detection of Cr⁶⁺ in real water samples. As a result of this groundbreaking study, we are able to develop an idea for building a multifunctional fluorescent probe, with potential applications in biotechnology, food analysis, and environmental analysis.

Designing and preparing amorphous solid dispersion (ASD) nanoparticles of poorly water-soluble active pharmaceutical ingredients is an efficient formulation approach to overcome the limitation of dissolution rate and bioavailability. This study aimed to demonstrate the feasibility of producing ASD nanoparticles of a poorly water-soluble antibiotic, sulfadiazine, in a polymeric carrier, polyvinylpyrrolidone (PVP), using supercritical CO₂ as the antisolvent (SAS). By three-stage investigations for neat sulfadiazine, neat PVP, and sulfadiazine/PVP system, the appropriate operating region for ASD design was reported, and the impact of various operating parameters on nanoparticle production was discussed. The comparison of solid-state properties of CO₂-processed samples was systematically investigated by SEM, PXRD, DSC, and FTIR analysis. At the optimal conditions, spherical ASD nanoparticles of sulfadiazine and PVP with a mean size of about 750 nm were successfully produced. In addition, the dissolution rate of the SAS-produced ASD formulation was considerably enhanced compared to that of the physical mixture of sulfadiazine and PVP. These results indicate that the supercritical CO₂ process efficiently produced ASD nanoparticles of sulfadiazine and PVP with improved dissolution behavior, total powder recovery above 80 %, and total concentration of up to 100 mg/mL.

In this paper, a new amidoxime compound, p-methylphenylethyl amidoxime (PEBH), was synthesized, and its flotation mechanism for separating azurite from quartz and calcite was studied. The results of flotation experiments showed that when the pH was 11 and the dosage of PEBH was 2.5 × 10⁻⁴ mol/L, the recovery and grade of azurite reached 94.32 % and 37.45 %, respectively. In contrast, the recovery of quartz is 11.97 %, and the grade is only 18.83 %. The recovery rate of calcite is 19.10 %, and the grade is only 2.54 %. Zeta test results show that the surface potential shift of azurite after PEBH treatment is much larger than that of quartz and calcite. It also proves that PEBH has a strong adsorption effect on the surface of azurite, while the adsorption effect on the surface of quartz and calcite is weak. XPS analysis results show that Cu²⁺ is the active site of PEBH adsorbed on the surface of azurite, and a stable five-membered chelating ring structure is formed after interaction. However, this obvious interaction did not occur on the surface of quartz and calcite. At the same time, the SEM-EDS test results also confirmed this view. Therefore, PEBH has the characteristics of high selectivity as a collector for azurite, making it a promising collector in the field of azurite flotation, providing a new choice for copper oxide recovery.

Direct combustion of residual carbon (RC) from coal gasification fine slag (CGFS) is an effective way of energy recycling. Improving the combustion reactivity of RC is crucial for large-scale treatment of CGFS. In this study, the RC was modified by mild oxidation, and the evolution mechanism of the structures of RC in the oxidation process was analyzed, and the essential relationship between the structural characteristics and combustion behaviors of the oxidized RC was revealed. The research results show that the combustion behavior and structural characteristics of the oxidized RC are obviously improved. The combustion temperature range of some oxidized RC is significantly compressed, the time required for complete combustion is shorter than that of RC, and the activation energy of the combustion reaction decreases. Compared with air or CO₂ oxidation, air–steam shows a stronger oxidation effect on the structure of RC, while the oxidation effect of CO₂-steam is weakened. The structural characteristics of the oxidized RC collectively determine its combustion reactivity. The RC oxidized by steam presents disordered carbon microcrystalline structure, well-developed pore structure and a high proportion of active groups, corresponding to the best combustion reaction activity. The excessive oxidation of RC by air–steam seems to destroy the dynamic balance between structural characteristics, which is also the main reason why the combustion reactivity of the corresponding oxidized RC is inhibited.

This study aimed to prepare a hybrid of cation-exchangeable stevensite-like magnesium-layered silicate and a synthetic mica (fluorophlogopite). The magnesium-layered silicate was synthesized via the reaction of magnesium chloride with colloidal silica in the presence of urea under hydrothermal conditions (100 °C or 140 °C for 2 d). The cation-exchange capacity of the stevensite-like silicate was influenced by the operating temperature; specifically, a higher capacity was achieved at a higher temperature (0.42 meq/g stevensite at 140 °C and 0.36 meq/g at 100 °C). The capacity was also affected by the solution pH, which was directly related to the growth rates of the octahedral and tetrahedral sheets. Upon addition of fluorophlogopite into the starting mixture, direct crystallization of the stevensite-like layered silicate occurred on the fluorophlogopite particles via hydrothermal treatment for possible applications as a cosmetic pigment.

The piezoelectric properties of multi-element doped (K, Na)NbO₃ ceramics are close to that of lead-based systems and expected to become environmentally friendly substitutes. To reduce the types of doped elements and achieve the repeated preparation of high-performance ceramics, we synthesized the Li-doped (K, Na)NbO₃ particles with high crystallinity and chemical stability by molten salt method. Different from the traditional method, the microcrystals were obtained by recrystallization of the Li-doped (K, Na)NbO₃ powder synthesized by solid state reaction in molten KCl and NaCl salts. The effects of the calcination temperature on phase structure, size and morphology of microcrystals were investigated. It was found that doping of Li⁺ could stabilize the crystal structure of (K, Na)NbO₃ so that no other heterophase was formed in the molten salts. The crystallization growth of microcrystals was controlled by oriented attachment mechanism. The thermal hysteresis loops of dielectric properties confirmed that the synthesized microcrystals had high chemical stability. This work will provide ideal raw materials for the development of high performance potassium sodium niobate ceramics.

Twin-screw melt granulation (TSMG) is one of the promising green technological approaches for the manufacturing of solid dosage forms of pharmaceuticals and nutraceuticals. PEG 8000 is one of the most popular TSMG binders. The effect of different low-melting grades of PEG on the TSMG granules’ properties is described in the literature, however, not enough attention was paid to their effect on the mechanical properties of tablets. The aim of this study was to investigate the effect of PEG 8000 particle size and twin-screw melt granulation temperature on the properties of resultant MCC-CaHPO₄ granulated powder and tablets. The effect of melt granulation temperature was investigated with a medium PEG 8000 fraction (200–400 µm). While the effect of melt granulation temperature was explored at 115, 135, and 155 °C, the effect of PEG 8000 particle size was investigated using small, medium, and big fractions (0–200, 200–400, and 400–500 µm, respectively) at 135 °C. The granules were investigated by microscopic methods and were characterised in terms of flowability, angle of repose, particle size distribution, bulk and tapped density. Tablets were prepared with a compaction simulator. The analysis of the tablets provided their respective in-die Heckel plots, plastic energy and elastic energy profiles, as well as tabletability, compressibility, and compactability. The microscopic methods reveal the effect of PEG 8000 particle size on the granule and tablet structure, as well as assume the effect of granulation temperature. These insights were used to explain the differences between the mechanical properties of the tablets that were prepared using different PEG 8000 particle size fractions and at various melt granulation temperature. Despite the improved powder rheology, the tablets prepared with the PEG 8000 formulation via melt granulation have shown higher plasticity and lower tensile strength compared to ungranulated directly compressed MCC-CaHPO₄.