Advanced Powder Technology最新文献

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.

The swirling air flotation technology has been extensively utilized in the field of oil-bearing wastewater treatment. However, methods for visualizing internal flow characteristics and optimizing equipment performance need further exploration. In this study, we employed computational fluid dynamics (CFD) method along with Euler-Euler model and PBM model to analyze the distribution characteristics of the flow field within a micro-cyclonic floatation tube. The Lagrange method was utilized to analyze the trajectory of oil droplets, providing information on separation efficiency for different oil droplet sizes. Furthermore, we designed and constructed a dedicated test device for evaluating the oil removal performance. Experimental investigations were conducted to examine the influence of dissolved gas pressure and gas inlet on pressurized dissolved gas effect, and the relationship between bubble quality and oil removal performance was demonstrated. Finally, based on response surface optimization design method, we determined optimal operating conditions for swirl flotation tubes.

Powder formation using a ball mill has found applications in various industries such as extractive metallurgy, nanomaterials, chemicals, materials science, and pharmaceuticals, but the particle size reduction rate, speed, and milling/ignition time required for each industrial application are very crucial. A novel environmentally-friendly parametric modeling of wet ball-milling- Na₂CO₃(aq) leaching at low temperature without roasting operation was carried out to recover vanadium from vanadium-bearing steel slag (VBSS). The paradigm shift in the source of strategic metals (SMs) globally validates the fact that the gangue of today is the valuable mineral of tomorrow. Due to the depletion of primary resources, the world has shifted focus towards recovering SMs from secondary resources to cater to its upsurge demands and sustainability worldwide satisfactorily. VBSS has proven to be a promising secondary resource from which SMs especially vanadium can be recovered more economically and environmentally via mechanical activation-assisted leaching. In previous research works, a rigorous process (high temperature, high stirring speed pressure MA- leaching with/without roasting) has been used to recover vanadium from VBSS. This present research work investigated the effective processing of VBSS by paying meticulous attention to the processing parameters via particle size reduction (reactivity) equation derivation considering the chemical solution. A vanadium recovery efficiency above 80 % was achieved from VBSS at a reaction/milling time of 30 min, ball size 10 mm, BPR 7.8, speed 140 rpm, leaching time 2hrs, leaching temperature 80 °C–90 °C, and stirring speed 300 rpm. Generally, the experimental and derived theoretical model results follow the same trend in perfect agreement.

Iridium-loaded titanium oxide (Ir − IrO₂/TiO₂) particles with unique structures have a potential to become an outstanding highly conductive material for various applications. In this paper, we investigated the effectiveness of annealing treatment of flame-made Ir − IrO₂/TiO₂ particles to enhance its electrical conductivity. Before annealing treatment, the Ir − IrO₂ species was amorphous even though the Ir − IrO₂ species uniformly covered the TiO₂ surface. After annealing treatment at temperature of 750 °C, the phase of IrO₂ changed from amorphous to crystalline phase, and the degree of crystallinity of IrO₂ increased. The electrical conductivity of the Ir − IrO₂/TiO₂ particles increased from 1.05 S.cm⁻¹ to 1.85 S.cm⁻¹ with increasing annealing temperature from before annealing to 750 °C, which demonstrates the improvement of the crystallinity of Ir − IrO₂/TiO₂ particles after annealing treatments.