Particuology最新文献

The increase in oily contaminated wastewater emissions has made it essential to develop efficient treatment approaches to mitigate its negative impact on the ecosystem and human health. In this research, a suspended catalyst photocatalytic membrane reactor (SPMR) is developed for simultaneous oil-water separation as well as pollutants degradation using ZnO as a photocatalyst and a submerged LED-UV light. A composite membrane unit was used in the reactor that was made of a polymeric layer and a superhydrophilic (SHPI) underwater oleophobic layer. The later was prepared by attaching ZnO nanoparticles (NP) on stainless steel mesh using the spraying method. The pure water flux of the composite membrane was comparable to that of the pristine polymeric membrane indicating minor resistance of the SHPI layer. For oil-water emulsion, water flux ∼1332 L m⁻² h⁻¹ was achieved at 20 kPa transmembrane pressure (TMP) with ∼99% oil separation efficiency. Using methylene blue dye (MB) decolourizations to assess simultaneous oil-water separation and pollutant degradation efficiencies, close to 86% dye decolourization and near complete oil water separation was achieved. The results suggest a promising potential of the proposed design for treatment of contaminated oily wastewater.

Lithium-rich cathode materials have garnered significant attention in the energy sector due to their high specific capacity. However, severe capacity degradation impedes their large-scale application. The employment of fast ion conductors for coating has shown potential in improving their electrochemical performance, yet the structural and chemical mechanisms underlying this improvement remain unclear. In this study, we systematically analyze, through first-principles calculations, the mechanism by which Li₂O-B₂O₃-LiBr (Hereafter referred to as LBB) coating enhances the electrochemical performance of the lithium-rich layered cathode material 0.5Li₂MnO₃·0.5LiNi_1/3Co_1/3Mn_1/3O₂ (Hereafter referred to as OLO). Our calculations reveal that the LBB coating introduces a more negative valence charge (average −0.14 e) around the oxygen atoms surrounding transition metals, thereby strengthening metal-oxygen interactions. This interaction mitigates irreversible oxygen oxidation caused by anionic redox reactions under high voltages, reducing irreversible structural changes during battery operation. Furthermore, while the migration barrier for Li⁺ in OLO is 0.61 eV, the LBB coating acts as a rapid conduit during the Li⁺ deintercalation process, reducing the migration barrier to 0.32 eV and slightly lowering the internal migration barrier within OLO to 0.43 eV. Calculations of binding energies to electrolyte byproducts HF before and after coating (at −7.421 and −3.253 eV, respectively) demonstrate that the LBB coating effectively resists HF corrosion. Subsequent electrochemical performance studies corroborated these findings. The OLO cathode with a 2% LBB coating exhibited a discharge capacity of 157.12 mAh g⁻¹ after 100 cycles, with a capacity retention rate of 80.38%, whereas the uncoated OLO displayed only 141.67 mAh g⁻¹ and a 72.45% capacity retention. At a 2 C rate, with the 2 wt% LBB-coated sample maintaining a discharge capacity of 140.22 mAh g⁻¹ compared to only 107.02 mAh g⁻¹ for the uncoated OLO.

The palladium-catalyzed Suzuki-Miyaura cross-coupling (SMC) reaction has received worldwide attention as a powerful and convenient synthetic tool for the formation of biaryl compounds. However, these reactions are highly dependent on the activity and stable of catalysts. Herein, the support morphology-dependent catalytic performance of SMC reactions was investigated. The truncated hexagonal bipyramid (α-Fe₂O₃-O) and rod-shaped morphologies of alpha-Fe₂O₃ (α-Fe₂O₃-R) were used as support to prepare PdCu nanoparticles (NPs) catalysts by NaBH₄ reduction method. For PdCu/α-Fe₂O₃-R catalysts, the smaller size of PdCu NPs and more low coordination Pd sites leading to its superior catalytic performance for SMC reactions. Furthermore, it can be easily recycled through centrifugation and reused several times without obvious loss on its catalytic performance. Identical location transmission electron microscopy method was used to investigate the structural evolution of PdCu/α-Fe₂O₃-R catalysts. The results found that its structure almost unchanged during the catalytic reaction.

Towards increasingly severe worldwide pollution of industrial solid waste red mud (RM) released from aluminum industry, constitutional valuable element Al has been successfully separated for a novel mild rotating hydrothermal synthesis (150 °C, 12 h, 5 Hz) of the uniform hierarchical porous flowerlike boehmite (γ-AlOOH) microspheres in the presence of appropriate urea, which exhibit distinctly small average diameter (1.52 μm) and narrow particle size distribution (PSD: 1.12–1.97 μm), as well as high specific surface area (129.37 m² g⁻¹). On the one hand, the rotating hydrothermal synthesis promotes the mass and heat transfer, enabling γ-AlOOH microspheres at a lower temperature within a shorter time. On the other hand, moderate rotation provides predominant shear force, rendering the uniform γ-AlOOH microspheres with small average diameter and narrow PSD. The optimal AlOOH–U2M-R5Hz microspheres demonstrate satisfactory adsorption performance for Congo Red (CR) and Methyl Blue (MB), with the maximum adsorption capacities of 602.4 and 1208.7 mg g⁻¹, respectively. Various isotherm models of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich are utilized, adsorption kinetics are analyzed, adsorption mechanism is uncovered based on hydrogen bonding and electrostatic attraction. The increase in the temperature or the presence of coexisting cations facilitates the adsorption of CR, whereas coexisting anions weaken the adsorption of CR on the AlOOH–U2M-R5Hz microspheres. Furthermore, the excellent recycling performances and especially dynamic adsorption (retainment of removal efficiency of approx. 99.0% within 1000 min) as well as authentic water bodies (e.g. tap water and river water) simulated wastewater treatment undoubtedly indicate great practical applications of the AlOOH–U2M-R5Hz microspheres, towards cleaner aluminum production and cost-effective sustainable solution to anionic dye-bearing wastewater.

In pursuit of effective adsorption materials for malodorous gases such as H₂S and to broaden the utilization avenues of lignin waste, this study employed the direct pyrolysis method to synthesize three types of alkali lignin graphitized carbons, namely C-800, KC-700, and KEC-700. Among them, KEC-700 exhibits a high specific surface area of 1672.9 m²/g, significantly superior H₂S adsorption performance compared to other materials, an adsorption breakthrough time of up to 220 min, and a sulfur capacity of 67.1 mg/g. Structural analysis showed that the more oxygen-containing functional groups of lignin charcoal and the larger specific surface area facilitated the adsorption of H₂S. After reaching adsorption saturation, the degree of graphitization of lignin carbon diminishes. The H₂S adsorption products primarily manifest as elemental sulfur and sulfate within the pores of lignin carbon measuring less than 2 nm. Through thermal regeneration, the charcoal effectively eliminates the elemental sulfur adsorption product. Nevertheless, sulfate removal proved unsatisfactory, as the adsorption efficiency of KEC-700 following two thermal regenerations was approximately 41% of that observed for fresh samples.

The present research focuses on improving the prediction of rotating particle collisions. Current particle-surface collision models do not accurately predict the particle rebound when taking rotation into account. Experimental data, such as the studies by Gorham and Kharaz (2000), Buck, Tang, Heinrich, Deen and Kuipers (2017), and Dong and Moys (2006) show that the Tsuji, Oshima and Morikawa (1985) model is inaccurate due to the incorrect tangential coefficient of restitution assumption. Hoomans, Kuipers, Mohd Salleh, Stein, and Seville (2001) introduced a similar model to the work by Tsuji et al. (1985) which includes a tangential coefficient of restitution but is only in two dimensions and does not consider out of plane rebounds. This work re-derives the particle collision model from the impulse equations for binary collisions in 3D while considering rotating particles. The derived equations in this work compares well to experimental particle-surface impact studies. The implications of this model are seen by investigating erosion due to particle collision in a simple pipe bend. It is shown that Tsuji et al. (1985) over predicts the erosion. These small differences in particle trajectories between the present model and the Tsuji et al. (1985) model will grow in complex flows with multiple close range particle impacts leading to inaccurate erosion predictions which will negatively impact the design of turbomachinery and pneumatic pipes.

To investigate the non-uniform distribution of different gases passing through the parallel cyclones, experiments were conducted on a circulating fluidized bed (CFB) equipped with six asymmetrical cyclones. A multi-tracer gas method was used, with CO, O₂, and CO₂ chosen to represent gases with different properties in the flue gas at the inlets of the cyclones. The uniformity of multi-gas distribution was evaluated by measuring the concentration deviations of each tracer gas passing through individual cyclones. The results indicate that the concentrations of multi-tracer gases are higher in the middle cyclone among the three, which are located on the tracer gas injection side during the test of single-side secondary air (SA) tracing. The maximum concentration deviation of tracer gases is for CO₂, while the minimum is for CO. At the three cyclone inlets on the opposite side, the tracer gas with higher density exhibits a more uniform distribution, and the gas uniformity decreases as the density decreases. The effects of superficial velocity, SA ratio, bed inventory, and tracer gas injection region on the uniformity of gas distribution were studied. The results show that superficial velocity and SA ratio primarily affect the uniformity of higher density gases, while bed inventory has a greater influence on lower density gases. The gas distributions are most non-uniform, especially for CO₂, when the tracer gas injection region is near the rear wall closer to the induced draft fan during the test of regional SA tracing.

Considering the strong dependence of agglomerate characteristics on various operating parameters, this study employs the control variable methodology (CVM) and response surface methodology (RSM) to investigate the influence of multi-factor interactions on particle growth during top-spray fluidized bed agglomeration. First, CVM is conducted to assess the effects of individual operating parameters on the agglomerate properties, such as mean particle size, relative width, and sphericity. Then, the interactive relationship between these input variables and the quality attributes of the process is investigated using RSM. The results show that the mean particle size increases with the increase of binder viscosity and spray rate, while it decreases with the increase of fluidization gas velocity and inlet gas temperature. The relative width of the particle size distribution increases with the spray rate, binder viscosity, and fluidization gas velocity, and hardly changes with the inlet gas temperature. The mean particle size is more sensitive to the binder spray rate at a lower level of fluidization gas velocity or a higher level of inlet gas temperature. The fluidization gas velocity corresponding to the maximum D₅₀ changes when the binder viscosity and binder spray rate are at different levels.

Regarding sugar and salt crystallization with large single crystals, the agglomerate thermodynamics and geometric morphologies, not the dynamics, dominate the particle size distribution (PSD). To consider this issue, a PSD design model is proposed for limited large crystal agglomeration. In this model, the agglomeration thermodynamic criticality is determined by estimating the adhesion and dispersion forces between single crystals. The geometric agglomerate morphologies are described by corresponding single crystal units stacking with porosity. By seed well-controlled of population, the key parameters of PSD (D01, D50 and D99) are precisely designed. For erythritol, the model design accuracies are 92%–99% in the 1.2 L and 10 L crystallizers, indicating that it can design PSD at various crystallization scales. Concerning the general research attention to microcrystal agglomeration kinetics (mostly active pharmaceutical ingredients), this model effectively guides the sugar and salt PSD design with limited large crystal agglomeration.