The rheological characterization of mineral slurries is a complex task, especially in the presence of coarse particles with high specific gravity, such as hematite. In laboratory rotational rheometers (LRRs), entrance effects, particle settling, and Taylor vortices can jeopardize the accuracy of the results. This paper presents a new methodology for the rheological characterization of mineral slurries in tubular devices and the Principle of Maximum Entropy (PME) supports this new approach. Iron ore slurries were prepared at mass concentrations of 36.8% and 43.6% solids and subjected to rheological characterization in LRR and a pumping loop tubular device (PLTD). The results from LRR revealed shear-thickening behavior for the slurries; whereas the results from PLTD, associated with entropic equations for the friction factor and shear rate, revealed shear-thinning behavior (at low shear rates) and shear-thickening behavior (at high rates). The results from LRR plus PLTD were plotted in a single rheogram, and curve fitting was accomplished by the power law model (R²=0.995), indicating an overall shear-thickening behavior. PME proved to be capable of supporting the rheological characterization of mineral slurries at shear rates above 1500s^–1 in PLTD, complementing the results obtained by LRR.

Particle engineering broadly refers to the controlled production of drug particles optimized for size, morphology, and structure. It encompasses both destructive (top-down) and constructive (bottom-up) particle formation processes, of which the most used for commercial dry powder inhaler products are milling and spray drying. In both cases, undesirable physicochemical changes may occur because of thermal and mechanical stresses and through interactions with solvents, and can be further potentiated through storage and interaction with atmospheric water. The occurrence and extent of these phenomena are dependent upon the process parameters and the starting material, which necessitates a thorough understanding of these factors to create a stable product with the necessary characteristics for lung deposition. This review covers commonly arising issues in particle engineering and mechanisms of prevention. Topics to be discussed relating to physical changes include (1) the unintended generation of crystalline disorder and amorphous regions in particles; (2) polymorphic transformations; (3) unintended crystallization when amorphization is desired; and (3) triboelectric charging. Topics to be discussed relating to chemical changes include (1) thermal and mechanically activated chemical reactions; and (2) crystalline disorder and chemical reactivity.

Numerical modelling offers the opportunity to better understand, predict, and optimise the behaviours of industrial systems, and thus provides a powerful means of improving efficiency, productivity and sustainability. However, the accurate modelling of industrial-scale particulate and particle–fluid systems is, due to the complex nature of such systems, highly challenging. This challenge arises primarily from three factors: the lack of a universally accepted continuum model for particulate media; the computational expense of discrete particle simulations; and the difficulty of imaging industrial-scale systems to obtain validation data. In recent years, however, advances in software, hardware, theoretical understanding, and imaging technology have all combined to the point where, in many cases, these challenges are now surmountable—though some distance remains to be travelled. In this review paper, we provide an overview of the most promising solutions to the issues highlighted above, discussing also the major strengths and limitations of each.

The presence of organic dyes from industrial effluents has caused growing environmental and human health concerns. Various remediation methods and materials are available to minimize the environmental impact and ensure safe drinking water. Nitride composite particles have recently emerged as one of the promising materials for the efficient and selective removal of toxic and hazardous substances (including organic and inorganic compounds) from industrial wastewater. This review summarizes recent advances in the disposal of organic dyed wastewater using advanced nitride composite particles, including graphitic carbon nitride-based nanocomposites, boron nitride composites, and two-dimensional transition metal nitrides. The selection of appropriate materials remains largely a trial-and-error approach at present. This review highlights multiple dye-removal mechanisms, such as photocatalytic degradation, dye-sorption behavior, and computational analysis, to aid the material selection and shed light on the interactions between organic dye contaminants and nitride composites.

In several industrial units and applications, particulate solids are exposed to peculiar process conditions that significantly affect their flowability. Accurate characterisation and prediction of these effects are crucial for proper design and operation control of the processes. Liquid content, environmental humidity, and temperature can directly modify the type and magnitude of the interparticle forces and, thus, the cohesive behaviour at the bulk scale. This paper reports a critical review of experimental and modelling studies regarding the quantitative assessment of the effect of powder liquid content, environmental gas humidity and temperature on the mechanics of dense particle assemblies. Particular attention is paid to novel setups and experimental protocols that aim to go beyond the limits of standard and commercial instruments. A multiscale approach is followed from the particle level to the bulk level.

Fine particles are widely used as intermediate and final products in industrial processes. Because particle properties are directly linked to the function and quality of the products, synthesizing monodispersed particles is a key technology. A microreactor, which comprises microchannels typically narrower than 1 mm, is a promising reaction tool because it offers excellent mixing and heat transfer performance. We used a microreactor for the synthesis of single-component and composite nanoparticles. This review introduces our synthetic results for functional nanoparticles including nickel, platinum–cobalt alloys, gold and silver nanoshells, patchy particles, core–shell clusters, and metal–organic frameworks. The microreactor we used is of the central-collision type and exhibits a characteristic mixing time 100~1,000 times shorter than that of the conventional batch mixing. The excellent mixing ability of the microreactor enables the synthesis of monodisperse particles in size and shape as well as core–shell particles with uniform shell thickness through instantaneous nucleation. More importantly, the microreactor realizes syntheses, which are not possible with batch reactors, by trapping reaction intermediates in a sequential reaction process and by rapidly changing the reaction temperature. These results demonstrate great advantages of using the microreactor for nanoparticle synthesis.

Custom-made nanomaterials are indispensable in the production of high-value goods in almost any industry. For many applications, materials with defined functional contacts on the nanoscale between different components are crucial. In heterogeneous catalysis, active nanoparticles are often dispersed on a support, and defined interfaces facilitate the stabilization of the active materials. This leads to strong metal-support interactions (SMSI), which determine the activity and selectivity of the catalytic reactions. In photocatalysts, hetero-contacts can significantly reduce electron–hole recombination after light excitation, leading to improved photoefficiency. By choosing materials with appropriate band levels, the redox window can be tuned for a specific reaction. In batteries, mixing the active material and carbon leads to improved electrochemical characteristics. All these applications have in common that different nanomaterials need to be mixed at the nano-level with defined interfaces. This review highlights the most suitable routes for gas-phase synthesis of particle heteroaggregates, their modeling, and their applications.

The COVID-19 pandemic has underscored the importance of wearing effective facepiece filtering respirators (FFRs) to reduce infection and disease transmission. One of the reasons causing the widespread prevalence was found to be the failure of N95-Equivalent FFRs (N95-EFs), i.e., efficiency <<95%, during the pandemic. To investigate the reasons causing the ineffectiveness of commercial N95-EFs, this study measured the efficiency of several dozens of commercially available N95-EFs following standard testing protocols. The specifications of the N95-EF including fiber diameter, solidity and surface potential of the main layer media of N95-EFs were also determined. We provide a simple method for manufacturers to quickly screen the efficiencies of their N95-EF products before distributing them to the market. We found that the failures of N95-EF are majorly attributed to overprediction of the efficiency due to i) missing neutralization of challenging particles, ii) too small or oversize of challenging particles, and iii) particle detectors with large sizing limits (>500nm). Based on the pressure drop, respirator area, and surface potential of the N95-EFs, an empirical equation is developed to fast screen and help design effective N95-EFs.

Chemical mechanical polishing (CMP) is a process that uses mechanical abrasive particles and chemical interaction in slurry to remove materials from the surface of films. With advancements in semiconductor device technology applying various materials and structures, SiO₂ (silica) nanoparticles are the most chosen abrasives in CMP slurries. Therefore, understanding and developing silica nanoparticles are crucial for achieving CMP performance, such as removal rates, selectivity, decreasing defects, and high uniformity and flatness. However, despite the abundance of reviews on silica nanoparticles, there is a notable gap in the literature addressing their role as abrasives in CMP slurries. This review offers an in-depth exploration of silica nanoparticle synthesis and modification methods detailing their impact on nanoparticles characteristics and CMP performance. Further, we also address the unique properties of silica nanoparticles, such as hardness, size distribution, and surface properties, and the significant contribution of silica nanoparticles to CMP results. This review is expected to interest researchers and practitioners in semiconductor manufacturing and materials science.