Enhanced oil recovery (EOR) in the last several years has become an important factor in oil production due to the shortfall in high quality crude oil. Heavy oil as one of the unconventional hydrocarbons is still vastly abundant in nature and is hence frequently explored with EOR. The viscous characteristic of heavy oil necessitates further in-situ upgrading processes to be executed before extraction. An interesting upgrading method is through aquathermolysis under the addition of catalyst. This review focuses on presenting nanoparticle catalysts, such as nickel-, iron- and cobalt-based nanocatalyst. The explanation covers topics from synthesis methods and characterization up to the effect of reducing the viscosity of heavy oil. Lastly, concluding remarks and future perspectives are highlighted regarding the visibility and available approaches of developing nanofluids for EOR.

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Zeta potential (ζ)-pH and yield stress (τ_y)-pH behaviour of a number of kaolinite and montmorillonite slurries, including CMS-sourced materials, were compared. The CMS KGa-2 and Crown kaolin with very similar elemental composition displayed almost identical ζ-pH and τ_y-pH behaviour. Both displayed a pH_ζ=0 at 3–4 where the maximum τ_y was located. This pH_ζ=0 was higher at higher ionic strength as the pH-dependent charge increased with ionic strength and the permanent structural charge being invariant. The other kaolinite slurries (Reidel and Unimin) with different composition showed different behaviour. The surface chemistry and rheological properties of CMS-sourced SWy-2 (Na-) and STx-1b (Ca-) montmorillonite and bentonite slurries were also compared. They all displayed a negative zeta potential that was insensitive to pH. STx-1b slurries required a much higher solid concentration to form a gel. Maximum τ_y occurred over a broad range of pH. This pH is ∼5 for SWy-2, 8 for STx-1b, <2 for bentonite and 12 for API bentonite. Their difference in clay mineral composition such as impurities and exchangeable cations were highlighted. The point of zero charge (pzc) of kaolinite and montmorillonite slurries obtained via Mular-Roberts pH-salt addition method did not correlate well with the pH_ζ=0 except for the KGa-2 and Crown kaolin.

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Magnetic nanoparticles provide a unique nanosystem for various smart therapy applications because of their biocompatibility, their nanostructures which can be prepared controllably to match with the interest of study and, specifically, their responses to an external magnetic field. Interests in utilizing magnetic nanoparticles for biomedical treatments originate from their external controllability of transportation and movement inside biological objects and magnetic heat generation which provide tremendous advantages for targeted drug delivery and controlled drug release as well as magnetic hyperthermia. Recent progress in synthesis and functionalization has led to the formation of various functional magnetic nanoparticles with controlled magnetic properties based on controlling their particle size, shape and composition. In this review, we focus on the synthesis, protection and functionalization of iron oxide-based magnetic nanoparticles in order to control magnetic properties of nanostructured systems. We also highlight the recent advances in the development of multifunctional therapeutic nanosystems combining magnetic nanoparticles and drugs as well as their superior efficacy in biomedical treatments with smart performance by including therapy and modulated drug delivery and release through magnetic heating.

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Small, quantum-confined semiconductor nanoparticles, known as quantum dots (QDs) are highly important material systems due to their unique optoelectronic properties and their pronounced structure-property relationships. QD applications are seen in the emerging fields of thin films and solar cells. In this review, different characterization techniques for particle size distributions (PSDs) will be summarized with special emphasis on strategies developed and suggested in the past to derive data on the dispersity of a sample from optical absorbance spectra. The latter use the assumption of superimposed individual optical contributions according to the relative abundance of different sizes of a colloidal dispersion. In the second part, the high potential of detailed PSD analysis to get deeper insights of typical QD processes such as classification by size selective precipitation (SSP) will be demonstrated. This is expected to lead to an improved understanding of colloidal surface properties which is of major importance for the development of assumption-free interaction models.

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This article reviews the pulmonary route of administration, aerosol delivery devices, characterization of pulmonary drug delivery systems, and discusses the rationale for inhaled delivery of siRNA. Diseases with known protein malfunctions may be mitigated through the use of siRNA therapeutics. The inhalation route of administration provides local delivery of siRNA therapeutics for the treatment of various pulmonary diseases, however barriers to pulmonary delivery and intracellular delivery of siRNA exists. siRNA loaded nanocarriers can be used to overcome the barriers associated with the pulmonary route, such as anatomical barriers, mucociliary clearance, and alveolar macrophage clearance. Apart from naked siRNA aerosol delivery, previously studied siRNA carrier systems comprise of lipidic, polymeric, peptide, or inorganic origin. Such siRNA delivery systems formulated as aerosols can be successfully delivered via an inhaler or nebulizer to the pulmonary region. Preclinical animal investigations of inhaled siRNA therapeutics rely on intratracheal and intranasal siRNA and siRNA nanocarrier delivery. Aerosolized siRNA delivery systems may be characterized using in vitro techniques, such as dissolution test, inertial cascade impaction, delivered dose uniformity assay, laser diffraction, and laser Doppler velocimetry. The ex vivo techniques used to characterize pulmonary administered formulations include the isolated perfused lung model. In vivo techniques like gamma scintigraphy, 3D SPECT, PET, MRI, fluorescence imaging and pharmacokinetic/pharmacodynamics analysis may be used for evaluation of aerosolized siRNA delivery systems. The use of inhalable siRNA delivery systems encounters barriers to their delivery, however overcoming the barriers while formulating a safe and effective delivery system will offer unique advances to the field of inhaled medicine.

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The influence of process conditions such as temperature and the presence of fines on the fluidization behaviour of gas-fluidized beds is of major importance in industrial fluid bed processes, which are often operated at temperatures well above ambient and where it is common practice to add fine particles to improve the reactor performance. Several works have demonstrated that process conditions can influence the role of the interparticle forces in the fluidization behaviour of powders. In particular, the beneficial effect on fluidization of adding fines to the bulk of the material is well known.
The objective of this paper is to review experimental and theoretical studies of gas-solids fluidized beds operated at high temperature and the effect of fines and fines distribution within the bed. The survey begins with a review of the effect of temperature on fundamental fluidization parameters such as minimum fluidization, bed expansion and deaeration, and the role of hydrodynamic and interparticle forces at ambient conditions and high temperature is discussed. The effect of temperature and fines and fines size distribution on the dynamics of gas-fluidized beds is considered next, highlighting areas of current gaps in knowledge. Given the complexity of the phenomena involved, a direct quantification of the particle-particle interactions in fluidized beds and of their changes under process conditions is very difficult. The review concludes by touching upon powder rheology as a methodology to evaluate indirectly the effects of the IPFs on fluidization. This leads to a review of the work done at UCL on linking rheological measurements to fluidization tests in the attempt to quantify the effect of process conditions, i.e. high temperature and the effect of fines on fluidization.

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Granular materials are common in daily life and in many industrial processes. Both fundamental research and industrial application studies are crucial for understanding the transport properties and segregation mechanisms of vibrating granular beds. One major related research topic is granular materials subjected to external vibration; such granular materials exhibit complex movement and Brazil nut segregation. Understanding the transport properties and the rising of an intruder immersed in granular materials is a challenge in granular flow research. This paper presents a review of transport properties and segregation phenomena in a vibrating granular bed, and discusses the relationship between transport properties and granular segregation. Furthermore, how the vibration conditions, liquid bridge force, bed height, surface roughness of granular materials, and a bumpy base of granular beds affect the transport properties, convection, and granular segregation are reported. The results indicate that the transport properties and segregation behavior are significantly influenced by the addition of small amounts of liquids and by the surface roughness and a bumpy base. Diffusive and convective motions are weakened as the base roughness increases, leading to a weaker Brazil nut effect.

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Precipitation defined as the rapid formation of moderately soluble crystalline or amorphous solid particles from a liquid solution under high supersaturation conditions is considered. It involves the simultaneous and fast occurrence of primary nucleation and growth of particles together with the secondary processes such as aggregation and breakage. It is shown how the effects of fluid flow and mixing affect the subprocesses forming the overall precipitation process. Examples are presented for reactive precipitation and antisolvent precipitation with supercritical fluids applied as the antisolvents.
The elementary subprocesses forming the overall precipitation process (i.e. macro-, meso-, micromixing, chemical reaction, nucleation and growth of particles, aggregation and breakage) are characterized by the related time constants and the application of time constants in the modeling and scale-up of precipitation processes is presented. The effects of turbulence on particle formation are simulated using mechanistic models, CFD and population balances (including the method of moments and the quadrature method of moments). The results of modeling are compared with experimental data.
Finally, it is shown in the context of practical applications to what extent the approaches discussed in this paper can be applied to “design” particles.

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In gravity-driven flows of different-sized (same density) particles, it is well known that larger particles tend to segregate upward (toward the free surface), and the smaller particles downward in the direction of gravity. Alternatively, when the particles are of the same size but different density, lighter particles tend to segregate upward and heavier particles, downward. When particles differ in both size and density, true of most mixtures of interest in industry and nature, the details are complicated and no rule based on gravity alone has captured the segregation behaviours. Gradients of granular temperature and kinetic stress (i.e., energy and stress associated with velocity fluctuations) offer alternative segregation driving forces, but have, until recently, been discounted as these dynamics are relatively small in dense flows. Recently, gradients in kinetic stress have been shown to play a significant role in segregating densely sheared particle mixtures, even where the kinetic stress is a relatively small percentage of the total stress. We review recent modelling advances accounting for this effect and validation in computational experiments. We show how this framework may be useful in capturing the complicated segregation phenomenology that emerges for dense sheared flows of particles different in both size and density.

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In this paper, we describe an industrial application of the discrete element method (DEM). The DEM has been applied to various powder systems thus far and therefore appears to be an established approach. However, it cannot be applied to many industrial systems because of several critical problems such as modeling of large-scale simulations, complexly shaped wall boundaries and free surface fluid flow. To solve these problems, novel models were developed by our group. A coarse-grain DEM model was developed for large-scale simulations, a signed distance function-based wall boundary model was developed for complexly shaped walls and a DEM-moving particle semi-implicit method was developed for solid-liquid flow involving a free surface. The adequacy of these models was demonstrated through verification and validation tests. Our approach shows promise in industrial applications.

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Blocking filtration laws consist of four different filtration mechanisms: complete blocking, standard blocking, intermediate blocking, and cake filtration. Blocking filtration laws for describing both the pore blocking and cake formation have been extensively employed over the past several decades to evaluate the increase in filtration resistance with the progress of filtration in the field of classical particulate filtration. In recent years, blocking filtration laws become widely used also in membrane filtration such as microfiltration and ultrafiltration of colloids. This paper gives an overview of the developments of blocking filtration laws and equations under constant pressure and constant rate conditions reported for the filtrate flow of Newtonian and non-Newtonian fluids. The fouling index evaluating the degree of membrane fouling was examined on the basis of the blocking filtration equations. The blocking filtration laws were reexamined to extend the range of their application. Moreover, various combined models developed based on the blocking filtration laws were introduced for describing more rigorously the complicated filtration behaviors controlled by more than one mechanism which occurs successively or simultaneously.

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This study reports a room temperature mechanochemical route for the synthesis of LaB₆ powders originated from related metal oxide powders as La₂O₃ and B₂O₃. Ca granules and B₂O₃ powders were respectively used as reducing agent and boron source in the experiments. This study is actually meaningful to create added value by using the native boron source of Turkey for the production of high-technology boron materials. Milling duration as the most important parameter of mechanochemistry was examined to reveal the ideal production conditions. Mechanochemically synthesized powders were subjected to selective HCl leaching in order to eliminate unwanted phases. Thermochemical software of HSC Chemistry^TM program was utilized to determine the reaction probability and to estimate the predicted products. Characterization investigations were carried out by X-ray diffractometer (XRD), differential scanning calorimeter (DSC), particle size analyzer (PSA), stereomicroscope (SM), scanning electron microscope (SEM), transmission electron microscope/energy dispersive spectrometer (TEM/EDS) and atomic absorption spectrometer (AAS). Nanosized LaB₆ powders were achieved with/without an insignificant amount of Ca₃(BO₃)₂ phase via mechanochemistry in a high-energy ball mill for 3 h and via leaching with 4 M and 6 M HCl. Lastly, the experimental outputs obtained by a calciothermic reduction were compared with those of magnesiothermic reduction.

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The Ca-HA is synthesized by reacting calcium carbonate (CaCO₃) and ammonium dihydrogen orthophosphate (NH₄H₂PO₄) in stoichiometric proportions. In this precipitation process, the ratio of Ca/P by moles is 1.67. The experiments were performed in a batch reactor at 25°C. From control parameters, the pH and the temperature were measured in line for all experiments. The tests were performed with two liquid-solid mass ratios (H₂O/CaCO₃) of 3 and 5. For each mass ratio, three stirring rates of 260, 400, and 600 rpm were tested. Samples of the synthesis were collected at different intervals and analysed by laser granulometry and by environmental scanning electron microscopy.
For the synthesis conducted at 260 rpm, synthesis monitoring was made using a contact probe in solution coupled to a Raman spectrometer in order to follow the formation of solid phase. This technique is valuable to follow the synthesis of Ca-HA in a concentrated solids suspension (around 20–30 wt%).
The results make it possible to propose a mechanism of the precipitation process of Ca-HA. It can be divided into four main stages: (i) dissolution of calcium carbonate (CaCO₃), (ii) precipitation of brushite (CaHPO₄.2H₂O), (iii) transformation of brushite into Ca-HA (Ca₁₀(PO₄)₆(OH₂)) and (iv) nucleation, growth and agglomeration of Ca-HA.

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A novel, fluorescent chemosensor based on β-(2-pyridyl)acrolein-rhodamine B (RB-AC) derivative was synthesized and its sensing performance with poly(ethylene glycol) dimethacrylate (PEGDMA) polymer particle was investigated. The prepared β-(2-pyridyl)acrolein-rhodamine B/poly(ethylene glycol)dimethacrylate (PEGDMA/RB-AC) particle was used for sensing of Al³⁺. The PEGDMA/RB-AC particles showed immediate “off–on” fluorescent responses toward Al³⁺. The fluorescent response was attributed to the spirolactam ring opening of RB-AC. This sensor particle showed high selectivity towards Al³⁺ in the presence of other competing metal ions. The sensitivity of PEGDMA/RB-AC particle was demonstrated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The binding stoichiometry and binding mode of the metal complex was established by Job’s plot and FT-IR spectroscopy.

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We present in this study that particle segregation in rotating drums can be controlled by end wall rotations. While the end wall rotational speed dominates the time required for reaching the steady state, the rotational direction of the end walls determines the segregation patterns and the shearing zone size. New segregation patterns with two well-mixed regions close to the end walls are observed in the drums with the end wall rotates in the direction opposite to the cylindrical wall. The end wall rotation causes the formation of the local valley and hill next to the wall. Particles flow into the valley and down the hill causing the formation of the convective flow cell at bed surface. It is the difference of the axial velocities between the large particles and small particles close to the end walls separating the particles of difference sizes in the axial direction. The controlling of the end wall roughness and rotating directions effectively enlarge the size of the end wall shearing zone; resulting segregation patterns which are different from the previous simple segregation band patterns.

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When a system of identical spheres settles under conditions of negligible surface and inertial forces an idealised form of sediment consolidation unfolds amenable to a universal description. We have described this complex process using a simple constitutive model expressed as an elementary scaling law in time, t, applied at the local particle level. The free-volume surrounding a particle consists of two volume contributions occupied by fluid, one portion fixed and the other portion variable, the latter of which declines with t⁻². A comprehensive system of analytical equations was derived using this one idea, and associated boundary conditions, to describe all aspects of the batch settling process. An experimental system exhibiting negligible surface and inertial forces was used to validate the model and hence assess the merits of the scaling law. Excellent agreement was achieved. The precise physics responsible for this scaling law, and the applicable boundary conditions, remain unclear at this stage. Hence this work is likely to motivate further work in this area, concerned with the dynamics of random consolidation of settling spheres.

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Fluidized bed coating has been used to coat pellets or tablets with functional substances for a number of purposes. In this coating process, particle wetting, drying and film formation are coupled to particle motion. It is therefore of interest to study particle motion in such fluidized beds and to use the results to develop a model for predicting the quality of the final product. In this paper, we present results from DEM-CFD simulations, i.e. discrete element method and computational fluid dynamics simulations of particle motion in a laboratory-scale Wurster fluidized bed that was also employed in positron emission particle tracking (PEPT) experiments. As the drag force is the dominant interaction between the gas flow and the particle motion in this type of fluidized bed, the effect of drag models on the particle motion is investigated. More specifically, the particle velocity and residence time distributions of particles in different regions calculated from five different drag models are presented. It is found that the Gidaspow and Tang drag models predict both particle cycle and residence times well. The HKL and Beetstra drag models somewhat overestimate the particle velocity in the Wurster tube and therefore predict a reduced number of recirculations and a significantly shorter cycle time.

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A pyrometallurgical reduction process for the recovery of copper and zinc from brass secondary slag (BSS) was studied. Specifically, the effect of reduction temperature and time on the conversion to metallic phases was investigated. The brass secondary slag was characterized by X-ray diffraction, inductively coupled plasma-atomic emission spectrometry, automatic elemental analysis, thermogravimetric analysis, and field emission scanning electron microscopy. A two-step reduction of BSS was identified. The step 1 comprised the reduction of ZnO, while the step 2 featured the reduction of ZnO·Al₂O₃. Furthermore, the application of a first-order reaction model with Arrhenius analysis, indicated a conversion of ZnO to Zn(g) that had a rate constant increasing from 1.4 ± 0.13 × 10⁻³ s⁻¹ at 900 °C to 2.18 ± 0.15 × 10⁻² s⁻¹ at 1050 °C. This reaction had an activation energy of 233.2 ± 26.1 kJ/mol. Secondly, the conversion of ZnO·Al₂O₃ to Zn(g) and Al₂O₃ increased from 1.54 ± 0.21 × 10⁻⁵ s⁻¹ at 900 °C to 1.09 ± 0.19 × 10⁻³ s⁻¹ at 1050 °C, and the activation energy was 376.7 ± 22.4 kJ/mol. This reaction mechanism and its associated kinetic data can be applied to optimize the operation conditions of recycling processes for Cu-containing wastes.

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The process of granule formation from aggregative cohesive powders under the action of mechanical vibration is studied. Vibration frequency and acceleration levels were set independently in the experiments. The process of agglomerate formation is examined by measuring the size distributions of the agglomerates and their resistance under uniaxial compression. The results indicate the formation of wide particle size distributions and hard and compact agglomerates. The experimental results and the interpretation of data suggest that, in order to produce agglomerates by mechanical vibration, powders should have flow functions with a flow factor value smaller than 3. In agreement with the theoretical framework proposed, agglomerate consolidation pressures and deformation at breakage seem to be almost independent of the agglomerate diameter and the vibration conditions.

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Binary fine particles were dispersed in glycerol aqueous solutions with different mixing ratios to study the effects of particle size distribution and fluid viscosity on the cake properties in dead-end filtration, such as average porosity, average specific filtration resistance and compressibility of cake. The average specific cake filtration resistance increases with increasing the fraction of small particles. However, the lowest cake porosity occurs under the volume fraction of large particles of 0.75. Comparing different methods for porosity estimations, model estimation is more accurate for those particles near pure composition, while simulation method is more suitable for moderate composition of particle mixtures. Furthermore, the cake porosity increases but the average specific cake filtration resistance decreases with increasing fluid viscosity. An 18 % porosity increase and a 30 % filtration resistance decrease are obtained when fluid viscosity increases from 1 to 10 × 10⁻³ Pa·s. The cake properties, such as the particle packing structure in the cake and the resulting filtration resistance, are affected not only by the particle size distribution but also by the fluid viscosity. The particle size distribution plays a much more important role on the cake compressibility than the fluid viscosity does.

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Precise enumeration of spores is crucial for accurate evaluation of spore survival in the presence of inactivating agents or extreme environmental conditions. Bacterial endospores tend to agglomerate, leading to low estimates of spore numbers. We have shown that addition of SDS to diluent used in counting bacterial endospores better disperses spores, leading to a ten-fold increase in counts. We attribute this effect to steric hindrance and electrostatic repulsion between micellar structures of SDS adsorbed at spore surfaces. We have also demonstrated that use of a low surface energy material (Teflon) improves spread-plate counts, an effect we attribute to lesser hold-up of liquid on Teflon versus glass.

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In this work we focus on the characterization of micro- and nano-powders typically adopted for chemical mechanical polishing, extensively used whenever the global and local planarization of surfaces is required as in nanoelectronic fabs. We present an innovative method for the accurate characterization of water suspensions of nanoparticles. It relies upon the combination of a new approach to extract light-scattering information from single particles and the recently developed diagnostic tool named Single Particle Extinction and Scattering. It can be used in line. Data interpretation becomes independent of any a-priori assumptions about the samples. The results of accurate measurements performed on ceria as well as aluminium oxide slurries are reported. We show the strong advantages of this method compared with traditional ones by explicitly reporting experimental results on calibrated spheres made of different materials. We discuss possible applications for in-line characterization of ultrapure water, chemicals, slurries for abrasive processes, for example, as well as the detection of any undesired particles – which could be the key for future improvements to advanced process control systems.

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Multi-Walled Carbon Nanotubes (MWCNTs) have promising properties that make them potentially useful in a wide variety of applications. The decoration of MWCNTs by metallic or semiconducting nanoparticles aims to intensify some of their properties, in particular thermal and electrical conductivity. Fluidized Bed Chemical Vapour Deposition (FBCVD) is an efficient process to uniformly coat powders by various materials. The coating by SnO₂, Fe and Si nanoparticles of MWCNTs (Graphistrength^®) tangled in balls of 360 microns in mean diameter using the FBCVD process has been studied. The influence of some deposition parameters with and without oxidative pre-treatment is analysed on the nucleation and growth of nanoparticles. The various results obtained indicate that the intrinsic surface reactivity of MWCNTs is high enough for CVD precursors involving the formation of highly reactive unsaturated species such as silylene SiH₂ formed from silane SiH₄ pyrolysis in the case of Si deposition. But it must be enhanced for less reactive CVD precursors such as tin tetrachloride SnCl₄ which needs the presence of oxygen-containing groups at the nanotube surface to allow Sn nucleation. So, provided the reactivity of the powder surface and that of the CVD precursors are well tuned, the FBCVD process can uniformly coat the outer surface of MWCNTs by metallic or semiconducting nanoparticles.

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The carbon pore-structure formed by MgO-templated method consists of nano-carbon wall and mesopore made with MgO. From MgO and its mixtures with resin that have high yield of carbon, micro-mesoporous carbons were obtained through their carbonization at 900 °C, followed by the dissolution of MgO. The carbon powder prepared by this method possesses high surface area without any activation process. The mesopore size of carbon powders is controlled by the crystallite size of MgO, and micropore amount depends on resin structure. Crystallinities of their carbon powders with heat-treatment up to 2500 °C were very uniform.

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Generally, indium-tin-oxides (ITO) thin film is prepared by the sputtering process with ITO target, but only 20 % of ITO yielded from the target is deposited on the substrate. Namely, about 80 % ITO is exhausted by the deposition elsewhere far from the substrate. The recycling process of indium is limited so that ca. 20 % ITO of the starting material is lost without any recovery. Even if the recycling of ITO has been carried out in this process, we should prepare ITO target of 5 times more than apparent use of ITO on film. If we change it to printing process from the sputtering, the reduction in ITO use is expected as ca. 50 %, considering the increase in film thickness by printing. Our target technology also includes ITO nanoink for the project. As a result, monodispersed ITO nanoparticles (NPs) with a cubic shape were fabricated by using quaternary ammonium hydroxide-assisted metal hydroxide organogels. These NPs have perfect uniformity in size with beautiful shape, and perfect single crystalline structure including Sn. As we were attempted to make thin film with ITO nanoink, it was successfully fabricated below 200 nm in thickness and the resistivity was drastically decreased below 1.0 × 10⁻³ Ω cm after heat treatments. GZO nanoink as substitute of ITO has also been developed.

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