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According to the dielectric design, a new kind of rare-earth (RE)-doped TiO2 particle was synthesized by means of sol−gel technique for use in electrorheological (ER) fluids. A distinct enhancement...

The effect of saccharides, such as glucose, on the photocatalytic decolorization of various dyes has been investigated using TiO2 as a photocatalyst in an aqueous solution saturated with nitrogen. An azo dye, such as Orangell, used as a typical dye, was reduced by cleavage of the azo linkage, as evidenced by the production of sulfanilic acid. All of the dyes tested were decomposed with first-order kinetics. The rate constants of decolorization in the aqueous solution saturated with nitrogen increased with the addition of a saccharide such as glucose. Furthermore, the effect of the reductive saccharides on the photocatalytic decolorization of dyes was quantitatively correlated with their dispersion force. The reaction rate of the photocatalytic decolorization of dyes in the aqueous solution saturated with nitrogen, including glucose, is 7 times that in the solution saturated with oxygen. On a etudie l'effet des saccharides, tel le glucose, sur la decoloration photocatalytique de differents colorants, avec le TiO2 comme photocatalyseur dans une solution aqueuse saturee par l'azote. Un colorant azoique, tel I'Orange II, utilise comme colorant typique, a ete reduit par clivage du lien azoique, comme le prouve la production d'acide sulfanilique. Tous les colorants testes ont ete decomposes selon des cinetiques de premier ordre. Les constantes de vitesse de la decoloration dans la solution aqueuse saturee par l'azote augmentent avec l'ajout de saccharides tel le glucose. Par ailleurs, l'effet des saccharides reducteurs sur la decoloration photocatalytique des colorants a ete correle quantitativement a leur force de dispersion. La vitesse de reaction de la decoloration photocatalytique des colorants dans la solution aqueuse saturee par I'azote, incluant le glucose, est de 7 fois celle obtenue dans la solution saturee par l'oxygene.

This paper considers a case study of using non-intrusive passive acoustic sensors for on-line monitoring of hydrocyclone performance. Acoustic emissions generated within a hydrocyclone treating fine silica slurries were collected using a single 190-kHz piezoelectric sensor mounted externally on the conical section of the hydrocyclone. The investigation indicates that the spectral characteristics of the signals are particularly sensitive to several key operating and process parameters of the hydrocyclone. The use of multivariate statistical analysis techniques allows the quantitative relationships between various operating parameters of the hydrocyclone and the statistical and spectral characteristics of the acoustic signals to be established. This suggests that the method is useful for on-line control and monitoring.

The paper is devoted to the theoretical investigation of the circular dichroism (CD) and optical rotatory dispersion (ORD) spectra of turbid layers with large particles of arbitrary shapes. The cases of oriented cylinders and spheroids are considered in detail. It is assumed that the optical thickness of layers is low and the refractive index of scatterers is close to the refractive index of a host medium, which is usually the case for bio-liquids. It is found that the simple correction function allows to transform CD and ORD spectra measured for turbid layers to that of particles. This result could be of importance for studies of living cells molecular structure changes during their life cycles.

An image-processing method is proposed to obtain the distribution of the removal efficiency of particles on a plate by an air jet. This method can be used to measure particle removal from a flat surface by processing the image of the reflected light from the surface. Factors affecting the particle removal efficiency such as air pressure, distance between the nozzle and the impinging surface and the impinging angle are discussed. Optimal conditions are determined to obtain the most effective particle removal by the air jet.

A decanter centrifuge of novel design was developed for the dewatering of fine-solids slurries having micron-range particles that form paste-like, flowable, hard-to-dewater cakes. The design combines a compound beach with a cake-flow control structure that allows expressed liquid from the cake in the dry beach region to be returned back to the liquid pool while maintaining high solids throughput. In order to provide optimal performance with various operating parameters (feed rate, centrifugal gravity, pool, differential speed, concentration of feed solids, and different slurry types), the cake-flow control is adjustable. The second part of the beach is preferably at zero angle. Tests showed that the new design allows increases in both solids dryness and solids throughput.

Two experimental studies were conducted with a novel moving granular bed filter (NMGBF). The first one was performed on a cold and dry mock-up module operated at room temperature and was aimed at a) proving the concept, b) establishing the operating patterns and flow profiles and c) optimizing the operating conditions. The gas flowrate and the geometry of the filter were the main variables studied. The second study was conducted on a prototype hot filter PDU (Process Development Unit) under real time operating conditions. The filter was one of the modules of a hot-gas-conditioning-train in a fluidized bed gasifier. Results showed similar particles collection efficiency for hot- and cold-dry filtration. The filter showed an efficiency of 99.9% over 55 h filtration time for particles larger than 1 μm, while for submicronic particles the efficiency is between 84% and 96% (weight basis). This paper presents and discusses the apparatus, the experimental methods and conditions as well as characteristic results on the two prototypes used. Deux etudes experimentales ont ete menees a I'aide d'un nouveau filtre a lit granulaire mobile (NMGBF). La premiere a ete menee sur une maquette froide et seche a la temperature ambiante et visait a (a) prouver le concept, (b) etablir les modeles de fonctionnement et les profus d'ecoulement et (c) optimiser les conditions operatoires. Les variables etudiees sont le debit de gaz et la geometrie du filtre La seconde etude a ete menee sur une unite de developpement de procedes prototype a filtre chaud dans des conditions operatoires en temps reel. Le filtre est un des modules du train de conditionnement a gaz chaud dans un gazeificateur a lit fluidise. Les resultats montrent une efficacite de collecte des particules comparable pour la filtration seche chaude et froide. Le filtre montre une efficacite de 99,9 % pour un temps de filtration de 55 h avec des particules au-dessus de 1 μm, alors qu'avec des particules inferieur au micron I'efficacite' se situe entre 84 et 96 % (sur la base massique). On decrit dans cet article I'appareil, les methodes experimentales et les conditions, ainsi que les resultats caracteristiques des deux prototypes utilises.

Viscous flow past an infinite periodic array of rigid spheres is considered. The hydrodynamic interaction of all the particles in the array is taken into account. An analytical solution of the problem is proposed. The forces exerted by the fluid on the array particles are calculated and an expression for the velocity of fluid filtration through the array is obtained. The results are compared with the previous theoretical and experimental results.

The simulations of elliptical particles in a pressure driven flow are performed using a lattice Boltzmann (LB) method. Effects of multi-particle interaction on the lateral migration and orientation of both neutrally and non-neutrally buoyant particles are investigated. Low and itermediate solid concentrations in terms of area fraction f a =13, 25, and 40% are included in these simulations.

Nuclear Magnetic Resonance (NMR) was used to investigate the extrusion behaviour of PTFE pastes in a ram extruder. By means of 1H-NMR imaging (MRI) it is possible to determine the local proton density and therefore, the local fluid concentration. The 19F-MRI provides the local solid concentration. Thus the local saturation and the local porosity can be calculated with the information of the local fluid and solid concentration. Furthermore displacement profiles can be derived from NMR images by means of correlation techniques without any preparation or marking of the pastes.

Phase characteristics are considered for the technology of materials based on disperse systems, which makes it possible to clearly represent the process of transformation of the structure throughout the total technological cycle and to determine the required level and the method for influencing a system for the purpose of optimum implementation of a particular stage or operation to ensure the formation of the optimum structure and to obtain end products with preset properties.

The basic regularities of the process of contactless precision treatment of a surface which is based on the distinctive features of the rheodynamics of a magnetized magnetorheological suspension are considered. The influence of the basic parameters of a magnetorheological suspension on the indices of the process of treatment is investigated. The high efficiency of the technology and the possibility of creating a completely automated process based on it are shown.

A kinematic and dynamic analysis of flows in a rotory‐pulsatory apparatus has been carried out. Based on this analysis, a method for calculating the main parameters of the apparatus with the use of minimum initial experimental information (the head at zero transit flow rate H0 and the flow rate at zero head Q0) has been developed.

Background Magnetic nanoparticles functionalized antibodies are used for in-vitro assays on bio-markers. This work demonstrates the synthesis of high-quality magnetic nanoparticles coated with antibodies against carcinoembryonic antigen (CEA). Various characterizations, such as particle size, particle suspension, bio-activity and the stability of bio-magnetic nanoparticles suspended in liquid, are studied. The properties for the assay of CEA molecules in serum are also studied. The assay method used is so-called immunomagnetic reduction. Results The results show that the effects of common materials in serum that interfere with detected signals are not significant. The low-detection limit is 0.21 ng/ml, which is well below the clinical threshold of 2.5 ng/ml. Conclusions The dynamic range for the assay of CEA molecules in serum is 500 ng/ml. By assaying serum CEA molecules from 24 normal controls and 30 colorectal-cancer patients, the threshold for the serum-CEA concentration to diagnose colorectal cancer is 4.05 ng/ml, which results in a clinical sensitivity of 0.90 and specificity of 0.87.

We have reviewed recent developments in diffusing wave spectroscopy (DWS) that have facilitated micro-rheological studies of soft solids and complex liquids. In particular, we have focussed on two novel ensemble-averaging methods, two-cell DWS and charged-coupled device DWS (CCD-DWS), that directly address problems of non-ergodicity and broken time–translation invariance in these materials. The applications of these methods to the study of slow evolutionary dynamics, mechanical aging and transient phenomena are also discussed.

Stirred tanks are used for several operations in industrial practice. Numerous scientific papers have been presented in literature dealing with experimental results on these applications. Comparisons and valuations of these data often fail because geometric parameters, experimental conditions, and measurement techniques differ notably. herefore, it can be observed that correlations derived on the basis of these experiments often show large discrepancies. In a cooperative test of nine German working groups different experiments were carried out in stirred tanks under completely standardized conditions. Thereby, common measurement techniques were examined in their reliability.

A phase doppler anemometer (PDA) was used to measure axial components of mean and fluctuation velocities of air and particles in a pipe of 80 mm inside diameter. Glass beads having mean diameter of 55 and 468 μm , respectively, were used, the density being 2590 kg / m 3 . The fine particles suppress the air flow turbulence while the coarse ones increase it. Mixing fine particles with coarse ones in 5–9% in mass increases the turbulence above that by coarse ones alone. The acceleration pressure drop due to the particles is increased as well above that by the fine particles alone, which is larger than that by the coarse ones alone.

Suspensions of fine alumina powder in a paraffin wax have been successfully formulated with viscosity values sufficiently low to allow ink-jet printing using a commercial printer. A commercial-grade paraffin wax, with stearylamine and a polyester, were used as the dispersant system. Suspensions with powder loadings up to 40 vol% were passed through the ink-jet printer head. Unfired ceramic bodies with a feature size of

The solid-liquid mass transfer coefficient for slurries agitated in rotating drums with baffles was measured using the dissolution of β-naphthol as a tracer in silica sand slurries. The effects of drum rotation rate (0.33 to 15 min−1), slurry holdup (4.4% to 17%) and solids volume fraction (0 to 0.62) on the solid-liquid mass transfer were investigated with a slurry particle diameter of 4.6 × 10−4 m. Mass transfer coefficients were corrected for the effect of particle shrinkage due to dissolution of the tracer. The mass transfer coefficient increased with increasing rotational speed of the drum from 0.005 to 0.045 mm.5-1. Two types of slurry motion were observed; well mixed slurry flowing over the baffles and segregation of solids on the baffles. The mass transfer coefficients from the present study, along with literature data, correlated with the Froude number to the 0.36 power, for Froude numbers from 10−6 to 10−1. Le coefficient de transfert de matiere solide-liquide pour des boues agitees dans des tambours rotatifs munis de chicanes a ete mesure au moyen de la dissolution du β-naphtol comme traceur dans des suspensions de sable de silice. Les effets de la vitesse de rotation des tambours (de 0.33 a 15 min−1), de la retention des suspensions (de 4.4 a 17%) et de la fraction volumique des solides (de 0 a 0.62) sur le transfert de matiere solide-liquide ont ete etudies avec un diametre de particules de boue de 4.6 × 10−4 m. Les coefficients de transfert de matiere ont ete corriges pour l'effet de la contraction des particules en raison de la dissolution du traceur. Le coefficient de transfert de matiere augmente avec la vitesse de rotation du tambour de 0.005 a 0.045 mm.5−1. Deux types de deplacement des suspensions ont ete observes: une boue bien melangee s'ecoulant au-dessus des chicanes et la segregation des solides sur les chicanes. Les coefficients de transfert de matiere de la presente etude, ainsi que des donnees issues de la litterature scientifique, montrent une correlation avec le nombre de Froude a la puissance 0.36 pour des nombres de Froude compris entre 10−6 et 10−1.

In industrial crystallization, attrition due to particle–crystallizer contacts is a primary source of generation of fragments, which greatly affects operating conditions, and the resulting size-distribution and morphology. The objective of this work is to contribute to the understanding of the attrition propensity of crystals in suspension, under conditions of impact at velocities which typically occur in crystallizers. Two types of parameters were studied: those related to the operating conditions (impact velocity, number of impacts, type of target) and those related to the properties of the crystals and of the solution which they are in. The rate of attrition increases with the velocity of impact and depends on the orientation and on the material of the target. An attempt to correlate the data to the impact energy is made.

Heat transfer mechanisms in the bulk and distributor regions of a slurry bubble column are investigated based on the measurements of local heat transfer in a 0.28 m diameter Plexiglas column. The gas, liquid and solid phases used are oil-free compressed air, tap water and 35 μm glass beads. The slurry concentration and superficial gas velocity are varied from 0 to 40 vol% and 0.05 to 0.30 m/s respectively. Measurements have been made with a fast response heat flux probe which provided local instantaneous heat transfer coefficients. The time-averaged heat transfer coefficients in the bulk region were on average about 50% higher than the distributor region of the column. The wall region heat transfer coefficients are well predicted by the correlation of Deckwer et al. (1980). Heat transfer mechanism in column centre can be adequately described by the consecutive film and surface renewal model. Les mecanismes de transfert de chaleur dans le coeur et dans la region du distributeur d'une colonne a bulles a suspensions sont etudies en mesurant le transfert de chaleur local dans une colonne en plexiglass de 0.28 m. Les phases gazeuse, liquide et solide utilisees sont de l'air cornprime dehuile, de l'eau du robinet et des billes de verre de 35 μm. On a fait varier la concentration des suspensions et la vitesse de gaz superficielle de 0 a 40% en volume et de 0.05 a 0.30 m/s, respectivement. Les mesures ont ete faites a l'aide d'une sonde de flux de chaleur a reponse rapide qui fournit les coefficients de transfert de chaleur instantanes locaux. Les coefficients de transfert de chaleur moyennes dans le temps dans le coeur etaient, en rnoyenne, environ 50% superieurs a ceux de la region du distributeur dans la colonne. Les coefficients de transfert de chaleur de la region de la paroi sont bien predits par la cordation de Deckwer et al. (1980). Le mecanisme de transfert de chaleur au centre de la colonne peut ětre adequatement decrit par le modele de renouvellement de surface et de film consecutif.

The bifunctional phosphine Ph2P(CH2)3Si(OEt)3 has been immobilized on MgO, TiO2, Al2O3, and SiO2 surfaces. The materials were studied by 27Al MAS, 29Si CP/MAS, 31P CP/MAS, and 31P suspension NMR sp...

The water–fine SiO2 particle suspension with a narrow-size distribution (mean diameter of 2.97 μm , standard deviation of 0.03 μm ) was heated in a rectangular vessel from a vertical wall and cooled from the opposing vertical wall. Temperature distribution and local particle concentration of the suspension were measured under various temperature differences between the opposing vertical walls. It was found that behaviors of natural convection in the suspension were classified into five patterns. The critical wall temperature difference that would give rise to change of the natural convection pattern decreased as the initial particle concentration decreased.

Biofouling is generally controlled by the use of additive chemicals, but the cost of using environmentally acceptable additives is rising. Consequently there is an interest in alternative methods that do not rely on the use of chemicals. Studies of the different techniques have been made including the use of ultrasound, tube inserts and the circulation of polymer fibres. The results of all three methods of control show considerable promise but further development work is required to optimize the variables and demonstrate cost effectiveness.

Electro-osmotic dewatering (EOD) of 9.1 wt % bentonite slurry was investigated using a stationary and rotating anode. The rotational speed varied from 0 to 300 rpm. Excessive slurry is necessary to...

The Stokes shape factor and drag coefficient of non-spherical particles in laminar regime have been investigated for specially prepared particles in different shapes with a wide range of particle spherities from 0.2 to 1.0. Based on the experimental results, the relationship between the Stoke shape factor and particle spherity has been correlated. The correlation of the Stoke shape factor with particle spherity is applied to determine particle spherity and the spherities of 10 kinds of agriculture particles in different shapes are obtained.

Sedimentation and suspension flows play an important role in modern technology. This special issue joins nine recent contributions to the mathematics of these processes. The Guest Editors provide a concise account of the contributions to research in sedimentation and thickening that were made during the 20th century with a focus on the different steps of progress that were made in understanding batch sedimentation and continuous thickening processes in mineral processing. A major breakthrough was Kynch's kinematic sedimentation theory published in 1952. Mathematically, this theory gives rise to a nonlinear first-order scalar conservation law for the local solids concentration. Extensions of this theory to continuous sedimentation, flocculent and polydisperse suspensions, vessels with varying cross-section, centrifuges and several space dimensions, as well as its current applications are reviewed.

Cet article fournit une vue d'ensemble sur des sujets d'ordre reglementaire relies au traitement des eaux usees, sur la direction probable que les futures exigences reglementaires vont prendre, et sur toutes nouvelles technologies requises pour satisfaire les exigences anticipees. Des pressions pour des reglements plus stricts gouvernant le traitement des eaux usees viendront probablement d'activistes environnementaux et d'un public inquiet, d'engagements globaux a des initiatives telles que la reduction des gaz a effets de serre ou la reduction de la diminution de l'ozone en haute atmosphere, et d'engagements envers des partenaires commerciaux pour une atmosphere d'equite des controles environnementaux. Les sujets touchent tous les aspects du traitement des eaux usees, incluant les emissions liquides solides et gazeuses. Pour plusieurs problemes, la technologie actuelle va satisfaire les exigences futures anticipees alors que pour d'autres defis, une nouvelle technologie ou une variante economiquement viable d'une technologie actuelle va etre requise. Des technologies economiquement efficaces ameliorees vont etre requises pour reduire les emissions des gaz a effets de serre et createurs de smog provenant d'usines de traitement d'eau usees. La disposition de residus solides provenant d'eau usees va continuer d'etre un des defis les plus significatifs auquel l'industrie fera face. Une des plus granites incertitudes repose dans le developpement de limites reglementaires pour des classes de composes connus comme etant persistants, bio-accumulables, ou des substances toxiques. Puisque les futures limites reglementaires proposees pour ces substances sont incertaines, les technologies requises pour satisfaire ces limites, quelles que soient, sont aussi incertaines.

Rheological properties of individual suspensions of quartz sand, quartz glass, and Nizhne-Uvel'skoe (NU) clay and compound suspensions of these components containing 20 – 80% NU clay are studied. The effect of NU content on rheological properties of the compound suspensions is considered. Structural and mechanical properties of plastic masses (with a moisture content of 10 – 20%) based on compound suspensions using a Tolstoi plastometer are studied. The data obtained are used to determine the main elastoplastoviscous and structural-mechanical properties of the plastic masses. The effect of the added HCBS on the rheological characteristics is considered.

The influence of pore sizes of nucleopore membranes and their shapes on the retention of polystyrene particles of 40–100 nm in size was studied. The interrelation between structural parameters of the nucleopore membranes found by various methods and the efficiency of filtration of calibrated particles were analyzed. The potential and limitations of the procedure for determining the efficiency of filtration of nanosized latex particles was demonstrated; the procedure was based on UV absorption spectroscopy.

Experiments were performed in mechanically agitated contactors with 6 (flat) blade turbine impellers, to study the effect of various operating parameters on minimum/critical speed required for complete suspension in two-phase (liquid-solid) as well as three-phase (liquid-solid-gas) systems. Based on 1212 experimental measurements, a unified empirical correlation is proposed, for the estimation of minimum impeller speed for solid suspension in both two-phase and three-phase systems in terms of fundamental, operational and geometrical variables.

A simplified spray drying granulation model of a hollow granule from dispersed-system slurries was proposed in this work. The granulation mechanism was analyzed to replace with the solid-liquid separation by filtration. The factors that affect the diameter and the strength of the granule were investigated from the simulation based on the model.

A water fine particle suspension with a uniform initial temperature and various initial concentration distributions in a rectangular vessel was heated from a vertical wall and cooled from the opposing vertical wall. The particle made of SiO2 had a narrow size distribution (mean diameter of 2.96μm, standard deviation of 0.023μm). In order to observe phenomena of the natural convection, the temperature distribution, local particle concentration of the suspension and position of first interface were measured under various temperature differences between the opposing vertical walls. To make the influence of initial particle concentration on the phenomena clear, natural convection of suspension with three patterns of concentration, i.e. a naturally or artificially formed gradient, or non-gradient, was investigated. The pattern of formation of layers was classified by Grashof number. Moreover, to make the influence of initial depth of suspension clear, the suspensions with three initial depths, 50, 100 or 160mm, were examined.

The advantages of replacing of rammed castables by vibration-placed castables as the material for fabricating the lining of blast-furnace runners are considered. Batches of environmentally safe vibration-placed castables commercially available from Dinur JSC bauxite-based HCBSs, modified with finely disperse quartz glass, are used as the binder. The castables were tested at the Nizhny Tagil Metal-and-Steel Works. Endurance of the castable under operating conditions of the main runner is 140 thousand tons of iron (to first repair) and greater than 1 million tons (to overhall). The overall consumption rate of the castable is 0.25 – 0.35 kg/ton iron and 0.10 – 0.15 kg/ton iron (in routine repair conditions), which is substantially higher in comparison with the traditionally used rammed castables. At present, 80% of the total number of operating blast-furnace runners at the NTMSW have a lining made of vibration-placed castables.