Showing papers in "Particulate Science and Technology in 2014"
TL;DR: In this article, the performance characteristics of the centrifugal slurry pump with multi-sized particulate slurry of bottom ash and fly ash mixtures were evaluated at rotational speed 1450rpm.
Abstract: The present study reports on the performance characteristics of the centrifugal slurry pump with multi-sized particulate slurry of bottom ash and fly ash mixtures. The performance characteristic of the pump was experimentally evaluated at rotational speed 1450 rpm for bottom ash slurries with and without the addition of fly ash in the concentration range of 10% to 50% (by weight). Addition of fly ash in the bottom ash was varied from 10% to 30% (by weight). The pump total head, overall efficiency, and pump input power at different flow rates were evaluated. The performance characteristics results show that the value of head and the efficiency of the pump depend on the solid concentration. It was also observed that the performance parameter of the pump strongly depends on slurry properties. The addition of fine particles fly ash in the coarser particles of bottom ash slurry, leads to reduce the additional head losses in the pump. The pump performance in terms of head and efficiency improved with addition o...
60 citations
TL;DR: In this article, a biogenic approach for the synthesis of gold nanoparticles (GNPs) by reducing chloroauric acid (HAuCl4) with three different plant extracts (from Angelica, Hypericum, and Hamamelis) is described.
Abstract: A biogenic approach for the synthesis of gold nanoparticles (GNPs) by reducing chloroauric acid (HAuCl4) with three different plant extracts (from Angelica, Hypericum, and Hamamelis) is described. The content of reducing compounds (polyphenols) in each plant extract was determined by photometric dosing. The formation of GNPs was tracked by ultraviolet-visible spectroscopy and their characterization was performed using transmission electron microscopy (TEM) and atomic force microscopy (AFM) imaging and FTIR spectra. GNPs, with diameters ranging from about 4 nm to 8 nm, were obtained at room temperature and pH value about 8. They present various shapes from spherical, to ovals, heart or polyhedral forms. Generally, the GNPs colloidal dispersions are rather stable in time, and the self assembly of GNPs is sparsely observed. However, at lower concentration of the plant extract the tendency to self aggregation of the GNPs increased. The plant extracts contain reducing agents, compounds with stabilizing effect ...
51 citations
TL;DR: In this paper, the synthesis of ZIF-8 nanoparticles by varying the synthesis parameters at room temperature was investigated, and the structural and morphology transformation of the resultant particles were characterized using x-ray diffraction, field emission scanning electron microscopy, and Brunauer-Emmett-Teller surface analysis.
Abstract: Zeolitic imidazole frameworks-8 (ZIF-8) is a subclass of metal-organic frameworks (MOFs) with the transition metal cations (Zn2+) linked by imidazolate anions forming tetrahedral frameworks in zeolite-like topologies. This article reports on the synthesis of ZIF-8 nanoparticles by varying the synthesis parameters at room temperature. The crystallization duration, molar ratios, and pH of the mixture solution were varied in order to study the effects of these parameters on the formation of ZIF-8 nanoparticles. The structural and morphology transformation of the resultant particles were characterized using x-ray diffraction, field emission scanning electron microscopy, and Brunauer–Emmett–Teller (BET) surface analysis. The CO2 adsorption characteristics of ZIF-8 nanoparticles were tested using CO2 physisorption analysis. Mature structural evolution was observed for ZIF-8 synthesized at 60 and 1440 min, but insufficient crystallization was found for ZIF-8 synthesized at 5 min. Meanwhile, ZIF-8 nanoparticles s...
51 citations
TL;DR: In this article, the particulate nanoporous material MCM-48 (Mobil Crystalline Material No. 48) was synthesized and characterized in order to use it as an adsorbent for the removal of adsorbate, such as aniline and nitro-substituted anilines, including 2-nitroaniline, 3-nitrogen-naphthane, and 4-nitropheniline from wastewater.
Abstract: The particulate nanoporous material MCM-48 (Mobil Crystalline Material No. 48) was synthesized and characterized in order to use it as an adsorbent for the removal of adsorbate, such as aniline and nitro-substituted anilines, including 2-nitroaniline, 3-nitroaniline, and 4-nitroaniline from wastewater. The characterizations of MCM-48 were investigated by applying XRD, SEM, EDAX, BET surface area, and FTIR. The adsorption kinetics was investigated too. The batch adsorption studies demonstrated that the MCM-48 had a significant ability to the adsorption of aniline and nitro-substituted aniline from wastewater. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The four molecules adsorbed according to type I Langmuir adsorption with a maximum uptake were calculated to be approximately 94 mg g−1. The findings showed that the kinetics of the reaction is very rapid and followed a pseudo-second-order model. It is clearly indicated that the Langmuir model is more suitable for ch...
31 citations
TL;DR: In this article, a comprehensive experimental analysis that defines typical fluidization characteristic curve for Geldart's classification groups is described, and the minimum fluidization, bubbling, and slugging velocities are defined.
Abstract: This article describes a comprehensive experimental analysis that defines typical fluidization characteristic curve for Geldart's classification groups. Geldart defined four types of materials which differ by the cohesion forces between particles. An experimental apparatus containing fluidized beds of four pipe diameters and fully controlled by LabVIEW was used to perform the fluidization tests. All tests were performed automatically by gradually increasing the air velocity and measuring the pressure drop over the bed. For each test, the fluidization curve was recorded and the minimum fluidization, bubbling, and slugging velocities were defined. It was found that the fluidization curve of material define accurately the Geldart's group to which the material belongs. In addition, was reviewed the reason for those materials and under which conditions the pressure drop increases in the slugging state. Finally, the influence of height to bed diameter H/D ratio on the shape of characterization curve was found. ...
30 citations
TL;DR: In this paper, the authors used the Falcon concentrator model SB40-VFD as an enhanced centigugal gravity separator for pyritic sulfur separation of El-Maghara coal ore.
Abstract: Pyritic sulfur separation of El-Maghara coal ore was studied using Falcon concentrator model SB40-VFD as an enhanced centigugal gravity separator. The coal sample was ground to below 100 µm to reach liberation between pyrite and coal. Optimization of the separation process has been studied using central composite rotatable design (CCRD) and response surface method (RSM). The studied working factors were the back-water pressure (psi) and rotation frequency (Hz) and their interactions, where the feeding rate and pulp density were kept constant through all experiments. A model describing the relation between pyritic sulfur separation efficiency percentage and the previously mentioned operating variables and their interactions, have been designed. Results showed that maximum separation efficiency reached 70.61%, with decreasing total sulfur, and pyritic sulfur contents reaching 1.72% and 0.48% from original assays reaching 2.90% and 1.60%, respectively. That maximum separation efficiency was attained at 78.38...
29 citations
TL;DR: In this article, a simple electrostatic separation method of peeling and gluten, which are two such nutriments contained in finely ground wheat grains, was validated using surface potential decay and direct charge measurements.
Abstract: Sieving and air classification are not efficient enough for the extraction of the high-nutritional-value constituents of wheat. The aim of this article is to validate a simple electrostatic separation method of peeling and gluten, which are two such nutriments contained in finely ground wheat grains. The electrostatic separator is composed of metallic grounded belt conveyer and a rotating roll electrode connected to a high voltage supply. The electrostatic behavior of peeling and gluten powders was characterized using surface potential decay and direct charge measurements. These first set of experiments pointed out the conductive behavior of these powders: in contact with a grounded electrode, they lose their charge in less than 10 s. In a second set of experiments, mixtures of 50% peeling and 50% gluten powders were processed by electrostatic separation. Experimental design methodology was used to model the outcome of the separation process as function of two control variables: the high-voltage applied t...
27 citations
TL;DR: Two fluid or Eulerian modeling incorporating the kinetic theory for granular particles and accounting for four-way coupling was performed to investigate the hydrodynamics and pressure drop characteristics of gas-solid flows in horizontal pipes as mentioned in this paper.
Abstract: Two fluid or Eulerian modeling incorporating the kinetic theory for granular particles and accounting for four-way coupling was performed to investigate the hydrodynamics and pressure drop characteristics of gas-solid flows in horizontal pipes. The model was validated by comparison with the experimental data found in literature and the predictions agreed reasonably well with experimental results. It was found that lift force along with particle-wall collision and specularity coefficient play significant role in the simulation of horizontal gas-solid flows. Granular temperature model by Ding and Gidaspow (1990) predicts the velocity profiles of both phases accurately. The gas-solid two-phase flow in the horizontal pipe generally has an asymmetric structure in the vertical direction, which is due to the effect of gravity. An extensive investigation was also done to study the effect of various flow parameters like particle properties, gas velocity, and solid concentration on pressure drop prediction. Finally...
26 citations
TL;DR: In this paper, the authors used locally available limestone fillers for the optimization of particle packing and flow behavior of cementitious pastes in concrete mixes in fresh state and for understanding interactions existing at the level of the interfacial transition zone between aggregates and cement paste.
Abstract: Mineral fillers can be defined as “inert materials included in a mix design for some useful purpose” (NF P18-508 Janvier 2012). They can be added to compounds in order to complete a large variety of final properties without increasing costs or to improve specific characteristics like hardness, brittleness, impact strength, compressive strength, softening point, fire resistance, surface texture, electrical conductivity, and so on. In Belgium, locally available limestone fillers are specifically very well adapted for the optimization of particle packing and flow behavior of cementitious pastes in concrete mixes. Limestone fillers may be easily characterized in terms of chemical and mineralogical properties. These properties are fundamental for the study of the behavior of concrete mixes in fresh state and for understanding interactions existing at the level of the interfacial transition zone between aggregates and cement paste. These properties are however insufficiently discriminant and particle size, as w...
26 citations
TL;DR: The best fitting isotherm model was the Radke-Prausnitz and kinetics model was pseudo-second order for two dyes for methyle adsorption.
Abstract: Adsorption of tartrazine and methylene blue from aqueous solution onto activated carbon has been investigated. Experimental datas obtained from dye adsorption have been studied by five two-parameter (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, and Frumkin), five three-parameter (Redlich-Peterson, Sips, Toth, Radke-Prausnitz, Koble-Corrigan) isotherm models. In this study, eight nonlinear error functions (sum squares errors, hybrid fractional error function, Marquardt's percent standard deviation, average relative error, sum of absolute error, the coefficient of determination, nonlinear chi-square test, and standard deviation of relative errors) were examined for isotherm equations. In order to clarify the adsorption kinetics fit of pseudo-first order and pseudo-second order kinetic models were used. The best fitting isotherm model was the Radke-Prausnitz and kinetics model was pseudo-second order for two dyes. Adsorption experiment showed that the maximum capacity of activated carbon's for methyle...
25 citations
TL;DR: In this paper, the authors used spherical glass beads with three different sizes 0.8-1mm, 1.5-mm and 2-mm to simulate a 6.5m long, 0.075m diameter horizontal pipe in conjunction with a LDA system.
Abstract: Dilute horizontal pneumatic conveying has been the subject of this experimental and numerical study. Experiments were performed utilising a 6.5 m long, 0.075 m diameter horizontal pipe in conjunction with a laser-Doppler anemometry (LDA) system. Spherical glass beads with three different sizes 0.8–1 mm, 1.5 mm, and 2 mm were used. Simulations were carried out using the commercial discrete element method (DEM) software, EDEM, coupled with the computational fluid dynamics (CFD) package, FLUENT. Experimental results illustrated that, for mass solid loading ratios (SLRs) ranging from 2.3 to 3.5, the higher the particle diameter and solid loading ratio, the lower the particle velocity. From the simulation investigations it was concluded that the inclusion of the Magnus lift force had a crucial influence, with observed particle distributions in the upper part of the conveying line reproducible in the simulation only by implementing the Magnus lift force terms in the model equations.
TL;DR: In this paper, the authors presented a numerical study of the granular lost circulation material (LCM) plugging behavior at a particle scale by means of discrete element method (DEM).
Abstract: Granular lost circulation material (LCM) is the most commonly used material to reduce drilling fluid loss in drilling industry Although, the plugging role of granular LCM in fracture is widely accepted by drilling engineers, the control and optimization are still limited due to the lack of the fundamental understanding of the LCM plugging process This article presents a numerical study of the granular LCM plugging behavior at a particle scale by means of discrete element method (DEM) The effects of the particle shape, size distribution, and concentration on the fracture-plugging performance are studied by a series of controlled numerical experiments The results are analyzed in terms of plugging depth and time spent before plugging They are useful to the development of a better understanding and the control of granular LCM plugging process in fractures
TL;DR: In this paper, the feasibility of producing nanoparticles from feather waste by enzymatic hydrolysis, followed by ultrasonic treatment was investigated, and the best condition in order to attain the smallest particles by a Box-Behnken design was found to be: enzyme concentration: 3.6%, substrate concentration: 5 ǫg/l and Hydrolysis time: 243 h.
Abstract: Feather is a waste product generated in large quantities from industrial poultry processing. Recycling of this renewable source of biopolymers has been the objective of many researches due to its high protein content, biodegradability, and biocompatibility. This study investigates the feasibility of producing nanoparticles from feather waste by enzymatic hydrolysis, followed by ultrasonic treatment. The effects of enzyme concentration, hydrolysis time and substrate concentration on particles size were evaluated to optimize the best condition in order to attain the smallest particles by a Box-Behnken Design. The optimum hydrolysis conditions were found to be: enzyme concentration: 3.6%, substrate concentration: 5 g/l and hydrolysis time: 243 h. Scanning electron micrographs indicated fiber fibrillation and degradation as it was progressively converted into particles form. The results of particle size analysis indicated the positive effect of sonication on reducing particles size. Fourier transform infrared...
TL;DR: In this article, the authors measured the concentration distribution of two fractions of glass-bead (ballotini) particles (medium size 0.44 and 0.53mm, respectively) in flows of heterogeneous slurry in a laboratory pipe of the internal diameter of 100mm using a radiometric device.
Abstract: Concentration distribution of two fractions of glass-bead (ballotini) particles (medium size 0.44 and 0.53 mm, respectively) in flows of heterogeneous slurry was measured in a laboratory pipe of the internal diameter of 100 mm using a radiometric device. Particles in such flows are supported by both interparticle contacts and turbulent eddies and the solids load must be considered as combined load composed of both contact and suspended load. Flows tend to be partially stratified and if high concentrated (mean volumetric concentration of solids higher than approximately 20%) they exhibit a sliding bed. It appears that two most common methods to calculate concentration profiles in settling-slurry flows are not able to handle the sliding bed adequately. A comparison of the test results with the Gillies-Shook model for combined-load flows shows that the modeling approach requires further refinements. An application of the more recent Kaushal-Tomita model based on the turbulent-diffusion concept is inappropria...
TL;DR: In this paper, the effect of various parameters such as initial pH value of the solution, contact time, temperature, and initial concentration of the cesium ion on the adsorption efficiencies of granular activated carbon (GAC) was studied systematically by batch experiments.
Abstract: GAC has been modified by loading of potassium nickel hexacyanoferrate (KNiCF) as a new adsorbent for cesium adsorption. The potassium nickel hexacyanoferrate-loaded granular activated carbon (KNiCF-GAC) was characterized using powder x-ray diffraction (XRD) and nitrogen adsorption-desorption isotherm data, infrared spectroscopy, and its cesium adsorption performance in aqueous solution was investigated. The effect of the various parameters such as initial pH value of the solution, contact time, temperature, and initial concentration of the cesium ion on the adsorption efficiencies of KNiCF-GAC have been studied systematically by batch experiments. The adsorption isotherm of KNiCF-GAC was studied and the fitted results indicated that the Langmuir model could well represent the adsorption process. The maximum adsorption capacity of Cs+ onto KNiCF-GAC was found to be 163.9 mg · g−1.
TL;DR: In this article, the qualitative phase analysis of studied powder samples and the morphology of powders after milling were determined using the x-ray diffraction method and scanning electron microscopy, respectively.
Abstract: Aluminum-substituted barium hexagonal ferrite particles BaAl x Fe12-x O19 with 0 ≤ x ≤ 3.5 have been prepared by solid state reaction method. The qualitative phase analysis of studied powder samples and the morphology of powders after milling were determined using the x-ray diffraction method and scanning electron microscopy, respectively. The barium hexagonal ferrite phase appeared to be the main component of the samples. The crystal size of BaFe12O19 phase is above 25 nm. The scanning electron microscopy images showed irregular shape and size of powder particles. According to the analytical method findings, the type of crystal lattice was confirmed to be hexagonal and the parameters of unit cell volume and x-ray density were determined. It is shown that such parameters decrease with increasing Al substitution from 699.019 to 696.702 A3 and 5.258 to 4.828 gm/Cm3, respectively. The values of lattice parameters, grain size, microstrain, and dislocation density of all samples were calculated. The c/a value ...
TL;DR: In this paper, self-nano-emulsifying granules (SNEGs) of poorly water soluble drug, Olmesartan Medoxomil (OLM) were formulated to improve its solubility and oral bioavailability.
Abstract: The present investigation was aimed to formulate self-nanoemulsifying granules (SNEGs) of poorly water soluble drug, Olmesartan Medoxomil (OLM) to improve its solubility and oral bioavailability. Acconon sorb 20, Tween 80, and Carbitol were selected as oil, surfactant and cosurfactant, respectively for the development of liquid self-nanoemulsifying system (L-SNEDDS), which subsequently adsorbed on a carrier (Aerosil 200) to develop SNEGs. The results of in vitro and in vivo study of OLM-SNEGs revealed remarkable improvement compared to pure OLM. The present study proposed SNEGs as one of the suitable approach for developing nanosized solid oral dosage forms of OLM.
TL;DR: In this article, multiwalled carbon nanotubes (MWCNTs) were added to polyacrylamide (PAM) hydrogels in different proportions to tune their electrical and mechanical properties.
Abstract: Multiwalled carbon nanotubes (MWCNTs) were added to polyacrylamide (PAM) hydrogels in different proportions to tune their electrical and mechanical properties. The choice of MWCNTs as a reinforcement is justified by the fact that these are highly conducting, fairly stable and flexible particles. A series of MWCNT/PAM hydrogels were prepared by freezing method. The characteristic absorption peaks at 1480 and 1213 cm−1 in the FTIR spectra reveal that MWCNTs are embedded in the PAM hydrogels. Powder x-ray diffractograms and thermogravimetric analysis (TGA) images show that the MWCNT/PAM hydrogels are crystalline, more thermally stable and have a higher electrical conductivity than a traditional PAM hydrogel. Scanning electron micrographs reveal about reduced pore size, homogeneous and denser texture. The swelling properties of all these hybrid hydrogels were found to be better than those of the parent PAM hydrogel. The Li–Tanaka equation was employed to produce the swelling parameters. The diffusion coeffici...
TL;DR: In this article, the ability of activated carbon prepared from waste to adsorb methylene blue from aqueous solution was investigated in a fixed-bed column, and the effect of flow rate and inlet methyleneblue concentration on the adsorption characteristics was investigated at 25°C. The results showed that the equilibrium data fitted Langmuir isotherm within the concentration range studied.
Abstract: In this study, the ability of activated carbon prepared from waste to adsorb methylene blue from aqueous solution was investigated in a fixed-bed column. The effect of flow rate and inlet methylene blue concentration on the adsorption characteristics of activated carbon was investigated at 25°C. Freundlich and Langmuir adsorption models have been used to represent the column equilibrium data. The Langmuir constants of Qo and b were determined as 6.38 mg · g−1 and 0.34 L · mg−1, respectively. The results showed that the equilibrium data fitted Langmuir isotherm within the concentration range studied. Four kinetic models, Adams-Bohart, Wolborska, Thomas, and Yoon-Nelson, were applied to experimental data to predict the break-through curves and determine the characteristic parameters of the column useful for process design. Results also indicate that the adsorption process can only deal with lower flow rates and lower concentrations of methylene blue solution if a high percentage of removal is required for e...
TL;DR: In this paper, the effect of formulation variables of self-nano-emulsifying drug delivery system (SNEDDS) of rosuvastatin (RSV) was analyzed.
Abstract: The objectives of present study were to understand the effect of formulation variables of self-nanoemulsifying drug delivery system (SNEDDS) of rosuvastatin (RSV). Box-Behnken design in conjunction with desirability function was used to evaluate the main effect, interaction effect and quadratic effect of independent formulation variables that included amounts of Acconon 200 E6, Cremophor RH40, and Lipoxol 300. For a better understanding of the selected variables for the optimal performance of RSV SNEDDS, the models were presented as three-dimensional response surface graphs. A fresh batch of optimized formulations and were prepared with optimized levels of the independent variables to yield dependent variables (Y1–Y6) values that were remarkably close to the predicted values. Drug excipient compatibility studies using the Fourier transform infrared spectroscopy, differential scanning calorimeter and x-ray diffraction indicated the absence of any incompatibility between RSV and selected excipients. The tra...
TL;DR: In this article, the simulation of the impact of ultrafine particles on the rigid partition wall of the multichannel cyclone by applying the discrete element method (DEM) is presented.
Abstract: This article focuses on the simulation of the impact of ultrafine particles on the rigid partition wall of the multichannel cyclone by applying the discrete element method (DEM). Ultrafine particles with diameters ranging from 0.1 to 10 µm are assumed to be most dangerous pollutants because of their property to easily penetrate the human circulatory system through the respiratory tract. An emphasis is placed on demonstrating the stick-rebound behavior of glass pollutant particles. The numerical experiment simulating the oblique impact load induced by mechanically generated inlet air flow has been numerically conducted. Hertz contact and short-range van der Waals attraction are the main forces describing normal contact, while their tangential counterpart is defined according to Coulomb friction law and by considering normal compression and attraction. Both normal and tangential models are modified to comprise the effect of energy dissipation due to adhesion hysteresis. Simulation results provide a theoreti...
TL;DR: In this article, aqueous polymeric microparticles with PVP K30 were prepared with or without aid of adsorbent (Aerosil200/Sylysia350) using spray-drying technique.
Abstract: In order to improve solubility and dissolution rate of poorly aqueous soluble telmisartan, its amorphous polymeric microparticles with PVP K30 were prepared with or without aid of adsorbent (Aerosil200/Sylysia350) using spray-drying technique. The pure drug and formulations were evaluated for their morphology, particle size, aqueous solubility, and in vitro drug release. Solid state characterization of pure drug and microparticles was carried out by Fourier transform infrared spectroscopy (FTIR), x-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). FTIR indicated hydrogen bonding interaction with an absence of any other chemical interaction between drug and excipient. The results of DSC and XRPD revealed transformation of crystalline drug to amorphous form which was confirmed by SEM. Significant solubility and dissolution enhancement was observed for all polymeric microparticles over pure drug and spray-dried pure drug. This enhancement was attr...
TL;DR: In this paper, the surface of natural zeolite sample was modified by using cationic surfactants in order to investigate its adsorption capacity to remove pesticides from wastewater.
Abstract: In the past decades, natural zeolites have found a important role in adsorption applications due to their local availability and low cost preparation. In this study, surface of natural zeolite sample was modified by using cationic surfactants in order to investigate its adsorption capacity to remove pesticides from wastewater. Data obtained from adsorption studies on organo-zeolites were compared with data obtained from those on activated carbon. To determine the adsorption process and properties, the effects of various operating parameters, pH of the solution (3–11), initial concentration of pesticides (5–20 mg · L−1), contact time (10–350 min), and temperature (25–55°C) were investigated in a batch adsorption technique. According to results, the adsorbed amount of fenitrothion on three different adsorbents decreased whereas those of trifluralin on the adsorbents increased with increasing temperature. Langmuir and Freundlich adsorption models were applied to experimental equilibrium data of pesticide ads...
TL;DR: In this article, a discrete element method (DEM)-compatible interaction model is proposed to model the normal interaction for the adhesive elastic contact, which is based on the Derjaguin-Muller-Toporov model of normal interaction.
Abstract: The adhesive–dissipative behavior of a microparticle under the oblique impact is investigated numerically and the new discrete element method (DEM)-compatible interaction model is elaborated. The modeling approach is based on the Derjaguin–Muller–Toporov model of normal interaction for the adhesive elastic contact. Adhesion hysteresis is specified by the loss of the kinetic energy governed by the fixed amount of the adhesion work, required to separate two adhesive contacting surfaces. This effect is captured in the new interaction model by adding an additional dissipative force component to normal contact during unloading and detachment. The essential feature of this approach, differing from that of the viscous damping model, is that, according to the proposed method, the amount of the dissipated energy is not influenced by the actual initial velocity during the entire contact. The influence of adhesion on slip friction is reflected by considering the adhesive normal force components in the Coulomb's law ...
TL;DR: In this article, a slug formation model is proposed based on theoretical analysis and indicates that the vibration amplitude, the vibration frequency, and the superficial air velocity all have significant effects on the slugging behavior.
Abstract: The periodic slugging behavior of Geldart D particles in a vibrated gas-fluidized bed (VFB) is favorable for some applications involving the processes of particles stratification, especially for fine coal beneficiation in a VFB. It is of great significance to conduct systematic studies on slug formation, slug coalescence and growth, slug rising velocity, and slugging frequency in a VFB of Geldart D particles. The slug formation model is proposed based on theoretical analysis and indicates that the vibration amplitude, the vibration frequency, and the superficial air velocity all have significant effects on the slugging behavior. Also, the comparison of predicted values and measured values of the slug height at its initial formation verifies that the slug formation model has high prediction accuracy. The dynamic of the coalescence of bubbles into an adjacent slug is qualitatively studied and the correlations of the slug height and the slug rising velocity are established, respectively. The results show tha...
TL;DR: In this paper, the results of an experimental measurement and visualization of coarse-grained fully stratified particle-water mixtures were presented, focusing on the study of the carrier liquid velocity field and behavior and local velocities of conveyed particles.
Abstract: This article describes the results of an experimental measurement and visualization of coarse-grained fully stratified particle-water mixtures. This article focuses on the study of the carrier liquid velocity field and behavior and local velocities of conveyed particles. Glass balls and graded pebble gravel of 6 mm mean diameter were conveyed by water in a horizontal smooth pipe loop with a transparent pipe viewing section of inner diameter 40 mm. The measurements were performed in the smooth pipe and the pipe with rough stationary bed created by two layers of spherical particles of the same mean diameter as the conveyed particles. Particle movement along the pipe bottom was studied and the effect of the stationary bed on local velocity values of the carrier liquid and conveyed particles were evaluated. It was concluded that in the flow with stationary bed the maximum liquid velocity is markedly shifted from the pipe center to its top. The coarse-grained particles moved principally in a layer close to the...
TL;DR: Sodium alginate glycerol beads could represent a promising oral drug delivery system to extend the release of theophylline through entrapment efficiency, drug release, and morphology of beads.
Abstract: Theophylline is the most useful bronchodilators for the treatment of severe reversible bronchospasm. The fluctuations of serum theophylline level in clinical practice and associated central nervous system side effects necessitate the development of an extended release formulation. In the present study, theophylline-loaded beads were prepared by extruding the dispersion of theophylline, sodium alginate, and glycerol into the cationic crosslinking solution of calcium chloride. The effect of the addition of glycerol was determined by entrapment efficiency, drug release, and morphology of beads. Absence of chemical interaction between drug, polymer, and counterions after production of beads was confirmed by Fourier transform infrared spectroscopy. Theophylline entrapment of up to 72% was achieved in beads with almost spherical shape and size ranging from 0.67 to 1.12 mm. Percentage entrapment of theophylline found to be more and release was extended up to the eleventh hour from the glycerol containing sodium ...
TL;DR: In this paper, entrainment of fine particle using a mixture of artificial ore (celestite:calcite; 1:1) was investigated in conventional and column flotation The effects of frother concentration and particle size were tested.
Abstract: The entrainment of particles in a flotation has been considered as one of the significant factors affecting both concentrate grade and recovery for a decades It is based on the changes depending on the establishment of linear relationship between water recovery and solid recovery In this study, entrainment of fine particle using a mixture of artificial ore (celestite:calcite; 1:1) was investigated in conventional and column flotation The effects of frother concentration and particle size were tested The results showed that the particle size and frother concentration had significant effect on the grade and recovery, flotation time, and fine gangue entrainment Entrainment factors for the conventional and column flotation were compared Kirjaveinen (1989) model was used for describing a specific entrained factor (P i ) of hydrophilic particles It has been found that Kirjaveinen model supports the results of this study
TL;DR: In this paper, the authors applied time series analysis techniques in time domain and average cycle frequency to characterize bubbling fluidization and found that the peak dominant frequency of the pressure fluctuations is about 1.5-2.5 Hz, corresponding to the macrostructures of the bed.
Abstract: Time series analysis techniques in time domain and average cycle frequency were applied to characterize bubbling fluidization. The experiments were carried out in a laboratory scale fluidized bed, operated under ambient conditions and various sizes of particles, measurement heights, and different superficial gas velocities. It was found that a minimum in average cycle frequency and flatness and a shift of skewness from negative to positive against velocity correspond to shift from macrostructures and finer structures of the flow rather than transition velocity from the bubbling to turbulent regime. The power spectrum estimation of the measured pressure fluctuations shows that the peak dominant frequency of the pressure fluctuations is about 1.5–2.5 Hz which is corresponding to the macrostructures of the bed. Accordingly, the onset of turbulent fluidization regime was detected through standard deviation analysis. It was shown that the simple analysis techniques still have interesting information about hydr...
TL;DR: In this paper, the performance of rice hull ash medium in removing water turbidity was investigated using scanning electron microscopy (SEM), x-ray diffractometer (XRD), and Fourier infrared spectroscopy (FTIR).
Abstract: This study characterizes the locally obtained samples of rice hull ash and investigates its performance on turbidity removal from water. Four samples of this material were studied, namely, unwashed parboiled rice hull ash (UPRHA), washed parboiled rice hull ash (WPRHA), unwashed unparboiled rice hull ash (UUPRHA), and washed unparboiled rice hull ash (WUPRHA). Scanning electron microscopy (SEM), x-ray diffractometer (XRD), and Fourier infrared spectroscopy (FTIR) were carried out to characterize these samples. A filtration process was carried out to investigate the effectiveness of the rice hull ash medium in removing water turbidity. The XRD results showed the silica, which is present in the ashes, to be cristobalite, quartz, and tridymite. The silica contents of the UUPRHA and WUPRHA were observed to be 77.10% and 98.24%, respectively, while those of UPRHA and WPRHA were 79.07% and 94.97%, respectively. The SEM images showed agglomeration of ash particles after the ashes were washed. The washed RHA samp...