Particle Size Distribution Of Suspension Research Articles

Preparation of fine suspensions using stirred media bead mill

Preparation of fine suspensions using stirred media bead mill

Limitations of Nanoparticles Size Characterization by Asymmetric Flow Field\u2011Fractionation Coupled with Online Dynamic Light Scattering

The development of reliable protocols suitable for the characterisation of the physical properties of nanoparticles in suspension is becoming crucial to assess the potential biological as well as toxicological impact of nanoparticles. Amongst sizing techniques, asymmetric flow field flow fractionation (AF4) coupled to online size detectors represents one of the most robust and flexible options to quantify the particle size distribution in suspension. However, size measurement uncertainties have been reported for on-line dynamic light scattering (DLS) detectors when coupled to AF4 systems. In this work we investigated the influence of the initial concentration of nanoparticles in suspension on the sizing capability of the asymmetric flow field-flow fractionation technique coupled with an on-line dynamic light scattering detector and a UV–Visible spectrophotometer (UV) detector. Experiments were performed with suspensions of gold nanoparticles with a nominal diameter of 40 nm and 60 nm at a range of particle concentrations. The results obtained demonstrate that at low concentration of nanoparticles, the AF4-DLS combined technique fails to evaluate the real size of nanoparticles in suspension, detecting an apparent and progressive size increase as a function of the elution time and of the concentration of nanoparticles in suspension.

Application of acoustic models for polydisperse emulsion characterization using ultrasonic spectroscopy in the long wavelength regime

Ultrasonic spectroscopy is a technique that often has been used for measuring the particle size distribution in suspensions and emulsions. The ability to analyze concentrated heterogeneous systems and optically opaque samples, without the need for dilution, is the major advantage over alternative technologies, such as light scattering method. Several physical models used to interpret the measured attenuation spectra have been applied considering monodisperse particles. However, the polydisperse particle distributions are found in many practical applications, for example, in crude oil emulsions during droplet coalescence or flocculation. The polydispersity effects are usually important and need to be incorporated into theoretical predictions. For this work, acoustic spectroscopy within the frequency range 6–14 MHz was used to measure the droplet size distribution of water-in-sunflower oil emulsions for a volume fraction range from 10 to 50 % and considering monomodal size distribution. The results obtained from experimental attenuation spectra have been compared with the predictions of acoustic models from simple and multiple scattering, extended multiple scattering, and other simpler models of propagation usually applied to the long wavelength regime. The droplet size distributions from theoretical and experimental attenuation spectra were calculated with a deconvolution algorithm. The size distribution results obtained by ultrasonic spectroscopy showed good agreement with those obtained by laser diffraction analysis. The findings indicate that the methodology employed in this study is suitable for polydisperse particle size characterization for moderate concentrations up to 20 %.

Получение микродисперсного тканеспецифического децеллюляризованного матрикса из суставного хряща свиньи

A method for obtaining a microdispersed tissue-specific matrix from decellularized porcine articular cartilage while maintaining morphological and functional properties of the extracellular matrix with no signs of cytotoxicity was developed. The cartilage particle size distribution in suspension after cryogenic grinding was determined using laser diffraction analysis. The range of sizes of the obtained cartilage microparticles suggests the possibility of their administration by injection (<220 μm). The combination of stages, including three freeze/thaw cycles (–196/37°C) followed by treatment with solutions of surface-active substances (surfactants), sodium dodecyl sulfate and Triton X-100, and DNase resulted in the complete removal of non-decellularized microparticles. The residual DNA content was 9.11 ± 1.13 ng/mg of tissue. The effectiveness of surfactant washing was assessed by the cytotoxicity of the matrix on the culture of human adipose derived mesenchymal stromal cells (hADSCs). To assess the hemocompatibility of the obtained samples, their hemolytic activity was studied in vitro. The adhesion and proliferation of hADSCs on the matrix surface were studied on day 21 of cultivation. The matrix did not exhibit hemolytic activity and cytotoxicity with respect to hADSCs. hADSCs in the samples were actively proliferating on the matrix surface. The biocompatibility and hemocompatibility of the obtained matrix in vitro indicate its potential for application in cartilage regenerative medicine.

Badanie rozkładu wielkości cząstek zawiesin w wodach opadowych

Badanie rozkładu wielkości cząstek zawiesin w wodach opadowych

Appearance of an artifact peak in the particle size distribution measured by DLS at low concentrations

The dynamic light scattering (DLS) method allows the determination of the particle size distribution of suspensions. At high dilutions, an artifact peak appears in the size distribution, which does not correspond to actual particles, but is caused by crossing the scattering volume boundaries by individual particles. The parameters of this peak are analyzed, the causes of its appearance and its effect on determined particle sizes are studied.

Effective viscosity in a wave propagation model for ultrasonic particle sizing in non-dilute suspensions.

Estimates of particle size distributions (PSDs) in solid-in-liquid suspensions can be obtained from measurements of ultrasonic wave attenuation. The technique is based on adaptively fitting theoretical wave propagation models to the measured data across a frequency range. These models break down at high solid concentrations and it is believed that this failure is due to the effective viscosity of the mixture in the vicinity of the particles being different from that of the continuous phase. This paper discusses PSD estimation when a number of different viscosity formulations are incorporated into the wave propagation model. The viscosity model due to Happel provides the best estimate of PSD in suspensions of medium concentration.

Effect of Degritting of Phenolic Extract from Sour Cherry Pomace on Encapsulation Efficiency—Production of Nano-suspension

The objective of this study was to study the influence of purification of sour cherry pomace extract on particle size distribution of suspension and on encapsulation efficiency of powders. In addition, antioxidant activity, surface morphology, and color of powder and capsules were determined. Extraction of phenolic compounds was performed at 30 °C with shaking at 70 rpm for 24 h with 1:20 solid–solvent ratio. Ethanol–water (1:1) was used as the solvent. Filtered extract was concentrated in a rotary evaporator and freeze dried to produce extracted phenolic powder (EPP). Purified extracted phenolic powder (PEPP) was obtained by degritting at 10,000 rpm for 2 min and then by freeze drying for 48 h. Purification reduced Sauter mean diameter (D[32]) of concentrated extract from 5.76 μm to 0.41 μm. In encapsulation, two types of coating materials were used. The first one contained 10 % maltodextrin (MD) and 90 % distilled water, while the second one contained 8 % MD, 2 % gum arabic (GA), and 90 % distilled water. Samples were homogenized using ultrasound (160 W, 50 % pulse) for 20 min. Microsuspensions containing EPP had D[32] of 1.65 and 1.61 μm when 10 % MD and 8 % MD-2 % GA aqueous solutions were used for coating, respectively. It was possible to obtain nano-suspensions when purification step was performed. Suspensions prepared with PEPP and 10 % MD and 8 % MD–2 % GA for coating had D[32] of 0.396 and 0.334 μm, respectively. As a result of purification, encapsulation efficiency of the capsules increased significantly from 86.07–88.45 % to 98.01–98.29 % (P < 0.001).

Modelling of Polymer Particle Formation Using Population Balance Model

The paper presents a study of formation of the primary particle size distribution in suspension “powder” polymerization of vinyl chloride. The process is modelled by means of a population balance model, and the primary particle size distribution inside the polymerizing monomer droplets is determined by analysing the population balance equation, governing the nucleation, growth, and aggregation of the primary particles, using the moment method. The infinite set of moment equations obtained by moment transformation was closed using a sum aggregation kernel, and for numerical experimentation a second order moment equation model was used. The results show how important are to choose the correct parameters in production of poly(vinyl chloride) by suspension polymerization. Changing the parameters a bit the quality of product may change significantly. The results presented in the paper illustrate well that the population balance model can be used for describing the process and a number its properties with sufficient accuracy.

Particle Size Distribution by Space or Time Dependent Extinction Profiles obtained by Analytical Centrifugation

AbstractThe particle size distribution of suspensions of fine particles was determined by a photocentrifuge from transmission/extinction profiles. Photocentrifuges provide a useful tool for the characterization and quality control of suspensions. While the variation of the light extinction curves caused by centrifugal segregation allows a qualitative description, a rigorous formulation provides a quantitative characterization. The present work reports on the determination of the particle size distribution using space and time resolved extinction profiles. The particle size distribution is obtained by analyzing the variation of the extinction at any point of the sample over the full centrifugation time or by analyzing the extinction variation over the entire sample length for any centrifugation time span. The advantage of the second method is the potential to save time.

Soil loss by splash and wash during rainfall from two loess soils

Physical processes occurring during surface seal formation through a rainstorm are well understood, but limited information is available regarding the quantity and particle size distribution of splash and runoff at certain time intervals. In this study, we evaluated the quantity and particle size distribution of suspensions of both splash and interrill runoff in two loess soils with different mineralogy and aggregate stability, and somewhat different particle size distribution, but similar organic matter content. The soils were subjected to simulated rainstorms of ∼ 40 turn h − 1 and 100 mm h −1 intensities. The amount of splash was about four times higher for the Saskatchewan soil (Typic Haploboroll) with high smectite than for the Grenada soil (Typic Fragiudalf) which is rich in Fe-oxyhydroxides. The amount of splashed material and sediment load increased with increased rainfall intensity for both soils. Splash was decreased after wetting of the soil surface. The decrease in splash rate was more rapid with high rainfall intensity. The amount of clay size particles of the splash was similar to the original soil material. Micromorphological observations confirmed the fluctuations in clay content with time, at the very surface. Soil materials splashed were much higher (10 to 20 times) than the interrill runoff losses. The latter was controlled by the rainfall intensity. The soil material from Saskatchewan, produced more than 11 Mg ha − 1 of interrill runoff with low rainfall intensity. High rainfall intensity produced 10 times more soil loss than low rainfall intensity. High amount of soil loss clearly shows that the Saskatchewan soil would benefit from erosion control measures. Both rainfall intensities removed preferentially more clay from the Saskatchewan B horizon material. This has important agronomic and environmental implications for this soil. Interrill soil losses from the Granada A horizon material were much less, with no clear evidence of preferential removal of clay size particles.

Comparison of numerical schemes for solving a spherical particle diffusion equation

A new robust iterative numerical scheme was developed for a nonlinear diffusive model which described sorption dynamics in spherical particle suspensions. The numerical scheme had been applied to finite difference and finite element models which showed rapid convergence and stability under wide ranges of partition coefficients. Comparisons were made with explicit finite difference and orthogonal collocation methods. The diffusive model assumes complete mixing in the bulk aqueous solution and considers intraaggregate transport within the suspended particles. The effect of particle size distribution of suspensions was also included in the model. Sorption was described using both linear and nonlinear isotherms.

Ultracentrifuge as a Versatile Tool to Study Preferential Interaction of Polymers in Mixed Solvents

Abstract Over the past five decades the analytical ultracentrifuge has been a versatile tool in the study of macromolecules and colloidal particles. Several textbooks [1–4] and review articles [5–10] deal with experimental techniques and theories for complete characterization of macromolecular species. However, the first published articles on the analytical ultracentrifuge dealt with the analysis of particle size distributions in suspensions of inorganic colloids. The emphasis has now shifted to organic polymers following the discovery that a large number of such polymers exist in nature. Before the development of the ultracentrifuge, the existence of such giant molecules was not recognized; the molecular kinetic units of proteins and of high organic polymers in solution were simply thought of as clusters of much smaller molecules, forming particles of undefined mass. Beginning with the elegant investigations of Svedberg [11, 12] on ultracentrifugation, such substances were revealed to be macromolecules, ...

Studies of the particle size distribution of suspensions of silica by a turbidimeter with an integrating sphere

Studies of the particle size distribution of suspensions of silica by a turbidimeter with an integrating sphere

An Improved Method of calculating Particle Size Distribution from Centrifugal Sedimentation Experiments

CENTRIFUGAL sedimentation methods are widely used for determining the particle-size distribution of suspensions of fine solids in liquids. Donoghue and Bostock1 give methods for calculating the cumulative weight size distribution of a sample from the experimental figures. This method is based on filling the centrifuge with the sample under examination, as opposed to the method initially used by Marshall2, and afterwards developed by others3,4, in which the sample is introduced as a thin layer superposed on a clear medium of slightly higher density. This latter method is likely to give inaccurate results with some systems due to the phenomenon of ‘streaming’. Using the former method, the particle size analysis is performed by running the centrifuge for a given time at constant speed and then measuring the amount of sample which has either sedimented to (or past) a certain radius in the centrifuge, or which remains above this radius. It is immaterial for the purpose of this note which method of measurement is used. The complete size distribution is determined by one of three methods: (1) The inner radius of the liquid surface and the outer radius of collection are kept constant and samples are collected after varying running times of the centrifuge. (We assume the centrifuge speed is kept constant for all experiments.) (2) The running time of the centrifuge is kept constant, as is the inner radius of the liquid, and the outer collection radius is varied. (3) The running time of the centrifuge is kept constant as before, but the outer collection radius is kept constant for successive measurements, while the inner liquid surface radius is varied.