Distribution Of Particles In Suspension Research Articles

A mesocosm experiment coupled with optical measurements to assess the fate and sinking of atmospheric particles in clear oligotrophic waters

It has recently been postulated that lithogenic particles such as Saharan dust strongly influence particulate organic carbon export to the deep ocean by acting as mineral ballast. However, our understanding of the processes involved remains scant. In the present study, optical measurements were performed to monitor variations in the concentration, composition and size distribution of particles in suspension within the water column after simulating a Saharan dust event in very clear Mediterranean waters off Corsica in June 2010. A new methodology set up in large mesocosms proved very successful in this regard. Values obtained simultaneously from three instruments (WetLabs ECO-BB3, WetLabs ac-9, Sequoia Scientific LISST-100) provided evidence that (1) part of the Saharan dust pool has a rapid settling velocity (∼24–86 m day−1), (2) particulate export following a dust event is a nonlinear multi-step process and (3) export is controlled in part by the formation of organic-mineral aggregates. This experimental study provides the first insight of the complex export processes occurring after a dust event involving both physical and biogeochemical forcings in clear oligotrophic waters.

A Survey of Complementary Methods for the Characterization of Dense Colloidal Silica

AbstractThe aim of this study is to enhance existing knowledge of different techniques developed for the characterization of stability and particle sizing of nanoparticles in dense dispersions subjected to interparticulate and hydrodynamic forces. Silica suspension, commercially known as Klebosol® 30R50 and consisting of a particle size of 80 nm on average, was investigated in the study over a wide range of concentrations. The investigations were carried out using different optical and acoustic techniques such as laser diffraction, multiple light scattering, photon correlation spectroscopy and acoustic spectroscopy. The study details the capabilities and limitations of these modern techniques based on the different physical principles behind the characterization of the size distribution of particles in suspensions. The results are presented in terms of particle size ranges, solid concentration and technological aspects such as online and offline analysis. An important finding is that many of these modern techniques need to be improved for applications at higher concentrations since the standard models become practically invalid because of the complex interaction of acoustic and optical waves with particles in suspensions of silica.

Dynamic mathematical model of deep bed filtration process

Deep bed filtration is commonly applied in clarification of dilute suspensions of particles ranging in size from about 0.1 to 50 μm. A suspension carrying solid particles of different sizes is passed through the porous bed of defined geometrical characteristics. It has been found that sizes of suspended particles and their distribution are very important physical parameters that influence deep bed filter efficiency. During the filtration process the bed porosity decreases, whereas interficial velocity increases due to the particle accumulation in filter bed. Mathematical model has been developed under the assumption that the plug flow model approximates flow of suspension through the bed. The second assumption is that a deposition kinetics is a function of local suspension's particle distribution and locally deposited particle distribution. In order to obtain the experimental data needed for determination of the process kinetics, a set of experiments has been carried out. So obtained experimental data consisted of the local suspension and deposit particle distribution values and also of the local rate values. All three empirical distributions are approximated by standard Logarithm-Normal distribution function. Each distribution is defined by two LN function parameters. Rate distribution parameters are formally dependent on the parameters that define suspension and deposit distribution. This relation has been established using the general regression neural network (GRNN). Thus defined model enables solving the system within given boundary conditions by approximating distribution functions with sums and using orthogonal collocation method for transformation of partial differential equations into a system of ordinary differential equations. Developed method can be applied in process simulation as long as the input concentration and distribution are within the range of experimental values for the kinetics determination. To test the developed method, experiments were conducted on the pilot scale deep bed filter having total height of 1m and diameter of 0.1m. The results show that a very complex process, as is deep bed filtration, can be successfully described using hybrid neural network.

Spatial Distribution of Particles in Suspension

Spatial Distribution of Particles in Suspension

The Determination of Size Distribution of Particles in Suspension by a Diffusion Technique

Summary Under the assumption of a logarithmic particle-size distribution, the geometric mean radius r̄ and the geometric standard deviation σ can be determined by means of radial diffusion transport and wall adsorption within a capillary. The possibility of simultaneous sedimentation is taken into account. The best fit of the experimental results to calculated curves is shown to confirm earlier estimates of the size of „radiocolloids" and Al2O3-powder.

EXPERIMENTAL AND STATISTICAL EVIDENCE OF THE PARTICULATE NATURE OF THE BACTERIOPHAGE

Experimental evidence is brought forward to show that the bacteriophage obeys very closely the laws of chance distribution of particles in suspension.

The Laws of Distribution of Particles in Suspension

The Laws of Distribution of Particles in Suspension