Sedimentation particle size analysis

Given tire a size dependence of tire settling rate, sedimentation can be used for particle size analysis. Indeed, a quick... 

Turbidimetric methods for particle size analysis (Refs 10, 16 27) are used in conjunction with sedimentation procedures to determine the concn of particles at given distances below the surface at successive time intervals. From these data, and Stokes law, particle size distribution can be calculated... 

US Dept of Commerce (1967) 37) R. Abbott, N. Gelber N. Liszt, Particle Size Analysis of Ammonium Perchlorate by the MSA Sedimentation Method", PATM 1778 (1967) 38) C.E. 

A complete particle-size analysis can require the use of various analysis technologies. A microscopic examination may be performed before the sieve analysis, which in turn can be followed by a sedimentation analysis or the recording and the evaluation of a diffraction pattern. 

It is our objective in this chapter to outline the basic concepts that are behind sedimentation and diffusion. As we see in this chapter, gravitational and centrifugal sedimentation are frequently used for particle-size analysis as well as for obtaining measures of solvation and shapes of particles. Diffusion plays a much more prevalent role in numerous aspects of colloid science and is also used in particle-size analysis, as we see in Chapter 5 when we discuss dynamic light scattering. The equilibrium between centrifugation and diffusion is particularly important in analytical and preparative ultracentrifuges. 

Sedimentation runs should be conducted at a constant temperature, not only so that Ap and T7 are known, but also to minimize disturbances due to convection. Any sort of disturbance will obviously disrupt the segregation of the particles by size that has occurred as a result of sedimentation. An intrinsic difficulty with the balance method lies in the fact that the liquid below the balance pan is less dense than the liquid with dispersed particles above the pan. Thus, there is a tendency for a counterflow of pure solvent to arise, which would introduce an error in the particle size analysis. 

Pye, K. and Blott, S. J. (2004b). Particle size analysis of sediments, soils and related particulate materials for forensic purposes using laser granulometry. Forensic Sci. Int. 144, 19-27. 

Temperature control is an important factor in determining particle size by sedimentation methods. During a typical run changes in spin fluid temperature of 2-4°C were common. This temperature change (DELTEMP) was used as the covariate in the analysis of covariance. 

Williams PS, Moon MH, Giddings JC (1992) Fast separation and characterization of micron size particles by sedimentation/steric field-flow fractionation role of lift forces. In Stanley-Wood NG, Lines RW (eds) Particle size analysis. Royal Society of Chemistry, Cambridge, pp 280-289... 

Correlation coefficients shoving the relation of Zn to Fe, Mn, organic carbon and particle size in sediments extracted vith either acetic acid, hydroxylamine hydrochloride in 0.01 nitric acid, ammonium oxalate, ammonium acetate, or concentrated nitric acid. English data vcre log transforried for statistical analysis. 

Brown and Skrebowski [37] first suggested the use of x-rays for particle size analysis and this resulted in the ICl x-ray sedimentometer [38,39]. In this instrument, a system is used in which the difference in intensity of an x-ray beam that has passed through the suspension in one half of a twin sedimentation tank, and the intensity of a reference beam which has passed through an equal thickness of clear liquid in the other half, produces an inbalance in the current produced in a differential ionization chamber. This eliminates errors due to the instability of the total output of the source, but assumes a good stability in the beam direction. Since this is not the case, the instrument suffers from zero drift that affects the results. The 18 keV radiation is produced by a water-cooled x-ray tube and monitored by the ionization chamber. This chamber measures the difference in x-ray intensity in the form of an electric current that is amplified and displayed on a pen recorder. The intensity is taken as directly proportional to the powder concentration in the beam. The sedimentation curve is converted to a cumulative percentage frequency using this proportionality and Stokes equation. 

NFX 11-681 Test Methods for Particle Size Analysis-Particle Size Analysis by Gravity Sedimentation in a Liquid Medium, 360... 

II ASTM C958 (1997), Standard Test Method for Particle Size-Analysis of Alumina or Quartz by X-ray Monitoring of Gravity Sedimentation, 360... 

Mueller, R., Kammler, H.K., Wegner, K., and Fkatsinis, S.E., The OH-surface density of SiOj and TiOj by thermogravimetric analysis, Langmuir, 19, 160, 2003. Bernhardt, C., Particle Size Analysis, Classification and Sedimentation Methods, Chapman Hall, London, 1994. 

Other samples of alkaline slurry were subjected to particle size analysis by sedimentation. With the —43 xm + 1.2 [im fraction this analysis was done in a 50-mm-diameter settling column of dilute slurry with a tared pan at the base to record continuously the mass of sedimented solid. The data were analyzed by the method of Oden (8), and the particle size distribution (Stokesian diameter), expressed on a mass percent basis, was calculated. 

Since PCBs are generally adsorbed on the particle surface, the concentration in sediment and soil samples is much more likely to be related to the particle surface area per volume unit than to the mass unit (16). For this reason, the concentration of each sample, expressed in pg g (dry weight), was normalized by dividing it by the relevant CS, expressed in square meters of surface per cubic centimetre of dry sample (m cm ), as obtained by particle size analysis (5). Table 9.9 shows the normalized mean concentration of the seven selected congeners along with the total and the normalized total mean PCB concentration. In this case, the calculated value of the total PCB content was very close to the experimental one (the difference was always lower than 10%). Table 9.10 shows the total mean PCB concentration and the normalized mean PCB concentration for each matrix analysed. In four stations where marine sediments were collected at different depths, a concentration of about 100-200 (pg g )/(m cm ) was generally observed in a surface layer of about 10-15 cm, while in deeper layers PCBs were below the LoDs. These results show that the normalized total mean PCB content in marine sediment samples was 150 (pg g )/(m cm ) and did not show any significant difference from open sea to the coastal line. Lake sediment and soil samples showed a normalised total mean PCB content of 240 and 130 (pg g )/(m cm ) which did... 

During particle size analysis, in addition to screening, sifting, and counting, sedimentation techniques are often used which produce unequivocal results only if the individual particles can move without influencing each other. For that reason, very dilute suspensions are used. Nevertheless, it is possible that agglomerates form or already... 

Since PCBs are adsorbed on the particle surface, normally coated with a thin layer of organic matter such as humic acid, the concentration in sediment and soil samples is much more likely to be related to the particle surface area per volume unit than to the mass unit. ° For this reason, the concentration of each sample, expressed in pgg dry weight, is normalized by dividing it by the relevant calculated specific surface area, expressed in square meters of surface per cubic centimeter of dry sample (m cm ), as obtained by particle size analysis. Comparisons among concentration values of organic pollutants relevant to samples with different particle size distribution may lead to erroneous conclusions if these are expressed in a conventional way. °... 

For particle-size analysis, the fine earth was treated with 3 M HjOj and sonicated (15 min, 15 kHz) coarse, medium and fine sand were retrieved by sieving at 0.25, 0.10 and 0.05 mm, respectively silt was separated from clay by sedimentation after dispersion in 0.01 M NaOH. The pHjj g was measured potentio-metrically (solid/liquid ratio of 1 2.5). Organic C and total N were measured on acidified samples using a Carlo Erba NA1500 analyser. Available P was determined according to Olsen et al. (1954). Effective cation exchange capacity (ECEC) was determined by summation of the cations displaced with 0.2 M BaCl2 and analyzed by atomic absorption with a Perkin-Elmer llOOB spectrophotometer. 

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