Suspension concentration determination

Thus, from sludge concentration c and the weight of a wet cake per kg of dry cake solids, x can be determined. If the suspension is dilute, then c is small and the product of m X c is small. This means that x will be almost equal to c. Since x depends on the product me, at relatively moderate suspension concentrations this effect will not be great and thus may be neglected. However, for the filtration of concentrated sludges, the mentioned phenomena will play some role, i.e., at constant feed the filtrate changes with time. 

Zinc (Zn) is added to insulin to retard its rate of absorption into the bloodstream. The total concentration of Zn in Zn insulin suspension is determined by atomic absorption spectophotometry. From the following data calculate the total concentration of Zn in a Zn insulin suspension in percentage of w/v from the following data ... 

Conditioning of the manganese oxide suspension with each cation was conducted in a thermostatted cell (25° 0.05°C.) described previously (13). Analyses of residual lithium, potassium, sodium, calcium, and barium were obtained by standard flame photometry techniques on a Beckman DU-2 spectrophotometer with flame attachment. Analyses of copper, nickel, and cobalt were conducted on a Sargent Model XR recording polarograph. Samples for analysis were removed upon equilibration of the system, the solid centrifuged off and analytical concentrations determined from calibration curves. In contrast to Morgan and Stumm (10) who report fairly rapid equilibration, final attainment of equilibrium at constant pH, for example, upon addition of metal ions was often very slow, in some cases of the order of several hours. 

Cells were transferred from an overnight liquid culture to fresh medium and grown overnight ( 18 h) on a gyrorotary shaker at room temperature. The cells were harvested by centrifugation (11,000 g, 10 min) and resuspended in sterile assay buffer (0.01 M phosphate buffer, Na salt, 0.26 M NaCl, pH 6.78 the pH prior to sterilization was 7.20). The cell concentration was adjusted to approximately 5 x 108/mL as judged by optical density of the solution. The actual numbers in dilutions of the cell suspensions were determined by direct counts. E. cloacae was grown as described, except that the M9 contained 0.5 g/L of NaCl. 

Silver iodide particles in aqueous suspension are in equilibrium with a saturated solution of which the solubility product, aAg+ai, is about 10 16 at room temperature. With excess 1 ions, the silver iodide particles are negatively charged and with sufficient excess Ag+ ions, they are positively charged. The zero point of charge is not at pAg 8 but is displaced to pAg 5.5 (pi 10.5), because the smaller and more mobile Ag+ ions are held less strongly than-the 1 ions in the silver iodide crystal lattice. The silver and iodide ions are referred to as potential-determining ions, since their concentrations determine the electric potential at the particle surface. Silver iodide sols have been used extensively for testing electric double layer and colloid stability theories. 

Further discussion of suspension conductivity and some practical examples for solids concentration determination, and for suspensions flowing in pipelines, are given elsewhere [85,86]. 

The viscosity of the corn stover suspensions was determined for concentrations up to 30%. The helical impeller method was ineffective above corn stover concentrations of 32%. 

Nephelometric turbidimeters are more accurate for measuring dilute suspensions and less sensitive to minor changes in instrumental design. Sensitivity increases with path length however, linearity is sacrificed at higher suspension concentrations and self-quenching can result in anomalously low turbidity levels.9 Obviously, dirty, scratched, or etched glassware, air bubbles, and vibration can all interfere with the accurate determination of turbidity. 

The emulsion technique was applied in the following manner Microliter quantities of the emulsifiable concentrates of the insecticides were added to distilled water. Portions of each suspension were diluted, and the concentrations of the insecticides in the final suspension were determined by electron capture gas chromatography. Appropriate amounts of the diluted emulsion suspensions were then added to about 1-liter samples of distilled water to provide concentrations of these pesticides at levels of less than one part per billion. 

To obtain additional information about ozone activity at the concentrations of greatest biological interest, oxidation-reduction (OR) potentials of buffered bacterial suspensions were determined after addition of various amounts of ozone. 

To obtain additional information about ozone activity at the concentrations of greatest biological interest, oxidation-reduction potentials of buffered bacterial suspensions were determined after addition of various amounts of ozone. It was reasoned that the oxidation-reduction potential at or close to the lethal concentration would exhibit a demonstrable change indicative of the corresponding activity. Figure 2 presents the results of the experiment there is a sharp break in the redox potential at an ozone concentration comparable to the level found to represent the lethal dose in the dosage-contact time experiments. A differential plot of the same data emphasizes this information (Figure 3). 

Using Eq. (8), the viscosity of the suspension is determined from the broth viscosity and volumetric concentration of solids. 

Total oil recoveries were estimated by sampling an unfiltered seawater suspension of oil through two XAD resin columns placed in series. The quantity of oil trapped in each column was then determined by IR absorbance. Three such experiments performed simultaneously showed that 92.4 dt 1.7% of the total oil recovered from both columns was collected on the first column. The average oil concentration in the seawater suspension was determined to be 116 dt 3 fxg/L, based on the total oil recovered by both first and second columns. 

The cellular concentration of the P. aeruginosa suspensions was determined through the light absorbance at 600 nm (MultiSpee-1501 Shimadzu, Japan). The absorbance value was eonverted in cell dry weight concentration (g/1) through a calibration curve. 

Cellular Viability and Concentration Determined by counting cells in nine squares of a Neubauer chamber after dying them with methylene blue solution. Viable cells were not colored, and dead cells were blue free yeast concentration was also obtained by filtering a known volume of cell suspension and drying the wet mass until the constant weight was achieved viability and concentration of immobilized yeast were determined as already described, after dissolution of the pectin gel [1.0 g of cured pellets was dissolved in 20 ml of 5% ethylenediaminetetraacetic acid (EDTA) solution at constant agitation]. The cell concentration was calculated as ... 

Fundamentally, the rheological properties of concentrated colloidal suspensions are determined by the interplay of thermodynamic and fluid mechanical interactions. This means that there exists an intimate relationship between the particle interactions, including Brownian motion, the suspension structure (i.e. the spatial particle distribution in the liquid), and the rheological response. With particles in the colloidal size range (at least one dimension <1 pm), the range and magnitude of the interparticle forces will have a profound influence on the suspension structure and hence, the rheological behaviour (4, 7). Both the fluid mechanical interactions and the interparticle forces are... 

The relationship between adhesive interaction and hydrodynamic phenomena was studied in [305]. The granular filter in this work was charged with sand, marble fines, or anthracite, with a grain diameter of 1.0-1.2 mm. The adhesion was rated by means of the coefficient of adhesion A ad, which is equal to the ratio between the number of adherent particles remaining after washing the filter and the total number of particles retained by the filter. The values of the coefficient of adhesion were determined by two methods by analysis for the content of trivalent iron, the quantity of which was proportional to the number of particles, and by measuring the suspension concentration. The results from these experiments are listed in Table XI.3. 

The stability of PEG-coated nanosphere suspensions was determined by measuring the critical coagulation/flocculation concentration as a ftmc-tion of electrolyte concentration (Stolnik et al, 1995). In the presence of... 

Figure 3.8 Determining if settling will be Type 1 or Type 3. A line through Cs tangent to the flux curve gives Cb, and Cbj. Type 2 settling occurs when initial suspension concentration is between Cb, and Cbj...

A height-time curve for the sedimentation of a suspension, of initial suspension concentration 0.1, in vertical cylindrical vessel is shown in Figure 3W1.1. Determine ... 

From Figure 3W3.2 we determine the minimum and maximum values of suspension concentration in the variable zone... 

Using this information we can plot the concentration profile in the test vessel 50 min after the start of the test. A sketch of the profile is shown in Figure 3W3.3. The shape of the concentration profile within the variable concentration zone may be determined by the following method. Recalling that the slope of the batch flux plot (Figure 3W3.1) at a value of suspension concentration C is the velocity of a layer of suspension of that concentration, we find the slope at two or more values of concentration and then determine the positions of these layers after 50 min ... 

Experience gained during the last decade in the determination of CBs in off-shore surface and deep waters has shown that concentrations are extremely low, much lower than reported earlier (see Table 22-1). Concentrations reported for the Mediterranean Sea (Tolosa et al, 1997 Schulz-Bull et al., 1997), the North Sea Schulz-Bull et al., 1991) and the Baltic Sea Schulz-Bull et al., 1995) were well above those found in surface waters of the open ocean Iwata et al., 1993 Schulz-Bull et a/.,1998). In deep-ocean water Schulz et al., 1988 Petrick et al, 1996 Schulz-Bull et al, 1998) much lower concentrations were found than in surface waters. In North Atlantic Deep Water, values of individual CBs were found to be < 0.01 pg/L, yet concentrations in solution were higher than those in suspended material on an equal volume basis. It turns out that the distribution of CBs between solution and suspension is determined primarily by molecular properties (characterized by octanol/water distribution coefficients). However, biological processes disturb the establishment of equilibria. This phenomenon has been observed in river water, in estuarine and coastal waters and during biologically active periods in the surface layer of the open ocean. 

Adsorption of ionic surfactants at the solid/solution interface is of vital importance in determining the stability of suspension concentrates. As discussed in Chapter 5, the adsorption of ionic surfactants on solid surfaces can be measured directly by equilibrating a known amount of solid (with known surface area) with surfactant solutions of various concentrations. After reaching equilibrium, the solid particles are removed (for example by centrifugation) and the concentration of surfactant in the supernatant liquid is determined analytically. From the difference between the initial and flnal surfactant concentrations (Ci and C2 respectively) the number of moles of surfactant adsorbed, F, per unit area of solid is determined and the results may be fitted to a Langmuir isotherm. 

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