Washing efficiency calculations

From the graph the value of R is estimated for n = 0.85 and uL/D = 152 at 0.18 so the amount of solute removed is (1-i ) ejqpressed as a percentage, i.e. 82%. This calculation assumes 100% washing efficiency, which is unlikely even on a pressure filter. The actual washing efficiency is probably about 50% when I assing and leakages are taken into account so the effective wash ratio would be 0.43 and the value of i falls to 0.59 and the value of solute removed becomes 41%. 

Using the value of uL/D calculated in Exanqtle 9.2 of 152 and an R value of 0.05 tire wash ratio can be estimated from the graph as about 1.1. For a washing efficiency of 50% the wash ratio must be doubled to give 2.2. 

The analysis for washing can be extended to a variety of modifications. These include simulation problems, use of efficiencies, calculation of maximum U/0 ratios, and calculations for cross-flow systems. The Kremser equation can also be applied to countercurrent washing with no additional assumptions. This adaptation is a straightforward translation of nomenclature and is illustrated in Example 14-1. Brian (1972) discusses application of the Kremser equation to washing in considerable detail. 

The conclusions drawn from the mass balances presented in Table 15.3 are further discussed in the next section. 15.6 Washing train design recommendations The countercurrent washing trains installed in industry often represent the most complex parts of the overall processes and are usually designed and Table 15.3 Three cases of mass balance calculations for liquid flows and solubles mass rates for comparison. Note that all three cases have the same washing efficiency, marked, and the point of thickest underflow, marked, has moved to the end of the train for case 3 ... 

The first literature report of a reaction of an isocyanate with wood is that due to Clermont and Bender (1957). In this study, DMF impregnated wood samples 1/8 in thick were suspended above phenylisocyanate liquid in a vessel heated at temperatures from 100 °C to 125 °C for various time intervals. Treated samples were washed with DMF, then water, then acetone, and dried in an oven at 105 °C. ASEs in the range of 60-80 % were reported for these samples. In view of the reactivity of DMF with isocyanates, the lack of an efficient clean-up procedure and the fact that ASE values were calculated from the first water-soak cycle only, this study is of limited value. 

Currently, there is no doubt that the most widely used method for extraction of tissue lipids is that of Bligh and Dyer (1959). Basically, this is a modification of the Folch method and employs a careful calculation of the amount of sample (tissue) water such that the overall mixture will have a final composition of chloroform-methanol-water of 1 2 0.8 (v/v). Thus, a singlephase extract can be obtained and extraction completed very rapidly, even within minutes. Recovery of the lipid in a chloroform-rich phase can be achieved by addition of equal volumes of chloroform (under certain conditions) and water to produce a two-phase system. The lower (CHC13) phase is subsequently washed with a methanol-water (1 0.9, v/v) mixture to allow removal of a substantial amount of the nonlipid contaminant with little or no problems with interfacial fluff formation or emulsions. However, even though this is a highly efficient method, it is still advisable that one take steps... 

Exactly 1.7 mg of a purified enzyme (MW =55,000) was incubated with an excess of iodoacetamide-C (S.A. = 2 fiCii mmole). The car boxy methylated protein was then precipitated, washed free of unreacted iodoacetamide-C , dissolved in a small amount of buffer, and the entire solution counted in a scintillation counter operating at 80% efficiency. In one hour, the sample gave 13,190 counts above background. Calculate the number of reactive SH groups per molecule of protein. 

GF/C). When the filter is dry, it is swirled using blunt-end forceps in a beaker containing 200 ml of ice-cold 5% trichloroacetic acid (TCA) and 20 mM sodium pyrophosphate for 2 min (repeated three times in a new solution). The filter is then dipped for 2 min in 70% ethanol and dried. The incorporated radioactivity can now be measured with a scintillation counter. If 1 ng of DNA was spotted, then 0.5-10 X 10 cpm should be expected. By comparing with the cpm obtained from the original sample, directly spotted and not washed, the efficiency of incorporation can be calculated (Table 7.15). 

Immunoassay techniques rely upon synthetic antibodies that have been developed to form a complex with petroleum substances. The antibodies in the test kit are immobilised on the walls of a special cell or membrane. Water samples can be added directly, whereas soils are solvent extracted into a suitable water miscible solvent and added to the cell. A known amount of enzyme with an affinity for the antibody is added. After equilibrium is established, the cell is washed to remove any unreacted material. Colour development reagents which react with the enzyme are added. A solution that stops colour development is also added at a specific time, and the optical density is then measured. Samples showing high optical density (colour intensity) contain low concentrations of analytes. Concentration is inversely proportional to optical density. Kits are generally available for, among others, TPH, BTEX and PAH. A correction factor supplied by the manufacturer is used to calculate TPH and this is subject to variation depending on the product type. These tests do not provide information on product type and have limitations dependent upon soil type and homogeneity. Also, field extraction techniques are not as efficient as laboratory-based extraction techniques. 

---