Washing time

As with the case of energy input, detergency generally reaches a plateau after a certain wash time as would be expected from a kinetic analysis. In a practical system, each of its numerous components has a different rate constant, hence its rate behavior generally does not exhibit any simple pattern. Many attempts have been made to fit soil removal (50) rates in practical systems to the usual rate equations of physical chemistry. The rate of soil removal in the Launder-Ometer could be reasonably well described by the equation of a first-order chemical reaction, ie, the rate was proportional to the amount of removable soil remaining on the fabric (51,52). In a study of soil removal rates from artificially soiled fabrics in the Terg-O-Tometer, the percent soil removal increased linearly with the log of cumulative wash time. 

Wash Time Cake-washing time is the most difficult of the filtration variables to correlate. It is obviously desirable to use one which provides a single cni ve for all of the data. Filtration theory suggests three possible correlations [Eqs. (18-59) to (18-61)]. These are listed below, beginning with the easiest to use ... 

Wash time/form time vs. wash vohime/form volume... 

Since the washing stage is essentially the case of filtration at constant cake thickness, q may be replaced by and assuming the viscosity of the washing liquid to be the same as that of the filtrate, the following relationship between washing time and filtrate amount is developed ... 

The filtration time of 20 m of a suspension in a filter press is 2.5 hours. Determine the approximate washing time of the cake for 2 m of water, assuming that the washing rate is 4 times less than that of filtration at the end... 

For question 14, how much will the washing time change if the filtrate viscosity is double and the viscosity of the wash water is 1 cP ... 

Determine the required washing time under the following set of conditions Washing Intensity — 6 Liters/m -min., Cake Thickness = 40 mm, Initial SoUds Concentration in the Filtrate of the Wash Water = 120 g/Liter Final Concentration = 2 g/Liter. Assume a wash rate constant, K = 375 cmVLiter. 

For the conditions described in the above question, determine the washing time if the amount of wash water is 2.4 Liter/m and the washing is cocurrent with the filtrate. 

The variable t in the foregoing equations is the actual time (/nncr) that is required to pass a volume V of filtrate through the medium and is only part of the total time of the cycle (tcyde). The rest of the cycle, which may include wash time, disassembly and assembly time, cleaning time, etc., we shall call dead time (Aead) ... 

Figure 1 Schematic diagram of a typical FIA peak. S, time of sample introduction T, residence time H, peak height A, area under peak Wb peak width at fixed height fw, wash time.

A plate and frame press gave a total of 8 m3 of filtrate in 1800 s and 11.3 m3 in 3600 s when filtration was stopped. Estimate the washing time if 3 m3 of wash water is used. The resistance of the cloth may be neglected and a constant pressure is used throughout. 

Sample and wash times are the dwell times of the sampling probe in the sample and water receptacle respectively. 

Figure 6.9 Effect of carry-over. Samples of high and low concentration were analysed with different wash times. Carry-over was more apparent with the shorter wash time.

Nevertheless, the effect of washing time was also examined. The results were that when the electrode was washed by 60 ml of electrolyte, the shoulder at 700 mV and the broad peak above 1200 mV still existed but their heists were decreased. Therefore they were likely to be attributed to physically adsorbed spedes, possibly methanol itself on the surface of platinum or the glass tube. 

The number and duration of washing steps can help with the reduction of background. As a rule of thumb, the volume of the wash should be twice the antibody dilution volume, and standard wash time should be 5x 4 min or 3x 10 min. Washing solutions used are PBST or TEST as buffering base, but Tween-20 is sometimes omitted when there is the chance that a low affinity antibody or a weakly bound antigen could be washed away. 

Since adequate washing cannot realistically be obtained in less than about 50 msec, the complex half-life must be at least 250 msec (k i < 2.8 s ) for reasonable binding measurements to be obtained. Uirfortunately, the dissociation rates of many important receptor-ligand complexes are faster than this and these are not amenable to measurement by these techniques. To study the equilibrium binding of [ Hjmuscimol, we routinely use a filtration (wash) time of 0.5 sec and a wash volume of 2 ml. 

The sequence of reactions is as follows at time 0, agonist (EC50) is applied (5s), followed by a brief period of recovery (25s) MTS and the other ligand are then co-applied for 10s, followed by a recovery period of 2min and 20s. This cycle is repeated until the reaction comes to apparent completion (i.e., further application of MTS produces no further alterations in Iagonist)- Depending on the concentration of protectant, the wash times may need to be adjusted accordingly. 

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