Turbidity point

To 5 ml. of water add 1-2 drops of the secondary amine if it does not dissolve, add a drop or two of concentrated hydrochloric acid. Place 1 ml. of the reagent in a test-tube, add 0 -5-1 ml. of concentrated ammonia solution, followed by 0-5-1 ml. of the above amine solution, A precipitate indicates a secondary amine. A shght turbidity points to the presence of a secondary amine as an impurity. 

Trubtmgs-grad, m. degree of turbidity, -mes-ser, m. turbidimeter nephelometer opac-imeter. -punkt, m. turbidity point, -stoff, m. substance causing turbidity. 

The other state variables are the fugacity of dissolved methane in the bulk of the liquid water phase (fb) and the zero, first and second moment of the particle size distribution (p0, Pi, l )- The initial value for the fugacity, fb° is equal to the three phase equilibrium fugacity feq. The initial number of particles, p , or nuclei initially formed was calculated from a mass balance of the amount of gas consumed at the turbidity point. The explanation of the other variables and parameters as well as the initial conditions are described in detail in the reference. The equations are given to illustrate the nature of this parameter estimation problem with five ODEs, one kinetic parameter (K ) and only one measured state variable. 

The model is very sensitive to the number of moles consumed at the turbidity point, to which there is no easy access. 

The aqueous solutions ofp-iso-octyl-phenyle-(-0-CH2-CH2-) OH show a demixing phenomenon at high T. Above a turbidity point Tt two phases appear (Fig. 8). The turbidity point Tr is a measure of the HHB-balance too. Fig. 24 shows Tt as function of the concentration CH1 of PlOP-n. With the length n of the ethylenoxid... 

During decompose the long range water structure changes can be studied by the polyethyleneoxide derivatives too. At the turbidity point Tr the organic phase con-... 

Fig. 24. The turbidity point Tk of aqueous solutions of PlOP-n as a function concentration of ether oxygen of P10P- and the ethyleneoxide-content n as parameter224 ...

Fig. 33. The additivity of ion-influence of the turbidity point of PIOP-9 (10 g/1) in water224)...

The efficiency of the fractionation is highly dependant upon the amount of methanol that is added to the toluene solution. We have found that employing a tubidity point of 50 C instead of 45°C results in poorer resolution the star/arm mixture. A turbidity point of 40°C provides good resolution but substantially lowers the yield of recoverable material. 

Since the structure of water can be characterized both in terms of the turbidity point Tturb and in terms of the surface tension cr, it was interesting to establish from further measurements, that an unequivocal linear dependence existed between Tturb and a. The experimental data shown could also therefore be correlated with da/dc, although the measurement accuracy of T rb determination is incomparably higher that of a ... 

Example The turbidity point T of PIOP-9 is more sensitive to... 

The turbidity point is neaxly insensitive on the PIOP-9 concentration indicating that the H-bonds of OH to the ether oxygen play the dominant role in the solubility process of PIOP-9- The greater influence of anions on T of PIOP-9 than cations make ion... 

The relation between different hydration spheres can be observed by the concentration dependence of salting-out effects of organic solutes (9,10,12,26). There may be, in addition, rivalry between the hydration of ions and of the organic solutes. Figure 8 shows that the turbidity point of PIOP-9 increases until KI concentration reach about 2 mol/1 and then decreases above 2 m. 

Since a resol can gel in the reactor, dehydration temperatures are kept well below 100°C, by applying vacuum. Tests have to be done to determine first, the degree of advancement of the resin, and second, when the batch should be discharged. Examples of methods of such tests are the measurement of the gel time of a resin in a 150°C hot plate or at 100°C in a water bath. Another method is measuring the turbidity point, that is, precipitating the resin in water or solutions of a certain concentration. 

An introduction to the typical resin synthesis of a UF resin used as an adhesive for wood products and in industrial applications is given below. It constitutes a handy formulation for those who want to work in this field. It is not a low-formaldehyde-emission formulation. To 1000 parts by mass of 42% formaldehyde solution (methanol < 1%) are added 22% NaOH solution to pH 8.3 to 8.5,497 parts by mass of 99% urea, and the temperature raised in 50 min from ambient to 90°C while maintaining pH in the range 7.3 to 7.6 by small additions of 22% NaOH. The temperature is maintained at 90 to 91°C until the turbidity point is reached (generally another 15 to 20 min). The pH is then corrected to 4.8 to 5.1 by addition of 30% formic acid, and the temperature is raised to 98°C. The water tolerance point is reached in 18 min and the pH is then adjusted to 8.7. Vacuum distillation of the reaction water with concomitant cooling is then initiated. After distillation of the wanted amount of water to reach a resin content of 60 to 65%, the resin is cooled to 40°C, 169 parts by mass of second urea is added, the pH is adjusted to 8.5 to 8.7, and the resin is allowed to mature at 30°C for 24 to 48 h resin characteristics solids content, 60% density, 1.268 g/cm free HCHO, 0.4% viscosity, 200cP pH, 8. 

In a reaction vessel charge at 25°C, 44.4 parts by mass of water, add 30% NaOH solution to pH 11.2 to 12.0, followed by 15.5 parts of 91% paraformaldehyde prills, 34.4 parts of melamine powder, 2.8 parts of caprolactam, and 2.5 parts of iV,iV -dimethylformamide while maintaining the temperature at 25° C heat in 40 min to 92 to 95°C. When the temperature reaches 80°C, adjust the pH with 30% NaOH solution, if necessary, to pH 9.9. At 93°C, cool to 90°C and maintain the temperature there. Adjust pH to 9.55 to 9.65 with formic acid. Hold the pH at this value while checking, adjusting, and recording the pH value every 10 min. Check for the turbidity point at 10-min intervals until the turbidity point is reached. At this time bring pH up to 9.95 to 10.05. Check, adjust, and record the pH every 10 min. Start distilling water under vacuum to a solid of 53 to 55%. Check the water tolerance at 10-min intervals until it is 170 to 180%. Then apply full vacuum and cool the resin to 30 to 35°C. 

In this case, the nonsolvent or a nuxture of the solvent and nonsolvent is added slowly to a solution of the polymer and solvent. The turbidity point is determined visually. 

Figure 6.25 Partial phase diagram of polysorbate 20-peppermint oil-water system from O Malley et ai [209]. Phases with compositions represented by the upper parts of the diagram are clear, those below, turbid. Point A represents 7.5 % oil, 42.5 % polysorbate 20, and 50.0% water.

Solutions of aromatic substances in glycerine, diluted with water to a point approaching that at which turbidity sets in, still retain the fresh smell of the flowers and can be used for very fine toilet washing water. I n order to proceed further with the dilution than is possible with, water alone, as soon as the turbidity point is reached, strongly diluted methylated spirits at 10-15 per cent, which niust be free from fusel oil, is added and this prevents separation cf the essential oils. 

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