Filtration ratio

To characterize polymer stability, the University of Texas at Austin uses the filtration ratio (FR), which is defined as... 

The viscosity of polysaccharides increases with increasing concentration of the biocides. This increase is attributed to cross-linking of the polysaccharide molecules. There were correspondent increases in millipore filtration ratios and filtration times on the addition of biocides or decrease in filterability. A methodology was established to select the most effective biocide on the basis of compatibility with the polymer and the ability to retard metabolic activity in the microflora of the surface and formation waters. 

Filtration ratio was computed as the ratio of the time of the second 50 ml to that of the last 50 ml of 250 ml polymer solution flowing through 2 micron Nuclepore filters (47mm) with 80 psi across the filter. Viscosity of the emulsion was measured with a Brookfield model LVT viscometer, using a number 2 spindle. Dilute solutions of the polymer were prepared (500 ppm active polymer in 0.3% NaCl) and viscosities were measured using a Brookfield LVT with UL adapter at 12 RFM. This 500 ppm solution was also used for screen factor and filtration ratio measurements. Filtration ratio measurements, as well as those of the viscosity of the emulsion concentrate and dilute solutions made from it were consistent, whether measured at the field laboratory or at the production plant of the supplier. 

Particle size is based on a filtration ratio P = 20. The minimum accuracy of the measuring method used is 20% of the limiting value of the class. 

Endo-exo ratios of the micelle-catalysed reactions have been determined by adding 0.25 mmol of 5.1c and 0.5 mmol of 5.2 to a solution of 5 mmol of surfactant and 0.005 mmol of EDTA in 50 ml of water in carefully sealed 50 ml flasks. The solutions were stirred for 7 days at 26 C and subsequently freeze-dried. The SDS and CTAB containing reaction mixtures were stirred with 100 ml of ether. Filtration and evaporation of the ether afforded the crude product mixtures. Extraction of the Diels-Alder adducts from the freeze-dried reaction mixture containing C12E7 was performed by stirring with 50 ml of pentane. Cooling the solution to -18 C resulted in precipitation of the surfactant. Filtration and evaporation of the solvent afforded the adduct mixture. Endo-exo ratios... 

Merthiolate/T4- )4-< 7 (3), sodium ethyLmercurithiosahcylate, known also as thimersol, is prepared from a 1 1 ratio of ethyhnercuric chloride/7(97-27-. and disodium thiosahcylate ia ethanol. After removal of the sodium chloride by filtration, the free acid is precipitated by acidification with dilute sulfuric acid. Purification is achieved by recrystallization from 95% ethanol, and the product, merthiolate, is obtained by neutralization with a stoichiometric amount of sodium hydroxide. 

Excess NaOH is used to start the reaction and not over 35% of the chromium is added as dichromate. At the end of the reaction, the thiosulfate is removed by filtration and recovered. The hydrous oxide slurry is then acidified to pH 3—4 and washed free of sodium salts. On calcination at 1200—1300°C, a fluffy pigment oxide is obtained, which may be densifted and strengthened by grinding. The shade can be varied by changes in the chromate dichromate ratio, and by additives. 

Manufacturing Processing and Uses. In commercial production, aqueous urea solution is mixed with acetaldehyde in 1 1 molar ratios. An acid catalyst is introduced into the reaction mixture which is staged at various process temperatures. After neutralization with a base, the CDU is separated from the mother hquor by filtration or spray drying. 

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

For all baths the anode to cathode ratio is 2 1 the baths are mechanically, hydrauhcaHy, or air agitated, and there is continuous filtration. 

The specific resistance coefficient for the dust layer Ko was originally denned by Williams et al. [Heat. Piping Air Cond., 12, 259 (1940)], who proposed estimating values of the coefficient by use of the Kozeny-Carman equation [Carman, Trans. Inst. Chem. Fng. (London), 15, 150 (1937)]. In practice, K and Ko are measured directly in filtration experiments. The K and Ko values can be corrected for temperature by multiplying by the ratio of the gas viscosity at the desired condition to the gas viscosity at the original experimental conditions. Values of Ko determined for certain dfists by Williams et al. (op. cit.) are presented in Table 17-5. 

Fabric filters are limited by physical size and bag-life considerations. Some sacrifices in efficiency might be tolerated if higher air-cloth ratios could be achieved without reducing bag life (improved pulse-jet systems). Improvements in fabric filtration may also be possible by enhancing electrostatic effects that may contribute to rapid formation of a filter cake after cleaning. 

The Ticona materials are prepared by continuous polymerisation in solution using metallocene catalysts and a co-catalyst. The ethylene is dissolved in a solvent which may be the comonomer 2-norbomene itself or another hydrocarbon solvent. The comonomer ratio in the reactor is kept constant by continuous feeding of both monomers. After polymerisation the catalyst is deactivated and separated to give polymers of a low residual ash content and the filtration is followed by several degassing steps with monomers and solvents being recycled. 

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