Polishing filtration

M Preparation of isopropyiidene peniciiiamine hydrochioride To the filtrate obtained In step (b) is added at 20°C to 25°C a total of 85 g of hydrogen sulfide. The precipitated HgS is filtered off and the filtrate is concentrated under reduced pressure to a volume of 200 to 500 ml. Following e polish filtration, the product-rich concentrate is mixed with 1.5 liters of isobutyl acetate. The mixture is refluxed at about 40 C under reduced pressure in equipment fitted with a water separation device. When no further water separates, the batch is cooled to 30t and filtered. The reactor is washed with 1 liter of acetone, which Is used also to wash the cake. The cake is further washed with 200 ml of acetone. The acetone washes are added to the isobutyl acetate filtrate and the mixture is refluxed for 20 to 30 minutes. After a holding period of one hour at 5°C, the crystals of isopropyiidene penicillamine hydrochloride are filtered and washed with 200 m of acetone. On drying for twelve hours at 25°C this product, containing 1 mol of water, weighs about 178 g (73%). 

Refrigeration. At least one major winery minimizes the amount of wine movement necessary by cold stabilizing the wine at 28° F (-2.22° C) in a jacketed tank until laboratory evaluation shows the wine to be cold stable. The wine is allowed to warm to 30°-32° F (-1. ll°-0° C), then a slurry of bentonite, which has been soaked at least overnight in hot water, is added to the wine at the level prescribed by the previously described laboratory procedure. When the bentonite has settled to the bottom of the tank, the wine is racked off the bentonite lees and filtered to a holding tank. The wine is now ready for polish filtration and bottling. 

Decolorization and Finishing. Decolor-ization is sometimes required for certain applications, mostly as an aesthetic preference. It is always desirable to solve these issues upstream. For example, color can be minimized by choice of fermentation medium components and control of the sterilization cycle so as to lessen the Maillard reactions between nitrogen and sugars and carameliza-tion. Color can also be reduced by treatment with activated carbon, use of antioxidants, and by diafiltration with membranes. Carbon-impregnated filter pads can be used to combine polish filtration with a decolorization step. 

Filtration on hermetic leaf filters, followed by polishing filtration. The spent cake is dried by steam blowing and the recovered oil is recycled. 

One method used to assure clear oil is to add a polish filtration step after the centrifuge dewaxing operation, as shown in Figure 9c With this system, a shp stream of oil is cooled and analyzed through a highly sensitive turbidity meter immediately after the deodorizer. When a haze is detected, the flow of oil is diverted through a chiller, filter aid added, and the mixture sent to a crystallizing tank. After... 

Autoxidation increases markedly with temperature. Salad oils degrade rather quickly with increasing temperatures due to their high unsaturation. From this standpoint, it is desirable to handle the oil at temperatures as low as possible during discharge from the deodorizer into the storage tank. In practice, however, it is not desirable to cool the oil below 45 °C (113 °F) prior to the polish filtration for the following reasons (1) moisture is apt to condense in the oil and (2) at lower temperatures the filtration rate decreases. 

Use polish filtration to remove insoluble impurities (good housekeeping). 

The final formulation of liquid detergent enzymes includes addition of stabilizers, antimicrobial substances, and glycols. This is followed by a final polish filtration to provide a clear liquid. If the enzyme broth is slated for dry product, the concentrate can either be stored for later use or applied directly for granulates. As with fermentation and downstream processing, formulations are often kept as closely guarded trade secrets in the biotechnology industry, and few publications on new approaches or new technologies are available in the literature. 

The possibility that microscreening alone might be adequate without polishing filtration was evaluated in the plugging tests summarized in Figure 17a. It appears that further treatment is necessary. 

Moderate decreases in viscosity in polishing filtration do not necessarily imply blopolymer loss. So long as polymer is not Incorporated In filtercake as it would be in dlatomaceous earth filtration (or if it can be backwashed off, even if it is), it should be possible to operate with a feed of higher viscosity than necessary for injection, and to recycle feed through the filtration apparatus, perhaps after dilution. Another possibility would be to recycle polishing filtration blowdown into the microscreening system. 

A suspension of 6.207 kg of (5)-TH(3C.(5)-CSA (95% d.e.) in toluene (124 L), water (9.9 L), and 30% NaOH (2.5 L) was stirred at 40°C until dissolution (40 min). After cooling to room temperature, the organic layer was separated and polish filtrated. The toluene was stripped off under reduced pressure until a minimum volume. Then, EtOH (74 kg) was added to the reaction mixture and the toluene/EtOH azeotropic mixture (bp 76.7°C azeotropic composition toluene EtOH 32 68) distilled at ambient pressure until a residual toluene content of maximum 1% was achieved (gas chromatography [GC] analysis). A mass adjustment (Ig (5)-TH(3C/5 g reaction mixture) was then performed by addition of EtOH (7.2 kg), followed by the addition of L-tartaric acid (1.986 kg) dissolved in water (305 L). The mixture was then heated for 1 h at reflux and stirred for 16 h at room temperature. The crystals were filtered, rinsed twice with water (17 L), and dried at 50°C under reduced pressure for 20 h to afford 4.595 kg of (5)-TH(3C-(L)-tartrate monohydrate (yield 86%, 99% d.e.). 

The feed solution is prepared by acid leaching, removal of gross solids by filtration or counter-current decantation, together with a final polishing filtration step, often in a sand-bed clarifier. Using such a feed, a typical cycle of operations for a four-column system with split elution is as follows ... 

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