Calcium hydroxide wash washed

Table IV shows brightness retention of newsprint papers. Borohy-dride treatment increased initial brightness by as much as 10 brightness units. A decrease in brightness is generally observed when newsprint is subjected to a Ca(OH)2 wash. Treatment with either 0.1 or 1.0 NaBH4 followed by 0.002 calcium hydroxide washing also increased the brightness of newsprint. For the newsprint samples, the borohydride treatment did not produce a significantly greater improvement in brightness retention than the calcium hydroxide wash alone.

Table V. Effect of Calcium Hydroxide Wash Concentration on Aging of Foldur Kraft Paper ...

Suitable catalysts include the hydroxides of sodium (119), potassium (76,120), calcium (121—125), and barium (126—130). Many of these catalysts are susceptible to alkali dissolution by both acetone and DAA and yield a cmde product that contains acetone, DAA, and traces of catalyst. To stabilize DAA the solution is first neutralized with phosphoric acid (131) or dibasic acid (132). Recycled acetone can then be stripped overhead under vacuum conditions, and DAA further purified by vacuum topping and tailing. Commercial catalysts generally have a life of about one year and can be reactivated by washing with hot water and acetone (133). It is reported (134) that the addition of 0.2—2 wt % methanol, ethanol, or 2-propanol to a calcium hydroxide catalyst helps prevent catalyst aging. Research has reported the use of more mechanically stable anion-exchange resins as catalysts (135—137). The addition of trace methanol to the acetone feed is beneficial for the reaction over anion-exchange resins (138). 

Lime-Sulfuric. Recovery of citric acid by calcium salt precipitation is shown in Figure 3. Although the chemistry is straightforward, the engineering principles, separation techniques, and unit operations employed result in a complex commercial process. The fermentation broth, which has been separated from the insoluble biomass, is treated with a calcium hydroxide (lime) slurry to precipitate calcium citrate. After sufficient reaction time, the calcium citrate slurry is filtered and the filter cake washed free of soluble impurities. The clean calcium citrate cake is reslurried and acidified with sulfuric acid, converting the calcium citrate to soluble citric acid and insoluble calcium sulfate. Both the calcium citrate and calcium sulfate reactions are generally performed in agitated reaction vessels made of 316 stainless steel and filtered on commercially available filtration equipment. 

In the production of caustic soda by the action of calcium hydroxide on sodium carbonate, 1 kg/s of sodium carbonate is treated with the theoretical quantity of lime. The sodium carbonate is made up as a 20 per cent solution. The material from the extractors is fed to a countercurrent washing system where it is treated with 2 kg/s of clean water. The washing thickeners are so arranged that the ratio of the volume of liquid discharged in... 

Wash in running tap water for 5 10 min. If the running tap water is not sufficiently alkaline to blue the sections, add a few drops of ammonium hydroxide or a small pinch of calcium hydroxide to about 500 ml of water, then rinse in tap water again. 

Pentaerythritol is made by mixing formaldehyde with calcium hydroxide in an aqueous solution held at 65-70 °C. Nitration of pentaerythritol can be achieved by adding it to concentrated nitric acid at 25-30 °C to form PETN. The crude PETN is removed by filtration, washed with water, neutralized with sodium carbonate solution and recrystallized from acetone. This manufacturing process for PETN results in 95% yield with negligible by-products. The process is summarized in Reaction 7.9 (overleaf). 

The anode liquor is neutralized by means of calcium hydroxide, and acetone is removed by distillation. The residue consists of calcium nitrate and glycol dinitrate. These are separated by filteiing and the product is washed with water in the usual way. For a certain time this method was used industrially. 

Casein and caseinates are generally made from skim milk by adding hydrochloric or sulfuric acid or by lactic acid fermentation. The isoelec-trically precipitated casein is washed and dried or neutralized with sodium hydroxide, potassium hydroxide, or calcium hydroxide to produce the corresponding caseinate and spray dried. Rennet casein is... 

The pulp recovered during screening may be transferred to a pulp-wash operation to yield further soluble solids by counter-current extraction with water. The washed pulp may be held for further processing or included with the bulk of ejected peel material from the extractors. This is milled, treated with lime (calcium hydroxide or calcium oxide) to break down pectin and reduce water retention, pressed, dried to c.10-12% moisture content and finally converted to pellets. Being high in carbohydrates these are used as filler in livestock feed blends. 

Liquid. Wear butyl rubber gloves, self-contained breathing apparatus, eye protection, and laboratory coat. In the fume hood, slowly add the hydrogen fluoride to a plastic pail of cold water (at least a 1 10 dilution of acid to water is suggested). Add excess calcium hydroxide or calcium carbonate. Let the precipitate settle for 24 hours. Wash the resulting solution into the drain. Allow the solid calcium fluoride residue to dry, and package and label for disposal in accordance with local regulations.7... 

Wear a face shield and goggles, laboratory coat, and butyl rubber gloves. Sweep potassium fluoride into a large beaker. In the fume hood, add water (about 13 mL/g of fluoride) and solid calcium hydroxide (about 0.6 g/g of fluoride) to the beaker, and stir for 24 hours. Filter. Wash the filtrate. The solid residue can be discarded with normal... 

Small Quantities. Wear eye protection, laboratory coat, and nitrile rubber gloves. Work in the fume hood. In a beaker, add 0.9 g of calcium hydroxide and 18 mL of water for every gram of sodium fluoride. Stir the resulting mixture for 24 hours. Filter. Wash filtrate into the drain. The solid residue can be discarded with normal refuse.4... 

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