Rapid drying

Both forms sublime very readily, even at room temperature a small sample on exposure to the air will completely volatilise in a short time, particularly on a warm day or if the sample is exposed to a gentle current of air. Hence the above method for rapid drying. A sample confined in an atmospheric desiccator over calcium chloride rapidly disappears as the vapour is adsorbed by the calcium chloride. A sample of the hexahydrate similarly confined over sodium hydroxide undergoes steady dehydration with initial liquefaction, for the m.p. of the hydrated-anhydrous mixture is below room temperature as the dehydration proceeds to completion, complete resolidification occurs. 

In order to dry the crystals, the Buchner funnel is inverted over two or three thicknesses of drying paper (i.e., coarse-grained, smooth surfaced Alter paper) resting upon a pad of newspaper, and the crystalline cake is removed with the aid of a clean spatula several sheets of drying paper are placed on top and the crystals are pressed flrmly. If the sheets become too soiled by the mother liquor absorbed, the crystals should be transferred to fresh paper. The disadvantage of this method of rapid drying is that the recrystallised product is liable to become contaminated with the Alter paper flbre. 

The beat method of drying, if time permits, is to place the crystals in a desiccator containing an appropriate substance (usually anhydrous calcium chloride, silica gel, or concentrated sulphuric acid) to absorb the solvent. More eflicient and more rapid drying is obtained with the aid of a vacuum desiccator (see Section 11,38 and Fig. 77, 38, 1). 

If a m.p. determination is required soon after recrystallisation, a small quantity may be rapidly dried by pressing it several times upon a pad of several thicknesses of filter or absorbent paper and placing it upon a watch glass in a warm place. A piece of unglazed porous plate may also be used. 

Sodium wire, produced with a sodium press (Fig. II, 47, 1), is 6rst collected in sodium-dried ether, the necessary quantity removed, rapidly dried between 61ter paper,and transferred to the flask. Tlirn shavings of sodium, although less satisfactoiy may also be employed, but it is important to avoid undue exposure of the sodium to the atmosphere which produces a surface film of sodium hydroxide. 

Liquid pyridine and alkylpyridines are considered to be dipolar, aprotic solvents, similar to dimethylformarnide or dimethyl sulfoxide. Most pyridines form a significant azeotrope with water, allowing separation of mixtures of pyridines by steam distillation that could not be separated by simple distillation alone. The same azeotropic effect with water also allows rapid drying of wet pyridines by distillation of a small forecut of water azeotrope. 

Manufacture. Aqueous sodium hydroxide, sodium bicarbonate, sodium carbonate, or sodium sulfite solution are treated with sulfur dioxide to produce sodium metabisulfite solution. In one operation, the mother Hquor from the previous batch is reinforced with additional sodium carbonate, which need not be totally in solution, and then is treated with sulfur dioxide (341,342). In some plants, the reaction is conducted in a series of two or more stainless steel vessels or columns in which the sulfur dioxide is passed countercurrent to the alkaH. The solution is cooled and the sodium metabisulfite is removed by centrifuging or filtration. Rapid drying, eg, in a stream-heated shelf dryer or a flash dryer, avoids excessive decomposition or oxidation to which moist sodium metabisulfite is susceptible. 

Very expensive Rapid drying of large objects suited to this method Applications for final stages of paper dryers Successful on foam rubber. Not fully developed on other materials... 

The polymerization in method [III] will probably be unsuitable for industrial production due to the heat of polymerization, but it can be used to produce a freeze-thaw stable adhesive with rapid drying and good adhesion to paper, which cannot be obtain by other polymerization methods. However, the water resistance of the latex film is not improved. 

Parlon has been used in pyrotechnic tracer formulations as a color intensifier and binder (Ref 4). It is also employed as a base for rapid drying concrete paints and alkyd enamels (Ref 5) Refs 1) G.F. Bloomfield, JChemSoc 1943, 289 2) Parlon, Properties and Uses , Hercules... 

Salicylic acid penetrates more deeply in the areas of inflammation and produces rapid drying of papules and pustules 1 or 2 days after the peeling. These beneficial effects are determined by the antimicrobic activity of salicylic acid, which also stimulates fibroblasts, inducing an improvement of the vascular component of rosacea. Application of salicylic acid in inflammatory rosacea is equally as safe and effective in residual or initial lesions. 

These gases deposit rapidly due to their reactivity with surfaces, and exhibit elevated dry deposition velocities rapid dry deposition has been confirmed in recent field studies in forests and the Arctic (Lindberg and Stratton 1998 Lindberg et al. 2002). At concentrations typical of raral or remote ecosystems, the dry deposition of RGHg and Hg(0) are far greater than PHg, although this species may be of importance under dry conditions near sources (Pirrone et al. 2000). 

Scheme 12.25 Rapid dry-media reactions under microwave conditions.

If the crude moist sulfonyl chloride is to be preserved, it must be thoroughly and reasonably rapidly dried. The checker found it very convenient to use a freeze-drying apparatus to remove the bulk of the moisture. 

In medicated soaps, substances of medicinal value are added. In some soaps, deodorants are added. Shaving soaps contain glycerol to prevent rapid drying. A gum called, rosin is added while making them. It forms sodium roslnate which lathers well. Laundry soaps contain fillers like sodium roslnate, sodium silicate, borax and sodium carbonate. 

Preliminary tests indicated that the distribution of inorganics within a particle could be a function of the rate at which the lignite sample was dried. Rapid drying rates resulted in a concentration of inorganics in the central zone of a particle, whereas slow drying rates resulted in a concentration at the outer perimeter of the particle. 

Co-solvent included to facilitate the rapid drying of gels without cracking. 

Lacquer A rapid-drying coating by evaporation of solvent only. It will redissolve in the solvent, and it may be lightly pigmented. 

Another procedure is to rapidly dry the solution at a rate that does not allow the elements to segregate. As an example, aerosols can be sprayed through a furnace heated at the reaction temperature of 900°C. This yields spherical submicronic particles that are most suitable to sinterable compacts. Another way is to spray the solution onto a substrate. This is a simple method of thick film deposition. Very ionic species such as nitrates dissolved in water can be sprayed onto a hot substrate. Long-chain carboxylates, soluble in volatile organic solvents, can be deposited as well, even at room temperature. 

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