Applications drying agents

Another valuable drying agent of general application is anhydrous calcium sulphate, marketed under the name of Drierite. It is rapid in its action, but has only a limited drying capacity because it forms the hydrate 2CaS04,H20 and thus combines with only 6-6 per cent, of its weight of water. The vapour pressure of the system ... 

A list of the common drying agents with their practical limitations and their important applications follows. 

Aluminium oxide. The commercial material, activated alumina, is made from aluminium hydroxide it will absorb 15-20 per cent, of its weight of water, can be re-activated by heating at 175° for about seven hours, and does not appreciably deteriorate with repeated use. Its main application is as a drying agent for desiccators. 

Drying agent. A solid material, such as alumina, with a large surface area per unit weight that readily adsorbs moisture, i.e., moisture will collect on its surface. Used in gas drying towers and other applications that require the removal of moisture for quality control. 

Direction of innovation The use of renewable raw materials and, closely linked with this, the compostability of prodnction waste are trend-setting. The absence of solvents was not traded in by nsing other problematic snbstances (such as e.g. chemical emulsifiers, drying agents or biocides). In professional applications the idea of water on wood and the comparatively long drying times are, however, considered with some reservations - despite the fact that the technical performance is in no way behind that of conventional products (EN certification). 

Lithium aluminum hydride is a flammable substance. It ignites spontaneously on grinding and reacts violently with water and many organic substances. Diethyl ether, tetrahydrofuran or another suitable solvent should be used in its synthetic applications. Dry or powdered limestone is an appropriate fire extinguishing agent. 

The gas stream containing sulfur dioxide is either dried before passing to the catalytic oxidation step, or is oxidized in the presence of water vapor with subsequent acid condensation and removal. When acid is produced from elemental sulfur, the air used for sulfur burning is predried. In all cases, typical plant designs use sulfuric acid from the process as a drying agent. Wet catalytic oxidation is relatively uncommon. Some applications of Haldor Topsme s WSA-2 wet gas catalysis process are described in the literature (97). 

Zirconium hydride, ZrH2, finds application as an antioxidant for rubber, in addition to being a moderator for nuclear fuel elements, and as a hydrogenation catalyst. Zirconium hydroxide, best formulated as Zr02 hH20 because of its variable water content, is used as a drying agent and absorbent and also has deodorant properties.19... 

Instead of amines, sulfonamides have also been used as starting materials, producing the highly reactive sulfonyl isocyanates, which have found applications in the manufacture of drugs for diabetics and as drying agents (qv) (4,9,16). 

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