Desiccant, use

A closed container containing a desiccant used to store samples in a moisture-free environment. 

Anhydrous lithium bromide [7750-55-8], LiBr, is a desiccant useful in the industrial drying of air. When it contains sufficient moisture it can be a... 

Desiccants Used in Static Drying. The most commonly used desiccants are discussed in this section activated alumina, siUca gel, and molecular sieves, which are discussed later under dynamic, sohd drying agents, are also widely used in static or batch-drying situations. 

Solid Desiccants. The sohd desiccants used in dynamic appHcations fad into a class caded adsorbents (see Adsorption). Because they are used in large packed beds through which the gas or Hquid to be treated is passed, the adsorbents are formed into soHd shapes that adow them to withstand the static (fluid plus sohd head) and dynamic (pressure drop) forces imposed on them. The most common shapes are granules, extmded pedets, and beads. 

Market Data. The largest U.S. manufacturer of molecular sieves for adsorbent and desiccant use is UOP, which has a production capacity of 18—20 million kg/year. W.R. Grace and Zeochem have about 7 and 2 million kg/year capacity, respectively (55). W.R. Grace is the largest producer of siUca gel desiccants. Activated alumina for use as adsorbent and desiccant is produced by LaRoche Chemicals (formerly Kaiser) and by Aluminum Company of America. About one-third of the U.S. supply of activated alumina adsorbent and desiccant is imported by Rhc ne-Poulenc. 

Adsorption Equilibrium Numerous purification and recovery processes for gases and liquids Activated carbon-based applications Desiccation using silica gels, aluminas, and zeolites Oxygen from air by PSA using LiX and 5A zeolites... 

Chu,)., Pryor, ).N., and Welsh, W.A. (1999) Desiccation using polymer-bound desiccant beads. US Patent 5,879,764. 

The best known of these defoliants are sodium chlorate which has the danger of starting fires, tributyl-phosphorotrithioite (merphos, Folex) its oxygenated relative tributylphosphorotri-thioite (DEF), and endothall (Accelerate). Recent research reports claim that amino methyl phosphonic acid and certain of its relatives were found to be more active than current commercial products. The best known desiccant used for defoliation of cotton is paraquat (1,1 -dimethyl-4,4 -bipyridinium) (8). 

Humidity Equilibration. The clays were humidified at 25°C in desiccators using a series of eutectic salts. Each dessicator was controlled at a different relative humidity using one of the saturated salt solutions listed in Table II. The samples were weighed repeatedly until equilibrium (constant weight) was reached. After the spectra were obtained, the samples were broken into three aliquots, reweighed and dried for -24 hours at 105°C to obtain the dry weights of the clay, from which the water contents were calculated. The water contents, as percent dry weight of the clay, are also shown in Table II. 

Table II. Eutectic Salts and Desiccants Used in Relative...

Lead Determine as directed under Lead Limit Test, Appendix TTTB, using a Sample Solution prepared as directed for organic compounds, and 5 pg of lead (Pb) ion in the control. Loss on Drying Determine as directed under Loss on Drying, Appendix EC, drying a sample at room temperature for 24 h in a vacuum desiccator using a suitable desiccant and maintaining a pressure of not more than 5 mm Hg. 

The use of silicone sealant for insulating glass (double glazing) gives excellent adhesion to glass which is unaffected by UV radiation but which must be used with a waterproof sealant such as polyisobutylene to reduce moisture vapour transmission (MVT). The use of silicone sealant alone will result in water condensation inside the unit in a relatively short period of time and would permit water vapour to be absorbed into the unit and eventually exhaust the desiccant used in the space. The use of small beads of polyisobutylene as a primary seal (Figure 6.3) reduces the MVT to a very low number, thus correcting the one deficiency of silicone (Panek and Cook, 1984). Sealants for SSG systems may be applied on... 

When removing or replacing the lid of a desiccator, use a sliding motion to minimize the likelihood of disturbing the sample. An airtight seal is achieved by slight rotation and downward pressure on the positioned lid. 

By what name is it known as a desiccant used in laboratory and industry ... 

Two hundred fifty milliliters of 1.1 M orthophosphoric acid is added with vigorous stirring to 250 ml. of 1 M uranyl nitrate or perchlorate solution. The solution is seeded with a few crystals of the product to promote immediate precipitation. The suspension is then stirred for 12 hours and the mother liquor removed by centrifuging or filtering. The precipitate is slurried in 250 ml. of ca. 0.01 M perchloric acid for 12 hours, and the suspension is filtered. The solid is then slurried twice in 125-ml. portions of acetone to remove solution and sorbed perchlorate and separated from each wash solution by filtration. The sample is dried in a vacuum desiccator, using continuous... 

Figure 22-5 shows a drying oven that will hold one rack of plates. Figure 22-6 shows a glass-type desiccator, and Figure 22-7, p. 258, a cabinet-type desiccator used to keep the plates dry. 

Decomposition or side reactions of the sample must be considered during drying. Material unstable under conditions of heat can be dried by setting it in a desiccator using a vacuum desiccator will hasten the drying process. If the sample is weighed without drying, the results will be on an as is basis and should be reported as such. 

OTHER COMMENTS used in wood preservation used as a weed killer used in the production of insecticides, herbicides, rodenticides, defoliants, and desiccants used in the treatment of syphilis, psoriasis, and as an antiparasitic agent in veterinary medicine used in the manufacture of battery grids, cable sheaths, glass, and boiler tubes. 

Considering the rather large amount of data required to implement virial methods even at 25°C (e.g., Tables 7.4-7.7), it is tempting to dismiss the methods as no more than statistical fits to experimental data. In fact, however, virial methods take chemical potentials measured from simple solutions containing just one or two salts to provide an activity model capable of accurately predicting species activities in complex fluids. Eugster et al. (1980), for example, used the virial method of Harvie and Weare (1980) to accurately trace the evaporation of seawater almost to the point of desiccation. Using any other activity model, such a calculation could not even be contemplated. Other... 

Shave the top of the rat s head and mount the rat in the stereotaxic frame (tooth bar 5.0 mm above interaural line see ref. 9) with lidocaine applied to the ear bars. Cover the eyes with a moistened tissue to avoid desiccation. Use a heating mattress thermostatted at TC to maintain the rat s body temperature. 

Hazardous Decomp. Prods. CO, CO2 emits toxic fumes underfire conditions Storage Store 0 C in cool, dry place keep tightly closed store with desiccant Uses Fragrance in cosmetics Manuf./Distrib. Aldrich http //www.sigma-aldrich.com... 

Uses Herbicide used to control broad-leaved and grass weeds in com, sugarcane, certain citms subtropical fmits (bananas, pineapple) and in noncropland. Preharvest and postharvest desiccant used in potatoes to control both crop and weeds. 

Transfer any recovered diethyl ether into the container for nonhalogenated organic liquids. Hush all aqueous and ethanolic solutions down the drain, and pour any other filtrates containing organic solvents into the container for nonhalogenated liquids. Spread the desiccant used in the drying tube on a tray in the hood and discard it in the container for nonhazardous solids after the volatiles are removed. 

Sodium borohydride Make sure that the crystalline sodium borohydride is stored in a desiccator use fresh chemicals only. Immediately before use dissolve 70 mg of sodium borohydride in 5 mL of distilled water (5 °C). 

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