Reagents and Chemicals

Viscosity measurement represents one of the simplest experimental techniques for characterizing polymers. In general, the viscosity of a polymer solution depends on the molecular weight of the polymer and on the configuration of the molecules. For essentially linear polymers such as the polyacrylamide flocculants, coiling of the molecule in response to changes in its environment leads to changes in viscosity which can be evaluated in terms of an effective radius of gyration.

For flexible molecules which form random coils in solution it can be shown that the radius of gyration (Rg), defined as the root-mean-square distance of the elements of the chain from its center of gravity, can be calculated from viscosity data using the following relation:

[n] = 14.7∅Rg/M………………………………………………(1)

where M is the molecular weight of the polymer, ∅ is Flory’s universal constant (2.1×10)21) and [n] is the intrinsic viscosity of the solution defined by:

in which n is the viscosity of a polymer solution of concentration C and η0 is the viscosity of the pure solvent.

It should be emphasized that the application of Equation 1 to aqueous solutions of polymer flocculants is approximate at best since it is by no means clear that ….Read more

Lime is transported in large volumes by the three common surface modes, i.e., barge, railroad, and truck.

Barge Transportation

Barges used in lime transportation have a capacity up to 1,500 tons and 1,400 ton loadings are very typical. The hulls of the barges are double skinned and constructed with water-tight sections. This type of barge design protects the lime in the cargo compartment in the event the outer steel surface of the hull is punctured or ripped open. The water-tight sectional design virtually insures that the barge will not sink if the outer hull surface is ruptured.

The lime is protected by barge covers. These barge covers may be rolled aside or lifted off during loading or unloading. Once the covers are closed they are weather-tight and protect the lime from rain, wind, and other adverse weather conditions.

Loading and unloading can only be done when there is no rain. Loading and unloading systems must also effectively control dust emmissions. Loading is accomplished by spouts and chutes that lower into the barge, vacuum (negative pressure) air lines literally pulls the dust from given points in the loading system. The air in the vacuum lines is cleaned and filtered through bag houses. A 1,400 ton ….Read more

Alkali metal ferrocyanides and their easily obtainable derivatives such as ferricyanides, nitroprussides, and hydroferrocyanic acid have found application in a wide variety of fields during the two centuries that they have been known. Through continued research new uses are being uncovered with increasing frequency.

Most of these applications depend upon oxidation-reduction potentials, sequestering and precipitating ability, color formation, or the high nitrogen content of the prussiates. In the following sections, the applicability of these properties to a number of specific uses will be discussed.

ANALYTICAL CHEMISTRY

Since ferrocyanides and their derivatives have found so many and such diverse applications in analytical chemistry, a complete coverage of the field is beyond the scope of this review. The following, however, will indicate some of the potential uses of these compounds as analytical reagents.

Potassium ferrocyanide has been found useful for the qualitative detection of certain sugars, the nitrite ion in urine, thiourea, a number of alkaloids, and various metals such as cadmium, iron, uranium, and zinc.

The quantitative determination of zinc, cadmium, cerous ion, uranyl ion, and lead also may be accomplished through the use of potassium ferrocyanide. The same salt has been reported in a new analytical method ….Read more

PHYSICAL PROPERTIES of Hydroferrocyanic Acid

Hydroferrocyanic acid is most conveniently prepared by the treatment of an alkali metal ferrocyanide with a strong mineral acid. A typical preparation would involve the treatment of a saturated aqueous solution of potassium ferrocyanide with concentrated hydrochloric acid. The acid separates as a crystalline solid that may be purified further by solution in ethanol and reprecipitation by the addition of ether.

Hydroferrocyanic Acid CHEMICAL PROPERTIES

Outside of neutralization and esterification, the chemical reactions of hydroferrocyanic acid are limited chiefly to the formation of addition compounds. These are formed with sulfuric acid, alcohols, ethers, aldehydes, ketones, and certain hydrocarbons. A brief description of the formation of these adducts and other reactions involving essentially nonionized hydroferrocyanic acid is given in the following paragraphs. Reactions of the acid in aqueous solution are included in the chapter dealing with the chemical properties of the ferrocyanide ion.

Reaction with Sulfuric Acid

The addition of small amounts of water to a saturated solution of hydroferrocyanic acid in concentrated sulfuric acid leads to the formation of a series of addition products that are said to have ….Read more