Acid precipitation plants

In 1942, Cohen i found that heparin, hyaluronic acid and chondroitin sulphuric acid precipitated plant viruses, including tobacco mosaic virus, and in this way several viruses were obtained in crystalline form. In tissue culture, heparinoids show a potent reversible inhibitory effect on the early interaction of Herpes simplex virus and cells i , with a minimum inhibitory concentration of 1 [Ag polyvinyl sulphate/ml. Effects have also been observed with encephalomyocarditis. Heparin has been identified as a component of the virulence-enhancing factor of hog gastric mucin. 

Trichloroethanoic acid, CCI3COOH. A crystalline solid which rapidly absorbs water vapour m.p. 58°C, b.p. 196-5" C. Manufactured by the action of chlorine on ethanoic acid at 160°C in the presence of red phosphorus, sulphur or iodine. It is decomposed into chloroform and carbon dioxide by boiling water. It is a much stronger acid than either the mono- or the dichloro-acids and has been used to extract alkaloids and ascorbic acid from plant and animal tissues. It is a precipitant for proteins and may be used to test for the presence of albumin in urine. The sodium salt is used as a selective weedkiller. 

Cooled dust-laden gas is dedusted in an electrostatic precipitator and sent to the cleaning unit to remove impurities such as arsenic, fluorine, and chlorine before being sent on to the sulfuric acid production plant. 

Acid rain is actually a catchall phrase for any kind of acidic precipitation, including snow, sleet, mist, and fog. Acid rain begins when water comes into contact with sulfur and nitrogen oxides in the atmosphere. These oxides can come from natural sources such as volcanic emissions or decaying plants. But there are man-made sources as well, such as power plant and automobile emissions. In the United States, two-thirds of all the sulfur dioxide and one-fourth of the nitrogen oxides in the atmosphere are produced by coal-burning power plants. 

In order to ensure a consistent supply of coal for steam generation, plants typically maintain an outdoor 90-day reserve supply. The pUes are usually not enclosed, so the coal comes in contact with moisture and air, which can oxidize metal sulfides to sulfuric acid. Precipitation then results in coal pile runoff with minerals, metals, and low pH (occasionally) in the stream. 

Both lime and slaked limes are use to reduce sulfur emissions, which contribute to acid precipitation, from power plants, particularly coal-fired plants. By using lime, more than 95% of the sulfur can be eliminated from the emissions. Calcium oxide reacts with sulfur dioxide to produce calcium sulfite CaOfe) + S02( —> CaS03(). Sulfur dioxide is also removed by spraying limewater in the flue gas. Limewater, also called milk of lime, is a fine suspension of calcium hydroxide in water. Other pollutants removed with lime include sulfur trioxide, hydrofluoric acid, and hydrochloric acid. 

Other workers (115-124 for example) have also centered their efforts on the role of phytic acid on zinc and iron bioavailabiliy from both soy and wheat products. It has been suggested (120) that the phytate-to-zinc molar ratio could be used to predict zinc bioavailability in high-phytate foods. Several groups (115, 117), including ours (113), 1 least partially supporT this hypothesis. However, recent work from our laboratory (112) involving soy protein of similar phytate-to-zinc molar ratios clearly demonstrates that zinc bioavailability is also altered by food processing. In this study, zinc from neutralized soy concentrates and isolates was shown to be less available to the rat than was the corresponding acid-precipitated products. This is unfortunate as alkaline conditions are commonly utilized for soy and other plant proteins to obtain beneficial functional properties. 

Figure 17. Weak acid recovery plant used by Sachtleben Chemie (based on know-how of Bayer AG) a) Heat exchanger b) Evaporator c) Injection condenser d) Stirred salt maturing vessels e) Filter press f) Bunker for pyrites g) Coal silo h) Bunker i) Mixing screw unit j) Covered store for mixed filter cake k) Calcination furnace 1) Waste-heat boiler m) Cyclone n) Electrostatic precipitator o) Stirred tank p) Storage tank q) Pump r) Cooler...

Title IV of the Clean Air Act Amendments of 1990 calls for a 10 million ton reduction in annual emissions of sulfur dioxide (S02) in the United Stales by the year 2010, which represents an approximately 40 percent reduction in anthropogenic emissions from 1980 levels, Implementation of Title IV is referred to as the Acid Rain Program the primary motivation for this section of the Clean Air Act Amendments is to reduce acid precipitation and dry deposition. To achieve these reductions, the law requires a two-phase tightening of the restrictions placed on fossil-fuel-lired power plants. 

Research has continued on the speciation of aluminium in water and in soil related particularly to the effects of acid precipitation. Species of particular concern are Alm, Al(OH)2+ and Al(OH)4. These species are the most toxic with regard to fish and plants. The presence of fluoride, sulfate and organic compounds that can form complexes with aluminium result in a lower degree of toxicity. Consequently, the objectives of a number of investigations have been the relationship of... 

The definition of environmental chemistry given above is illustrated for a typical environmental pollutant in Figure 2.3. Pollutant sulfur dioxide is generated in the anthrosphere by combustion of sulfur in coal, which has been extracted from the geosphere. The S02 is transported to the atmosphere with flue gas and oxidized by chemical and photochemical processes in the atmosphere to sulfuric acid. The sulfuric acid, in turn, falls as acidic precipitation, where it may have detrimental effects, such as toxic effects, on trees and other plants in the biosphere. Eventually the sulfuric acid is carried by stream runoff in the hydrosphere to a lake or ocean, where its ultimate fate is to be stored in solution in the water or precipitated as solid sulfates and returned to the geosphere. 

Acidic compounds, in effluents from coal-fired power plants, 119t Acidic deposition dry deposition, 3 history and discussion, 3-8 wet forms, 3 Acidic precipitation... 

The Japanese Society of Soil Science and Plant Nutrition provided the soil map for assessing the susceptibility of Japanese soils to acid precipitation (7). Fig. 6 shows a summary of the map together with the annual deposition of sulfate (excess) at eleven stations in Japan. The most susceptible and most tolerant areas are distinguished on the map. The soils in unmarked regions of the map have intermediate susceptability. 

A. Wada et al, Map for assessing susceptibility of Japanese soils to acid precipitation, Japanese Society of Soil Sci. and Plant Nutrition, 1983. 

See also Acid precipitation Acidic gases, collection from coal-fired power plants, 84-91 Acridine, nitrogen contents, 305 Acridine char... 

Acidification Release of oxides of sulfur and nitrogen (SOx, NOx) Chemical oxidation and deposition of acid compounds Acidic precipitation and lowering of pH in lakes and soils Ecosystem changes and plant/animal death Acidification Potential (AP)... 

Common oil and coal combustions add pollution to the atmosphere. Sulphuric acid is a main factor in acid precipitation. Both industrial production and ordinary consumption are responsible for this t)q)e of pollution. In addition to sulphuric acid we also find some nitric acid in the precipitation. Both sulphur and nitrogen are vital plant nutrition elements. As a rule the plants will find sulphur enough in the soil but lack sufficient nitrogen sources. Many other elements are included in the incinerating gases. 

A certain amount of aluminium is mobilized through the effect of acid precipitation and ends up in streams which carry it to lakes, where all life, both plant and animal, is harmed, to the extent, in many cases, of all the fish dying out. The increase of aluminium in the water causes intense production of mucus on the surface of fish gills, the result of which is to reduce gas exchanges through the gills, leading to death by asphyxia. 

Humans also affect the nitrogen cycle through the emissions of large quantities of NO gases to the atmosphere. The most important sources of emission are automobiles, power plants, home furnaces, and factories. The emitted NO is an important air pollutant, because it is critical in the photochemical oxidative reactions by which toxic ozone is formed, and because the NO is an important source of nitrate in acidic precipitation. 

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