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Nitric Acid
Description: Nitric acid is a colorless, yellow, or red liquid. It is used in the manufacturing of pharmaceuticals, jewelry, urethanes, rubber chemicals, inorganic and organic nitrates, and nitro compounds for fertilizers, dye intermediates, explosives, and other organic chemicals. It is used in the printing industry for photo-engraving, the engineering industry, metallurgy, etching steel, ore flotation, and reprocessing spent nuclear fuel. The largest use of nitric acid, approximately 74-78%, is for the manufacture of ammonium nitrate, followed by the manufacture of cyclohexanone (8-9%), dinitrotoluene (4%), and nitrobenzene (3-4%). Synonyms are azotic acid, hydrogen nitrate, nitrous fumes, nitryl hydroxide. acid nitrique (French), acido nitroco (Italian), acido nitrico (Spanish), aqua fortis, azotic acid, azotowy kwas (Polish), engraver's acid, hydrogen nitrate, Kyselina dusicne (Czech), nital, nitrous fumes, nitryl hydroxide, salpetersaure (German), salpeterzuuroplossingen (Dutch). Chemical properties: Nitric acid has a characteristic choking odor that is acrid and suffocating. It is a strong, monobasic acid and an oxidizing agent. It is a caustic and corrosive liquid which will attack some forms of plastics, rubber, and coatings. It is not combustible, but may give off poisonous oxides of nitrogen and acid fumes when heated in fires. It will react with water or steam to produce heat and toxic, corrosive, and flammable vapors. It reacts violently with alcohol, turpentine, charcoal, sodium and potassium analogs, and organic refuse. It reacts explosively with metallic powders, carbides, cyanides, sulfides, alkalies, turpentine, cesium, rubidum acetylides, and many reducing agents. Acetone is oxidized violently by mixed nitric-sulfuric acids, and if the mixture is confined in a narrow-mouthed vessel, it may be ejected or explode. Mixtures of fumic nitric acid and acetonitrile are high explosives. A jet of ammonia will ignite in nitric acid vapor. Arsine, phosphine, and tetraborane are all oxidized explosively byfuming nitric acid; cyclopentadiene reacts explosively with fuming nitric acid. Phosphine, hydrogen sulfide, and selenide all ignite when the fuming acid is dripped into the gas. Nickel tetraphosphide ignites with fuming nitric acid, and tetraphosphorus diiodide triselenide reacts explosively with it. Hydrogen telluride ignites with the cold concentrated acid, sometimes exploding. In the presence of traces of oxides, it attacks all base metals except aluminum and special chromium steels. It is soluble in cold and hot water, and ether. It stains woolen fabrics and animal tissue a bright yellow. It increases the flammability of combustible organic and readily oxidizable materials, and can cause ignition of some of these materials. Identification: Health effects: Symptoms of overexposure to nitric acid are irritation of eyes, mucous membranes, and skin; delayed pulmonary edema, pneumonitis, bronchitis, and dental erosion. Nitric acid can be corrosive to the skin, eyes, nose, mucous membranes, respiratory and gastrointestinal tracts, or any tissue with which it comes in contact. Severe burns can occur with necrosis and scarring. Chronic exposure may cause changes in pulmonary function, chronic bronchitis, conjunctivitis, and overt symptoms resembling acute viral respiratory tract infection. Acute exposure can cause delayed dyspnea, circulatory collapse, corneal ulcers, corneal opacity, nasal irritation, throat burn or irritation, shock, cardiac insufficiency, pulmonary edema, dyspnea, headache, gastritis, esophageal and gastric burns, ischemic lesions, dermatitis, and weak or rapid pulse. Exposure Values Economics: In 1997, 9.074 million tons of nitric acid were produced in the United States, a decrease from the 1996 volume of 9.205 million tons. U.S. manufacturers of nitric acid are Air Products and Chemicals, Inc., Pace, FL, and Pasadena, TX; Angus Chemical Co., Sterlington, LA; Apache Nitrogen Products, Inc., Benson, AZ; Arco Chemical Co., Lake Charles, LA; Bayer Corporation, Baytown, TX, and New Martinsville, WV; Cedar Chemical Corp., Vicksburg, MS; CF Industries, Inc., Donaldson, LA; Coastal Chem, Inc., Cheyenne, WY; Coastal Refining and Marketing, Inc., St. Helens, OR; DuPont, Orange, TX, Victoria, TX, and Beaumont, TX; Dyno Nobel Inc., Donora, PA, and Louisiana, MO; El Dorado Chemical Co., El Dorado, AR; Farmland Industries, Inc., Beatrice, NE, Dodge City, KS, Enid, OK, and Lawrence, KS; First Chemical Corp., Pascagoula, MS; Hercules Inc., Parlin, NJ; ICI Explosives USA Inc., Joplin, MO; IMC AgriBusiness Inc., North Bend, OH; IMC Nitrogen Co., East Dubuque, IL; LaRoche Industries Inc., Cherokee, AL; Crystal City, MO; and Orem, UT; Mississippi Chemical Corp., Yazoo City, MS; Monsanto Co., Pensacola, FL; Nitram, Inc., Tampa, FL; PCS Nitrogen, Inc., Savannah, GA; PCS Nitrogen Fertilizer, Augusta, GA, Clinton, IA, Geismar, LA, La Platte, NE, and Wilmington, NC; PCS Nitrogen Ohio, Lima, OH; Rubicon, Inc., Geismar, LA; J.R. Simplot Co., Helm, CA, and Pocatello, ID; Terra Industries Inc., Sergeant Bluff, IA, and Woodward, OK; Terra Nitrogen, Catoosa, OK, and Verdigris, OK; Trademark Nitrogen Corp., Tampa, FL; U.S. Army, Baraboo, WI, Kingsport, TN, Charleston, IN, Radford, VA, Lawrence, KS, and Chattanooga, TN; Unocal Corp., Kennwick, WA, and West Sacramento, CA; Welland Chemical Inc., Newell, PA; and Willard Grain and Feed, Pryor, OK. Regulation: The Occupational Safety and Health Administration (OSHA) issues permissible exposure limits for nitric acid, time-weighted average, of 2 ppm (5 mg/m3), and 4 ppm (10 mg/m3), short-term exposure limit. Nitric acid is regulated under the Emergency Planning and Community Right-to-Know Act; Clean Water Act; and Comprehensive Environmental Response, Compensation, and Liability Act. Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986, releases of more than one pound of nitric acid into the air, water, and land must be reported annually and entered into the Toxic Release Inventory (TRI). Under Section 302 of the Emergency Planning and Community Right to Know Act of 1986, nitric acid is listed as an Extremely Hazardous Substance and has a threshold planning quantity of 1,000 lbs. Facilities having a threshold quantity of 15,000 lbs of fuming nitric acid are subject to the Risk Management Program Rule, Section 112r of the Clean Air Act. National Overview of 1998 Toxics Release Inventory See EPA's Toxic Release Inventory. Notations: The NIOSH recommended exposure limits (RELs) are time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek. A short-term exposure limit (STEL) is designated by "ST" preceding the value; unless noted otherwise, the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday. A ceiling REL is designated by "C" preceding the value. Any substance that NIOSH considers to be a potential occupational carcinogen is designated by the notation "Ca." The OSHA permissible exposure limits (PEL) are found in Tables Z-1, Z-2, and Z-3 of the OSHA General Industry Air Contaminants Standard (29 CFR 1910.1000). Unless noted otherwise, PEL are TWA concentrations that must not be exceeded during any 8-hour workshift of a 40-hour workweek. A STEL is designated by "ST" preceding the value and is measured over a 15-minute period unless noted otherwise. OSHA ceiling concentrations (designated by "C" preceding the value) must not be exceeded during any part of the workday; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 15-minute TWA exposure. In addition, there are a number of substances from Table Z-2 (e.g., beryllium, ethylene dibromide, etc.) that have PEL ceiling values that must not be exceeded except for specified excursions. For example, a "5-minute maximum peak in any 2 hours" means that a 5-minute exposure above the ceiling value, but never above the maximum peak, is allowed in any 2 hours during an 8-hour workday. Information Sources:
Originally published in Environment Writer by the National Safety Council. Reprinted with permission. Environment Writer Metcalf Institute for Marine and Environmental Reporting University of Rhode Island Graduate School of Oceanography Office of Marine Programs Narragansett, RI 02882 Tel: 401-874-6211; Fax: 401-874-6485 Disclaimer * Copyright 2002-2006 * All rights reserved. * University of Rhode Island |