 | Hydrochloric acid: Encyclopedia II - Hydrochloric acid - Applications
Hydrochloric acid - Applications
Hydrochloric acid is a strong inorganic acid that is used in many industrial processes. The application often determines the required product quality.
Hydrochloric acid - Regeneration of ion exchangers
An important application of high-quality hydrochloric acid is the regeneration of ion exchange resins. Cation exchange is widely used to remove ions such as Na+ and Ca2+ from aqueous solutions, producing demineralized water.
Na+ is replaced by H3O+
Ca2+ is replaced by 2H3O+
Ion exchangers and demineralized water are used in all chemical industries, drinking water production, and many food industries.
Hydrochloric acid - pH control and neutralization
A very common application of hydrochloric acid is to regulate the basicity (pH) of solutions.
OH- + HCl → H2O + Cl-
In industry demanding purity (food, pharmaceutical, drinking water), high-quality hydrochloric acid is used to control the pH of process water streams. In less-demanding industry, technical-quality hydrochloric acid suffices for neutralizing waste streams and swimming pool treatment.
Hydrochloric acid - Pickling of steel
Pickling is an essential step in metal surface treatment, to remove rust or iron oxide scale from iron or steel before subsequent processing, such as extrusion, rolling, galvanizing, and other techniques. Technical-quality HCl at typically 18% concentration is the most commonly-used pickling agent for the pickling of carbon steel grades.
Fe2O3 + Fe + 6HCl → 3FeCl2 + 3H2O
The spent acid has long been re-used as ferrous chloride solutions, but high heavy-metal levels in the pickling liquor has decreased this practice.
In recent years, the steel pickling industry has however developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidised bed HCl regeneration process, which allow the recovery of HCl from spent pickling liquor. These are two Pyrohydrolysis ACREG Processes. The most common regeneration process is the ACREG Dependeq ASTEC - Process, applying the following formula:
4FeCl2 + 4H2O + O2 → 8HCl+ 2Fe2O3
By this means, a closed acid loop is established. The ferric oxide by product of the regeneration process is a valuable by-product, used in a variety of secondary industries.
HCl is not a common pickling agent for stainless steel grades.
Hydrochloric acid - Production of inorganic compounds
Numerous products can be produced with hydrochloric acid in normal acid-base reactions, resulting in inorganic compounds. These include water treatment chemicals such as iron(III) chloride and polyaluminium chloride (PAC).
Fe2O3 + 6 HCl → 2 FeCl3 + 3 H2O
Both iron(III) chloride and PAC are used as flocculation and coagulation agents in wastewater treatment, drinking water production, and paper production.
Other inorganic compounds produced with hydrochloric acid include road application salt calcium chloride, nickel(II) chloride for electroplating, and zinc chloride for the galvanizing industry and battery production.
Hydrochloric acid - Production of organic compounds
The largest hydrochloric acid consumption is in the production of organic compounds such as vinyl chloride for PVC, and MDI and TDI for polyurethane. This is often captive use, consuming locally-produced hydrochloric acid that never actually reaches the open market. Other organic compounds produced with hydrochloric acid include bisphenol A for polycarbonate, activated carbon, and ascorbic acid, as well as numerous pharmaceutical products.
Hydrochloric acid - Other applications
Hydrochloric acid is a fundamental chemical, and as such it is used for a large number of small-scale applications, such as leather processing, household cleaning, and building construction. In addition, a way of stimulating oil production is by injecting hydrochloric acid into the rock formation of an oil well, dissolving a portion of the rock, and creating a large-pore structure. Oil-well acidizing is a common process in the North Sea oil production industry.
Many chemical reactions involving hydrochloric acid are applied in the production of food, food ingredients, and food additives. Typical products include aspartame, fructose, citric acid, lysine, hydrolyzed protein, and gelatin. Food-grade (extra-pure) hydrochloric acid can be applied when needed for the final product.
Other related archives15th century, 1772, 17th century, 1818, 1863, 1988, 20th century, 800, Acid, Akzo Nobel, Alkali Act, Arab, Basilius Valentinus, Benedictine, CFCs, Cation exchange, Chemical engineering, Chemical industry, Chloric acid, Chloride, Chlorous acid, Cl, Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, Dangerous goods, Davy, Dow Chemical, EU classification, Erfurt, Germany, FMC, Freon, Georgia Gulf Corporation, Glauber, H, Humphry Davy, Hydrochloride, Hydrogen chloride, Hypochlorous acid, Industrial Revolution, Inorganic chemistry, Issoundun, France, Jabir ibn Hayyan, Jabir ibn Hayyan (Geber), Johann Rudolf Glauber, Joseph Priestley, Karlstadt am Main, Germany, Leblanc process, Leeds, England, List of chemistry topics, List of inorganic compounds, MDI, Mannheim process, Middle Ages, Nicolas Leblanc, North Sea oil, PVC, Penzance, England, Perchloric acid, Phosgene, Pickling, Priestley, Risk and Safety Statements, Solvay process, TDI, Teflon, Tessenderlo, Tosoh Corporation, World War I, Yemeni, absorbed, achlorhydria, acid dissociation constant, acid-base reactions, activated carbon, alchemist, alkaline, alveolar, antacids, aqua regia, aqueous, ascorbic acid, aspartame, atoms, azeotrope, base, basic, basicity, battery, bisphenol A, bleach (NaClO), boiling, building, calcium carbonate, calcium chloride, canon, capillary, carbonic acid, catalyst, chemical analysis, chemical reactions, chemical substance, chemical warfare, chlor-alkali, chlorate, chloride ion, chlorinated, chlorine, chlorite, citric acid, cleaning, cocaine, common salt, concentration, concentrations, conjugate base, construction, copper(II) oxide, corrosive, crystal, crystallization, demineralized, density, digestive fluid, dissociate, drinking water, electrolyzed, electroplating, epithelial, epithelium, eutectic, eutectic points, evaporation, exothermic, extrusion, ferrous chloride, flocculation, fluorinated, food, food additives, fructose, galvanizing, gastric acid, gastroenteritis, gelatin, heartburn, heavy-metal, heroin, hydrogen, hydrogen chloride, hydrolysis, hydronium, hypochlorhydria, hypochlorite, ice, industrial organic compounds production, ingredients, ingredients in food, inorganic, ion exchange resins, ions, iron, iron oxide, iron(III) chloride, leather, liquid, lumen, lung, lysine, melting points, membranes, metal, metals, molarity, monoprotic acid, mucus, mustard gas, neutralizing, nickel(II) chloride, nitric acid, oil production, oil well, organic, organic compounds, oven, oxidation-reduction, pH, paper, parietal cells, peptic ulcers, perchlorate, permanganate (KMnO4), pharmaceutical, philosopher's stone, physical properties, plastic, polyaluminium chloride (PAC), polycarbonate, polyurethane, pressure, priory, production, protein, proton, proton pump inhibitors, pulmonary edema, reagent, rolling, rust, safety, salt, scientists, soda ash, sodium chloride, sodium hydroxide, sodium sulfate, solution, spent acid, steel, stomach, storage, strong acid, strong acids, sulfuric acid, swimming pool, systematic, temperature, tight junctions, titration, tonnes, transport, vapours, vinyl chloride, vitriol, wastewater treatment, water, zinc chloride
 Adapted from the Wikipedia article "Applications", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki |
