Testing Status of Agents at NTP
USES OF ALUMINUM
5.0 USES
Among the numerous applications of aluminum and its alloys, the major uses are in packaging (25% consumption; e.g., drink cans and foil for pie plates and frozen foods), building and construction (15%; siding and roofing, doors, and windows), transportation (34%; bodies, trim, and mechanical parts of cars, boats, and planes), and electrical applications (8%; overhead transmission lines, cable sheathing, and wiring) (ATSDR, 1999).
Aluminum compounds, likewise, have a wide range of uses in industrial, domestic, consumer, and medicinal products. Table 4 summarizes the uses of several of these compounds.
Because aluminum is more efficient at binding phosphorus than iron, resulting in the greater reduction of sludge, alum, aluminum chlorohydrate, and several high basicity PAC products were being considered over the iron salts as the preferred coagulants for wastewater (Boswell, 1998). PAC, which contains a larger amount of aluminum than alum, was taking over some market share from alum and the iron salts. However, with the passing of the D/DBP Rule amendment to the SDWA in 1998, the use of PAC and alum became limited (Jarvis, 2000). Furthermore, restriction has been placed on the levels of sulfate in potable water. Ferric chloride, therefore, is currently the preferred coagulant. Other commercially available polynuclear aluminum coagulants are polyaluminum silicate-sulfate (PASS) and acidified bauxite (PAX) (Milette and Basisio, 1989; Masschelein, 1992; both cited by LaZerte et al., 1997).
Besides water treatment, alum's other principal market is the pulp and paper industry; together they account for about 95% of consumption (Heydorn et al., 1985). The major use of alum in the pulp and paper industry is to precipitate rosin size on paper fibers. PAC, however,
Table 4. Uses of Aluminum Compounds
| Compounds | Uses |
|
alums* | as a hardening agent and setting accelerator for gypsum plaster; in tanning and dyeing; in styptic pencils (former use) |
| aluminas* |
in water treatment; as an accelerator for concrete solidification (high alumina cements) |
| alkoxides* | in varnishes; for textile impregnation; in cosmetics; as an intermediate in pharmaceutical production |
| borate* | in the production of glass and ceramics |
| carbonate* | in antacids |
| chlorides | anhydrous form: as an acid catalyst (especially in Friedel-Crafts-type reactions); as a chemical intermediate for other aluminum compounds; in the cracking of petroleum; in the manufacture of rubbers and lubricants; as an antiperspirant hexahydrate form: in the preservation of wood; in the disinfection of stables and slaughterhouses; in deodorants and antiperspirants; in cosmetics as an astringent; in the refinement of crude oil; in dyeing fabrics; in manufacture of parchment paper |
| chlorohydrate | as the active ingredient in many antiperspirants and deodorants |
| hydroxide | in stomach antacids (including Maalox®, Mylanta®, and Delcid®); as a desiccant powder; in antiperspirants and dentifricesa; in packaging materials; as a chemical intermediate; as a filler in plastics, rubber, cosmetics, and paper; as a soft abrasive for brass and plastics; as a glass additive to increase mechanical strength and resistance to thermal shock, weathering, and chemicals; in ceramics; to lower the plasma phosphorus levels of patients with renal failure |
| isopropoxide* | in the soap and paint industries; in waterproofing textiles |
| nitrate | in antiperspirants; for tanning leather; as a corrosion inhibitor; in the preparation of insulating papers; on transformer core laminates; in incandescent filaments; in cathode ray tube heating elements |
| oxide | in the production of aluminum; in the manufacture of abrasives, refractories, ceramics, electrical insulators, catalysts and catalyst supporters, paper, spark plugs, crucibles and laboratory works, adsorbent for gases and water vapors, chromatographic analysis, fluxes, light bulbs, artificial gems, heat resistant fibers, food additives (dispersing agent), and in hollow-fiber membrane units used in water desalination, industrial ultrafiltration, and hemodialysis; as a dosimeter for measuring personnel radiation exposure |
| phosphate | in over-the-counter stomach antacids |
| phosphide |
as an insecticidal grain fumigant |
| silicate* | as a component of dental cement; in antacids and food additives |
| sulfate | as a flocculent for water purification systems and sewage treatment; in the paper and pulp industry; in fireproofing and waterproofing cloth; in clarifying oils and fats; in waterproofing concrete; in antiperspirants; in tanning leather; as a mordant in dyeing; in agricultural pesticides; as an intermediate in the manufacture of other chemicals; as a soil conditioner to increase acidity of plants; in cosmetics and soap; in the preparation of aluminum acetate ear drops Solutions containing 5-10% aluminum sulfate: as local applications to ulcers; to arrest foul discharges from mucous surfaces |
| trioxide* | as an absorbent, abrasive, and refractory material |
Sources: ATSDR (1999); *IPCS (1997)
a
used as an abrasive in toothpaste; however, due to its costliness for the developing world, there is a drive towards using calcium carbonate (CaCO3) (Williams, 2000)is taking over alum's share since rosin-sized and unsized paper grades are being produced at high pH levels (PR Newswire, 1998). Given via intravesical irrigation, alum, furthermore, has also been used for decades to control severe hemorrhagic cystitis (Kravoussi et al., 1986; cited by Nakamura et al., 2000). It is also added as an adjuvant to allergenic extracts for hyposensitization or in the preparation of vaccines (May et al., 1986; cited by Klein, 1997).
Like alum, sodium aluminate markets include water treatment and papermaking industry (Heydorn et al., 1985). In the latter, it is a substitute for aluminum sulfate. In the former, it is used to treat potable water and industrial wastewater, serving as a water softener, as a flocculant to trap suspended solids, and to precipitate inorganic phosphates. Captive production of sodium aluminate is chiefly for the manufacture of sodium aluminosilicates and to coat titanium dioxide pigments to improve the pigment's resistance to ultraviolet light.
Additionally, water-soluble aluminum phthalocyanine-polymer conjugates are used as photosensitizers for photodynamic therapy of cancer (Brasseur et al., 1999). In a further application, a knee joint patellofemorotibial metal/polymer porous-coated uncemented prosthesis and its uni-compartmental model, intended for implantation to replace a knee joint or part of it, respectively, have a femoral component made of a surface-hardened titanium-aluminum-vanadium alloy, and tibial and patellar resurfacing components made of an ultra-high molecular weight polyethylene compound fixed to a metal base made of the alloy (FDA, 2000b).
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