Aluminum aqueous

Zinc phosphating is primarily used for the surface treatment of steel and zinc as well as composites of these metals with aluminum. Aqueous phosphoric acid solutions (pH 2.0-3.6) containing dissolved acidic zinc phosphate, Zn(H2P04)2. are used. 

The coordination number of a given metal ion, such as Co + or Al + (which indicates the number of ligands attached to it), often varies from ligand to ligand. For example, whereas for aluminum, aqueous chloride forms [AlCU]" and the addition of another chloride ligand (a fifth and a sixth) is not easy, up to six fluoride ligands coordinate rather readily, forming A1F . 

The mechanism of complex formation for organic-aluminum chelates probably involves a dissociative mechanism, as the aquo-aluminum aqueous complex involves a full octahedral coordination shell (Hewkin and Prince... 

Reaction of hexamethylbenzene with methyl chloride and aluminum chlonde gave a salt A which on being treated with aqueous sodium bicarbonate solution yielded compound B Suggest a mechanism for the conversion of hexamethylbenzene to B by correctly infemng the structure of A... 

Iodine Acetaldehyde, acetylene, aluminum, ammonia (aqueous or anhydrous), antimony, bromine pentafluoride, carbides, cesium oxide, chlorine, ethanol, fluorine, formamide, lithium, magnesium, phosphorus, pyridine, silver azide, sulfur trioxide... 

Mild steel is a suitable material of constmction for storage and handling of DMAC at ambient temperatures. Aluminum or stainless steel is recommended for cases involving very stringent color or iron contamination requirements. Mild steel is not recommended for high temperature service or handling aqueous solutions of less than 50 mol % (82.86 wt %) DMAC. 

Aqueous solutions of 50% acrylamide should be kept between 15.5 and 38°C with a maximum of 49°C. Below 14.5°C acrylamide crystallizes from solution and separates from the inhibitor. Above 50°C the rate of polymer buildup becomes significant. Suitable materials of constmction for containers include stainless steel (304 and 316) and steel lined with plastic resin (polypropylene, phenoHc, or epoxy). Avoid contact with copper, aluminum, their alloys, or ordinary iron and steel. 

Environmental Considerations. Environmental problems in Ziegler chemistry alcohol processes are not severe. A small quantity of aluminum alkyl wastes is usually produced and represents the most significant disposal problem. It can be handled by controlled hydrolysis and separate disposal of the aqueous and organic streams. Organic by-products produced in chain growth and hydrolysis can be cleanly burned. Wastewater streams must be monitored for dissolved carbon, such as short-chain alcohols, and treated conventionally when necessary. 

Aqueous solutions of caustic soda aie highly alkaline. Hence caustic soda is ptimatily used in neutralization reactions to form sodium salts (79). Sodium hydroxide reacts with amphotoric metals (Al, Zn, Sn) and their oxides to form complex anions such as AlO, ZnO. SnO ", and (or H2O with oxides). Reaction of AI2O2 with NaOH is the primary step during the extraction of alumina from bauxite (see Aluminum compounds) ... 

The first reported synthesis of acrylonitrile [107-13-1] (qv) and polyacrylonitrile [25014-41-9] (PAN) was in 1894. The polymer received Htde attention for a number of years, until shortly before World War II, because there were no known solvents and the polymer decomposes before reaching its melting point. The first breakthrough in developing solvents for PAN occurred at I. G. Farbenindustrie where fibers made from the polymer were dissolved in aqueous solutions of quaternary ammonium compounds, such as ben2ylpyridinium chloride, or of metal salts, such as lithium bromide, sodium thiocyanate, and aluminum perchlorate. Early interest in acrylonitrile polymers (qv), however, was based primarily on its use in synthetic mbber (see Elastomers, synthetic). 

There are several processes available for the manufacture of cryoHte. The choice is mainly dictated by the cost and quaUty of the available sources of soda, alumina, and fluoriae. Starting materials iaclude sodium aluminate from Bayer s alumina process hydrogen fluoride from kiln gases or aqueous hydrofluoric acid sodium fluoride ammonium bifluoride, fluorosiUcic acid, fluoroboric acid, sodium fluosiUcate, and aluminum fluorosiUcate aluminum oxide, aluminum sulfate, aluminum chloride, alumina hydrate and sodium hydroxide, sodium carbonate, sodium chloride, and sodium aluminate. 

The manufacture of cryoHte is commonly iategrated with the production of alumina hydrate and aluminum trifluoride. The iatermediate stream of sodium aluminate from the Bayer alumina hydrate process can be used along with aqueous hydrofluoric acid, hydrogen fluoride kiln gases, or hydrogen fluoride-rich effluent from dry-process aluminum trifluoride manufacture. 

Compounds containing fluorine and chlorine are also donors to BF3. Aqueous fluoroboric acid and the tetrafluoroborates of metals, nonmetals, and organic radicals represent a large class of compounds in which the fluoride ion is coordinating with trifluoroborane. Representative examples of these compounds are given in Table 5. Coordination compounds of boron trifluoride with the chlorides of sodium, aluminum, iron, copper, 2inc, tin, and lead have been indicated (53) they are probably chlorotrifluoroborates. 

The magnesia and alumina suspension is prepared by treatment of an aqueous solution, containing aluminum and magnesium salt in the desired proportion, with sodium hydroxide. The coprecipitated aluminum and magnesium hydroxides are collected by filtration, washed free of soluble salts, and stabilized by the addition of a suitable hexatol. 

In aqueous solution, malic acid can be mildly corrosive toward aluminum and corrosive to carbon steel. Under normal conditions, it is not corrosive to stainless steels, which usually are the constmetion materials for processes involving malic acid. Malic acid is also virtually noncorrosive to tinplate and other materials used to package acidulated foods and beverages (Table 3) (27). 

Corrosion by Various Chemicals and Environments. In general, the rate of corrosion of magnesium ia aqueous solutions is strongly iafluenced by the hydrogen ion [12408-02-5] concentration or pH. In this respect, magnesium is considered to be opposite ia character to aluminum. Aluminum is resistant to weak acids but attacked by strong alkaUes, while magnesium is resistant to alkaUes but is attacked by acids that do not promote the formation of iasoluble films. 

In a reversal of the reaction with SiCl, aluminum can be introduced into the framework by reaction of the hydrogen or ammonium form with gaseous AlCl (36). Similarly, reaction with aqueous ammonium fluoroaluminates replaces framework-Si with Al (37). When alumina-bound high siUca 2eohtes are hydrothermaHy treated, aluminum migrates into framework positions and generates catalyticaHy active acid sites (38). The reaction can be accelerated by raising the pH of the aqueous phase. 

Rosin sizing usually involves the addition of dilute aqueous solutions or dispersions of rosin soap size and alum to a pulp slurry (44—46). Although beater addition of either coreactant is permissable, addition of both before final pulp refining is unwise because subsequently exposed ceUulose surfaces may not be properly sized. The size and alum should be added sufficiendy eady to provide uniform distribution in the slurry, and adequate time for the formation and retention of aluminum resinates, commonly referred to as size precipitate. Free rosin emulsion sizes, however, do not react to a significant degree with alum in the pulp slurry, and addition of a cationic starch or resin is recommended to maximize retention of size to fiber. Subsequent reaction with aluminum occurs principally in the machine drier sections (47). 

Available Forms. Phthalocyanines are available as powders, in paste, or Hquid forms. They can be dispersed in various media suitable for aqueous, nonaqueous, or multipurpose systems, eg, polyethylene, polyamide, or nitrocellulose. Inert materials like clay, barium sulfate, calcium carbonates, or aluminum hydrate are the most common soHd extenders. Predispersed concentrates of the pigments, like flushes, are interesting for manufacturers of paints and inks (156), who do not own grinding or dispersing equipment. Pigment—water pastes, ie, presscakes, containing 50—75% weight of water, are also available. 

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