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Toxicity of silicon

Vaughan GL, Trently SA The toxicity of silicon carbide whiskers, a review. J Environ Sci Health A Environ Sci Eng Toxic Hazard Subst Control 31(8) 2033-54, 1996... [Pg.632]

Because of its use in semiconductors, silicon has emerged as a key element in modem technology. Concurrent with this phenomenon has been an awareness of the toxicity of silicon compounds, many of which, fortunately, have relatively low toxicities. This section covers the toxicological aspects of inorganic silicon compounds. [Pg.259]

Table 28. Toxicity of silicone compounds and main substances used in their production... Table 28. Toxicity of silicone compounds and main substances used in their production...
Substances which have a deleterious effect on the taste and/or smell of the products for human consumption derived from the aquatic environment Toxic or persistent organic compounds of silicon Inorganic compounds of phosphorus and elemental phosphorus Non-persistent mineral oils and hydrocarbons of petroleum origin Cyanides, fluorides... [Pg.517]

GTP is a safe operation. A runaway polymerization can be quickly quenched with a protonic solvent. Since the group transfer polymerization goes to completion, no unwanted toxic monomer remains the silicone group on the living end after hydroxylation is removed as inactive siloxane. The living polymer in GTP is costlier than traditional polymerization techniques because of the stringent reaction conditions and requirements for pure and dry monomers and solvents. It can be used in fabrication of silicon chips, coating of optical fibers, etc. [Pg.42]

The toxicity of lead-containing greases has led to alternative products being used for the protection of components where the product is likely to come in contact with rubber. Of those products considered silicone-based greases have been found to be particularly suitable and their application to hydraulic equipment components such as brake cylinders, where they can provide internal protection against corrosion both during transit and use, has been found particularly beneficial. [Pg.763]

Some elements come in and out of fashion, so to speak. Sixty years ago, elemental silicon was a chemical curiosity. Today, ultrapure silicon has become the basis for the multibillion-dollar semiconductor industry. Lead, on the other hand, is an element moving in the other direction. A generation ago it was widely used to make paint pigments, plumbing connections, and gasoline additives. Today, because of the toxicity of lead compounds, all of these applications have been banned in the United States. [Pg.3]

Coprecipitation is a partitioning process whereby toxic heavy metals precipitate from the aqueous phase even if the equilibrium solubility has not been exceeded. This process occurs when heavy metals are incorporated into the structure of silicon, aluminum, and iron oxides when these latter compounds precipitate out of solution. Iron hydroxide collects more toxic heavy metals (chromium, nickel, arsenic, selenium, cadmium, and thorium) during precipitation than aluminum hydroxide.38 Coprecipitation is considered to effectively remove trace amounts of lead and chromium from solution in injected wastes at New Johnsonville, Tennessee.39 Coprecipitation with carbonate minerals may be an important mechanism for dealing with cobalt, lead, zinc, and cadmium. [Pg.796]

Biological species such as enzymes, whole cells, antibodies and even bacteria can all be successfully entrapped in silica sol-gel matrices, often with enhancement of activity with respect to the free biologicals. In these cases, the process is adapted to eliminate toxic alcohols which are typically released in conventional sol-gel processes based on the hydrolysis of silicon alkoxides. Two such methods are the use of silicon alkoxide... [Pg.129]

Cocker, K.M., Evans, D.E., and Hobson, M.J., The amelioration of aluminium toxicity by silicon in higher plants solution chemistry or an in planta mechanism Physiol. Plant., 104, 608, 1998. [Pg.434]

Until 1982, most alkoxysilanes had been produced from chlorosilanes and alcohols. Hydrochloric acid was therefore still a problem. In 1982, a process was developed in which TMOS could be made directly from elemental silicon and methanol [5]. In the production of silicate coatings, TMOS is first converted to TEOS by an alcoholysis reaction with ethanol. This prevents toxic methanol vapors from escaping from the curing coating. The TEOS is partially hydrolyzed with the rest of the hydrolysis occurring at the time of application. This is therefore a way to produce silicates without chlorine. (If a practical method for converting alkoxysilanes to alkylsilanes could be found, there would also be a nonchlorine method of production of silicones.)... [Pg.161]

Today the toxic effect of silatranes has been thoroughly studied1-3,16-44a b The toxicity of silatranes varies greatly and is mainly dependent on the nature of substituents at the silicon atom. Most toxic of all known silatranes are 1-arylsila-tranes, 4-XC6H4Si(OCH2CH2)3N, where X = CH3, Cl, H (Table 1). These compounds are almost twice as toxic as such well-known poisons as strychnine and hydrocyanic acid. They produce an intensive stimulation of the motor and respiratory centres1-3,30-34,44,when administered at lower than lethal doses... [Pg.79]

Hydration of the benzene ring in 1-phenylsilatrane leads to a sharp decrease of its toxicity (the LDS0 value of 1-cyclohexylsilatrane is 150 mg/kg). The toxicity of 1-arylsilatranes drops even more on separation of the aromatic ring from the silicon atom by the methylene group (LDS0 of 1-benzylsilatrane is 1115 mg/kg) (Table 1). [Pg.81]

Some attempts have been made to explain the high toxicity of 1 -arylsilatranes by the presence of the transannular Si-N bond and pentacoordinate silicon in their molecules1,2- 34 ... [Pg.87]


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See also in sourсe #XX -- [ Pg.1384 ]




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