Iron oxide toxicity

Industrial Wastewater Treatment. Industrial wastewaters require different treatments depending on their sources. Plating waste contains toxic metals that are precipitated and insolubiHzed with lime (see Electroplating). Iron and other heavy metals are also precipitated from waste-pidde Hquor, which requires acid neutralization. Akin to pickle Hquor is the concentrated sulfuric acid waste, high in iron, that accumulates in smokeless powder ordinance and chemical plants. Lime is also useful in clarifying wastes from textile dyeworks and paper pulp mills and a wide variety of other wastes. Effluents from active and abandoned coal mines also have a high sulfuric acid and iron oxide content because of the presence of pyrite in coal. 

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. 

Some chemical processes use energy directly to drive the transformation. For example, the conversion of iron ore, iron oxide, to iron metal requires chemical energy to remove the oxygen atoms. In early times the iron ore was heated with charcoal in more recent times it is heated with refined coal (coke), but in both cases the result is conversion of coal or wood into carbon monoxide, which is toxic but can be burned to carbon dioxide to generate needed heat. There is now interest in devising processes that do not use carbon in this way, but use electrical energy to avoid the production of carbon oxides. 

Hydrochloric acid. Strong acids are used frequently for the purpose of sample dissolution when water will not do the job. One of these is hydrochloric acid, HC1. Concentrated HC1 is actually a saturated solution of hydrogen chloride gas, fumes of which are very pungent. Such a solution is 38.0% HC1 (about 12 M). Hydrochloric acid solutions are used especially for dissolving metals, metal oxides, and carbonates not ordinarily dissolved by water. Examples are iron and zinc metals, iron oxide ore, and the metal carbonates of which the scales in boilers and humidifiers are composed. Being a strong acid, it is very toxic and must be handled with care. It is stored in a blue color-coded container. 

Although O2 leakage compromises the root s internal aeration, some leakage is desirable for a number of purposes. These include oxidation of toxic products of anaerobic metabolism in submerged soil such as ferrous iron (van Raalte, 1944 Bouldin, 1966 van Mensvoort et al., 1985) nitrification of ammonium to nitrate, there being benefits in mixed nitrate-ammonium nutrition (Kronzucker et al., 1999, 2000) and mobilization of sparingly soluble nutrients such as P (Saleque and Kirk, 1995) and Zn (Kirk and Bajita, 1995) as a result of acidification due to iron oxidation and cation-anion intake imbalance. 

Methyl isocyanate (MIC) is a colorless liquid that must be stored in a cooled enclosure before it is subsequently used in the manufacture of carbamate, a common insecticide. MIC liquid is highly reactive in the presence of water and iron oxide, and it generates heat. In sufficient quantities, this heat may generate vapor, which, as explained previously, is highly toxic. Three adjacent bunkers were used for MIC storage. These were mounted in a berm and a refrigeration coil was used to ensure that the temperature did not exceed 5°C. A vent gas scrubber was used to prevent vapor escape, and despite a low operating pressure, a closed relief... 

Isomorphous substitution of iron oxides is important for several reasons. In the electronics industry, trace amounts (dopants) of elements such as Nb and Ge are incorporated in hematite to improve its semiconductor properties. Dopants are also added to assist the reduction of iron ores. In nature, iron oxides can act as sinks for potentially toxic M", M and M heavy metals. Investigation of the phenomenon of isomorphous substitution has also helped to establish a better understanding of the geochemical and environmental pathways followed by Al and various trace elements. Empirical relationships (e. g. Fe and V) are often found between the Fe oxide content of a weathered soil profile and the levels of various trace elements. Such relationships may indicate similarities in the geochemical behaviour of the elements and, particularly for Al/Fe, reflect the environment in which the oxides have formed (see chap. 16). 

Francis AJ, Dodge CJ. 1990. Anaerobic microbial remobilization of toxic metals coprecipitated with iron oxide. Environmental Science and Technology 24 373-378. 

Iron oxide pigments produced from pure starting materials may be used as colorants for food and pharmaceutical products [3.42], Synthetic iron oxides do not contain crystalline silica and therefore are not considered to be toxic, even under strict Californian regulations. 

There are several major types of chronic lung disorders that can be caused by exposure to toxicants. A common symptom of chronic lung damage is chronic bronchitis. Among the toxicants that cause this condition are ammonia, arsenic, cotton dust (brown lung disease), and iron oxide from exposure to welding fumes. 

Keywords nanoparticles, ultrafine particles, pulmonary toxicology, toxicity, liposomes, carbon nanotubes, iron oxide, titania, silica, asbestos... 

Iron oxides are not toxic per se, and iron ions in the oxide framework do not yield ROS as do most asbestos fibers26 or quartz particles, particularly when doped by iron. To investigate whether this also takes place when the oxides are prepared in nano-size form we have compared the surface reactivity of one fine, micron-sized specimen of Fe203 (mean diameter 0.1 pm, Fe2C>3-F) to that of an... 

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