Global Solutions With Titanium For Arsenic Removal And Water Purification

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                                                     Arsenic Facts         

 Arsenic is a naturally occurring metal in soils. Eating foods or drinking water with too much arsenic can cause health problems.

Arsenic is a chemical element that has the symbol As and atomic number 33. This is a notoriously poisonous metalloid that has many allotropic forms; yellow, black and gray are a few that are regularly seen. Arsenic is not found free in nature, but its compounds are widely distributed in minerals. Arsenic and its compounds are used as pesticides, herbicides, insecticides and various alloys. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices.

Non-cancer effects can include thickening and discoloration of the skin, stomach pain, nausea, vomiting; diarrhea; numbness in hands and feet; partial paralysis; and blindness. Arsenic has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate.

Arsenic is very similar chemically to its predecessor phosphorus, so much so that it will partly substitute for phosphorus in biochemical reactions and is thus poisonous, although in subtoxic doses soluble arsenic compounds act as stimulants, and were once popular in small doses as medicinals by people in the mid 18th century. Arsenic compounds were also once used to dope racehorses.

When heated rapidly it oxidizes to arsenic trioxide; the fumes from this reaction have an odor resembling garlic. Arsenic and some arsenic compounds can also sublimate upon heating, converting directly to a gaseous form. Elemental arsenic is found in two solid forms: yellow and gray/metallic, with specific gravities of 1.97 and 5.73, respectively.

Arsenic and many of its compounds are especially potent poisons. Arsenic kills by enzyme inhibition because enzymes are the best documented targets of metals; in this case, it causes toxicity. These metabolic interferences lead to death from multi-system organ failure, probably from necrotic cell death, not apoptosis. A post mortem reveals brick red colored mucosa, due to severe hemorrhage.

The EPA has set the arsenic standard for drinking water at .010 parts per million (10 parts per billion) to protect consumers served by public water systems from the effects of long-term, chronic exposure to arsenic. Water systems must comply with this standard by January 23, 2006, providing additional protection to an estimated 13 million Americans.

The Office of Environmental Health (OEH) recommends testing all new wells for arsenic and other primary metals before the water is used for drinking or cooking purposes.

The Arizona Department of Health Services (ADHS) has developed a simple method to determine if the arsenic levels are too high, using a color code.

                    In the following text, ppb is parts per billion and mg/L is milligrams per liter.

Green: Less than 10 ppb or 0.01 mg/L. It is OK to drink and cook with this water.

Yellow: 11/200 ppb or 0.011/0.2 mg/L. Consumption of water containing arsenic in this range will increase the risk of  long term or chronic health problems.

Red: Above 200 ppb or 0.2 mg/L. This water should NOT be used for drinking or cooking! This level is a cause for concern and it is strongly suggested that you obtain your drinking water from another source immediately that is known to have no detectable arsenic, or install and maintain a home treatment device.
Water with 500 ppb of arsenic or less can be used for bathing, laundry, and brushing teeth. Children should not use this water for brushing their teeth.

Elemental arsenic and arsenic compounds are classified as "toxic" and "dangerous for the environment" in the European Union under directive 67/548/EEC.

The IARC recognizes arsenic and arsenic compounds as group 1 carcinogens, and the EU lists arsenic trioxide, arsenic pentoxide and arsenate salts as category 1 carcinogens.

Arsenic is known to cause arsenicosis due to its manifestation in drinking water, “the most common species being arsenate [HAsO42- ; As(V)] and arsenite [H3AsO3 ; As(III)]”. The ability of arsenic to oxidized between As(III) and As(V) makes its availability in the environment possible. According to Croal, Gralnick, Malasarn, and Newman, “[the] understanding [of] what stimulates As(III) oxidation and/or limits As(V) reduction is relevant for bioremediation of contaminated sites (Croal). The study of chemolithoautotrophic As(III) oxidizers and the heterotrophic As(V) reducers can help the understanding of the oxidation and/or reduction of arsenic.

Arsenic contamination of groundwater has led to a massive epidemic of arsenic poisoning in Bangladesh[3] and neighboring countries. It is estimated that approximately 57 million people are drinking groundwater with arsenic concentrations elevated above the World Health Organization's standard of 10 parts per billion. The arsenic in the groundwater is of natural origin, and is released from the sediment into the groundwater due to the anoxic conditions of the subsurface. This groundwater began to be used after western NGOs instigated a massive tube well drinking-water program in the late twentieth century. This program was designed to prevent drinking of bacterially-contaminated surface waters, but unfortunately failed to test for arsenic in the groundwater.(2) Many other countries in Southeast Asia, such as Vietnam, Cambodia, and Tibet, are thought to have geological environments similarly conducive to generation of high-arsenic groundwaters.

Arsenic is prevelant in many western and southwestern states like California, Arizona, Texas, Nevada, and New Mexico. There is significant concentrations in the northern United States as well, including parts of Michigan, Wisconsin, Minnesota and the Dakotas are known to have concentrations of arsenic in ground water.

Arsenic can be removed from drinking water through co-precipitation of iron minerals by oxidation and filtering. When this treatment fails to produce acceptable results, adsorptive arsenic removal media may be utilized. Several adsorptive media systems have been approved for point of service use in a study funded by the United States Environmental Protection Agency (U.S.EPA) and the National Science Foundation (NSF).

Titanium is the most reliable, effective, and long lasting media. It consist of granular of titanium oxide with strong affinity for arsenic, lead, and other heavy metals.

Using this media, magnetic separations of arsenic at very low magnetic field gradients have been demonstrated in point-of-use water purification with high–surface area and monodisperse magnetite (Fe3O4) nanocrystals. Using the high specific surface area of Fe3O4 nanocrystals, the mass of waste associated with arsenic removal from water has been dramatically reduced.

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