Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form is important to industry.
The primary use of metallic arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining, however
A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably many other species, including humans.
Arsenic is notoriously poisonous to multicellular life. Arsenic trioxide compounds are widely used as pesticides, herbicides and insecticides. As a result, arsenic contamination of groundwater supplies is a problem that affects millions of people around the world.
Arsenate is a divalent anion with affinity for anion resins similar to but slightly lower than that of sulfate Arsenate can be exchanged by strong base anion exchange resins and then adsorbed into the iron hybrid adsorbent of ASM-10-HP.
Except for Gallium arsenide (used as a semiconductor), other arsenide compounds are generally only of academic interest. Gallium arsenide is an important semiconductor because it has much lower electrical resistance than silicon and therefore lower power use and less heat generation.
In most cases arsenite should be oxidized to arsenate so that it is converted to a form more easily removed. Oxidation can be accomplished with chlorine or with oxygen catalyzed by various redox medias.