2. Arsenic and its compound application and removal

Elemental arsenic has a limited application mainly as lead and brass alloy's ingredient, but its compounds are widely used in the industry. The gallium arsenide (GaAs) is extensively used in the electronic industry for high-frequency integrated circuits, laser diodes, and Light Emission Diodes (LEDs); the arsenic oxide is used in glass production industry; the arsenic sulfides

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

are used as pigments in textile. There is a revival of the interest in arsenic as medicine for the treatment of acute promyelocytic leukemia, multiple myeloma, myelodysplastic syndrome, and various resistant solid tumors. Other applications of the arsenic compounds include the paper industry, the pyrotechnic industry, and so on. Arsenic compounds were used as pesticides in the past.

Inorganic forms of arsenic are more toxic than the organic ones. Arsenic oxides are the most common threat because arsenite and arsenate salts are the most toxic. These forms are compo-

The two forms of inorganic arsenic reduced (trivalent arsenic) and oxidized (five valent arsenic) can be absorbed and accumulated in tissues and body fluids. The trivalent form is more toxic and reacts with thiol groups. Very few organs and systems are not affected by the toxic effects of arsenic. The arsenic compound toxicity decays in the following order: As(III) > monomethylarsine oxide > dimethylarson > monomethylarsenate > As(V). The toxicity of As(III) is 10 times greater

The "total arsenic" determined in a sample most often do not represent a valuable information, because of the different properties and different toxicity of its species [19, 20]. The main problem is the easy conversion of the arsenic species to another caused by the pH changes, the presence of reducing agents, oxidizers, and certain bacterial strains able to produce a lot of organic As-species [21, 22]. That is why the As speciation is the only important way to characterize the origin of the As-related problems such as its toxicity and biogeochemical cycling and to find the best procedure for drinking water treatment. Unfortunately, As speciation remains challenging, because of the interference between the arsenic species possessing different toxicity [23], which is typical for the

The best analytical methods for As speciation are considered those, including chromatographic separations [26, 27] such as IC [28] and HPLC [29], coupled with a sensitive detection system, such as ICP–MS, AFS–HG, and AAS–HG [30]. Specific sorbents and exchange resins have been developed and applied recently for this purpose [31–35]. Apart from the chromatographic and non-chromatographic methods for the arsenic species separation, simple and cost-effective electrochemical methods were developed recently based on the distinct As-species electro-

In spite of the arsenic and its compounds important industrial application, the greatest attention is paid to their influence on the human health, especially in case of long temp action by contaminated drinking water and food. That is why detailed studies on arsenic toxicity and cancer provoking mechanisms were realized. The toxicity of the arsenic species may differ 10 and more times from one to another, so their transformation caused by condition changes (as pH, dissolved oxygen, and bacterial activity) during the sample transportation and conservation prior the laboratory analysis may cause false results. For this reason, simple analytical techniques and sensors for arsenic speciation have been developed able to realize in-situ speciation to evaluate the real toxicity of contaminated water, food, or soil samples. To prevent

.

Introductory Chapter: Arsenic

5

http://dx.doi.org/10.5772/intechopen.78399

nents of geological formations and are extracted into groundwater.

than that of As(V) and the lethal dose for adults is 1–4 mg kg<sup>1</sup>

4. Analytical methods for arsenic quantification

organic As-species [24, 25].

chemical properties [36, 37].

5. Conclusion

The conventional methods most applied for arsenic removal are:

