**5. Conclusion**

**Technology for arsenic** 

Adsorption Cheap materials,

18 Arsenic - Analytical and Toxicological Studies

Chemical coagulation Effective for

Electrocoagulation Efficient for

Ion exchange Efficient for

Membrane technologies Efficient in

effective and efficient removal

industrial wastewater treatment plants and efficient for As(V) removal

arsenic removal. Low maintenance costs. No chemicals or pH adjustment. Low operating costs

As(V) removal. Exchange resins are available; the selective resins for removing arsenic are one of the most important requirements to provide high removal. Together with hybrid solution is an excellent technology

arsenic removal. No chemical reagents. No sludge. Small dimensions for membrane treatment plant. Easy automation and control

**Advantage Disadvantage Some specific** 

Further treatment for regeneration and consumption of

Chemical required. pH adjustment needed. Large volumes of sludge that needs further treatment

Applicable only on batch scale. Passive oxide films for on the electrode. High energy consumption

Interference with other ions. Easily blocked. Huge amount of chemicals

Removal of arsenic depends on the pressure, pH value, solute concentration, temperature of feed

solution

**Table 3.** The comparison and future perspective of different technologies for arsenic removal.

chemicals

**feature**

Additional filter for removal of fine particles is required

Arsenic leaching out from sludge

No generation of secondary pollutants

Using this kind of technique depends on the pH values of water

Arsenic is concentrated in the retentate

**Future perspective**

Still attractive as an efficient and cheap technology for As removal. Finding new, environmentally friendly sorbent is still a challenging task

Not attractive as a solution, only if it coupled with electrochemical techniques

Attractive for future investigations. Need to overcome the lack of application on a large

Attractive only if selective and sensitive chemical agents are included in ion-exchange process

Attractive in future perspective. With decrease of investment the MST will prevail in arsenic removal technologies. Different membrane materials and processes need to be evaluated to select the optimum for each

situation

scale

**removal**

Arsenic contamination of water has been reported as a critical issue in many articles, which reflects the latest state-of-the-art understanding of the behavior and toxicity of various arsenic species. Many water sources in the world contain low concentration of arsenic (mostly traces of arsenic, level of μg L−1 or less). If the concentration of arsenic in drinking water is higher than 10 μg L−1, which is the WHO provisional guideline value for arsenic, it causes various health problems. All arsenic compounds dissolved in water are toxic. In natural waters, arsenic appears most often in inorganic forms and to a lesser extent in organic form. Inorganic species, arsenic acids (H3 AsO3 and H3 AsO4 ) and their ions are more toxic than organic forms. In addition, As(III) species are more toxic than As(V) ones. The valence (+III and +V), the type of arsenic species, ionic or molecular forms are dependent on the oxidation–reduction condition and pH of the water. Arsenic in water occurs in both inorganic and organic forms, but inorganic species are predominant in natural waters. In neutral conditions, As(V) species are completely in ionic form (H2 AsO4 − and HAsO4 2−), while As(III) is in molecular form (H3 AsO3 or HAsO2 ).

different species as well as on the type of matrices. For arsenic speciation, the choice of the most appropriate method is of great importance for obtaining reliable and accurate results.

Arsenic in Water: Determination and Removal http://dx.doi.org/10.5772/intechopen.75531 21

The authors are grateful to the Ministry of Education and Science of the Republic of Serbia

which supported our scientific work (projects no. TR37009, TR37010 and III43009).

**Acknowledgements**

**Abbreviations**

Arsenic compounds

As arsenic

iAs inorganic arsenic

oAs organic arsenic

As(III) arsenite ion

As(V) arsenate ions

AsB arsenobetaine

AsC arsenocholine

MMA monomethylarsenic acid

DMA dimethylarsenic acid

TMAO trimethylarsine oxide

IC ion chromatography

MS mass spectrometry

TETRA tetramethylarsonium ion

Methods and techniques for arsenic determination

AES atomic emission spectrometry

ASV anodic stripping voltammetry

CSV cathodic stripping voltammetry

HPLC high-performance liquid chromatography

ICP-MS inductively coupled plasma-mass spectrometry

Arsenic compounds are colorless and odorless, and testing water for arsenic is an important strategy for the health and well-being of people. Working with a water professional to monitor and maintain the quality of the well and water supply is an important responsibility.

In this work, methods for arsenic and arsenic speciation separation, determination and removal were reviewed. There are numerous methods for separation and determination of arsenic species in water. It is very important to recognize easy, simple and inexpensive methods to estimate the very low concentrations of arsenic.

The total concentration of arsenic in drinking water can be detected by simple Gutzeit method, and some similar colorimetric methods of comparing stains produced on treated paper strips. Although its minimum detectable concentration is 1.0·μ L−1, these tests should be used when only a qualitative or semiqualitative detection is needed.

For precise, and reliable determination of arsenic in water, only sophisticated analytical techniques as ICP-MS, GF-AAS and HG-AAS can be applied. These methods are approved by US EPA. The features of these methods are high sensitivity, high accuracy, minimal sample volume; no sample pretreatment and short measurement time with minimum detectable concentration of 0.1 μ L−1. They are expensive, need lot of knowledge for operating and interpretation of data.

For As speciation analysis, well-established methods that involve the coupling of separation techniques, such as HPLC with a sensitive detection system, that is, ICP-MS, are recommended, and they are mostly used. Through the limits, it is possible to define the smallest concentration of analyte that can be reliably detected and quantified. Limit of detection for the HPLC-ICP-MS system is 0.001 μ L−1. This system is also expensive and needs lot of knowledge for operating and interpretation of data.

In all works, a special attention is paid to the preservation of arsenic species in environmental water samples for reliable speciation analysis. An appropriate procedure for the extraction of arsenic species from water should be accomplished without changing any original state of arsenic. This is still a challenging topic for research. The proposed system showed themselves to be accurate, precise and time efficient, as just a very simple sample treatment is required. Successful application of all methods required considerable practice.

Sorption processes (ion exchange, adsorption, chemisorption) with regeneration capability are proven as efficient and low-cost treatment methods for the removal of arsenic species from water. Separation of arsenic species using these new selective and chemically active sorbents recognize as a cost- and time-saving alternative to the traditional extraction techniques. The major drawback of all these techniques is that they are unable to remove As(III) efficiently.

Membrane separation technologies, such as RO, NF, UF, MF, are recommended for the removal of arsenic from water in water treatment plants.

Although there are numerous research papers focused on extraction techniques, yet it is not possible to set universal extraction procedures. These procedures depend on the presence of different species as well as on the type of matrices. For arsenic speciation, the choice of the most appropriate method is of great importance for obtaining reliable and accurate results.
