Arsenic sensors


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Arsenic sensors

  1. 1. Environmental Chemistry Go Green – With Green Department of Chemistry IIT Guwahati 15/11/2014
  2. 2. Term Paper Presentation Arsenic Sensors Guided by :- Professor Kingsuk Mahata Assistant Professor Department of Chemistry
  3. 3. Team Members- The Arsenic Group • SKV Shreyash Rai Gaurav Agrawal Saurav Pandey
  4. 4. Contents 1. Arsenics – The metalloid 2. Arsenate Poisoning 3. Arsenic contamination of ground water 4. Chemical Sensing -Fluorophore and receptor 5. What is APC-Merrified Polymer 6. Detection of Arsenic 7. Estimation of Arsenic Concentration 8. Removal of Arsenic from Drinking water
  5. 5. 1. The Element Arsenic
  6. 6. ARSENIC
  7. 7. Chemical Properties • When heated in air, arsenic oxidizes to arsenic trioxide; the fumes from this reaction have an odor resembling garlic. • This odor can be detected on striking arsenide minerals such as arsenopyrite with a hammer. • Arsenic sublimes upon heating at atmospheric pressure, converting directly to a gaseous form without an intervening liquid state at 887 K (614 °C.Arsenic makes arsenic acid with concentrated nitric acid, arsenious acid with dilute nitric acid, and arsenic trioxide with concentrated sulfuric acid.
  8. 8. 2. Arsenic Poisoning • Arsenic poisoning is a medical condition caused by elevated levels of arsenic in the body. • The dominant basis of arsenic poisoning is from ground water that naturally contains high concentrations of arsenic. • A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning from drinking water
  9. 9. Relative Toxicity
  10. 10. Biological Action • Arsenic interferes with cellular longevity by inhibition of an essential metabolic enzyme pyruvate dehydrogenase (PDH) complex, which catalyzes the oxidation of pyruvate to acetyl-CoA by NAD+. • With the enzyme inhibited, the energy system of the cell is disrupted resulting in a cellular apoptosis episode.
  11. 11. Signs and Symptoms • Symptoms of arsenic poisoning begin with headaches, confusion, severe diarrhea, and drowsiness. • As the poisoning develops, convulsions and changes in fingernail pigmentation called leukonychia striata may occur. Aldrich Mee’s lines (leuchoparonychia) on nails are also seen. • When the poisoning becomes acute, symptoms may include diarrhea, vomiting, blood in the urine, cramping muscles, hair loss, stomach pain, and more convulsions. The organs of the body that are usually affected by arsenic poisoning are the lungs, skin, kidneys, and liver.
  12. 12. Ground Water Contamination • Arsenic contamination of groundwater is often due to naturally occurring high concentrations of arsenic in deeper levels of groundwater. • It is a high-profile problem due to the use of deep tubewells for water supply in the Ganges Delta, causing serious arsenic poisoning to large numbers of people • A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water
  13. 13. Occurence in Water • However, cationic As(III) species rarely exist in the environment; rather, toxic arsenic species existing in the environment are either [HAsO4]2− (AsV ) or [HAsO3]2− (AsIII ). • Although inorganic arsenic species(AsIII and AsV ) are present to a greater extent in natural water, lesser amounts of Monomethylarsonic acid(MMA) and Dimethylarsonic acid (DMA) also exist • . Arsenic acid tends to exist as the ions [HAsO4]2− and [H2AsO4]− in neutral water, whereas arsenous acid is not ionized.These occur due to erosion of arsenic rocks.
  14. 14. Contaminated Forms • Arsenic Acid Arsenous Acid Arsenic and Arsenous Acids and their derivatives are responsible for ground water contamination
  15. 15. Tolerance Level World Health Organization recommended tolerance value of 10 ppb for drinking water.
  16. 16. World Map
  17. 17. Affected areas of ASSAM
  18. 18. 4. Chemical Sensors
  19. 19. PET Mechanism
  20. 20. 5. APC-Merrifield Polymer • Merrifield Resin is a polystyrene resin based on a copolymer of styrene and chloromethylstyrene. • In addition, this polymer is also cross- linked with divinylbenzene present in the monomer composition up to 5% APC is appended on chloromethyl polystyrene polymer
  21. 21. Preparation 2,6-bis((Z)-(2-((pyridin-2-yl)methylthio)phenylimino)methyl)-4- methylphenol (APC)
  22. 22. 6. Sensing Technique by PET
  23. 23. Emission Spectra of Arsenate bound APC
  24. 24. 7. Estimation of Concentration of arsenate ion
  25. 25. Comparision of Spectra
  26. 26. Effect Of other Ions on detection
  27. 27. Detection of intracellular arsenate • The arsenate compounds may exist as free ions in the water or may be found combined with one or more organism. • Many bacteria has arsenic components in their cell. This is called intracellular arsenic. Even this arsenate in cells can be detected by APC sensors. • The APC is cell permeable and generates bright green fluorescence upon interaction with intracellular arsenate. Hence the APC can be useful in detection of intracellular arsenate
  28. 28. 8. Removal Of Arsenic • Removal of arsenate from drinking water is done by using APC-Merrifield polymer. The drinking water is passed through syringe column containing merrifield polymer. • The concentration of arsenate was measured in the effluent using the developed method. Moreover, arsenate sorbed polymer beads were subjected to SEM and fluorescence microscopy. The results indicate that the polymer can efficiently remove the arsenate present in the water. • Additionally, both the images indicated that arsenate has been sorbed onto the resin as the color of the fluorescence image turned green and the morphology and surface of the bead abruptly changed. The further testing of purified water showed very less concentration of arsenic hence supporting the process.
  29. 29. Arsenate contaminated water APC functionalised merrified polymer+arsenate Turn on Fluroscence Arsenate contaminated water APC stained microbes grown in As contaminated water
  30. 30. Arsenic treatment • Coagulation/filtration (also known as flocculation) removes arsenic by coprecipitation and adsorption using iron coagulants. Coagulation/filtration using alum is already used by some utilities to remove suspended solids and may be adjusted to remove arsenic. • Iron oxide adsorption filters the water through a granular medium containing ferric oxide. Ferric oxide has a high affinity for adsorbing dissolved metals such as arsenic. The iron oxide medium eventually becomes saturated, and must be replaced.
  31. 31. coagulation
  32. 32. Arsenic treatment • Activated Alumina is an adsorbent that effectively removes arsenic. Activated alumina columns connected to shallow tube wells in India and Bangladesh have removed both As(III) and As(V) from groundwater for decades • Ion Exchange has long been used as a water- softening process, although usually on a single- home basis. Traditional anion exchange resins are effective in removing As(V) • Both Reverse osmosis and electrodialysis (also called electrodialysis reversal) can remove arsenic with a net ionic charge.
  33. 33. APPLICATIONS • This method can be used to detect arsenic in the form of arsenate ions from groundwater. Even the intracellular arsenic present inside cells of bacteria can also be detected by this method. • The sensor can be used to calculate and maintain the composition of arsenic in medicines used by people. Further applications includes determination of the arsenic concentration in arsenic based pesticides. • It can also be used to get the arsenic composition in arsenic based semiconductors like Gallium- Arsenic which is used as LED and in solar panels
  34. 34. Conclusion • APC, a new low cost arsenate sensor with visible light excitation can detect as low as 0.001 mM arsenate. • Estimation of Arsenate concentration is obtained from the plot of intensity vs concentration. • Removal of arsenate concentration is done by APC- implanted Merrified polymer. • Simultaneous detection, determination and removal of arsenate by fluorescence method using a single substance are reported for the 1st time. • The presence of other ions doesn’t affect the detection process of arsenate by APC sensor. • The method can be used to remove arsenate impurities from water and make it fit for drinking.