The ppt give a deep understanding of arsenic contamination and its detection , estimation and removal by sensors.

1. Environmental Chemistry
Go Green – With Green
Department of Chemistry
IIT Guwahati
15/11/2014

2. Term Paper Presentation
Arsenic Sensors
Guided by :-
Professor Kingsuk Mahata
Assistant Professor
Department of Chemistry

3. Team Members- The Arsenic Group
• SKV
Shreyash Rai
Gaurav Agrawal
Saurav Pandey

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. 1. The Element Arsenic

6. ARSENIC

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. 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. Relative Toxicity

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. 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. 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. 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. Contaminated Forms
•
Arsenic Acid Arsenous Acid
Arsenic and Arsenous Acids and their derivatives
are responsible for ground water contamination

15. Tolerance Level
World Health Organization
recommended tolerance value of 10
ppb for drinking water.

16. World Map

17. Affected areas of ASSAM

18. 4. Chemical Sensors

19. PET Mechanism

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. Preparation
2,6-bis((Z)-(2-((pyridin-2-yl)methylthio)phenylimino)methyl)-4-
methylphenol (APC)

22. 6. Sensing Technique by PET

23. Emission Spectra of Arsenate bound APC

24. 7. Estimation of Concentration of arsenate ion

25. Comparision of Spectra

26. Effect Of other Ions on detection

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. 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. Arsenate contaminated water
APC functionalised
merrified polymer+arsenate
Turn on Fluroscence
Arsenate contaminated
water APC stained microbes grown in
As contaminated water

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. coagulation

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. 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. 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.