Arsenic

1
Arsenic

• I am evil, poisonous smoke
• But when from poison I am freed,
• Through art and sleight of hand,
• Then can I cure both man and beast,
• From dire disease ofttimes direct them
• But prepare me correctly, and take great care
• That you faithfully keep watchful guard over me
• For else I am poison, and poison remain,
• That pierces the heart of many the one.
• (Valentini, 1694)

2
Antiquity

• Arsenic was one of the first elements known to
  man regardless of whom you credit with its
  discovery.
• 4th Century B.C. Aristotle referred to arsenic
  as sandarach, which is arsenic trisulfide.
• 1st Century B.C. Pliny states that arsenic is
  found in gold and silver mines.

3
Middle Ages

• 11th Century 3 species of arsenic are known
  white (arsenic trioxide), yellow (arsenic
  trisulfide) and red (arsenic disulfide).
• 13th Century Albertus Magnus commonly credited
  with discovering metallic arsenic.
• 16th Century Schröder describes process for
  isolating metallic arsenic.
• Others credit Paracelsus, the father of
  toxicology, with the first isolation of metallic
  As.

4
Newer History

• Following Schröders isolation of As via a
  reduction, N. Lemery also isolates metallic
  arsenic by heating arsenic trioxide with soap.
• 18th Century Arsenic is understood enough to be
  classified as a semi-metal.
• Today Many Southeast Asian countries have
  arsenic-contaminated water supplies.

5
Alchemy of Arsenic

• Mined by early Greek, Chinese and Egyptian
  civilizations and believed to have mystical
  powers.
• Its poisonous qualities were recognized early and
  often seen as supernatural.
• See its alchemical symbol

6
The Name

• zarnikh?arsenikon?arsenic
• Arsenic originally takes its name from the
  ancient Persian word zarnikh, meaning yellow
  orpiment (arsenic trisulfide).
• The word was adopted into Greek as arsenikon and
  later anglicized as arsenic.

7
Historical Uses of Arsenic

• Arsenic was used in Victorian times by women to
  make skin and complexion whiter and smoother.
• In 1900, Paul Ehrlich found the arsenic compound
  Salvarsan, which was used to kill
  syphilis-causing bacteria.

8
King of Poisons

• Arsenic has been used as a poison for thousands
  of years.
• While hemlock was the poison of choice for the
  Greeks, arsenic became the poison of choice for
  everyone from the Romans to people in Renaissance
  times.
• Dioscorides, a physician in Neros court,
  described As as a poison 1st Century B.C.

9
Poison of Kings

• Arsenic poisoning of political enemies became so
  popular in ancient Rome that, in 82 B.C., that
  the Lex Cornelia was issued, believed to be the
  first law against poisoning.
• Strong evidence was brought forth by John Marsh,
  founder of the Marsh test for detecting arsenic,
  suggesting Napoleon was administered lethal doses
  of Arsenic by someone in his personal guard.
  Marshs test was not taken seriously by the jury
  and the accuser, who later confessed, was
  acquitted.

10
Gift of the Borgias

• The prominent Italian family invited many guests
  to their home and poisoned them by putting
  arsenic in their wine and then, via church law,
  confiscating what they owned. A pope and
  multiple cardinals were even killed by arsenic
  poisoning by the Borgias.
• Many to this day maintain that arsenic greatly
  improves the taste of wine.

11
Famous Arsenic Poisonings

• Charles Francis Hall, Arctic explorer, punished
  insolent crew members by forcing them to ingest
  arsenic.
• Claire Booth Luce, once American ambassador to
  Italy, was compelled to resign her position after
  becoming severely ill from unknowingly ingesting
  chips of the arsenic-based paint that was falling
  from the ceiling.

12
More Arsenic Poisoning

• In 1878, two Connecticut women poisoned and
  beaten the case became the subject of the novel
  Arsenic Under the Elms by Virginia McConnell.
• In 1998, a mass arsenic poisoning in Japan took
  place via curried beef being served at a
  festival. 4 died, 40 severely wounded. The
  trial is ongoing now.

13
Arsenic Eaters

• In 18th Century Austria, mountaineers began
  consuming arsenic in small quantities in order to
  build up a tolerance against it and so protect
  themselves from their poisoning by their enemies.
• Research on lab animals has shown that a certain
  amount of tolerance can be built up against
  arsenic exactly why this tolerance occurs is, to
  this day, is uncertain.

14
WW2 Poison Gas

• Under the name Lewisite, the Nazis developed a
  poison gas based on arsenic designed for mass
  poisoning of enemy troops. Upon contact with the
  sulfur in the protein keratin found in hair, huge
  blisters form and hydrochloric acid is produced
  as a byproduct.
• The British responded by developing dimercaprol,
  which drew As from other body parts to prevent
  the poison from working.

15
General Information

• Name arsenic
• Symbol As
• Atomic number 33
• Atomic weight 74.92160
• Group number 15
• Group name Pnictogen
• Period number 4
• Electron configuration Ar 3d10 4s2 4p3

16
General Information (contd)

• Standard state solid at 298 K
• Sublimates at 887 K
• Color metallic grey
• Classification Metalloid
• Fist isolated by reduction of orpiment (As2S3)
  using heat, eggshells (CaCO3), and charcoal
• As2S3(s) 3CaCO3(s) 6O2(g) ? ? As2O3(s)
  3CaSO4(s) 3CO2(g)
• 2As2O3(s) 3C(s) ? 4As(s) 3CO2(g)
• Oxidation States 3, 5

17
General Information (contd)

• Crystal structure rhombohedral
• Electronegativity 2.18 (Pauling scale)
• Ionization energies1st 947.0 kJ/mol 2nd 1798
  kJ/mol 3rd 2735 kJ/mol
• No Naturally occurring Isotopes present
• 75As 100

18
Reactions of Arsenic

• Reactions with Oxygen
• 4As(s) 5O2(g) ? As4O10(s)
• 4As(s) 3O2(g) ? As4O6(s)
• Arsenic Does Not React with Water under Normal
  Conditions
• Reactions With Halogens
• Reacts with F2 (g) 2As(s) 5F2(g) ? 2 AsF5(g)
  colorless
• 2As(s) 3F2(g) ? 2AsF3(l) colorless

19
Reactions of Arsenic (contd)

• Reactions With Halogens (contd)
• 2As(s) 3Cl2(g) ? 2AsCl3(l) colorless
• 2As(s) 3Br2(g) ? 2AsBr3(s) pale yellow
• 2As(s) 3I2(g) ? 2AsI3(s) red
• Other Common Compounds Include
• Arsenic acid (H3AsO4)
• Arsenous acid (H3AsO3)
• Arsenic trioxide (As2O3)
• Arsine (Arsenic Trihydride AsH3)
• Cadmium arsenide (Cd3As2)
• Gallium arsenide (GaAs)
• Lead hydrogen arsenate (PbHAsO4)

20
Biological Reactions

• Present as As5 and As3
• As3 is the Most Toxic Form
• Also known as Arsenite or Inorganic Arsenic
• A Mixture of As5 and As3 Compounds Were
  Commonly Used in the Treatment of Disease in the
  19th Century
• Most Notably Arsenic was Present in Fowlers
  Solution
• This solution was highly regarded as a cure all
  and ingested by children and adults alike

21
Biological Reactions (contd)

• What is the Mechanism by which Arsenic is Toxic?
• Arsenic is an Allosteric Inhibitor of Enzymes
• This means that it modifies a regulatory site on
  an enzyme decreasing/preventing its function
• It Specifically Targets Lipothiamide
  Pyrophosphatase and Dihydrolipoamide
• These enzymes are both important components of
  metabolism, specifically the Pyruvate
  Dehydrogenase Complex

22
Biological Reactions (contd)

• The Reaction Mechanism of Inhibition is as
  follows

23
Biological Reactions (contd)

• The Reaction Is one of Redox
• The Sulfhydryl groups are Oxidized creating an
  Arsenic compound that prevents reduction of the
  Sulfur Groups
• This prevents metabolism from moving forward at
  the Pyruvate Dehydrogenase Complex

24
Biological Reactions (contd)

• Prevention of the Metabolic Breakdown of Pyruvate
  leads to Starvation on a Cellular Level
• There is also a build-up of compounds such as
  pyruvate that lead to neurological damage
• This leads to death from multi system organ
  failure

25
Environmental Effects of Arsenic

• On January 23, 2001, the Environmental
  Protection Agency finalized the Arsenic Rule,
  which reduced the drinking water maximum
  contaminant level (MCL) for arsenic from 50 parts
  per billion (ppb) to 10 ppb. All community and
  nontransient noncommunity water systems are
  required to comply with this new standard by
  January 23, 2006. The contamination of a drinking
  water source by arsenic can result from either
  natural or human activities. Arsenic is an
  element that occurs naturally in rocks and soil,
  water, air, plants, and animals. Volcanic
  activity, the erosion of rocks and minerals, and
  forest fires are natural sources that can release
  arsenic into the environment. Although about 90
  percent of the arsenic used by industry in the
  United States is currently used for wood
  preservative purposes, arsenic is also used in
  paints, drugs, dyes, soaps, metals and
  semiconductors. Agricultural applications,
  mining, and smelting also contribute to arsenic
  releases.

26
Arsenic Concentrations in United States
27
Health Effects

• Dissolved arsenic found in ground water is
  generally in inorganic form, as arsenite,
  As(III), and arsenate, As(V). Most arsenic is
  present as arsenite, which tends to be more
  mobile in ground water than arsenate. Arsenite
  is more difficult to remove than arsenate and has
  the potential to generate more health concerns.
  Ingesting inorganic arsenic over many years
  (chronic exposure) increases the risk of skin
  cancer and tumors of the bladder, kidney, liver,
  and lung. It has also been found to cause blood
  vessel damage, heart problems, darkening of the
  skin, and nervous system damage. Recently, the
  National Academy of Sciences (NAS) has reviewed
  the updated toxicological database for arsenic
  and has determined that cancer risks from arsenic
  exposures are greater than previously estimated.
  This prompted a call to lower the drinking water
  standard for arsenic in order to protect human
  health. Reducing arsenic from 50 ppb to 10 ppb
  will prevent cancerous diseases, as well as
  numerous cases of non-cancerous
• diseases, such as skin conditions and heart
  disease.

28
EPA Water Regulations

• Due to adverse health and environmental effects
  Arsenic levels
• regulated in potable water and discharges into
  nonpotable water
• Arsenic levels in potable water
• Currently 50 ppb (est. 1942)
• New Regulations 10 ppb (2006)
• Arsenic discharges into non-potable waters,
  generally
• Fresh Water 36 ppb
• Sea Water 340 ppb

29
Uses Of Arsenic

• Agriculture Lead arsenate, copperacetoatoarsenite
  , sodium arsenite,
• calcium arsenate and organic arsenic compounds
  are
• used as pesticides. Methyl arsonic acid and
  dimethyl arsinic acid are
• used as selective herbicides.
• Forestry Chromated copper arsenite,sodium
  arsenate and zinc arsenate are used as wood
  preservatives.
• Industry Arsenic is used in the preparation of
  dyes, poisonous
• gas, transistor, as a component of
  semiconductor, as a preservative in tanning and
  in the industry of textile, paper etc.
• Pharmaceutical Small amount of arsenic continue
  to be used as drugs in some countries. Medicine
  arsenic has been used since the 5th century BC
  when Hippocrates recommended the use of an
  arsenic sulfide for the treatment of abscess.
  Arsenic preparations have been used for the
  treatment of skin disorder, tuberculosis,
  leukemia, asthma, leprosy, syphilis, amoebic
  dysentery etc.. Homeopaths are also using
  arsenic as drug.

30
Uses of Arsenic in Agriculture

• Arsenic-based chemicals were used to kill boll
  weevils and to remove plants' leaves before
  harvest. Quite a lot of land in Mississippi and
  Arkansas that previously grew cotton is now used
  for rice cultivation. When rice was initially
  first grown in these soils, the crop often failed
  because of the an arsenic-induced disease known
  as straighthead. So new, straighthead-resistant
  rice varieties were bred that could withstand the
  arsenic.

31
Problems With Arsenic in Agriculture

• Rice grown in the United States contains an
  average of 1.4 to 5 times more arsenic than rice
  from Europe, India and Bangladesh, according to a
  survey of grains from around the world. Rice is
  the agricultural product most likely to contain
  high levels of arsenic because it's grown in
  flooded paddies. The watery, oxygen-free
  environment causes naturally occurring arsenic in
  the soil to be freed and thus more readily taken
  up by the plant.

32
Uses of Arsenic in Forestry

• In Australia, a treatment called Copper Chrome
  Arsenic(CCA) is used in the forests. The copper
  in the treatment acts as a fungicide while the
  arsenic acts as an insecticide. The arsenic in
  this treatment makes this potentially hazardous
  to humans and the environment. According to a
  number of studies undertaken in US, Europe and
  Australia, arsenic leaches out of CCA treated
  timber over time, accumulating on the surface of
  CCA treated timber and in the surrounding soil
  which can eventually travel down to ground water
  and/or be washed into downstream rivers and
  creeks.
• Paints and sealants can be used to contain the
  arsenic within the timber but this is only a
  short-term measure, typically lasting for only 6
  months.

33
Problems With Arsenic in Forestry

• In short, issues arising from CCA treated timber
  are as follows
• Accumulation of arsenic on the treated timbers
  surface, directly exposing humans to arsenic.
• Accumulation of arsenic in surrounding soils,
  thus contaminating soils and increasing the risk
  of arsenic uptake by plants.
• Arsenic leaching into ground water and downstream
  waterways, which can lead to plants and
  animal-uptake of arsenic.
• Because of the potential hazards of CCA, it is
  advised that CCA- treated timber be properly
  disposed of within a lined landfill. The timber
  should not be recycled, burned or mulched. This
  may be problematic in the more remote parts of
  PNG where properly constructed and lined
  landfills may not exist!!!!

34
Pharmaceutical Uses

• A homeopathic remedy uses tiny amounts of arsenic
  that could cure stomach cramps, according to
  European research.
• The technique uses the similiar principle - the
  idea that poisons that produce vomiting and
  stomach cramps can reverse the symptoms when
  heavily diluted.
• Arsenic trioxide (As2O3 ATO) has been
  considerable in the treatment of relapsed acute
  promyelocytic leukemia (APL), inducing partial
  differentiation and promoting apoptosis of
  malignant promyelocytes.

35
Arsenic III vs Arsenic V

• Arsenic is found in the environment in two
  forms Arsenic V (arsenate), and Arsenic III
  (arsenite). Arsenic V is the oxidized state
  commonly found in surface water and some ground
  water sources. Arsenic III is not oxidized and is
  found in ground water sources. Most of the
  arsenic found in ground water and occurs in the
  Arsenic III state. The Best Available
  Technologies for compliance identified by EPA are
  recommended for removing arsenic in the Arsenic V
  state. In order to use these technologies to
  remove Arsenic III, the Arsenic III must be
  oxidized to the Arsenic V state prior to
  treatment. Pre-oxidation technology includes
  chlorination, potassiumpermanganate and ozone.

• Contaminants That Inhibit Oxidation of As (III)
• Sulfide
• Total Organic Carbon
• Iron - Fe (II)

36
Treatment Options

• There are two categories of options that water
  systems may choose to comply with the new arsenic
  standard non-treatment options and treatment
  options. Non-treatment options such as blending a
  high arsenic water source with another source
  that is lower in arsenic, replacing water sources
  with new sources or becoming consecutive to
  another water system, tend to be more economical
  and easier to implement and manage than treatment
  options. Typically there is a one-time capital
  cost and minimal maintenance cost associated with
  the non-treatment options.
• Treatment options may include activated alumina
  (or another type of adsorptive media), reverse
  osmosis point-of-use (POU) devices, modified lime
  softening or oxidation/filtration (including
  greensand filtration). Treatment options are
  usually more expensive to implement and more
  complicated to manage than non-treatment options,
  and may require substantial capital investments.
  Treatment processes for arsenic are complex and
  require appropriately trained and certified water
  system operators.

37
Removal of Arsenic from water Conventional
technologies

• Coagulation/Filtration Essentially
  precipitation and filtration processes (alum,
  ferric salts, lime, ect.)
• Absorptive Processes Primarily alumina Al2O3
• Ion exchange with strong base anion exchange
  resins
• Reverse osmosis

38
Removal of Arsenic from water Emerging
technologies

• Iron oxide coated substrates (sand, alumina,
  ect.)
• Precipitation iron oxides
• Granular ferric hydroxide Fe(OH)3
• -Currently the most popular

39
Non-Treatment Options

• Non-treatment options may require lower initial
  financial investment and less maintenance than
  treatment options. However, some non-treatment
  options may require significant changes to the
  overall configuration and operation of the water
  system. These options do not involve actively
  altering the chemistry of water before it is sent
  to customers. They include
• Blending the contaminated source with another
  source that contains lower arseniclevels (a new
  source may require a new or revised Water
  Appropriation Permit)
• Modifying source water contributions to a well
  by altering the well design (an option if the
  well is screened at multiple depths)
• Replacing water sources (a new source may require
  a new or revised Water Appropriation Permit)
• Interconnecting to another water system and
  abandoning wells with elevated arsenic levels

40
Sorption Process(Activated Alumina)

• The sorption process utilizes an adsorptive
  medium, either activated alumina or iron based,
  of very small grains which are packed into one or
  more large pressure vessels. Water is
  continuously passed through the vessel(s) until
  the medium is exhausted, when it is simply
  disposed of and replaced with fresh medium or the
  media is regenerated. The alumina media can be
  disposed of in a normal landfill without
  regeneration.
• Key considerations
• Optimal pH 5.5 8.3 activated alumina is more
  economical at the low end of the pH range
• Low operator skill required
• Low water loss
• Medium cost
• Spent media and backwash water do not generate
  hazardous wastes

41
Membrane Process (Reverse Osmosis)

• Reverse osmosis uses high pressure to force
  water through a membrane with microscopic holes
  that prevent arsenic and other large contaminants
  from passing through. For systems serving fewer
  than 100 connections and an average population of
  less than 300, POU treatment may be a reasonable
  option. POU devices are typically installed under
  the kitchen sink and are considered to be cost
  effective. The devices must each be tested at
  the normal frequency (once per year for surface
  water, once every three years for ground water)
  to determine if they comply with current
  standards.
• Key considerations
• Ease of installation
• Treats only water used for human consumption
  (typically about 2 of a systems total flow)
• Low initial capital costs
• Reduces engineering costs associated with
  construction of full-scale treatment

42
Precipitation Process (Oxidation/Filtration)

• This technology oxidizes naturally occurring
  iron, which binds to arsenic and is then removed
  by filtration.
• Key considerations
• Optimal pH 5.5 8.5
• Optimal Iron levels gt 0.3 mg/L
• Medium operator skill required
• Medium costs
• Wastes generated are the backwash water and
  sludge
• Disposal of backwash water may require a ground
  water discharge permit

43
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