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copper oxide facts

updated sat 26 jul 08

 

Ivor and Olive Lewis on sat 19 jul 08


Something else for the Archives.
Those who have access to "Phase Diagrams For Ceramists" (1976) might
care to study Diagram 164 , Cu2-SiO2 , by A. S. Berezhoi. L. I.
Karyakin and I. F Dudavskii. (p86)
This shows that above 1060 deg C there will be Solid Silica and
liquid Copper Oxide. This seems to suggest that Silicon dioxide is not
soluble in liquid Copper oxide nor are their liquids miscible above
the melting point of Silica. Nor is there any chemical interaction
that would lead to the production of a Copper Silicate.
CRC Hand book of Chemistry and Physics list a Copper Borate. CAS No
39290-85-2.
Black Copper oxide is soluble in molten Borax which solidifies to a
pale green glass.
Best regards,
Ivor Lewis.
Redhill,
South Australia.

Lee Love on sat 19 jul 08


On Sat, Jul 19, 2008 at 2:11 AM, Ivor and Olive Lewis
wrote:

> This shows that above 1060 deg C there will be Solid Silica and
> liquid Copper Oxide.

That is really useful to know. Ceramics can easily replace
antibacterial copper and brass doorplates. Some hosptials are switch
back from stainless steel to copper/brass because the steel doorplates
are not antibacterial and antiviral like copper containing ones.

Also, one of the factors for people switching from copper to
plastic water containers in India is the cost. Ceramic containers
containing copper would be less expensive than the traditional metal
containers. Manufacturers could also investigate plastics containing
copper.
--
--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/

"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi

Ivor and Olive Lewis on sun 20 jul 08


Dear Lee Love
I am not sure it is wise to infer that Copper oxide has the same
antibacterial activity as the patina which devlops on metallic copper.
The point about the note below was that Copper Oxide and Silicon
Dioxide do not mix or form binary compounds so exposure to an acid
will always induce leaching of Copper.
I should point out that Copper Borate is rated as insoluble in Water
but soluble in acid.
Best regards,
Ivor Lewis.
Redhill,
South Australia.


> This shows that above 1060 deg C there will be Solid Silica and
> liquid Copper Oxide.

<antibacterial copper and brass doorplates. Some hosptials are switch
back from stainless steel to copper/brass because the steel doorplates
are not antibacterial and antiviral like copper containing ones.>>

Des & Jan Howard on sun 20 jul 08


Lee
I noticed a number of work socks in a store last city trip that stated
they contained copper as an antibacterial measure. The copper being part
of the fibre not just a treatment of the yarn.
Could be the start of something good?
Des

Lee Love wrote:
> That is really useful to know. Ceramics can easily replace
> antibacterial copper and brass doorplates. Some hosptials are switch
> back from stainless steel to copper/brass because the steel doorplates
> are not antibacterial and antiviral like copper containing ones.
>
> Also, one of the factors for people switching from copper to
> plastic water containers in India is the cost. Ceramic containers
> containing copper would be less expensive than the traditional metal
> containers. Manufacturers could also investigate plastics containing
> copper.

--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850

02 6373 6419

Lee Love on sun 20 jul 08


On Sun, Jul 20, 2008 at 1:39 PM, steve graber wrote:
> this is an old known fact, yet exploited in areas where it simply doesn't work. such as socks.
> Jacuzzi, other spa manufacturers, exploits this by adding silver threads to their filters.

Steve, maybe you didn't see my previous post, but they are doing
chlorine free pool filtering and drinking water filtering using
copper/zinc filters.

Funny thing is, the chlorine in city water and its reaction
to other chemicals is probably a bigger health hazard than anything
you put the water in. That is why I use a 10 stage filter for my
drinking water.


--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/

"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi

Steve Mills on sun 20 jul 08


--- On Sat, 7/19/08, Des & Jan Howard wrote:
From: Des & Jan Howard
Subject: Re: Copper Oxide facts
To: CLAYART@LSV.CERAMICS.ORG
Date: Saturday, July 19, 2008, 11:26 PM

Lee
I noticed a number of work socks in a store last city trip that stated
they contained copper as an antibacterial measure. The copper being part
of the fibre not just a treatment of the yarn.
Could be the start of something good?
Des

Like Green Feet???

Steve
Bath
UK

Lee Love on sun 20 jul 08


On Sun, Jul 20, 2008 at 1:10 AM, Ivor and Olive Lewis
wrote:
> Dear Lee Love
> I am not sure it is wise to infer that Copper oxide has the same
> antibacterial activity as the patina which devlops on metallic copper.

Your assignment is to test this. ;^) (haha. You are always handing
out assignments.)

--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/

"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi

Lee Love on sun 20 jul 08


On Sat, Jul 19, 2008 at 5:26 PM, Des & Jan Howard wrote:
> Lee
> I noticed a number of work socks in a store last city trip that stated
> they contained copper as an antibacterial measure. The copper being part
> of the fibre not just a treatment of the yarn.
> Could be the start of something good?

Sometimes, the old ways are better. Some folks a phobic about
anything that is not "new, improved, cutting edge, break thru", but
that is just as close minded as refusing o recognize new discoveries.

If it works, use it!

The pennies seems to be keeping the mildew out of the
de-chlorinated water. When I get a chance, I will experiment with
copper liner glazes for vases.

--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/

"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi

steve graber on sun 20 jul 08


this is an old known=A0fact, yet exploited in areas where it simply doesn't=
work.=A0 such as socks.=A0 =0AJacuzzi, other spa manufacturers,=A0exploits=
this by adding silver threads to their filters.=A0 the idea being "it kill=
s bacteria".=A0 actually while it does keep bacteria from growing on the FI=
LTER, it does little to the tub.=A0 but it's a great sales pitch line.=A0 =
=0Arecall the old days when they'd use copper sheets to cover the bottom of=
a square rigger sailboat?=A0=A0that was to keep the barnicals from growing=
there.=A0 generally it works.=A0 =0Aperhaps there is a value in pottery bo=
wls.=A0 it certainly looks nice.=A0 but i doubt there is an appreciable amo=
unt of bacteria killed this way.=A0 =0Asee ya=0A=A0Steve Graber, Graber's P=
ottery, Inc=0AClaremont, California USA=0AThe Steve Tool - for awesum textu=
re on pots! =0Awww.graberspottery.com steve@graberspottery.com=0A=0A=0A=0A-=
---- Original Message ----=0AFrom: Des & Jan Howard =
=0ATo: CLAYART@LSV.CERAMICS.ORG=0ASent: Saturday, July 19, 2008 3:26:46 PM=
=0ASubject: Re: Copper Oxide facts=0A=0ALee=0AI noticed a number of work so=
cks in a store last city trip that stated=0Athey contained copper as an ant=
ibacterial measure. The copper being part=0Aof the fibre not just a treatme=
nt of the yarn.=0ACould be the start of something good?=0ADes=0A=0ALee Love=
wrote:=0A> That is really useful to know.=A0 Ceramics can easily replace=
=0A> antibacterial copper and brass doorplates.=A0 Some hosptials are switc=
h=0A> back from stainless steel to copper/brass because the steel doorplate=
s=0A> are not antibacterial and antiviral like copper containing ones.=0A>=
=0A>=A0 =A0 =A0 Also, one of the factors for people switching from copper t=
o=0A> plastic water containers in India is the cost.=A0 Ceramic containers=
=0A> containing copper would be less expensive than the traditional metal=
=0A> containers.=A0 Manufacturers could also investigate plastics containin=
g=0A> copper.=0A=0A--=0ADes & Jan Howard=0ALue Pottery=0ALue=A0 NSW=0AAustr=
alia=0A2850=0A=0A02 6373 6419=0A=0A=0A=0A

jonathan byler on mon 21 jul 08


silver works nice too, and from what I understand, leaches less, (and
is also less toxic???.) coper oxides and sulfides are rather nasty,
as I can attest to. Once as a foolish youth, I ate some soup out of
a copper bowl that had a fair bit of oxide in it. result was instant
vomiting. not cute. oh, well. at least i survived it with no
permanent damage.

I have ceramic water filters impregnated with silver that are
supposed to be anti-viral/anti-bacterial. they have super fine pores
and metallic silver finely dispersed in the ceramic structure. I
read once that people used to keep a small bar of silver in their
water storage container in order to keep down the bacteria, etc.
they also wrote that this is another reason people used to use silver
water pitchers if they could. can't remember the source anymore.

-jon


jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849

On Jul 19, 2008, at 9:59 AM, Lee Love wrote:

> On Sat, Jul 19, 2008 at 2:11 AM, Ivor and Olive Lewis
> wrote:
>
>> This shows that above 1060 deg C there will be Solid Silica and
>> liquid Copper Oxide.
>
> That is really useful to know. Ceramics can easily replace
> antibacterial copper and brass doorplates. Some hosptials are switch
> back from stainless steel to copper/brass because the steel doorplates
> are not antibacterial and antiviral like copper containing ones.
>
> Also, one of the factors for people switching from copper to
> plastic water containers in India is the cost. Ceramic containers
> containing copper would be less expensive than the traditional metal
> containers. Manufacturers could also investigate plastics containing
> copper.
> --
> --
> Lee Love in Minneapolis
> http://mashikopots.blogspot.com/
> http://claycraft.blogspot.com/
>
> "Let the beauty we love be what we do.
> There are hundreds of ways to kneel and kiss the ground." --Rumi

Ivor and Olive Lewis on tue 22 jul 08


As I recall there is an Apothecary's nostrum that is known as "Lunar
Caustic" which was used to bathe the eyes of new born infants to guard
against infection from Maternal Syphilis.
Lunar Caustic is a powerful disinfectant, now known as Silver Nitrate.
Best regards.
Ivor Lewis.
Redhill,
South Australia.

Lee Love on tue 22 jul 08


On Mon, Jul 21, 2008 at 11:21 AM, jonathan byler wrote:

> and metallic silver finely dispersed in the ceramic structure. I
> read once that people used to keep a small bar of silver in their
> water storage container in order to keep down the bacteria, etc.
>

Folks put silver dollars in their milk pitchers.

--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/

"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi

Neon-Cat on thu 24 jul 08


Copper, copper patina, copper oxides, birds, and pennies in a birdbath -
this post answers all my personal questions regarding ideas presented in
this interesting thread.

(this post contains a lot of sub- and superscripts in the chemistry reaction
notes section; it has been sent in an HTML version and is best viewed in
HTML/rich text)

The free copper ions generated by copper metal, copper oxides, and other
copper compounds, including those comprising copper patina, are the lethal
agent in copper algicides, pesticides, and bacteriastats - shine those
pennies and read on...

Although copper metal is insoluble in water, copper metal can be corroded by
water to yield water-soluble copper ions (Cu1+ and Cu2+). The corrosion of
copper in water is affected by temperature, pH, water hardness, other
substances in the water (oxygen, hydrogen, other elements, and organic
substances), and other paramaters such as the partial pressure hydrogen, the
reaction equilibrium constants (as calculated from Gibbs free energy for
reactions), the water ionization constant, etc.

Copper oxidizes slowly in air, corroding to produce a brown or green patina.
At higher temperatures the process is much faster and produces mainly black
copper oxide (CuO).

With natural weathering, lustrous, reddish copper will first turn a rich red
bronze color and eventually progress to a green, blue-green, or turquoise
color in the presence of air, moisture, atmospheric contaminants, salt, and
other chemicals. This observed coloration is called a 'patina' - a thin
layer of oxidative corrosion of the copper on the surface of the copper
metal composed of a layer of copper oxides. The distinctive green color of
aged copper is specifically called 'verdigris' (verde gris or 'the green of
Greece') and is a 1:1 mole mixture of Cu(OH)2 (Copper II hydroxide) and
CuCO3 (copper II carbonate).

The following gives a general timeline for the beginnings of a verdigris
patina:

7-9 years in saline climates (i.e. near the coast)
5-8 years near heavy industry
10-14 years in urban areas
30 years or more in a clean environment

See copper weathering photos:
http://www.copper.org/applications/architecture/arch_dhb/finishes/pdf/weathe
ring_chart.pdf

The chemical equation for the reaction that creates Verdigris:
2Cu (s) + H2O (g) ---> Cu(OH)2 (s) + CuCO3 (s)
where "s" is solid and "g" is gas

In practice, there are two forms of copper oxide when copper oxidizes in the
air. The first is copper (I) oxide, also known as cuprous oxide (Cu2O) and
the second is copper (II) oxide, or cupric oxide (CuO).

The chemical reaction that produces cupric oxide through oxidation in air:
2 Cu (s) + O2 (g) ---> 2 CuO (s)
CuO (s) + H2 (g) ---> Cu (s) + H2O (g)
CuO is a solid that does not separate into free ions of Cu2+ and O2-.

The Cu+1 ion is rarely found in solution because it tends to
disproportionate to Cu2+ and Cu:

2Cu+ (aq) -----> Cu2+ (aq) + Cu (s)

The energy content of refined metals and alloys is higher than that of the
original ores. In the process of corrosion, under either atmospheric or
aqueous conditions, metals and alloys, and any associated patinas, are
constantly trying to change back into lower energy ores or ore-like
compounds.

Copper oxide corrosion on surfaces can be removed by mechanic methods
(sanding, scraping, wire-brushing) or chemical means (nitric acid,
hydrochloric, sulfuric, etc.).

Some corrosion, reduction, oxidation, and precipitation reactions for copper
(under aqueous and/or atmospheric conditions):

Cu+ + e -----> Cu (s)
Cu2+ + 2e -----> Cu (s)
Cu2+ + e -----> Cu+
Cu + H2O2 (hydrogen peroxide) -----> Cu+ + OH + OH
Cu2O (s) + 2H+ + 2e ---> 2Cu (s) + H2O
CuO (s) + 2H+ -----> Cu2+ + H2O
CuO + 1/2 H2 + H+ -----> Cu+ + H2O
CuO + H2 ---> Cu + H2O
CuO + CO ---> Cu + CO2
Cu2O + 4H+ -----> 2Cu2+ + H2O
2Cu2+ + H2O + 2e ---> Cu2O (s) + 2H+
Cu2O + 2H+ ---> 2Cu+ + H2O
2Cu2+ + O2 ---> 2Cu2O
2CuO (s) + 2H2 + 2e ---> Cu2O (s) + H2O
Cu (s) + H+ -----> Cu2+ + H2 (g)
Cu + H+ -----> Cu+ + 1/2 H2 (g)
Cu (s) + 2 H+ -----> Cu2+ + H2 (g)
O2 (g) + 4H+ + 2Cu (s) -----> 2H2O + 2 Cu2+

Cupric oxide with acid treatment:

CuO + 2HNO3 ---> Cu(NO3)2 + H2O
CuO + 2HCl ---> CuCl2 + H2O
CuO + H2SO4 ---> CuSO4 + H2O

A micrograph for Cu2O (available on page 11):
http://lib.tkk.fi/Diss/2004/isbn9512270226/isbn9512270226.pdf

In a paper by P. Dorsey and P. Hanrahan the researchers discuss the natural
patina formation on clean copper in marine, urban and rural environments.
The corrosion seen on the surface of copper and that sometimes transforms
deeper layers of copper is comprised of multiple oxide layers. During
research it was demonstrated that in all three environments, the substance
of the patina immediately adjacent to clean copper surfaces was copper (II)
sulfide (CuS), followed by a layer of the mineral cuprite (Cu2O), better
known to us potters as cuprous oxide or red copper oxide or copper (1)
oxide. Continuing to explore outward the researchers discovered atacamite,
or copper (II) chloride hydroxide - Cu2Cl(OH)3 - a deep-green halide mineral
along with blue to blue-green posnjakite, or copper sulfate hydroxide
hydrate, Cu4(SO4)(OH)6(H2O). Depending upon the specific environment, other
copper sulphate hydroxides and numerous other organic and inorganic
compounds have been known to turn up as part of a patina, for example
malachite, antlerite, brochantite, and gerhardtite. The formation of both
copper sulfide, a brownish-black tarnish, and cuprite with its reddish brown
color may happen relatively quickly when copper is exposed to the
environment but the other layers of copper compounds generally take a much
longer time to develop. Two representative examples of these slowly
developing copper compounds are the two green minerals brochantite, Copper
Sulfate Hydroxide, Cu4SO4(OH)6, and antlerite, Copper Sulfate Hydroxide,
Cu3SO4(OH)4. Copper minerals in the sulfate class can be notoriously
difficult to identify correctly.

On a given object (bowl, statue, wire, value, coil, penny, roof, etc.) the
amount of naturally occurring patina can also be attributed to to the shape
of the object and internal stresses generated during the objects creation --
some forms lend themselves to a more efficient capturing of atmospheric
contaminants. Corrosion occurs most aggressively when copper and another
dissimilar metal are in contact with each other and exposed to the
environment although it is usually the other metal, not copper, that
corrodes first. Copper oxide in layers of cuprous oxide (Cu2O) and Cupric
oxide (CuO) are very thin (on the order of a few tenths of a micron to
perhaps a few microns). These oxide layers actually serve to protect the
underlying copper. However, as the cupric oxide layer progressively extends
deeper into the copper it eventually affects entire small forms (like
electrical wire) turning them black, brittle, and less stable and
functional. This effect can be concentrated locally as a pit or sometimes a
crack, or it can extend across a wide area to produce general wastage.
Localized corrosion that leads to pitting may provide sites for fatigue
initiation. In some environments corrosive agents such as seawater may lead
to greatly enhanced growth of fatigue cracks. Pitting corrosion also occurs
much faster in areas where microstructural changes and the fracturing of the
cuprous and cupric oxide thin films have occurred due to welding operations,
frequent mechanical start-ups and shut-downs, load changes, extreme
variations in temperature, etc. Microbial-induced corrosion, often a
possibility, is the result of bacteria slime forming inside or on pipes and
vessels. In such cases the activities of the bacteria create an environment
capable of corroding copper. Organic debris also helps create an environment
conducive to corrosion.

The pH of copper in solution plays an important role in corrosion. Copper in
an aqueous solution experiences minimal corrosion at pH 8.8 - 9.6. Copper is
susceptible to corrosion by acids and strong alkaline solutions, especially
in the presence of oxygen or oxidants. Formation of the copper ions occurs
most readily from the oxide state when pH is just below 7.0. In the pH range
between 2 and 5, the dissolution of Cu is very rapid, and the formation of a
stable surface oxide layer, which can passivate metal surfaces, is hindered.
A protective oxide surface layer can only be formed in weak acid or alkaline
solutions. A plate of copper in open air will normally corrode one to two
micrometers per year. At a given relative humidity, cuprous oxide forms
according to an approximately logarithmic rate law. In addition, an aqueous
adlayer of constant mass physisorbs (through weak Van der Waals forces) on
the surface. Increased relative humidity stimulates the physisorption of
water and enhances the nucleation rate of oxide grains, thereby increasing
the formation rate of cuprous oxide.

In general, an increase in temperature causes an increase in copper ion
formation in either atmospheric or aqueous environments.

Different waters vary in their resistance to changes in their chemistry. All
waters contain divalent metals such as calcium and magnesium that cause
water to have properties characterized as hardness and softness. If water is
"hard," it is less likely to leach copper. If water is soft, then it has low
hardness. Waters with low hardness (less than 50 mg/L as calcium carbonate)
are more susceptible to the factors affecting corrosion. Very soft water can
actually corrode the pipes and vessels in which it is contained or carried
resulting in elevated levels of copper in the water.

In water a transition from O2-consuming to H2-evolving copper corrosion has
long been observed. The oxidative corrosion rate of copper in water (at
neutral pH) occurs in the range of 200-300 ppb. It is often measured as a
function of dissolved oxygen in aqueous systems. For example, at neutral pH
and 100 ppm dissolved oxygen the corrosion rate for copper is 47 mg/m2 per
day. For Lee and others using copper in birdbaths the good news is that
copper pennies, wire and rods have limited potential to release copper to
plain water. If using pennies dated 1983 or later, zinc toxicity would be a
greater worry than copper toxicity if a large bird or pet were able to
access and swallow the penny. For pennies minted from 1962 to 1982 the metal
composition is 95% copper and 5% zinc. From 1983 on pennies all contain
97.5% zinc with a thin (2.5%) copper plating. During 1982, both copper and
zinc cents were minted and can be most easily differentiated by weight --
copper pennies weigh 3.11 grams and zinc pennies weigh 2.5 grams.
The diameter of a penny is 19.05 mm or 0.75 inches. The surface area of a
penny is 662.48 mm2. Thus, from one copper penny (any mint date) the copper
corrosion rate is roughly 0.031 mg/day. If you had one penny in one liter of
water at neutral pH and 100 ppm dissolved oxygen and the corrosion process
released all the copper it could in that 24-hour period, then the water
concentration of copper would be 0.031 ppm (31 ppb). You would need to clean
any protective oxide coating from the penny each day for optimum results.
Although copper is potentially toxic to birds avian toxicity from copper is
not commonly reported. The type of material used to construct a birdbath as
well as anything introduced into the water (avian excrement, seeds, dirt,
etc.) would affect the amount of copper available to birds. Copper strongly
adsorbs to organic matter, carbonates and clay, reducing its bioavailability
and affecting the rate of copper ion production.

Copper toxicity is a major concerns affecting both wild and captive avian
populations. In all avian species, the kidney and liver are the major target
organs. Toxic effects in birds include reduced growth rates, lowered egg
production, and developmental abnormalities. Reference ranges of blood
concentrations of these metals in large numbers of birds with no history of
environmental exposure have not been widely reported. In one study ranges
for plasma concentrations for copper were studied in wild parrots that had
minimal environmental exposure to copper. Measurements of plasma copper
concentrations followed a normal distribution, which resulted in reference
ranges (mean 2 SD) of 0.07-0.19 ppm (70 -- 190 ppb). It should be noted
that copper toxicity is usually diagnosed in birds using tissue samples
rather than blood, serum, or plasma. One study indicated that small ducks
experience toxic symptoms when they ingest 100 mg of copper per kg of daily
diet.

There is some uncertainty in the finding of risk to birds and mammals
because, although copper is toxic at high concentrations, it is also an
important essential trace element for terrestrial animals. Many terrestrial
animals have the ability to cope with some amount of excess copper exposure
by storing it in the liver and bone marrow. As indicated by the laboratory
toxicity studies, exposure to high levels of copper in the diet can
overwhelm the ability of birds and mammals to maintain homeostasis. However,
animals that are repeatedly exposed to levels of copper that do not cause
permanent harm may undergo enzymatic adaptation that allows them to cope
with greater levels of exposure.

At any rate, I'm satisfied that birds are not harmed by the addition of a
penny, dull or shiny, into a birdbath. I wouldn't use more than one penny in
a birdbath myself if I got tired of cleaning algae by mechanical methods.
Good news, too -- should poor blighted honeybees visit the one-penny
birdbath available data from acute toxicity studies indicates that copper is
practically nontoxic to bees.

Zinc, a major component of post-1982 pennies, might be more of a concern as
a toxin than copper. Zinc is toxic to mammals in varying quantities.
Swallowing a penny that is 97.5% zinc can cause damage to the stomach lining
due to the high solubility of the zinc ion in the acidic stomach. Zinc
toxicity, mostly in the form of the ingestion of pennies minted after 1982,
is commonly fatal in dogs where it causes a severe hemolytic anemia. In pet
parrots zinc is highly toxic, too. Yes, parrots and other birds have been
reported to ingest pennies.

Of note -- the proportion of release rates of copper and zinc from alloys
differed significantly from their proportions in the pure metals. Bronze,
for example, shows relatively constant release rates of copper, being
similar to that of pure copper sheet. Alloys and the pure metals behave very
differently when exposed to water. Accordingly, release rates from pure
metals cannot be used to predict release rates of individual constituents
from their alloys.

The EPA's Office of Water regulates contaminants in water in the United
States, with 1.3 parts per million set as the Maximum Contaminant Level Goal
for copper. Households may be exposed to levels of soluble copper in
drinking water that are above the acceptable drinking water standard of
1,300 ppb especially if the water is corrosive and the plumbing is of copper
with copper or brass piping and fixtures. The average concentration of
copper in tap water ranges from 20 to 75 ppb (0.020 to 0.075 ppm). However,
many households have copper concentrations of over 1,000 ppb (over 1
milligram per liter of water). This is due to the corrosion of copper as
water sits in pipes overnight. Water that is allowed to run for 15-30
seconds will have concentrations of copper below the acceptable drinking
water standard.

The concentration of copper in lakes and rivers ranges from 0.5 to 1,000 ppb
with an average concentration of 10 ppb. The average copper concentration in
groundwater (5 ppb) is similar to that in lakes and rivers; however,
monitoring data indicate that some groundwater contains levels of copper (up
to 2,783 ppb) that are well above the standard of 1,300 ppb for drinking
water. This copper is generally bound to particles in the water. Lakes and
reservoirs recently treated with copper compounds to control algae or
receive cooling water from a power other forms that can settle into
sediments. This can limit exposure to copper unless the sediments are
stirred and agitated and actually ingested.

Soil generally contains between 2 and 250 ppm copper, although
concentrations close to 17,000 ppm have been found near copper and brass
production facilities. High concentrations of copper may be found in soil
because dust from these industries settles out of the air, or wastes from
mining and other copper industries are disposed of on the soil or allowed to
wash into soils. plant can have high concentrations of dissolved copper.
Once in natural water, much of this copper soon attaches to particles or
converts to

Health Effects:

Copper compounds are used as effective algicides (algaecides) and pesticides
and as such are toxic to invertebrates (animals without backbones: e.g.
insects and their larvae, spiders, crayfish, worms, snails, slugs, mussels,
clams, etc.), amphibians, and fish and many other aquatic organisms.
Organisms within all three groups are equally sensitive to chronic copper
toxicity. Aquatic plants may be damaged or killed during the use of copper
algicides. There is a moderate potential for bioaccumulation in plants.
Beneficial bacteria and fungi may also be destroyed by copper compounds. And
although copper has been used for many years as an effective algicide in
fishery operations only a thin line separates effective algae-treatment
levels from lethal overdoses to fish. Not all fish are equally tolerant of
one of the most widely used algicides, copper sulfate; trout and salmon, for
example, are highly susceptible to the baneful effects of copper compounds.
The free copper ions generated by copper and copper compounds are the lethal
agent in copper algicides and pesticides. Sensitive algae may be affected by
free copper at low parts per billion concentrations in freshwater.

While mammals are not as sensitive to copper toxicity as aquatic organisms,
toxicity in mammals includes a wide range of animals (humans included) and
symptoms of copper poisoning include liver cirrhosis, necrosis in kidneys
and the brain, gastrointestinal distress, lesions, low blood pressure, and
fetal mortality.

When working with copper patinas it is worth noting that copper corrosion
products may react with and become diffusible through skin exudates (sweat
and sebum). Chloride ion, low-molecular-weight acids and amino acids in
sweat, and fatty acids in sebum all have the potential to solubilize copper
and copper compounds to form copper salts and soaps whose molecular
characteristics (size and polarity) will determine the rate and route of
cutaneous penetration.

Yet more factoids:

Copper (metal)
Melting point: 1084.62 C (1984.32 F)
Insoluble in water
Copper ions (Cu+1 and Cu+2) can be released from copper metal.

Cuprous oxide (Cu2O, Red copper oxide, Brown copper oxide, Copper I oxide,
Cuprite)
Melting point: 1232 C (2250 F)
Stable in dry air but gradually oxidizes in moist air to Cupric oxide.
Cuprous oxide is practically insoluble in water and organic solvents.

Cupric oxide (CuO, Black copper oxide, Copper II oxide, tenorite)
cupric oxide, CuO.
Cupric oxide (CuO) m.p.: 1026 C (1879 F)
Cupric oxide is insoluble in water

Of interest:
The group Potters For Peace works with local communities to provide
low-tech, low-cost, colloidal silver-enhanced ceramic water purifiers made
using local clays:
http://s189535770.onlinehome.us/pottersforpeace/

References available upon request.

Marian
Neon-Cat Ceramics
www.neon-cat.com
neoncat@flash.net


-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Lee Love
Sent: Sunday, July 20, 2008 9:24 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Copper Oxide facts

On Sun, Jul 20, 2008 at 1:10 AM, Ivor and Olive Lewis
wrote:
> Dear Lee Love
> I am not sure it is wise to infer that Copper oxide has the same
> antibacterial activity as the patina which devlops on metallic copper.

Your assignment is to test this. ;^) (haha. You are always handing
out assignments.)

--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/

"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi

Ivor and Olive Lewis on fri 25 jul 08


Dear Marian,
A lot of information there.
I wonder if you have checked those equations out to ascertain if they
are feasible. I think there are problems with that reaction between
pure Copper and Hydrogen peroxide. This seems very doubtful and may
not fulfil the necessary thermodynamic conditions for a spontaneous
reaction. Surely some of the others would only proceed if drive by a
high EMF
I notice that none of the Equations you supply give a reaction with
Silicilic Acid.
Best regards,
Ivor Lewis.
Redhill,
South Australia.

Neon-Cat on fri 25 jul 08


Silicilic Acid? As in Na2Si4O9, the sodium tetrasilicate? Oh Ivor, I was
trying to see if birds were gonna die off in the penny-in-a-birdbath trick.
I really should win the lotto and cross the ocean and have that pot of tea
with you; it would probably be a real pleasant trip and a half.

Of course the posted equations are correct for copper corrosion in air or
water. They're in many standard references and have been for years. In the
past I worked in the trades as a steam boiler operator and one of my duties
was to prevent copper corrosion. During that time friends called me "Boiler
Woman" and my mother cried. It was a fun and educational period of life,
kinda like life with clay - every day different, each with its challenges
and interests. The equations I posted are for non-pressurized systems under
moderate heat changes, like one might find in a birdbath or in water pipes
or around the clay studio.

I know you and others want to know more about acids (vinegar) and clay. You
want to know more about the family of sodium silicates, too? Or silicic
acid? As relates to copper or what? It is real hard to make a chatty email
post explaining chemistry and complicated subjects. I was happy to know
(deeply) why birds won't die drinking water that's been minimally enhanced
by copper ions. That shiny undamaged pennies work best was also good to nail
down. After journeying down through layers of corrosion and gliding on
smooth copper surfaces I forget - was Lee's birdbath of unglazed (or glazed)
clay? Your segue confuses me.

I collect data sometimes for further use (hence the long previous post),
like for copper based glazes, cone 10 reduction or Raku. I made several very
interesting glazes and surface treatments in the last few weeks - one with
copper, one with hematite (Fe2O3). The hematite is my favorite - fired it
looks like real rock. This is my weekend to stay cool, focused, and do a
little sculpting. My mind is not now "into" science. But will be again, I've
got decisions to make (or avoid making). Post back with what might interest
you the next go-round.

Here's a nice (short, semi-boring) video of sodium silicate solution
reacting with acetic acid to form silicic acid:
http://ie.youtube.com/watch?v=R54vivyrYbE

Cheers!
Marian

-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Ivor and Olive
Lewis
Sent: Friday, July 25, 2008 1:44 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Copper Oxide facts

Dear Marian,
A lot of information there.
I wonder if you have checked those equations out to ascertain if they
are feasible. I think there are problems with that reaction between
pure Copper and Hydrogen peroxide. This seems very doubtful and may
not fulfil the necessary thermodynamic conditions for a spontaneous
reaction. Surely some of the others would only proceed if drive by a
high EMF
I notice that none of the Equations you supply give a reaction with
Silicilic Acid.
Best regards,
Ivor Lewis.
Redhill,
South Australia.