KLASIFIKACE KOVů
JAN TŘÍSKA, CENTRUM VÝZKUMU
GLOBÁLNÍ ZMĚNY AV ČR
ČESKÉ BUDĚJOVICE
S VYUŽITÍM MATERIÁLů
PROF. MASAROVIČOVÉ
BRATISLAVA
Pearson R:
Hard and soft acids and bases, HSAB, part I.
Fundamental principles.
J. Chem. Educ. 45 (1968) 581-587
Rozdelenie kovov na slabé a silné
akceptory na
základe vytváraných stabilných komplexov
s
ligandami
Nieboer E, Richardson DHS :
The replacement of the nondescript term
„heavy metals“ by biologically and
chemically significant classification of
metal ions. Environ. Pollut. (Ser B) 1
(1980) 2-26
Klasifikácia kovov podľa biologicky
relevantných
vlastností
Classification of Metals by Biologically Relevant Properties
from Nieboer and Richardson 1980
H
Li
He
Be
B
C
N
O
F
Ne
Na Mg
Al
Si
P
S
Cl
Ar
Ga Ge A s Se
Br
Kr
I
Xe
K
C a Sc
Ti
V
Cr
Mn Fe
C o Ni
C u Zn
Rb Sr
Y
Zr
Nb Mo Tc
Ru Rh P d A g C d In
Sn
Cs Ba
La
Hf
Ta
Os Ir
Pb Bi
P o A T Rn
Ra A c Rf
Ha
Dy Ho Er
Tm Y b Lu
Fr
W
C e Pr
Th
Pa
Re
Pt
Nd Pm Sm Eu
U
A u Hg Tl
Gd Tb
Np P u Am Cm B k Cf
Sb
Te
Es Fm Md No Lr
blue = Class A metals
red = Class B metals
yellow = borderline between A and B
pink = Class B or borderline, depending on oxidation state
Klasifikácia kovov pomocou ionových
charakteristík a elektronegativity:
Ionový index = z2/r kde z je mocenstvo a r je ionový
polomer - je mierou možnosti vytvoriť iónovú
väzbu
Kovalentný index = Xm2*r kde Xm je elektronegativita
- určuje schopnosť Me iónu prijať e- od donora –
ligandu
podľa závislosti ionový index vs. kovalentný index,
klasifikujeme kovy ako kovy triedy B, hraničné kovy a
kovy triedy A
trieda A = kovalentný index <1.75 („O seeking")
hraničné = kovalentný index >1.75<3.4
trieda B = kovalentný index >3.4 (“N or S seeking")
Zovšeobecnenie:
Kovy s veľkým ionovým polomerom a
vysokou
elektronegativitou sú toxickejšie
Poradie toxicity: B > hraničné > A
Katióny typu B (napr. Hg2+, Pb2+, Cu+):
- pri tvorbe komplexov zohráva úlohu kovalentná
väzba
- tieto kovy vytvárajú stabilnejšie komplexy ako
katióny typu A
- komplexy s ligandami obsahujúcimi N sú
stabilnejšie ako komplexy s ligandami
obsahujúcimi O
-trend tvorby komplexu medzi kovom typu B
a donorovou skupinou ligandu je nasledovný:
S > I > Br > Cl > N > O > F
- pre organizmus sú kovy typu B najtoxickejšie
Mechanizmus toxického účinku
katiónov
kovov typu B
- ich vysoká toxicita súvisí s vysokou afinitou
k S-donorovým ligandom, ktoré sa nachádzajú
na mnohých makromolekulách;
- vytvárajú však aj stabilné komplexy s ligandami
obsahujúcimi O, a to vo väčšej miere ako kovy
typu A a hraničné kovy
- môžu sa viazať na katalytické centrá enzýmov, na
membránové proteíny a vytláčať esenciálne kovy
z metaloproteínov
Hraničné kovy:
- do tejto skupiny patria hlavne Cd, Fe, Zn a Ni
- sú schopné tvoriť komplexy so všetkými typmi
donorových ligandov
- tieto kovy majú určitý podiel charakteru kovov
skupiny B, pričom tento charakter typu B závisí od
umiestnenia kovu v periodickej tabuľke a rastie
smerom zľava doprava a zhora dole
- z hľadiska ich afinity k atómom síry, dusíka
alebo kyslíka patria medzi katióny skupiny A a B
Mechanizmus toxicity hraničných
kovov
- mechanizmus toxicity spočíva väčšinou v
ich schopnosti vytláčať kovy skupiny
A alebo iné prechodné katióny (Zn)
z metaloproteínov
- tieto kovy sú zvyčajne menej toxické ako
kovy skupiny B, ale môžu byť oveľa
toxickejšie ako kov skupiny A
Klasifikácia kovov podľa Nieboera a
Richardsona
Trieda A = kovalentný index <1.75 („O seeking")
(Na, Ca, Mg, K)
Hraničné = kovalentný index >1.75<3.4
(Cd, Fe, Zn, Ni)
trieda B = kovalentný index >3.4 (“N or S
seeking")
(Hg, Cu, Pb)
Toxické účinky kovov:
 vytláčanie esenciálnych kovov z
biomolekúl
 blokovanie esenciálnych funkčných
skupín biomolekúl
 zmena konformácie biomolekúl
 narušenie integrity membrán
 modifikácia niektorých iných biologicky
aktívnych látok
KLASIFIKACE A TOXICITA KOVů
TOXICITA KOVů
KLASIFIKACE A TOXICITA KOVů
KLASIFIKACE A TOXICITA KOVů
MĚĎ
• Hornictví
• Zpracování kovů
• Průmyslové odpadní vody
pivovary (0,4 mg/L), čistírny a prádelny (1,7 mg/l)
• Městské splachy
• Popílky ze spalování
• Algicidy
MĚĎ - TOXICITA
• Esenciální prvek v nízkých koncentracích
(kofaktor), hemocyanin
• Toxický pro rostliny (nahrazuje Mg v chlorofylu)
řasy a lišejníky
• pH a biodostupnost (uhličitanové komplexy)
• Komplexy s huminovými látkami
KLASIFIKACE A TOXICITA KOVů
KLASIFIKACE A TOXICITA KOVů
Properties of heavy metals

They occur near the bottom of the periodic table
 Have high densities
 Toxic in nature
 Nondegradable
Note: Arsenic is not actually a metal but is a
semimetal i.e. its properties are intermediate
between those of metals and nonmetals.
Transport phenomenon

Water
 Food
 Air
 Adsorption or absorption onto various materials
Example: Over half of the heavy metal input into
Great Lakes is due to deposition from air.
Toxicity of heavy metals

Mercury is highly toxic in vapor form but
lead,cadmium and arsenic are more toxic in their
cationic form
 Toxicity arises from strong affinity of the heavy
metal cations for sulfur
 Medicinal treatment for heavy metal poisoning is
done by chelation therapy by administering
compounds known as chelates
Example : British Anti-Lewisite(BAL), ethylene
diamine tetra acetic acid(EDTA).
Toxicity of trace heavy
metals
Toxicity of trace heavy
metals
Mercury

Most volatile of all metals
 Highly toxic in vapor form
 Liquid mercury itself is not highly toxic,
and most of that ingested is excreted
RTUŤ
• Zvětrávání hornin (Hg, HgS)
• Průmyslové aplikace
výroba vinylchloridu z acetaldehydu
elektrolýza
nátěry, farmaceutické přípravky
• Zemědělství (fenylmerkuriacetát)
• Spalovací procesy cca 5000 t/rok
Sources of Mercury
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Elemental mercury is employed in many
applications due to its unusual property of being a
liquid that conducts electricity
Used in electrical switches, fluorescent light bulbs
and mercury lamps
Emission of mercury vapor from large industrial
operations
Unregulated burning of coal and fuel oil
Incineration of municipal wastes
Emissions from mercury containing products
:batteries, thermometers, etc.
Mercury amalgams: dental fillings
Health effects
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Skin burns
Irritation of nose and skin
Rashes
Excessive perspiration
Damage to the kidneys
Damage to vision
Minamata disease
Dysfunctions of the central nervous
system
Loss of hearing and muscle
coordination
Severe brain damage
Death
Concentration of Mercury Vapor Indoors
Concentration
of Mercury
Mercury
Concentration Comments
Location
Vapor
Indoors
(mg / m³)
House 1
21 months after painting with latex
paint
Study room
68.2
Living
69
room
Bed room 1 66.5
Bed room 2 139
House 2:
Living
room
House 3:
Bed room
164
4 months after painting with latex
paint
262
9 months after painting with latex
paint
Concentration of Mercury
Vapor Indoors
Source: Foote, 1972.
BIOGEOCHEMICKÝ CYKLUS RTUTI
OLOVO
•
•
•
•
•
•
•
Zvětrávání hornin (cca 180 000 t/rok)
Hornictví, zpracování kovů (cca 135 000t/rok)
Spalovací procesy (uhlí a ropné produkty)
Spalování odpadu
Nátěry a baterie
Spalování benzinu (před 1989, cca 270 000t/rok)
Spalovací procesy cca 5000 t/rok
Sources of lead

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
Commonly used in the building
industry for roofing and flashing and
for soundproofing
Used in pipes
When combined with tin, it forms
solder, used in electronics and in other
applications to make connections
between solid metals
Lead is also used in ammunition
Note: Lead shots have been banned in
United States, Canada, Netherlands,
Norway and Denmark
Lead is used in batteries and sinkers
in fishing
Sources (contd.)

Used in paints
Lead chromate is the yellow pigment
used in paints usually applied to
school buses. Lead is also used in
corrosion-resistant paints and has a
bright red color
 Used in ceramics and dishware
The leaching of lead from glazed
ceramics used to prepare food is a
major source of dietary lead,
especially in Mexico
 In the past, lead salts were used as
coloring agents in various foods
 Lead is used in some types of PVC
mini-blinds
Health effects

At high levels, inorganic lead is a general
metabolic poison
 Lead poisoning effects the neurological and
reproductive systems, example: downfall of
roman empire
 Lead breaks the blood-brain barrier and
interferes with the normal development of
brain in infants
Health effects(contd.)

Lead is observed to lower IQ levels in
children
 Lead is transferred postnatally from the
mother in her breast milk
 At elevated levels, lead poisoning would
eventually result in death
Lead content of House Dust
Source: Roberts et al., 1990.
Facts about lead
 The human groups most at risk of lead
poisoning
poisoning are fetuses and children
under the age of seven
 Chronic lead poisoning from wine and
other sources is one of the factors in
the downfall of the roman empire
 Episodes of lead poisoning were
recorded through the middle ages and
even until recent times
 A recent study in Mexico indicated
that pregnant women can decrease the
lead levels in their blood and
presumably in the blood of their
developing fetus by taking calcium
supplements.
KLASIFIKACE A TOXICITA KOVů
KLASIFIKACE A TOXICITA KOVů
KLASIFIKACE A TOXICITA KOVů
KADMIUM
• Hornictví, zpracování kovů (Cd je isomorfní se
Zn)
• Pokovování
• Nikl-kadmiové baterie
• Fotovoltaické panely
• Plastické hmoty (Cd stearát – stabilizátor)
• Spalovací procesy (uhlí cca 2 ppm Cd, topné oleje
cca 0,5 ppm Cd)
• Zemědělství (superfosfáty)
Cadmium

Cadmium lies in the same subgroup of
the periodic table as zinc and mercury,
but is more similar to zinc
 Coal burning is the main source of
environmental cadmium
 Incineration of wastes containing
cadmium is an important source of the
metal in the environment
 Cadmium is most toxic in its ionic
form unlike mercury
Note: Mercury is most toxic in vapor
form and lead, cadmium and arsenic
are most toxic in their ionic forms.
Sources of Cadmium


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Cadmium is used as an electrode in
“nicad” batteries
Cadmium is used as a pigment in
paints(yellow color)
It is also used in photovoltaic devices
and in TV screens
Cigarette smoke
Fertilizers and pesticides
Note: The greatest proportion of our
exposure to cadmium comes from our
food supply- seafood, organ meats,
particularly kidneys, and also from
potatoes, rice, and other grains.
KADMIUM - TOXICITA
• Metalothioneiny (MT), metaloproteiny
• MT v játrech přecházejí do ledvin – odbourání a
uvolnění Cd - nefrotoxicita
• Vytěsňuje Zn z biologických molekul
• Mechanismus příjmu buňkou je podobný jako u
Ca
• Zemědělství (superfosfáty) - fytotoxicita
Health effects
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Severe pain in joints
Bone diseases
Kidney problems
Its lifetime in the body is several years
Areas of greatest risk are Japan and central Europe
In very high levels it poses serious health
problems related to bones, liver and kidneys and
can eventually cause death.
Arsenic

Arsenic oxides were the common poisons
used for murder and suicide from roman
times through to the middle ages
 Arsenic compounds were used widely as
pesticides before the organic chemicals era
 Arsenic is very much similar to
phosphorous
Sources of Arsenic
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Pesticides
Mining, smelting of gold, lead, copper and nickel
Production of iron and steel
Combustion of coal
Leachate from abandoned gold mines
Used as a wood preservative
Herbicides
Tobacco smoke
Wallpaper paste and pigments in wallpaper
Health effects
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Birth defects
Carcinogen:
Lung cancer results from the inhalation of
arsenic and probably also from its ingestion. Skin
and liver cancer, and perhaps cancers of the
bladder and kidneys, arise from ingested arsenic
Gastrointestinal damage
Severe vomiting
Diarrhea
Death
Recent studies on
arsenic exposure

Arsenic emitted from a coppersmelting plant in Bulgaria has been
shown recently to have produced a
three-fold increase in birth defects in
new born children in that area
 Most daily exposure of arsenic by
north American adults is due to food
intake, especially of meat and seafood
 Under humid conditions of molds in
wallpaper paste and arsenic pigments
in wallpaper, instances of mysterious
illness and death have been reported
Recent studies..(contd.)

Recent studies have shown that about
1% of Americans consume drinking
water that has arsenic levels of 25 ppb
or more, and in Utah and California
water supplies have been found to
contain as much as 500 ppb
 Scientists have estimated that there is a
one-in-a-thousand lifetime risk of
dying from cancer induced by normal
background levels of arsenic ( this
equals the risk estimate due to tobacco
smoke and radon exposure ).
General sources of heavy
metals in residential houses

Infiltration from outside, along with
the dust carried on shoes and clothes
 Indoor sources include old-lead and
latex based paints, domestic water
supply, burning of wood, and tobacco
smoke
 Pesticides and fungicides are major
sources of arsenic and mercury
indoors
STANOVENÍ KOVů - AAS
STANOVENÍ KOVů - AAS
STANOVENÍ KOVů- GRAFITOVÁ
KYVETA
MARSHOVA ZKOUŠKA (1836)
STANOVENÍ KOVů - ICP
STANOVENÍ KOVů - ICP
STANOVENÍ KOVů – POROVNÁNÍ
METOD