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

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po AT Rn

Fr Ra Ac Rf Ha

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

from Nieboer and Richardson 1980

blue = Class A metalsred = Class B metalsyellow = borderline between A and Bpink = Class B or borderline, depending on oxidation state

Klasifikácia kovov pomocou ionovýchcharakteristík a elektronegativity: Ionový index = z2/r kde z je mocenstvo a r je ionový

polomer - je mierou možnosti vytvoriť iónovú väzbu Kovalentný index = Xm

2*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 aRichardsona

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 metalsProperties 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 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 metalsToxicity 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 Toxicity of trace heavy metalsmetals

Toxicity of trace heavy metalsToxicity of trace heavy metals

Yes0.5

Lung damage and Irritation or respiratory system

Inhalation, ingestion, and absorption through skin

Chromium

Yes0.05Lung, liver and kidney damage; Irritation of respiratory system

Inhalation and ingestion

Cadmium

Yes0.20Irritation of respiratory system, Liver and Kidney damage, Loss of appetite, nausea and vomiting etc

Inhalation and ingestion

Arsenic

Carcinogen (suspected by NIOSH)

TWA by ACGIH(mg / m³)

Toxicity EffectRoute of Entry

Metal

Toxicity of trace heavy Toxicity of trace heavy metalsmetals

Toxicity of trace heavy metalsToxicity of trace heavy metals

Yes1.00Lung, liver and kidney damageInhalationNickel

No0.15Lung and liver damage; loss of appetite, nausea etc

Inhalation and ingestion

Lead

Yes0.05(vapor)

Irritation of respiratory system; lung, liver and kidney damage

Inhalation,ingestion and absorption through skin

Mercury

Carcinogen (suspected by NIOSH)

TWA by ACGIH(mg / m³)

Toxicity EffectRoute of entryMetal

MercuryMercury

Most volatile of all metalsHighly toxic in vapor formLiquid 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 MercurySources of Mercury 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 Health effects 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 Concentration of Mercury Vapor IndoorsVapor Indoors

Concentration of Mercury Vapor IndoorsConcentration of Mercury Vapor Indoors

9 months after painting with latexpaint262

House 3: Bed room

4 months after painting with latexpaint164

House 2: Livingroom

139 Bed room 2

66.5 Bed room 1

69 Livingroom

68.2 Study room

21 months after painting with latexpaint

House 1

CommentsMercuryConcentration

(mg / m³)Location

Concentration of Mercury Concentration of Mercury Vapor IndoorsVapor Indoors

Concentration of Mercury Vapor IndoorsConcentration of Mercury Vapor Indoors

Office away from laboratory398LaboratoryNear the desk592LaboratoryNear the sink930Hospital laboratoryInactive for previous 4 days307Hospital laboratory

Mixing area for Hg-amalgam1295Dentist’s office

Hg thermometer broken in the past5550Dentist’s office

Painted with latex paint 6 months before

4950Doctor’s room

203Office building

New home, painted with latex paint 30 days before1560

House 4:Living room

CommentsMercury Concentration

(ng / m³)Location

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 leadSources of lead 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.)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 effectsHealth effectsAt high levels, inorganic lead is a general

metabolic poisonLead 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.)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 DustLead content of House DustLead content of House DustLead content of House Dust

214013501530860Lead content of soil, ppm

1320430780320Lead content of dust, ppm

636.7263.5Total amt. Of dust, g / m²

72767173Home age (yrs)

96325No. of homes studied

After RemodelingWalk-off MatShoes onShoes offActivities

Source: Roberts et al., 1990.

Facts about lead Facts about lead poisoningpoisoning

The human groups most at risk of lead 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 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 Sources of Cadmium 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 Health effects

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

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 ArsenicSources of Arsenic 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 Health effects 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 Recent studies on arsenic exposurearsenic exposure

Arsenic emitted from a copper-smelting 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..(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 General sources of heavy metals in residential housesmetals 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