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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

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klasifikace kov

KLASIFIKACE KOVů

JAN TŘÍSKA, CENTRUM VÝZKUMU GLOBÁLNÍ ZMĚNY AV ČR

ČESKÉ BUDĚJOVICE

S VYUŽITÍM MATERIÁLů

PROF. MASAROVIČOVÉ

BRATISLAVA

slide2
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

slide3
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

slide5
Klasifikácia kovov pomocou ionových

charakteristík a elektronegativity:

Ionový index= z2/rkde z je mocenstvo a r je ionový polomer - je mierou možnosti vytvoriť iónovúväzbu

Kovalentný index = Xm2*rkde 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(„Oseeking")

hraničné= kovalentný index>1.75<3.4

trieda B= kovalentný index>3.4(“NorS seeking")

slide6
Zovšeobecnenie:

Kovy s veľkým ionovým polomerom a vysokou

elektronegativitou sú toxickejšie

Poradie toxicity:B > hraničné > A

slide7
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

slide8
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 proteínya vytláčať esenciálne kovy z metaloproteínov

slide9
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

slide10
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

slide11
Klasifikácia kovov podľa Nieboera a

Richardsona

Trieda A= kovalentný index<1.75(„Oseeking")

(Na, Ca, Mg, K)

Hraničné= kovalentný index>1.75<3.4

(Cd, Fe, Zn, Ni)

trieda B= kovalentný index>3.4(“NorS seeking")

(Hg, Cu, Pb)

slide12
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

slide17
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
m toxicita
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
properties of heavy metals
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
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
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).

mercury
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
slide27
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
Sources 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
olovo
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
Sources 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 effects1
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
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
Lead content of House Dust

Source: Roberts et al., 1990.

facts about lead poisoning
Facts about lead poisoning
  • 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.
kadmium
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
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 effects2
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 arsenic
Sources 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 effects3
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 arsenic exposure
Recent studies on arsenic 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 metals in residential houses
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