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KLASIFIKACE KOVů

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 KOVů

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  1. KLASIFIKACE KOVů JAN TŘÍSKA, CENTRUM VÝZKUMU GLOBÁLNÍ ZMĚNY AV ČR ČESKÉ BUDĚJOVICE S VYUŽITÍM MATERIÁLů PROF. MASAROVIČOVÉ BRATISLAVA

  2. 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

  3. 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

  4. 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")

  5. Zovšeobecnenie: Kovy s veľkým ionovým polomerom a vysokou elektronegativitou sú toxickejšie Poradie toxicity:B > hraničné > A

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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)

  11. 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

  12. KLASIFIKACE A TOXICITA KOVů

  13. TOXICITA KOVů

  14. KLASIFIKACE A TOXICITA KOVů

  15. KLASIFIKACE A TOXICITA KOVů

  16. 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

  17. 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

  18. KLASIFIKACE A TOXICITA KOVů

  19. KLASIFIKACE A TOXICITA KOVů

  20. 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.

  21. 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.

  22. 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).

  23. Toxicity of trace heavy metals

  24. Toxicity of trace heavy metals

  25. 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

  26. RTUŤ • Zvětrávání hornin (Hg, HgS) • Průmyslové aplikace výroba vinylchloridu z acetaldehydu elektrolýza nátěry, farmaceutické přípravky • Zemědělství (fenylmerkuriacetát) • Spalovací procesy cca 5000 t/rok

  27. 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

  28. 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

  29. Concentration of Mercury Vapor Indoors

  30. Concentration of Mercury Vapor Indoors Source: Foote, 1972.

  31. BIOGEOCHEMICKÝ CYKLUS RTUTI

  32. 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

  33. 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

  34. 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

  35. 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

  36. 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

  37. Lead content of House Dust Source: Roberts et al., 1990.

  38. 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.

  39. KLASIFIKACE A TOXICITA KOVů

  40. KLASIFIKACE A TOXICITA KOVů

  41. KLASIFIKACE A TOXICITA KOVů

  42. 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)

  43. 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.

  44. 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.

  45. 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

  46. 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.

  47. 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

  48. 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

  49. 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

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