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Lecture 3

Lecture 3. Hazardous Waste – Chapter 2. Common Hazardous Wastes. Most common classes of hazardous compounds: Petroleum products Solvents Pesticides Polychlorinated biphenyls Dioxins Metals. Common Hazardous Wastes. Need to learn the language of Haz Waste

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Lecture 3

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  1. Lecture 3 Hazardous Waste – Chapter 2

  2. Common Hazardous Wastes • Most common classes of hazardous compounds: • Petroleum products • Solvents • Pesticides • Polychlorinated biphenyls • Dioxins • Metals

  3. Common Hazardous Wastes • Need to learn the language of Haz Waste • Nomenclature and Structure required to • Determine rates of transport & transformation • Evaluate toxicity and risk • Design remediation • Organic Carbon – • molecules containing carbon and hydrogen and possibly oxygen, nitrogen, phosphorus, sulfur, and halogens, derived from a biological source

  4. Common Hazardous Wastes • Inorganic – minerals • Carbon bonding • Two types of bonding • Ionic – donation of valence electron, NaCl • Covalent • shared valence electrons, following the octet rule • Atoms want to fill their outmost shell, H2 • Overlap of orbitals

  5. Common Hazardous Wastes • Electrostatic forces hold both ionic and covalent bonds together • Organic compounds have covalent bonds, carbon can not release a donated electron completely • Many chemical bonds exhibit characteristics that are covalent and ionic (dipole)

  6. Common Hazardous Wastes • Dipole • Charge separation resulting from the covalent bond between two different atoms • The electron cloud is pulled towards the larger electron density • Negative dipole – atom with higher e- density • Positive dipole – atom with fewer e- • Bond polarity (electron density) can affect treatment of hazardous waste, determining treatment technologies

  7. Common Hazardous Wastes • Nomenclature • Two major divisions of organic compounds • Aliphatic compounds – straight and branched chains of carbon atoms, classified as alkanes, alkenes, alkynes, etc. • Aromatic comopounds – carbon-based rings with resonating conjugated double bonds (benzene)

  8. Common Hazardous Wastes • Isomerism • The different ways to write chemicals: • Empirical formula – glucose, CH2O, ratio of the elements in the molecule • Chemical formula – C6H12O6, number of each atom in the molecule • Structural formula – drawing of the compound with straight lines representing the bond

  9. Common Hazardous Wastes • Isomers • the different arrangements that organic compounds can take while having the same chemical formula • Three dimensional movement of the atoms • The more carbon atoms, the more isomers • Widely different characteristics

  10. Common Hazardous Wastes • Organic Nomenclature Systems • International Union of Pure and Applied Chemists (IUPAC) • Common and Trivial Names • Trade Names Need to have a basic understanding of all three in dealing with hazardous waste

  11. Common Hazardous Wastes • Alkanes • Straight or branced chains of carbon and hydrogen • Bonds are not fixed, but are constantly rotating •  bonds – 3D • Table 2.2 Names of straight-chain alkanes up to 20 carbons • Isomers of alkanes with more than 4 carbons can cause a nomenclature nightmare

  12. Common Hazardous Wastes

  13. Common Hazardous Wastes • The nomenclature problem with alkanes is solved through the use of substituent groupes or radicals • For alkanes the radicals are called alkyl groups and lack on H from the parent group • -CH3 Methyl • -CH2-CH3 Ethyl • Table 2.3 Common Alkyl Groups

  14. Common Hazardous Wastes • IUPAC Nomenclature for Alkanes • Select the carbon skeleton with the longest chain as the parent compound • Assign numbers to the carbons where the alkyl group is attached • If more than one of a given substituent group is attached to the skeleton, use a prefix to show how many of these groups are on the molecule • Commas always separate numbers and hyphens always separate words • The order of the substituent groups in the name should be alphabetical

  15. Common Hazardous Wastes • Common Names of Alkanes / Alkyl Derivatives • Perfix iso-, used in the petroleum industry for naming alkanes branced at one end, primarily for smaller alkanes • In industry the prefixes in Table 2.5 are often used

  16. Common Hazardous Wastes • Alkenes • Characterized by a double bond somewhere in the molecule • ylene is the older IUPAC • ene is the new, but everyone uses ylene suffix • No rotation occurs around the double bond, the carbons are fixed • Table 2.6 gives the rules for naming Alkenes

  17. Common Hazardous Wastes • Rules for naming Alkenes • The longest carbon skeleton containing the double bond serves as the basis for naming the compound, -ene suffix instead of –ane • Number the first double-bonded carbon on the longest chain so that it has the lowest possible # • Name alkyl substituents in the same manner as alkanes • Give a special prefix to an alkene across the plane of the double bond cis – same side, trans – continues on the opposite side of the double bond

  18. Common Hazardous Wastes • Alkynes and Organic Acids • Alkynes • Triple carbon-carbon bond named the same as alkanes, except with a –yne suffix • Organic Acids • Contain a carboxylic group –COOH, in place of one terminal methyl group, -anoic acid suffix • Aldehyde • COH, -al suffix • Cyclohexane

  19. Common Hazardous Wastes • Aromatic Compounds • Alternating single and double bonds between carbon atoms joined in a ring • Resonating double bond, provides stability, has an aromatic (sweet) odor • Naming, substituent first followed by benzene or Ph, for phenyl • When more than one group is added to a ring, the name of the position on the ring is stated as • Ortho (-o), Meta (-m), or Para (-p)

  20. Common Hazardous Wastes • Polycyclic Aromatic Hydrocarbons (PAH) • Two or more benzene rings bound together • Also known as polynuclear aromatic compounds (PNA) • PNA is a more general term, the molecule can contain O, N, or S • PAH’s contain only C in the ring • petroleum products, cigarette smoke, automobile exhaust • Smallest PAH’s are naphthalene and anthracene • There are 35 prescribed IUPAC compounds • Table 2.8 gives the Nomenclature rules

  21. Common Hazardous Wastes • PAH Nomenclature Rules • Draw the PAH rings so that two of the sides are vertical • Draw as many rings as possible in a horizontal line • Number the periphery of the ring clockwise, starting at the first carbon atom not a part of ring fusion, of the right hand ring of the top row

  22. Common Hazardous Wastes • Petroleum • Naturally occurring complex mixture of hydrocarbons • Big problem! • UST’s – put underground to prevent fires, now leaking into groundwater • Used by everyone, 2.43 x 109 barrels/year • Used in auto’s, heating, power generation, etc.

  23. Common Hazardous Wastes • Petroleum • Contamination not due to consumption but how much UST’s leak and how many spills there are • Crude oil and petroleum products are highly variable • Consist primarily of aliphatic and aromatic hydrocarbons

  24. Common Hazardous Wastes • Four classes of PAH’s in Crude oil: • Parafins – alkanes • Olefins – alkenes • Napthenes – cycloalkanes • Aromatics – monocyclic aromatic hydrocarbons and PAH’s

  25. Common Hazardous Wastes • Petroleum • Crude oil • Refined, Reformed, and Distilled before use • Refining involves: separtation (distillation), conversion (cracking), and upgrading (hydrocracking) • Distillation ranges shown in Table 2.11 • BTX • Benzene, Toluene, Xylene, an important group found in gasoline, 6-36% of gasoline

  26. Common Hazardous Wastes • Non-Halogenated Solvents • Most common are petroleum distillates, aliphatic and aromatic hydrocarbons, alcohols, ketones, esters, and ethers • Used for cold cleaning, metals degreasing, paint stripping, carriers in paint, varnishes and ink

  27. Common Hazardous Wastes • Hydrocarbons • Mineral spirits – paint thinner, dry cleaning • BTX also used for cleaning • Ketone • Table 2.14 for nomenclature rules • C=O in the middle of a carbon chain • Common names are used most often, Acetone, etc.

  28. Common Hazardous Wastes • Alcohols and Esters • Alcohol has the (-OH) group, -ane is replaced by (-anol) • Esters are derivatives of alcohol, -ane is replaced by -anate

  29. Common Hazardous Wastes • Halogenated Solvents • Halogenated hydrocarbons produce better solvents than non-halogenated • Chlorination is the most wide spread industrial practice for metals cleaning • They contaminate GW in Metro areas due to dumping • High density, relative high water solubility, low degradability

  30. Common Hazardous Wastes • Common halogenated hydrocarbons • Methylene chloride, Chloroform, Carbon Tetrachloride • Dip cleaning is primarily responsible for environmental releases • Other major category of chlorinated derivatives • Chlorinated derivatives of ethane and ethylene • TCA, TCE and PCE

  31. Homework • Chapter 2: 1, 3, 4, 5, 8

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