Lecture 3 Hazardous Waste – Chapter 2. Common Hazardous Wastes Most common classes of hazardous compounds: Petroleum products Solvents Pesticides Polychlorinated

Lecture 3Lecture 3

Hazardous Waste – Chapter 2

Common Hazardous WastesCommon Hazardous Wastes

Most common classes of hazardous compounds:

Petroleum products Solvents Pesticides Polychlorinated biphenyls Dioxins Metals


Need to learn the language of Haz WasteNomenclature 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


Inorganic – mineralsCarbon 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


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)


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


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)


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


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


Organic Nomenclature Systems 1. International Union of Pure and Applied Chemists

(IUPAC)

2. Common and Trivial Names

3. Trade Names

Need to have a basic understanding of all three in dealing with hazardous waste


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

Common Hazardous WastesCommon Hazardous WastesNumber Name

1 Methane

2 Ethane

3 Propane

4 Butane

5 Pentane

6 Hexane

7 Heptane

8 Octane

9 Nonane

10 Decane

11 Undecane

12 Dodecane

13 Tridecane

14 Tetradecane

15 Pentadecane

16 Hexadecane

17 Heptadecane

18 Octadecane

19 Nonadecane

20 Eicosane


– 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


IUPAC Nomenclature for Alkanes1. Select the carbon skeleton with the longest chain as the

parent compound2. Assign numbers to the carbons where the alkyl group is

attached3. 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

4. Commas always separate numbers and hyphens always separate words

5. The order of the substituent groups in the name should be alphabetical


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


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


Rules for naming Alkenes1. The longest carbon skeleton containing the double

bond serves as the basis for naming the compound, -ene suffix instead of –ane

2. Number the first double-bonded carbon on the longest chain so that it has the lowest possible #

3. Name alkyl substituents in the same manner as alkanes

4. 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


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


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)


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


PAH Nomenclature Rules1. Draw the PAH rings so that two of the sides are

vertical

2. Draw as many rings as possible in a horizontal line

3. 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


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.


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


Four classes of PAH’s in Crude oil:– Parafins – alkanes– Olefins – alkenes– Napthenes – cycloalkanes– Aromatics – monocyclic aromatic

hydrocarbons and PAH’s


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


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


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.


Alcohols and Esters– Alcohol has the (-OH) group, -ane is replaced

by (-anol)– Esters are derivatives of alcohol, -ane is

replaced by -anate


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


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

HomeworkHomework

Chapter 2: 1, 3, 4, 5, 8

Documents

Lecture 3 Hazardous Waste – Chapter 2. Common Hazardous Wastes Most common classes of hazardous compounds: Petroleum products Solvents Pesticides Polychlorinated