1 / 92

Envr 725

Envr 725. Tues. and Thurs- 3 credit hours, room 2303 MHRC 2 pm to 3:15 pm Snow days call 942 4880 or cell 919 619 3701 http://www.unc.edu/courses/2010spring/envr/725/001/Envr725.html (use internet explorer) Rich Kamens: 966 5452; kamens@unc.edu ;

fergal
Télécharger la présentation

Envr 725

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Envr 725 • Tues. and Thurs- 3 credit hours, room 2303 MHRC • 2 pm to 3:15 pm • Snow days call 942 4880 or cell 919 619 3701 • http://www.unc.edu/courses/2010spring/envr/725/001/Envr725.html (use internet explorer) • Rich Kamens: 966 5452; kamens@unc.edu; • Rose Cory: 966-3529; rmcory@email.unc.edu

  2. Introduction to Environmental Physical Organic Chemistry • Environmental chemistry may be defined as "the study of sources, reactions, transport, effects, and fates of chemical species in water, soil, and air environments, and the effects of technology thereon.” Manahan, 1994

  3. Class objectives: • Highlight some important areas in environmental chemistry • present some of the common techniques that environmental chemists use to quantify process that occur in the environment • It is assumed that everyone has courses in organic and physical chemistry.

  4. Class objectives: • Partitioning is a thread that runs through the course • Linear free energy relationships will be used to help quantify equilibrium and kinetic processes

  5. Thermodynamics • ui = uo1 +RT ln pi/p*iL • fi = i Xipi*pure liquid • RT lnfi hx /fiopure liq = RT lnfi H2O/fiopure liqfihx = fi H2O • ln Kp = a 1/T+b

  6. Vapor pressure How to calculate boiling points

  7. Vapor pressure and Henry’s law sat P sat sat *    i K P V iL iw sat iaw iw C iw Solubility and activity coefficients Octanol-water partitioning coefficients

  8. Additional Principles • Organic Acid-bases and LFERs • diffusion • chemical spills and mass transfer • Organic reactions in the environment • Solid- liquid interactions • photochemistry

  9. Homework, quizzes, exams • To insure that most of us stay reasonably current with the lectures and readings, an option is to have 6-8 unannounced quizzes throughout the semester. • They will take ~10 minutes. The first quiz will be on Chapter 2 since we will not cover Chapter 2. Quizzes will count 10% of your grade.

  10. Another option is a set of short questions to be answered and handed in before most lectures (5% of grade)—your choice!

  11. There will be a homework problem set associated with each assigned chapter of the book. It is due a week after the completion of the book chapter. • These problem sets should take between 3 and 10 hrs. Answers will graded and returned to you as soon as possible. These will count for 25% of your grade.

  12. In addition, you are expected to work through the illustrative examples and problemswhich have answers in the test on your own. • Some of these could appear on exams • There will be three exams (70% of your grade ), 25% homeworks, 5%???

  13. Important Environmental Issues • Global warming and stratospheric ozone depletion • Concentration of environmental pollutants at the poles; pesticides in foods, etc. • Buildup of environmental chemicals in the oceans; contamination of soil and ground water • Particle exposure, photochemical oxidant exposure, acid deposition • Energy shortages

  14. Why the interest? There are more than 70,000 100, 000 synthetic chemicals that are in daily use: solvents components of detergents dyes and varnishes additives in plastics and textiles chemicals used for construction antifouling agents herbicides, insecticides,fungicides pharmaceuticals

  15. Some examples of environmental chemicals Polynuclear Aromatic HC (PAHs) Dioxins Ketones PCBs CFCs DDT O3, NO2, aerosols, SO2

  16. PAHs Formed from small ethylene radicals “building blocks” produced when carbon based fuels are burned Sources are all types of burning in ChiangMai, Thailand:a) 2-stroke motorcycle engines b) cars- light diesels c) open burning d) barbecued meat??

  17. Combustion Formation of PAH Badger and Spotswood 1960

  18. Some PAH structures fluoranthene naphthalene anthracene benz(a)anthracene phenanthrene benzo(a)pyrene [BaP]

  19. PAHs Naphthalene, phenanthrene and anthracene are found in the gas phase pyrene and fluoranthene are in both the gas and particle phase BaA and BaP are mostly on the particles, Why???

  20. PAHs Metabolized to epoxides which are carcinogenic; O PAH are indirect acting mutagens in bacterial mutagenicity tests (Ames-TA98+s9) methyl PAHs are often more biologically active than PAHs

  21. Carcinogenic tests with PAHs Professor Gernot Grimmer extracted different types of smoke particles He then took the extract and applied it to mouse skin and implanted it into rat lungs How did he obtain extracts? How did he fractionate his extracts??

  22. Extraction by soxhlet extraction starts with solvent (MeCl2) in a flask

  23. Hot solvent fills this chamber and bathes the filter Heat

  24. The solvent in the filter chamber then drains back into the heated flask withchemicalsfrom the particleson the filter Heat

  25. The organic liquid in the soxhlet flask can be concentrated by evaporation by a dry nitrogen stream or rotary evaporation • the extract can then be fractionated into different polarity compound groups

  26. Professor Grimmer fractionated the exhaust extracts HPLC uv orfluorescencedetector Total Total PAH 2&3 rings PAHs>3 rings Total-PAHs

  27. What did Grimmer see when exposed rats and mice to the different fractions? • skin painted mice • implanted rat lungs

  28. Analysis of reaction products • soxhlet extraction for 3 hours • blow up with dry gentle flow of nitrogen to about 0.5 to 1 ml • evaporation to about 0.5 to 1 ml • 1 to 2 ul injected directly to GC-MS (EI and CI) • The remainder solution: derivatization

  29. In environmental samples why don’t we see some large highly oxygenated compounds that form in the atmophere?? Reverse reactions to the original aldehyde parent structures can occur during sample work up/solvent extraction procedures;

  30. PFBHA O-(2,3,4,5,6-pentafluorobenzyl) -hydroxylamine for carbonyl groups

  31. Pentafluorobenzyl bromide (PFBBr)derivatization for carboxylic and hydroxyl groups P F B B r F F H C C H 3 3 O O H C H C O H C O F C H B r 2 2 F F F F H C C H O 3 3 O C H C O C H F H O C H B r 2 2 F F F F F F C H C H O O 3 3 C H C O C H F O C 2 H B r F C H 2 2 2 F F F F

  32. BSTFA for carbonyl, hydroxyl, and/or carboxylic

  33. GC-EIMS for Oxygenated Terpenoids

  34. Thermal desorption particle beam mass spectrometry (Paul Ziemann) Particle generator or smog chamber

  35. Chlorinated dibenzo dioxins and Furans These are some of the most toxic organics in the environment - LD50 Created by burning organics which have chlorine; incineration is a big source of atmospheric dioxins and furans bleaching in making paper is another source

  36. Combustion Formation of Dioxins from Polychlorinated phenol O H Clx . OH Clx Flame . O O H + Polychlorinated Phenol C l y O + OH O Cly Cly Clx O Clx O H Chlorinated dibenzo dioxin Shaub & Tsang, ES&T 1983.

  37. They have the following general structures O Cl x O Cl y chlorinated dioxin

  38. Cl x Cl y They have the following general structures O Cl x O Cl y chlorinated dioxin O chlorinated furan

  39. O Cl Cl Cl Cl O More than 200 different structures are possible The most toxic is either the 2,3,7,8 tetrachlorodibeno dioxin or furan

  40. These types of compounds produce toxic enzymes: arylhydrocarbon hydroxylase and 7-ethoxyresorufin deethylase At low concentrations they may behave as environmental estrogens

  41. Environmentally, they are unreactive and can be transported long distances They did not start to show up in the environment until the 1920s when there was a big increase in the production of chloro-organics (Professor Ron Hites, and students)

  42. Environmental Fate of Chlorinated Dioxins and Furans(Czuczwa and Hites, 1984) • Collected core sediment samples from southern Lake Huron in the USA • Based on sedimentation rates they established age vs. concentration profiles for chlorinated dioxins and furans

  43. US coal consumption vs chlorinated aromatic production

  44. Chlorinated aromatic production vs dioxinand furan conc. in lake core samples

  45. PCBs in the U.S. Great Lakes • PCBs were banned in the early 1970s • In 1980 Eisenreich and co-workers estimated that still 85% of the PCBs in the US great lakes came from atmospheric sources.

  46. Polychlorinated biphenyls (PCBs) • Total Flux = Jair + Jrain + Jparticles • Jair = vw ( Cw-P/KH)if resistance to mass transfer is in the water phase • Jair = va (Cw KH - P)/RT if resistance is in the gas phase

  47. In the late 1980s a fugacity model was used to represent the distribution of PCBs in different environmental compartments • RT lnfair /fiopure liquid = RT lnf H2O/fiopure liquid • fair= f H2O

  48. In 1990 Eisenreich and co-workers reported that ambient measurements over the great lakes were generally constant for the past 10 years. • For the past 15 years sources to the lakes had declined because of the PCB ban. • Based on mass transfer calculations it was proposed that during the summer months the lakes were actually a source of atmospheric PCBs.

  49. Polychlorinated biphenyls (PCBs) used as coolants - insulation fluids in transformers, capacitors , plastercisers, additives to epoxy paints are thermally stable and biologically stable can exist in the gas and particle phases

More Related