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Lesson Three: Applying the 12 Principles of Green Chemistry

Module Four: Real World Solutions


Assignments

For more background on the thinking discussed in this module, please read the articles below, and answer the following questions. Your quiz may cover some of this material.

  1. Read about the current and past winners of the Presidential Green Chemistry Challenge Awards?
  2. Consider some successes that aren't necessarily award-winning, but nevertheless high-impact chemistry in industries as varied as Nike to Nylon in William McDonough's Cradle to Cradle Case Studies.
  3. Information on Petretec—Dupont's Technology for Polyester Regeneration.

Exercises

Here are some exercises to help you more deeply consider some of the issues you are exploring in this module.

Imagine you are the chemist responsible for selecting a solvent for a multi-ton reaction.  Two generic solvents, A and B, have been shown in the lab to carry out the synthesis equally well.  They are outlined here in this chart:

Solvent A Solvent B



Boiling point 160°C

Boiling point 50°C

Vapor pressure 0.5 mm of Hg

Vapor pressure 20 mm of Hg

Density 0.9

Density 1.7

Odor threshold 300 ppm

Odor threshold 0.1-0.2 ppm

Worst case ecotoxicity EC50 4 mg/L

Worst case ecotoxicity EC50 0.5 mg/L

Molecular wt. 10000 (liquid polymer)

Molecular wt. 150

Log Kow 0.8

Log Kow 4.5

Conductivity 2 × 106 Ps/M

Conductivity 1.5 Ps/M

Dielectric constant 25

Dielectric constant 2.3

Biodegradable in water

Slow biodegradation in water

Acute hazards: danger if ingested.

Acute hazards: causes severe burns.

Heat of combustion: 15000 btu/lb

Heat of combustion: 5500 btu/lb

Autoignition temperature 240°C

Autoignition temperature 365°C

  1. Besides efficient synthesis, there are other health and safety issues to consider.  Use the solvent data in the chart to decide whether A or B is the better choice for each situation below.
    1. Workers will have to climb into the reaction tank between each production batch and hose down the walls with water.  Which solvent is better, A or B?  Why?
    2. A and B are both petroleum-based, and the cost of petrosolvents has increased by 400% in the last few years.  If the solvent could be separated from the process and recycled, the economic savings could be enormous.  However, it is crucial that the recycled solvent not be contaminated with water used in the purification stages.  A or B?  Why?
    3. It appears that the recycling process can recover 98% of the solvent with every batch.  The remaining 2% will have to be incinerated or mixed with aqueous waste streams and kept in an open-air biotreatment lagoon for 2 weeks.  A or B?  Why?
    4. Because of the turbulent flow used in the chemical reactor, there is some concern that static charge will be generated and accumulate on the surface layer of the solvent, creating a risk of sparking.  A or B?  Why?
  2. Read this article, and then circle the structure below that represents bisphenol A (2,2'-Bis(4-hydroxyphenyl)propane):
    Molecular Structures