Green analytical chemistry Flashcards
There are 12 principles of green chemistry, mention some
- Prevention of waste
- Atom economy
- Less hazardous chemical synthesis
- Designing safer chemicals
- Safer solvents
- Design for energy efficiency
- Use of renewable feedstocks
- Reduce derivatives
- Catalysis
- Design for degradation
- Real time analysis for pollution prevention
- Inherently safer chemistry for accident prevention
There are 7 principles of green analytical chemistry. Mention some
- Prevent or reduce formation of waste
- Use less toxic chemicals
- Design energy efficient analytical systems
- Avoid chemical catalysts, derivatisation reagants, auxiliary substances
- Catalysis is better than stoichiometric reactions
- In situ analysis is better than off-line analysis
- Use safer chemistry to prevent accidents
Is hexane or heptane better to use (better for the environment)?
Heptane
What are the steps of sample preparation?
Extraction
Homogenousation
Enrichment (increase concentration of analyte)
Removal of interferences (increased selectivity)
Trueness and precision
Sample preparation is full of biases, mention a few.
From where you pick the sample (is it representative?)
How you extract it
Which solvent you use
How do we design a “green” solvent?
Low toxicity to humans and environment
Naturally occurring (could be about an already installed infrastructure such as water)
Produced from renewable source
Energy efficient in terms of production and usage
Which solvent is better methanol or ethanol?
Methanol is toxic to humans, ethanol is easily produced
What is environmental performance?
It is how we calculate how “green” something is
Are chlorinated solvents an issue?
Yes and currently no other solvents to replace it because the physiochemical properties of chlorinated solvents are hard to find in other solvents
What is EHS?
Environment, Health and Safety. A standard industry uses a lot.
Which organic solvents are the most “green”?
Ethanol and methyl acetate
What is a solvent selection tool?
Simulation tool to help you decide on the best solvent to use. Calculates what chemical properties you need.
Is supercritical carbon dioxide a sustainable alternative to organic solvents?
Yes
Does supercritical CO2 dissolve polar compounds?
No
Can pressured hot (subcritical) water be used as a solvent?
Yes
Is CE a greener separation method?
Yes
What is LCA?
Life cycle assessment
What are CO2 equivalents?
A way to classify green house gasses, they are “translated into” CO2 to be able to compare
Select 3 out of 12 principles of green chemistry and explain them in the context of green analytical chemistry methodology
Prevent waste
Safer chemicals
Efficient
What are the biggest challenges to achieve greener analytical chemistry methods?
Solvents (especially hard to find replacement for chlorinated solvents)
Efficient systems
What are the requirements for a solvent to be considered “green”?
From renewable sources
Not toxic to humans or environment
Not too energy demanding to use or produce
“Recyclable”
What is contradictory about hexane and heptane with regards to which one is greener?
Hexane is toxic to the environment but heptane has a higher boiling point and thus requires more energy. It is more expensive too.
Describe EHS and LCA as approaches to describe greenness
Define the term functional unit from LCA
It is the aim of the study, a quantified function provided by the product/system that is being studied. When you compare things they have to have the same function. eg. a water bottle with tap water does not really have the same function as a sparkling water sold on a bottle.
Define the term system boundaries from LCA
It is the scope of the study. Limits of time and geography. What should be included, machines and personnel? Start and end point of study
Define the term hotspot analysis from LCA
You can divide up the system you are looking at into categories such as “resources”, “production”, “consumption” and “waste treatment”
Define the term effect category from LCA
What is miniaturisation?
Lab on a chip is an example. Uses less of everything. Smaller inner diameter of column and smaller/fewer stationary particles. Microfluidics
What is hyphenation?
A technique where a separation technique is coupled with an online spectroscopic detection technology is known as hyphenated technique, e.g., GC–MS, LC-MS.
Another example is that extraction and liquid chromatography happens in the same process
Motivate why hyphenation and miniaturisation are two approaches in green analytical chemistry
Miniaturisation uses less of everything.
Hyphenation does things more efficiently
Why is in-situ analysis considered a green approach?
Samples do not have to be transported (?)
List three examples of green solvents and motivate why they are considered green
Subcritical water (already installed infrastructure and not harmful to environment, the heating is an issue though)
Supercritical CO2 (it will be reused and is a byproduct from other processes so very green, not toxic and does not contribute to greenhouse gasses)
Ethanol (not toxic to humans or environment, relatively low boiling point, has a good low score on the EHS scale)
Why is supercritical CO2 considered green?
it will be reused and is a byproduct from other processes so very green, not toxic and does not contribute to greenhouse gasses
How would you compare two different analytical methods in terms of their environmental impact? Will you use methods/tools to enable comparison?
One could use the EHS score for the methods, looking at the solvents used, the energy used. Yes it is good to use well-established methods and tools
An analytical method consists of
1) sample prep
2) chromatography
3) detection
Explain how to make each step greener
1) Important to use a “green” solvent for dissolving the sample. Use an energy efficient way of extraction. Perhaps have the extraction and chromatography in the same process (hyphenation).
Explain briefly the two concepts of sustainable development and green chemistry, what are similarities and differences?
Sustainable development is a very broad term that covers many different fields. Green chemistry is a subsection of sustainable development and is a way of making the chemical process more environtally friendly.
In EHS each category has 3 points and sums up to a total of 9. What are the three points in each category (Environment, Health and Safety)
E:
Pollution of water
Pollution of air
Biodegradability
H:
Chronic toxicity
Irritability (breathing, eczema)
Acute toxicity
S:
Reactivity
Flammability/ explosivity
Release potential
Mention some organic solvents that have a good EHS score
Methyl acetate
Ethanol
Methanol
Ethyl acetate
Propanol
Butyl acetate
Butanol
What is in-situ analysis?
analysis is conducted at the site where production happens
How do you do an LCA?
Define aim (functional unit) and scope (system boundaries).
Inventory (energy, materials)
Assessment of environmental impact
Interpretation of results
