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Green Chemistry > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

Principle 1 Sustainability

A

Waste prevention likely involves reducing the use of materials or repurposing former waste products into a circular economy-type lifecycle

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2
Q

Principle 2 Sustainability

A

Prioritizing atom economical reactions means using more of all atoms in the start components and avoiding waste generation, which is sustainable

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3
Q

Principle 3 Sustainability

A

Less hazardous chemical synthesis means that the processes will be safer for both humans and the environment, making it less likely for us to damage either ourselves or the environment in a way that compromises future generations

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4
Q

Principle 4 Sustainability

A

Designing safer chemicals means that the chemicals will be safer for both humans and the environment, making it less likely for us to damage either ourselves or the environment in a way that compromises future generations

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5
Q

Principle 5 Sustainability

A

Safer solvents and auxiliaries means that the processes will be safer for both humans and the environment, making it less likely for us to damage either ourselves or the environment in a way that compromises future generations

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6
Q

Principle 6 Sustainability

A

By designing for energy efficiency, we can reduce our energy demand (and thus our natural resource demand), making it easier to conserve enough for the next generations to have as much as we do

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7
Q

Principle 7 Sustainability

A

The use of renewable feedstocks means that we are not depleting materials, and are instead using replenishing materials. These replenishing materials will still be available to future generations, while using depleting materials means less would be available to them. This is clearly sustainable

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8
Q

Principle 8 Sustainability

A

Reducing derivatives means that we have less waste production resulting from chemical processes, meaning that we are making more with the same amount and getting closer to a circular lifecycle

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9
Q

Principle 9 Sustainability

A

Catalysts reduce waste generation, resource consumption, and energy use, making them a very sustainable tool (when implemented carefully)

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10
Q

Principle 10 Sustainability

A

Designing for degradation means we are designing chemicals to integrate with, and not disrupt, natural nutrient and resource cycling processes. We are making what we use now available in the same way to future generations

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11
Q

Principle 11 Sustainability

A

Real-time analysis for pollution prevention helps us keep our environment healthy and running as it needs to in order to provide for future generations

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12
Q

Principle 12 Sustainability

A

Inherently safer chemistry for accident prevention means we are designing molecules to be less toxic, which almost always means making them more environmentally friendly as well. Environmentally friendly materials are less likely to compromise future generations’ wellbeing

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13
Q

What is sustainability?

A

Sustainability is the idea of using resources with regard to future generations and ensuring they have the same access we do now. It is often thought of as a triple bottom line: satisfying social, environmental, and economic criteria for success

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14
Q

What are UN SDG goals that have direct links to Green Chemistry?

A

Good health and wellbeing, clean water and sanitation, affordable and clean energy, industry innovation and infrastructure, sustainable cities and communities, responsible consumption and production, climate action

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15
Q

What is life cycle thinking/life cycle assessment (LCA)?

A

LCA means assessing the environmental and human health impacts of a product by looking at the entire life cycle of product and all of its inputs and outputs

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16
Q

Major product lifecycle stages

A

Materials extraction, manufacturing, distribution, usage, and end-of-life

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17
Q

What is an LCA case study?

A

Proctor & Gamble, 2001, laundry detergent, found that the vast majority of environmental impacts were from warm water washing

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18
Q

At what stage of the product lifecycle can green chemistry have the most impact?

A

Manufacturing (also extraction/processing and end of life)

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19
Q

Why do companies perform an LCA?

A

Environmental performance, optimization of operations (efficiency), determining relevant environmental indicators, identifying areas for improvement, and as a marketing/PR technique

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20
Q

What is circular economy?

A

Circular economy is the idea of moving away from linear life cycles and making it so that there is no waste; materials and products are constantly recycled, reused, or regenerated instead of disposed

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21
Q

Renewable resource/feedstock

A

A raw material to supply a machine or industrial process that is replenished on a relevant (human) time scale

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22
Q

What makes a feedstock a viable renewable resource?

A

Replenishing on a relevant time scale, sustainable across the entire life cycle, functional, and economical

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23
Q

What are types of renewable feedstocks?

A

CO2 (functionalize it), biomass (lignin, algae, corn, switchgrass, poplar, willow, sorghum, bamboo, kelp), agricultural waste (manure)

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24
Q

Valorization

A

Process of reusing, recycling, or composting biomass waste materials into more useful materials, chemicals, fuels, or energy

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25
Q

Lignins

A

Rich source of aromatic carbon found in plant support tissues. Currently used in paper and bioethanol industries. Potential for use as a “drop-in “ chemical for phenols (typically petroleum based) in many products

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26
Q

Terpenes

A

Natural hydrocarbons of the form (C5H8)n where n >= 2. Often have a strong and pleasant odor. Currently used in biosolvents and bioplastics. Example: limonene degreaser product is safer, performs comparably, and smells better

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27
Q

Biomass valorization advantages

A

Reduced carbon footprint and waste, reduced dependence on fossil fuels (volatile prices), additional value stream for businesses, increase business reputation, creates more environmentally responsible products

28
Q

Sugar as a platform chemical

A

Glucose -> furan derivatives -> aromatic chemicals via Diels-Alder cycloaddition

29
Q

Renewable feedstock challenges

A

Material complexity, cultivation (land use competition), need for new processes and infrastructure

30
Q

Solvents in everyday life

A

Cleaning products, lighter fluid, washer fluid, paint

31
Q

Volatile organic compounds (VOCs)

A

Organic compounds with low polarity and low ambient vapor pressure. They are are highly reactive and vaporize easily, causing them to contribute to both air pollution and negative health effects through inhalation

32
Q

Supercritical fluids

A

Substances at temp & pressure above critical point where there are no distinct liquid and gas phases. These lie between liquid and gas on phase transition graphs

33
Q

Supercritical fluid advantages

A

Fine-tuning of properties when temp & pressure are close to critical point, easily separated and extracted b/c materials not soluble in the liquid or gas form of the fluid are often soluble in the supercritical fluid

34
Q

Ionic liquids

A

Salts that are liquid at room temperature (composed of cations and anions)

35
Q

Ionic liquid advantages

A

Highly tunable (choice of anion and cation), nonvolatile, nonflammable, highly stable

36
Q

Water-based chemistry advantages

A

Safe, cheap, non-toxic, nature does it, can yield better results than organic solvents

37
Q

How does a ball-mill work for chemical reactions?

A

It is used in mechanochemistry. It grinds reactants into very small particles, increasing both specific surface area and surface defects, which speed up the reaction. It can be used in solventless reactions. Motion –> Friction –> Heat –> RXN

38
Q

What is catalysis?

A

Increase in the rate of a reaction due to a catalyst lowering the activation energy

39
Q

Advantages of a catalyst

A

Reduced energy, less stoichiometric reagent use, less by-products, and less waste

40
Q

Two types of catalysis

A

Homogeneous (same phase) vs heterogeneous (different phases)

41
Q

Biocatalysis

A

A catalytic reaction where proteins and enzymes perform chemical transformations

42
Q

Biphasic catalysis

A

Reactions occur at the intersection of two liquid layers (usually aqueous and organic) where reactants can travel between layers while the desired product remains in one layer, making for easy separation. Commonly used quaternary ammonium salts

43
Q

Biphasic catalysis advantages

A

High productivity and selectivity, easy separation, use of benign solvents

44
Q

Biocatalysis / enzymes advantages

A

Precision, run in water at ambient temp, pressure, and pH, no toxic or rare earth metals, very high selectivity, no toxic waste

45
Q

Biocatalysis / enzymes disadvantages

A

Slower reaction times, more dilute samples, more expensive isolation and recovery, quick activity loss, inhibition from temperature pressure or pH

46
Q

Biocatalysis case study

A

S-Ibuprofen, A. nigher epoxide hydrolase selectively hydrolyzes R-enantiomers of ibuprofen, leaving only desired (active) S-enantiomers and reducing waste

47
Q

Photocatalysis

A

Use of light as an energy source to activate catalysts that cause chemical transformations (ex: photosynthesis, chlorophyll is a natural photocatalyst). Excited electrons move to the conduction band and help promote organic compound oxidation and decomposition into CO2 and water. Used in breakdown of toxic chemicals like arsenic

48
Q

Metal organic frameworks

A

3-D microporous crystalline materials made of inorganic metal nodes and organic linkages. They have very high surface area and finely tunable pore size. Used in gas storage and separations (as filters)

49
Q

Zeolites

A

3-D frameworks of crystalline hydrated alumino-silicates consisting of (Al or Si)O4 tetrahedra. They have tunable pore size and acidities (they are acidic in water). They can increase selectivity and reduce waste by serving as catalysts. Commercially used for making p-xylene from toluene

50
Q

How does a catalytic converter work?

A

Pt and Pd catalysts remove hydrocarbons and CO, while the RH catalysts remove NOx

51
Q

Haber-Bosch process

A

Use of an iron catalyst, high heat, and high pressure to force the equilibrium reaction of N2 and H2 to NH3 (ammonia) to completion. Very important in terms of fertilizer production

52
Q

Waste Treatment Pyramid

A

Idea that there is a hierarchy of waste management methods: prevention, reduction, reuse, recycling, energy recovery (incineration/pyrolysis), and disposal (landfill)

53
Q

How do incineration and pyrolysis differ? (Recovery)

A

In incineration, solid organic waste is combusted reducing solid mass by 95-96%. In pyrolysis, thermal decomposition at 200-300 Celsius in the absence of oxygen leads to valorization of biomass to create biochar, bio-oil, and syngas.

54
Q

What are recycling techniques?

A

Recycling and composting

55
Q

What are reuse techniques?

A

Gasification (CO and H2 - syngas - created by reacting at high temperatures without combustion) and alcohol production

56
Q

What are reduction techniques?

A

Reduced or no solvent, self separation, material deposition, and using waste as a feedstock

57
Q

Reduced solvent case studies

A

Sildenafil citrate (Viagra) –> 1300 L/kg waste to 7 L/kg
dNTPs –> solvent reduced 95%, haz waste 65%
Ethylene oxide –> replace chlorine with molecular oxygen, reducing waste by 16x

58
Q

Examples of waste feedstocks

A

Electrocatalytic oxidation of glycerol to platform chemicals (polylactic acid), neutralization of red mud through sodium ion extraction before use as bricks, cement, tiles and pollution control

59
Q

Biodegradation

A

Process by which microbial organisms transform or alter the structure of chemicals. Can occur aerobically or anaerobically

60
Q

Ready biodegradability

A

Remove 70% of dissolved organic carbon and achieve 60% theoretical oxygen demand or CO2 production within a 10-day window of a 28-day test

61
Q

Ultimate biodegradability

A

60-70% of organic carbon converted to CO2 within 28 days

62
Q

What is bioaccumulation?

A

The gradual accumulation of substances in an organism when the uptake of that substance is greater than the rate at which it is lost by catabolism or excretion.

63
Q

What are features that make molecules bioaccumulative?

A

Anything that reduces biodegradability: high molecular weight, halogens, quaternary carbons, excessive branching, polycyclic aromatic structures

64
Q

What is the biodegradability index?

A

A calculation that estimates the time scale during which a molecule will degrade aerobically

65
Q

What is the difference between composting and recycling?

A

Recycling converts waste materials into new materials and is usually used with metal, plastic, paper, glass, while composting involves the biological decomposition of organics into a material (compost) that is non-toxic to plant growth

Green Chemistry (4 decks)

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