S10-S12 Flashcards

1
Q

What is biodegradation?

A

Biodegradation is the digestion or breakdown of any complex compounds into simpler molecules with the help of living organisms that occurs naturally.

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2
Q

What is bioremediation?

A

Bioremediation is a process of degradation of environmental contaminants by microbial consortia via a man-made engineered execution plan to get the desired product.

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3
Q

Biodegradation VS Bioremediation

A

Principle
1: It solely depends on the metabolic capabilities of the microorganisms to progressively convert hazardous contaminants to soluble and stable compounds.
2: Based on the degradative capabilities of microbes but also on the factors such as temperature, nutrient supplements, aeration, and more, controlled by humans that help in enhancing the remediation process

Type of Process
1: Self-paced, naturally occurring process.
2: An artificially engineered remediation process employing microorganisms.

Time
1: It is a slow-paced process since it requires time to transform contaminants into water and carbon dioxide completely.
2: Fast-paced process dealing with the transformation of pollutants into a stable form.

Human Intervention
1: Human intervention is not required, as it is a natural process
2: Experts and Scientists carefully design the execution plan to monitor and analyze in order to get the desired result

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3
Q

Bioremediation CRITERIA

A
  1. Microorganisms must have the needed catabolic activity (i.e., capacity to degrade organic matter.)
  2. Those organisms must have the capacity to transform the compound at reasonable rates and bring its concentration to levels that meet regulatory standards.
  3. They must not generate products that are toxic at the concentrations likely to be achieved during the remediation.
  4. The site must not contain concentrations or combinations of chemicals that are markedly inhibitory to the biodegrading species, or means must exist to dilute or otherwise render the inhibitors innocuous.
  5. The target compound(s) must be available to the microorganisms.
  6. Conditions at the site or bioreactor must promote microbial growth or activity (e.g., an adequate supply of inorganic nutrients, sufficient O2 or some other electron acceptor, favorable moisture content, suitable temperature, and a source of carbon and energy for growth ) if the pollutant is to be cometabolized.
  7. The cost of the technology must be lower or, at worst, not higher than that of other technologies which can also destroy the target substance.
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4
Q

Techniques for Soil Bioremediation

A
  1. Ex-Situ Bioremediation
    Ex-situ means to remove contamination mat to a remote treatment location.
    Disadvantage: Poses a hazard to spreading contamination or risking an accidental spill during transport.
  2. In-Situ Bioremediation
    Bioremediation process is done at the contamination site defines the in-situ method.
    In situ is the preferred bioremediation method, as it requires less mechanical efforts to eliminate spreading contaminants and prevent the spread of pollutant through transportation or pumping away to other treatment locations.
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5
Q

2 Classes of Ex-Situ Bioremediation

A
  1. Slurry Phase
    This technique involves the process of combining contaminated soil with water and other additives in a large bio-reactor and mixed to keep the indigenous micro-organisms in contact with the contaminants.
    Essential nutrients, oxygen are added and the conditions in the bio-reactor are ensured at optimum environment for the micro-organisms to degrade the contaminants. Slurry-phase is a relatively rapid process compared to other biological treatment processes specifically for contaminated clays.
  2. Solid Phase
    Solid phase treatment is used to treat soils in above-ground treatment area. This area equipped with collection systems to check the contaminants from escaping the treatment. The parameters like moisture, heat, nutrients, and oxygen are controlled to enhance rate of degradation. Solid-phase systems are simple to process and maintain in spite of, it requires a large amount of space and more time of treatment than slurry-phase processes.
    Three Solid Phase Techniques:
    Land Farming, Solid Biophiles, and Composting
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6
Q

2 Classes of In-Situ Bioremediation

A
  1. Intrinsic Bioremediation
    Intrinsic bioremediation is a process for converting environmental pollutants degrades to non-toxic forms through the immanent abilities of naturally occurring microbial population at the site. This process is usually employed in underground places as such underground petroleum tanks. This technique deals with stimulation of indigenous microbial population by feeding them nutrients and oxygen to increase their metabolic activity.
  2. Enhanced (Engineered) Bioremediation
    This technique involves the introduction of specific microorganism to the contaminated site. Engineered in situ bioremediation accelerates the degradation process by enhancing the physicochemical conditions to increase the growth of microorganism.
    Techniques:
    Bio-venting, Bioslurping, Biosparging, Bioaugmentation, Phytoremediation, and Mycoremediation
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7
Q

Advantages and Disadvantages of Microbial Bioremediation

A

Advantages
1. Public Acceptance
2. Low Cost Technology
3. It can be done in situ and ex situ

Disadvantages
1. Takes relatively long to achieve treatment
2. May not be effective on all contaminants
3. Pollutant and environmental limitations
4. Specialized expertise are required in designing and implementing.

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8
Q

Applications of Microbial Bioremediation

A
  1. Wastewater and industrial effluent treatment
  2. Soil and land treatment
  3. Control of air pollution
  4. Solid waste management
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9
Q

Microbial Bioremediation Strategies

A
  1. In situ Bioremediation
  2. Ex situ Bioremediation
  3. Bioreactors
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10
Q

Microbial Bioreactors in Bioremediation

A
  1. Slurry Phase Bioreactors
  2. Partitioning Bioreactors
  3. Stirred Tank Bioreactors
  4. Biofilter Bioreactor
  5. Airlift Bioreactor
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11
Q

Factors Affecting Microbial Bioreactor Performance

A
  1. Environment-related factors
  2. Temperature
  3. pH
  4. Nutrients
  5. Moisture
  6. Electron acceptor
  7. Reactor design-related factors
  8. Organism-related factors
  9. Pollutant-related factors
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12
Q

What is Phytoremediation?

A

Bioremediation process that employs varieties of plants to eliminate, transfer, maintain, extract or degrade contaminants in the soil and groundwater.

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13
Q

Mechanisms of Phytoremediation

A

Phytoextraction
Phytostimulation
Phytostabilization
Phytodegradation
Phytovolatilization
Rhizofiltration

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14
Q

Factors affecting efficiency of phytoremediation

A

Contaminated area
Concentration of contaminant
Plant biomass
Accumulation potential of plant
Tolerance of plants
Plant species

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15
Q

Advantages of phytoremediation

A

Environment-friendly
Cost-efficient
Long-term applicability
Multiple contaminants can be removed
Least harmful method

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16
Q

What is catalytic biodegradation

A

Sometimes referred to as “aerobic biodegradation”. It is the breakdown of organic contaminants when oxygen is present.

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17
Q

Catalytic biodegradation compounds

A

Aliphatic compounds
Halogenated aliphatics
Alicyclic hydrocarbons
Aromatic hydrocarbons

The more complex the structure is, the harder it is to degrade via aerobic degradation.

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18
Q

What is non-catalytic biodegradation

A

Sometimes referred to as
“anaerobic biodegradation”. Organic decompositions are done when oxygen is not present.
Under anaerobic conditions, organic compounds are often degraded by an interactive group or consortium of microorganisms.

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19
Q

Process of non-catalytic biodegradation

A
  1. Hydrolysis
  2. Acidogenesis
  3. Acetogenesis
  4. Methanogenesis
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20
Q

Catalytic vs non-catalytic biodegradation

A

Catalytic
Rapid degradation
No pungent-smelling gas produced

Non-catalytic
Slow process
Pungent-smelling gas produced (methane)

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21
Q

What are bio-based, bio-sourced, plant-based polymers

A

Bio-based, bio-sourced, and plant-based polymers are polymers which will mostly biodegrade in compost. Plant-based polymers are derived from plant molecules.

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22
Q

What is Polymerization

A

Polymer was formed through a process called polymerization, the chain-linking of individual rings (small molecules or monomers) with same or different sizes and compounds to form one long or large molecule; thus, the word polymer was derived (in Greek, poly means “many” and mer means “part”).

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23
Q

Polymer Analysis and Characterization

A
  1. Natural Polymers - isolated from natural materials
  2. Synthetic Polymers - synthesized from low molecular weight compounds
  3. Organic Polymers - Polymers whose backbone chains are essentially made from carbon
  4. Inorganic Polymers - Polymers whose backbone chains are NOT made from carbon
  5. Thermoplastic Polymers - soften on heating and stiffen on cooling
  6. Thermosetting Polymers - undergo chemical change on heating and convert themselves into an infusible mass
  7. Plastics - shaped into a hard and tough utility article by the application of heat and pressure.
  8. Elastomers - When vulcanized into rubbery products exhibiting good strength and elongation
  9. Fibers - Polymers with long filament-like materials, whose length is at least 100 times its diameter, polymers are said to be converted into fibers
  10. Liquid Resins - used as adhesives, potting compounds, sealants, etc. in liquid form
24
Types of POLYMER RECYCLING
PRIMARY RECYCLING/RE-EXTRUSION a closed loop polymer recycling method using mechanical reprocessing. Primary recycling is used extensively to recycle process scrap within an industry. SECONDARY/MECHANICAL RECYCLING an effective method of recycling conventional plastic waste into new raw materials without changing the basic structure of the material. TERTIARY/CHEMICAL RECYCLING involves the recovery of petrochemical constituents of a polymer through chemical cracking. This method can be used to effectively treat highly contaminated and heterogeneous polymers and turn them into high-quality products, which makes this method a better alternative than mechanical recycling. QUATERNARY/ENERGY RECOVERY also known as incineration, is a method of recycling plastic waste by burning to produce energy in the form of electricity, steam, and heat.
25
STEPS TO RECYCLE POLYMER WASTE
COLLECTION SORTING WASHING RESIZING IDENTIFICATION COMPOUNDING
26
Synthetic vs Natural Fibers
A synthetic fiber is one that is man-made and doesn’t exist in nature. This is in contrast to natural fibers, like cotton, wool, and linen, which are harvested from natural sources, then spun into yarn.
27
WHAT ARE POLYESTERS
Polyesters are petroleum-based polymers which are held together by chemical links called ester bonds. They are lightweight and are often used for casual wear.
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WHAT ARE RECYCLED POLYESTERS
A recycled polyester is made from plastic waste that is broken down and re-processed to create fabric.
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WHAT ARE BIODEGRADABLE POLYESTERS
Biodegradable polyesters can be created by adding organic compounds into the chemical mix used to form the fabric.
30
WHAT ARE COMPOSITES
A composite is defined as a multiphase material or a composition of material differing in composition, which remain bonded together, but retain their identities and properties, without going through any chemical reaction.
31
WHAT IS A GREEN COMPOSITE
a hybrid of a reinforcement material made of natural fibers (plants or cellulose derivatives) and matrix material (resin). The resin is generally a polymer matrix made of either renewable or non-renewable resources. The natural fibers, also called biofibers, can be made from wood fibers (softwood and hardwood) or from non-wood fibers (hemp, wheat, flax, jute, sisal, kenaf, etc).
32
APPLICATIONS OF BIOCOMPOSITES
ELECTRICAL/ELECTRONICS BUILDINGS/PUBLIC WORKS ROAD AND RAIL TRANSPORTS MARINE AND CABLE TRANSPORTS AIR AND SPACE TRANSPORTS WATER TREATMENT
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NATURAL FIBERS REINFORCED COMPOSITES
ANIMAL-BASED FIBERS PLANT-BASED FIBERS MINERAL-BASED FIBERS
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MINERAL-BASED FIBERS
CARBON - stronger in a particular direction making it easier for the composite to bear heavy loads GLASS - low cost of production, good chemical resistance, high tensile strength, and excellent insulating properties KEVLAR - very high ratio of tensile strength to weight and the lowest specific gravity among the currently used reinforcing fibers
35
Importance of adding additives or fillers
Adding additives or fillers can transform the plastic so that it meets the intended use without sacrificing its good qualities.
36
ADDITIVES
are used to modify and enhance resin properties that become a part of the polymer matrix
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Types of additives
PLASTICIZERS COLORANTS BIOCIDES/ANTIMICROBIAL AGENTS ANTISTATIC AND ANTIFOGGING AGENTS LUBRICANTS FLAME RETARDANTS/SMOKE SUPPRESSANTS STABILIZERS REINFORCING AGENTS
38
FILLERS
reduce the cost of composites and frequently impart performance improvements that might otherwise be achieved by the reinforcement and resin ingredients alone. Fillers are often referred to as extenders. Fillers can improve mechanical properties including fire and smoke performance by reducing the organic content in composite laminates.
39
BIO-BASED FILLERS
Natural fibers such as plant fibers and cellulose based fibers are the most commonly used bio-fillers which are available worldwide for reinforcing various types of polymer matrices.
40
What is Green Chemistry?
“the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances” “applies across the life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal”
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Motivation for Green Chemistry
1. Tarnished image of chemistry 2. The cost of waste 3. Waste reduction at source (cleaner air, water, and environment) 4. Safer products, safer workplace 5. Higher yields, fewer synthetic steps, reduced waste
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12 Principles of Green Chemistry
1. Design chemical products and processes to prevent waste 2. Design chemicals and products for maximum safety 3. Minimize hazards in chemical synthesis 4. Use renewable feedstocks wherever possible 5. Use catalysts for optimum conditions of chemical synthesis 6. Avoid chemical derivatives 7. Maximize atom economy 8. Use safer reaction media 9. Increase energy efficiency 10. Design for degradability of chemicals and products 11. Use in-process real-time monitoring and control 12. Minimize the potential for accidents
43
The Kværner Process and Esterification Chemistry
Rohm and Haas have described the use of ion-exchange resin catalysts as solid acid replacements for homogeneous catalysts in a number of esterification reactions. The use of these polymeric catalyst minimizes waste streams compared with homogeneous catalysts in the manufacture of butane diol (a solvent used in the manufacture of some plastics, elastic fibers, and polyurethanes. This process has been commercialised by Rohm & Haas with Kvaerner Process Technology and has been used successfully by BASF in three large-scale plants.
44
Synthesis of Ibuprofen
Brown Synthesis of Ibuprofen a six-step process and results in large quantities of unwanted waste chemical byproducts that must be disposed of or otherwise managed has poor atom economy because much of the waste generated is a result of many of the atoms of the reactants not being incorporated into the desired product (ibuprofen) 40% atom economy Green Synthesis of Ibuprofen industrial synthesis of ibuprofen that is only three steps most of the atoms of the reactants are incorporated into the desired product (ibuprofen) only small amounts of unwanted byproducts are produced (very good atom economy) thus lessening the need for disposal and mediation of waste products 77% atom economy
45
Photochemical reactions
- initiated by the absorption of light, rather than by heat or the action of conventional reagents. * The activation energy needed is provided by photons, which are non-material and disappear in the process. Three general benefits from photochemical reactions: Lower usage of reagents Lower reaction temperatures Control of selectivity
46
Conventional reagents vs Photons as reagents
Conventional reagents need to be stored may be hazardous or prone to deterioration reactions need to be heated thermal heating does not generate photochemical products cycloadditions, reactions involving singlet oxygen, etc.) Photons as reagents can be switched on and off at will not too hazardous photons directly supply energy only option for highly selective photochemical reactions reaction temperature can be chosen to minimize the yield of by-product
47
Green metrics
Atom Economy Atom Economy = MW of desired product / MW of all reactants x 100% - by Barry Trost (1995) - an extremely useful tool for quickly assessing the mass of waste that will be generated in alternative routes to a particular product E factor E factor = kg of waste / kg of product - by Sheldon (1997) - higher E factor = more waste and greater negative environmental impact; ideal E factor is zero Environmental Quotient - not only the mass but also the environmental burden of the waste needs to be considered. - 1 kg of sodium chloride doesn’t have the same impact on the environment as 1 kg of a chromium (VI) compound or 1 kg of dichloromethane solvent. - also called E factor or Q factor in high school education of green chemistry in some parts of Europe
48
Examples of Solid Acid Catalysts
Silica-based catalysts Polymer-based catalysts Zirconia-based catalysts Zeolite-based catalysts Hydroxyapatite-based catalysts Carbon-based catalysts
49
What is process intensification?
It is any chemical engineering development that leads to substantially smaller, cleaner, safer, and more energy efficient technology or that combines multiple operations into fewer devices (or a single apparatus).
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What makes a process “intensified”?
Gives every molecule the same processing experience Matches the mixing and transport rates with the reaction rate Offers significant enhancements in heat and mass transfer rates Allows the reaction to run at the speed at which it wants to run and not at the speed at which the equipment permits it to run Improves selectivity and yield Improves product quality and validation Rapid grade change through easy cleaning Rapid response to set points For certain processes, the laboratory scale may be the full scale
51
Example of a reactor employing intensified processes
Spinning Disc Reactor (SDR) - a technology that utilizes the effects of centrifugal force and is capable of producing highly sheared thin films of the surfaces of rotating discs/cones. - used successfully to perform free-radical as well as condensation polymerizations. Advantages of SDR high convective heat-transfer coefficients and mass-transfer coefficient values provides micro-mixing and an appropriate fluid dynamic environment for achieving faster reaction kinetics
52
Eco-friendly Chemistry
Refers to the chemistry of chemicals or substances that pose very minimal to no harm to the environment whether through their manufacture, use, or disposal
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Clean Chemistry
Combines green chemistry principles and pollution prevention methods for the goal of sustainability and safety for the people and the environment
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Eco-friendly Chemistry & Clean Chemistry Advantages
Very minimal harm to the environment Fewer hazards and usually biodegradable Pollution prevention
55
What are Scrubbers
A chemical scrubber or scrubber system is a system that is used to remove harmful materials, mainly sulfur, from exhaust gases in industrial plants and facilities. Wet scrubbing - exhaust gases pass through water containing various chemicals, mainly calcium carbonate, to remove sulfur oxides Dry scrubbing - uses pulverized limestone (mainly composed of calcium carbonate)
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Less Toxic Solvent Substitutes
SOLVENT - SUBSTITUTE Benzene - Toluene n-Hexane - 2,5-Dimethyl-hexane Glycol ethers - 1-Methoxy-2-propanol
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Advantages of Green Chemistry
Green Chemistry normally costs less in strictly economic terms Efficient usage of materials, maximum recycling, minimum use of virgin raw materials Reducing or even eliminating waste production