Chapter 9 Final Flashcards
What are the environmental effects of plastic pollution?
- Soil and water contamination,
- Flooding due to choked drainage systems,
- Breeding grounds for mosquitoes (increasing malaria risk),
- Air pollution from burning single-use plastics (SUPs),
- Reduced soil fertility and groundwater recharge.
What are the health effects of BPA (Bisphenol A)?
- Reproductive disorders,
- Male impotence,
- Heart disease in women,
- Changes in sex hormones in men,
- Type 2 diabetes,
- Brain function, memory, and learning issues.
What are the three major forms of plastic contributing to pollution?
- Micro-plastics (less than 5 mm),
- Macro-plastics (size >20 mm),
- Mega-plastics.
What is primary recycling, and what is another name for it?
Primary recycling, also known as mechanical recycling, is the process of recycling plastic by collecting, sorting, cleaning, shredding, melting, and reprocessing post-consumer or post-industrial plastic waste into new products.
What are the main steps involved in primary recycling?
- Collection and Sorting,
- Cleaning and Shredding,
- Melting and Extrusion,
- Pelletization,
- Manufacturing New Products,
- Quality Control.
Why is sorting important in the primary recycling process?
Sorting ensures that plastics with similar resin types and melting points are grouped together, which is crucial for efficient recycling and high-quality output.
What happens during the cleaning and shredding step in primary recycling?
- Cleaning: The sorted plastic waste is cleaned to remove contaminants like dirt, labels, and residual contents.
- Shredding: The cleaned plastic is shredded into smaller pieces or flakes to increase surface area, making it easier to process in subsequent steps.
What is the purpose of melting and extrusion in primary recycling?
- Melting: The shredded plastic is melted down using heat.
- Extrusion: The molten plastic is forced through an extruder to shape it into pellets or new product forms.
What is pelletization, and why is it important?
Pelletization is the process of cooling and solidifying molten plastic into small pellets or granules. These pellets serve as raw materials for manufacturing new plastic products.
What are some challenges of primary recycling?
- Quality Degradation: Recycled plastic may have lower quality than virgin plastic.
- Material Contamination: Contaminants like food residues and different plastic types can reduce the quality of recycled material.
- Downcycling: Recycled plastics may be of lower quality with each recycling cycle.
- Energy Intensive: The process can be energy-intensive, especially during melting and reprocessing.
- Limited Applications: Recycled plastics may not be suitable for all applications due to lower performance.
What is chemical recycling, and what is its primary goal?
Chemical recycling, also known as tertiary recycling, is the process of breaking down complex polymers in plastics into their molecular components or building blocks. The primary goal is to create new materials or products from these components.
What are the main methods of chemical recycling?
- Depolymerization,
- Pyrolysis,
- Gasification.
What is depolymerization, and how does it work?
Depolymerization is a chemical recycling process that breaks down large polymer chains into smaller monomer units using heat, pressure, and/or chemical catalysts. The output is a mixture of monomers that can be used to produce new plastics.
What are the two types of depolymerization methods?
- Hydrolytic Depolymerization: Uses water (hydrolysis) to break chemical bonds in polymers like PET.
- Enzymatic Depolymerization: Uses enzymes to catalyze the breakdown of polymer chains into monomers.
What is pyrolysis, and what are its outputs?
Pyrolysis is a thermal degradation process that breaks down plastics in the absence of oxygen at high temperatures. Outputs;
- Gases (syngas),
- Liquid oil,
- Solid char.
