Chemistry

Home > Chemistry > Core > Production of materials > Production of materials: 2. Biomass research

9.2 Production of materials: 2. Biomass research

Extract from Chemistry Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW.
[Edit:25Jun08]

Prior learning: Preliminary modules 8.5.1, 8.5.3

Background: Fossil fuels are non-renewable resources, available in fixed amounts. Human activity has the potential to completely exhaust reserves of fossil fuel resources. Biomass, organic matter produced by photosynthesis in plants, is a renewable resource. Biomass consists mostly of cellulose and can be used and then formed again from its products by the input of solar energy during photosynthesis. If the matter involved is recycled, biomass could be a source of raw materials for as long as the sun supplies solar energy.

Biomass FAQs Department of Energy, USA

discuss the need for alternative sources of the compounds presently obtained from the petrochemical industry

• Petrochemicals are chemicals made from compounds in petroleum or natural gas. Currently Australia has petroleum reserves that will last about ten years and natural gas reserves that will last about one hundred years. Fossil fuels have taken hundreds of millions of years to accumulate. Over 95% of fossil fuel is burnt as a source of energy and once burnt, fossil fuels are no longer available. Less than 5% of fossil fuel is used to make plastics and only a small percentage of that plastic is recycled. If energy and material needs are to be met in the future, alternative sources will be needed as fossil fuel sources are used up.

The need for alternatives and Oil reserves
Key Centre for Polymer Colloids, University of Sydney , Australia.

explain what is meant by a condensation polymer
describe the reaction involved when a condensation polymer is formed

• A condensation polymer is formed by monomer molecules condensing out small molecules (such as water) as the polymer chain forms.
   
• For example, when two glucose monomer molecules react through two hydroxy groups -OH, an H-OH molecule is condensed out, leaving an -O- linking the two monomer molecules. The first two glucose molecules to join condense out an H-OH, and every glucose molecule added to the growing chain then condenses out another H-OH.

Condensation Polymerisation Key Centre for Polymer Colloids, University of Sydney, Australia.

describe the structure of cellulose and identify it as an example of a condensation polymer found as a major component of biomass
 

• Cellulose is a flat, straight and rigid molecule.

  

• The bulky -CH₂OH groups, represented above as LOH , are on alternate sides of adjoining glucose units.
   
• Many of the hydroxy groups form hydrogen bonds that hold the cellulose chains together.

  

• The hydrogen bonding results in long strong cellulose fibres. This accounts for why wood is a strong building material. The reduced availability of hydroxy groups in the cellulose structure, due to their involvement in hydrogen bonding between the chains, makes it insoluble in water and resistant to chemical attack.
   
• Cellulose is a natural condensation polymer. Most dry plant material consists of up to 50% cellulose. Approximately 500 000 000 000 (5 x 10¹¹) tonnes of cellulose are produced each year by land plants.

Cellulose Key Centre for Polymer Colloids, University of Sydney, Australia.

identify that cellulose contains the basic carbon-chain structures needed to build petrochemicals and discuss its potential as a raw material

• A three carbon-chain and a four carbon-chain are present within the structure of a glucose monomer in a cellulose chain. These carbon-chains have attached hydrogen and hydroxy groups.
   
• The carbon-chain sections could be changed to chemicals that, at present, are mostly made from petroleum. If a chemical process can be developed or a micro-organism found that can break the glucose into three carbon-chains and four carbon-chains this would be very useful. Many polymers are made using three carbon monomers (such as polypropylene in Australian 'paper' currency) or four carbon monomers (such as those used to make synthetic rubbers). Thus biomass, a renewable resource, could be used instead of fossil fuel, a non-renewable resource, to make polymers (like in money and tyres!).

Making use of cellulose and Are we there yet?
Key Centre for Polymer Colloids, University of Sydney, Australia.

use available evidence to gather and present data from secondary sources and analyse progress in the development and use of a named biopolymer. This analysis should name the specific enzyme(s) used or organism used to synthesise the material and an evaluation of the use or potential use of the polymer produced related to its properties

A biopolymer is a naturally occurring polymer generated using natural resources like plants and micro-organisms.

• This syllabus point allows you to use available evidence to propose ideas that demonstrate coherence and logical progression.
  
  
  Some biopolymers that you may wish to research are:

  •  Biopol
  •  Polyhydroxyalkanoate (PHA)
  •  Polyhydroxybutyrate (PHB)
  •  Polyhydroxyvalerate (PHV)
  •  PHB-PHV copolymer
  •  Polylacticacid (or polylactide PLA)
  •  Protein based polymers (PBP)
  •  Cyclodextrins (CD)
  
   
• Try to gather information from a range of resources including popular scientific journals. Use information published in the last three years to assess current developments in the use of biopolymers.
   
  Some starting points include:

  • search engines such as Google
  • online resources such as the Biopolymer portal
  • popular scientific journals, such as Nature and
  • New Scientist
  • digital technologies like CD-ROMs
  • science specific Internet sites such as Nova   and Science Daily  
  
   
• You could appropriately present the information gathered using a table like the following.
   

  Information source	Properties of the biopolymer	Enzyme or organism used	Use or potential use of the polymer

  
   
• Analyse the information gathered by making an evaluation of the use or potential use of the selected biopolymer. This evaluation should be based on criteria or values such as economic, social cost, environmental, political and energy benefit. List the criteria or values you use in your evaluation.

Bugs making plastic Key Centre for Polymer Colloids, University of Sydney, Australia.

---

| Copyright | Disclaimer | Contact Us | Help