Write notes on Biofuel cells and biodegradable plastics.
Answers
bio fuel cells are those which are made with the composition of biological waste matter like gobar gas fuel which is made in the presence of methanogens bacteria in then.
biodegradable plastic are those which decompose easily by bacteria and not polluted the environment it is free of black carbon
Types of bio plastic.
Biobased Polyster Plastics That Biodegrade
bioplastic spoon fork lunch box
Plastics that are derived from plants are called biobased plastics. Not all of these are biodegradable; for example there are biobased pet bottles made to be durable. The biobased plastics that biodegrade are made of two materials: biomass and polysters derived from plants. There are two kinds of biobased polysters: polylactide acid (PLA) and polyhydroxyalkanoate (PHA).
Polyhydroxyalkanoate (PHA)
PHA is produced naturally by bacteria and Genetically Modified Organisms (GMO) plants, but there are plans to try production from food waste. Polyhydroxybutyrate or PHB is also a kind of PHA that is widely used. PHAs are expensive to make as only limited quantities can be produced from bacteria.
Uses: PHAs are used as food wraps, cups, plates, coating for paper and cardboard, and 'many medical uses, including sutures, gauzes, and coatings for medicines' according to a report by the Centre for Industry and Education Collaboration (CIEC report). It can replace most of the major fossil fuel based plastic types currently used, such as PE, PS, PVC, and PET points out Bio Based Press.
PHA-blended starch/cellulose plastics: Some plastic items are made entirely of PHA, as in case of water bottles notes Bio Based Press. However, since production of PHA is expensive, it is also blended with starch and cellulose to make it more economical. This has the added advantage of improving the rate of decomposition according to the Dartmouth Undergraduate Journal of Science (DUJS).
Biodegradation: It can be completely compostable in environments that are rich in microbes and fungi, especially soil. These microbes breakdown the PHA with the help of enzymes. The time necessary to degrade depends on the concentration of microbes in the environment.
PHA takes two months to decompose in backyards, according to Bio Based Press.
Polylactide Acid (PLA)
The DUJS explains that PLA is a thermoplastic made through fermentation by bacteria. PLA are actually a long chain of many lactic acid molecules. Since there are many inexpensive means of producing lactic acid, these have only to be polymerized or joined. Therefore, PLA is less expensive than PHA. However, PLA is brittle and its application is more restricted than PHA. Manufacturers get around this problem by including additives or polymers.
Uses: It is made into grocery bags, food packaging, bottles, cups, and plates. Since it decomposes well in the presence of acids, it is used in some medical applications like medical sutures and plates, where it dissolves after 90 days notes the CIEC report. It is also used in 3-D printing of objects.
PLA and polymer blends: PHA can also be blended with polymers from renewable sources to improve its qualities according to DUJS.
Biodegradation: PLA cannot be composted easily in the backyard because temperature and water levels needed are not available in this environment.
PLA can take six-12 months to degrade in soil.
About bio cell:
An enzymatic biofuel cell is a specific type of fuel cell that uses enzymes as a catalyst to oxidize its fuel, rather than precious metals.
Enzymatic biofuel cells work on the same general principles as all fuel cells: use a catalyst to separate electrons from a parent molecule and force it to go around an electrolyte barrier through a wire to generate an electric current. What makes the enzymatic biofuel cell distinct from more conventional fuel cells are the catalysts they use and the fuels that they accept. Whereas most fuel cells use metals like platinum and nickel as catalysts, the enzymatic biofuel cell uses enzymes derived from living cells (although not within living cells; fuel cells that use whole cells to catalyze fuel are called microbial fuel cells). This offers a couple of advantages for enzymatic biofuel cells: Enzymes are relatively easy to mass-produce and so benefit from economies of scale, whereas precious metals must be mined and so have an inelastic supply. Enzymes are also specifically designed to process organic compounds such as sugars and alcohols, which are extremely common in nature. Most organic compounds cannot be used as fuel by fuel cells with metal catalysts because the carbon monoxide formed by the interaction of the carbon molecules with oxygen during the fuel cell’s functioning will quickly “poison” the precious metals that the cell relies on, rendering it useless. Because sugars and other biofuels can be grown and harvested on a massive scale, the fuel for enzymatic biofuel cells is extremely cheap and can be found in nearly any part of the world, thus making it an extraordinarily attractive option from a logistics standpoint, and even more so for those concerned with the adoption of renewable energy sources.
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