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Thread: industrial production of ethanol from sugar cane

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    Senior Member Loz_metalhead's Avatar
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    industrial production of ethanol from sugar cane

    I cant find any information on this...I have searched google multiple times. I also need chemical equations that are involved in the process. I have the obvious fermentation process.

    Please help

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    Cadet PLooB's Avatar
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    Have you tried wikipedia?

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    Senior Member Loz_metalhead's Avatar
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    I am confused about the dehydration...

    Sugar cane can be used to produce ethanol commercially in large amounts.

    The first stage in ethanol production from sugar cane is milling. The grains from the sugar cane are passed through hammer mills. These hammer mills grind them into a fine powder. This fine powder is now called meal.

    The meal is then sent to the mashing system. At the mashing system, the meal is mixed together with enzymes and water.

    This mixture is then passed through cookers which heat up the mixture. This heat effect turns the starch into its liquid form. The enzymes start breaking down the sugar cane to pure to sugars. This mash from the “cookers” is cooled and then allowed to enter the fermentation stage

    The yeast is added to the mash, which converts the sugars into ethanol and carbon dioxide as it acts as a biological catalyst. The carbon dioxide can be removed as the industry is only interested in keeping the ethanol as its end product.

    Enzymes produced by yeast, such as invertase, are necessary for the fermentation processes to occur. Sugar cane is broken down into glucose and fructose:
    (invertase)
    C12H22O11 + H2O * C6H12O6 +C6H12O6
    (cane sugar) (water) (glucose) (fructose)

    The glucose is then further fermented to produce ethanol:
    (zymase)
    C6H12O6 * 2C2H5OH + 2CO2

    During the fermentation process, nutrients such as phosphoric acid and urea are allowed into the fermenters to ensure that the yeast continues growing. The maximum concentration of ethanol that can be produced is 15%. At concentrations higher than this, the ethanol will start to kill the yeast and the production of ethanol will stop.

    The mixture is then continually pumped into a distillation system where the ethanol is removed from the mixture and then the mixture can be left to ferment again.

    The alcohol that is removed during distillation is approximately 96-97% pure. This is then
    dehydrated to remove the last impurities and water molecules. After this process, the ethanol can then be sold commercially as it is anhydrous.

    Dehydration equation

    The process is the same as corn...which was another question..argh

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    That is a great response Loz_metalhead

    however, in exam conditions, students need to be able to summarize this information into a more succinct form so that it is easily followed by the examiner. This of course ensures that you get the maximum marks

    (i would also recommend organizing your notes in point form. Markers often prefer a more visual response which makes uses of labelled diagrams, point form, tables, steps or even flow diagrams)


    The syllabus requirement is:
    summarize the processes involved in the industrial production of ethanol from sugar cane

    A more succinct, simple response would be:

    - ethanol may be produced by the fermentation of sugars which are found in molasses such as sugar cane
    - fermentation is the process that converts glucose into ethanol and CO2
    - conditions of fermentation include:
    ~ catalysts that are found in yeast which contain enzymes called
    zymase, catalysing glycolysis i.e. the conversion of glucose
    to ethanol
    ~ aqueous solution of sugar to which yeast is added
    ~ anaerobic conditions i.e. the absence of oxygen
    ~ high temperatures (37 degrees celsius)
    - overall equation for the fermentation of glucose is:

    zymase
    C6H12O6 (aq) ------> 2C2H5OH(aq) + 2CO2 (g)

    (word eqn: glucose ---> ethanol + carbon dioxide)

    - the concentration of ethanol that may be produced is only about 15% fo the mixture. Above this level, yeast is killed by ethanol and fermentation stops
    - to produce higher conentrations of ethanol, the mixture is purified using fractional distillation (this is an expensive process)


    also, Loz_metalhead, your dehydration confusion can be easily solved...

    dehydration is indeed part of the process, however it is unimportant and need not be mentioned in an exam reponse if it confuses you. In this case, dehydration just means getting rid of the water molecules remaining in mixture to increase the purity of ethanol

    However, do not get this confused with the dehydration of ethanol which is another syllabus point, where dehydration means the conversion of ethanol into ethene

    in summary, there are two 'types' of dehydration:
    1. the one mentioned by Loz_metalhead which is involved in the purification of ethanol when it is obtained from sugar cane. This is just a process that gets rid of the water

    2. by far the more important dehydration that is explicitly mentioned in the chemistry syllabus which says...

    syllabus point:
    describe the dehydration of ethanol into ethylene and identify the need for a catalyst in this process and the catalyst used

    briefly, this syllabus dot point requires the following reponse:

    - dehydration is the conversion of ethanol into ethene (AKA ethylene)
    - ethanol can be dehydrated to ethene using concentrated sulfuric acid

    conc. H2SO4
    ethanol -------------> ethene + H20


    therefore, it is best to leave out the dehydration in the purification of ethanol if it confuses you, as dehydration for the chemistry syllabus means the conversion of ethanol into ethene using concentrated sulfuric acid

    Here are a few more hints for chemistry:

    i recommend going through the whole syllabus as you learn it at school and write succinct, point form / visual notes

    only learn what is needed for the course, do not overburden yourself with too much unnecessary information. Ask your teacher what is required in an exam response so you don't write unnecessary information that won't get you marks. You can also ask me since i have had experience with what the markers are looking for in responses

    at the end of each huge topic, draw up a simple flow diagram so you can organize your thoughts in a visual manner

    anyways, i hope that helped ^^...

    email me if you need any help with maths, physics or chemistry. I have lots of notes directly addressing the HSC syllabus

    Best of luck!
    Last edited by COCO_moiselle; 26 Nov 2005 at 2:01 PM.

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    nice work COCO_moiselle

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    Magician, and Lawyer. Mountain.Dew's Avatar
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    mmm for something interesting, u might like to try some beer sites, like tooheys, fosters, VB to find out how they make their beer, as an EXAMPLE of INDUSTRIAL PRODUCTION.
    B Comm/LLB @ USyd (V)


    Yeah, I feel old...as an undergrad. lol.

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    Cadet me-mfhs's Avatar
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    Re: industrial production of ethanol from sugar cane

    oo0oh thanks heaps ^^!


    s w e e t h o n e y b 7




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    Re: industrial production of ethanol from sugar cane

    I also need help on this dot point. The full point from the syllabus is: Process information from secondary sources to summarise the process involved in the industrial production of ethanol from sugar cane.

    COCO_moiselle's reply was just a summary of the fermentation of glucose, and not 'information from secondary sources'?

    I am stuck here, I don't know whether they are asking us to simply summarise the fermentation process or use secondary sources to gain a more detailed response.

    Also, I have looked through various past papers and cannot seem to find any questions on this particular dot point. If anyone can find a question on it, please let me know as it will help
    Last edited by Danger; 30 Dec 2007 at 2:38 PM.

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    Re: industrial production of ethanol from sugar cane

    How about this response:

    Molasses, obtained from sugar cane have high sucrose content. The molasses are mixed with water to allow sucrose to react with water to produce glucose and fructose.

    The glucose and fructose obtained is then allowed to ferment under fermentation conditions to produce ethanol and carbon dioxide.

    [insert equations here]

    - the concentration of ethanol that may be produced is only about 15% fo the mixture. Above this level, yeast is killed by ethanol and fermentation stops
    - to produce higher conentrations of ethanol, the mixture is purified using fractional distillation (this is an expensive process)
    Last edited by Danger; 30 Dec 2007 at 12:37 PM.

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    You feeling lucky, punk? o.bi.sess's Avatar
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    Re: industrial production of ethanol from sugar cane

    That would be a good response for a 3-4 marker. Anything higher needs slightly more detail. You would definitely the equations and conditions for sucrose into glucose and fructose. You would also need to describe the confitions for fermentation, and why the conditions have to be so.

    And if it was the monster 7-8 marker, you might want to consider why sugar cane/corn is used for fermentation and what ethanol is used for/its importance in society.
    "I told you to chip at it! Not to take a bloody sledgehammer to it!"

    BE (Ind Chem) @ UNSW

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    Re: industrial production of ethanol from sugar cane

    Quote Originally Posted by Danger
    I also need help on this dot point. The full point from the syllabus is: Process information from secondary sources to summarise the process involved in the industrial production of ethanol from sugar cane.

    COCO_moiselle's reply was just a summary of the fermentation of glucose, and not 'information from secondary sources'?

    I am stuck here, I don't know whether they are asking us to simply summarise the fermentation process or use secondary sources to gain a more detailed response.

    Also, I have looked through various past papers and cannot seem to find any questions on this particular dot point. If anyone can find a question on it, please let me know as it will help
    I think the process information from secondary sources part will probably be more a guide for in-school assessments (research essays etc) because I really doubt you'd ever be asked to rote learn your sources and reference them in an exam. The only other way the secondary sources part could be incorporated would be if there were passages in the exam itself you were supposed to discuss.

    The purpose of the dot point I think is basically so that (in theory) you go away and find a heap of sources and from them come up with a summary of the process but of course if you get that summary another way it will be exactly the same for you in terms of the HSC.

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    Talking Re: industrial production of ethanol from sugar cane

    WOW! gee thankx

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    Re: industrial production of ethanol from sugar cane

    what happens during the filtering part of the production of ethanol from sugar cane.... i mean the steps... how does the sugar cane get filtered before the fermentation process?

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    Smile Re: industrial production of ethanol from sugar cane

    Prior to fermentation, the sugar cane needs to be processed. Firstly, leaves are removed from the plant (generally by burning them off- difference in boiling points of plant material + sugar). You are then left with the stems that contain the sugar cane itself... this is then extracted from the plant and you are left with two main products-sugar and molasses.

    Sugar goes on to be further processed to form different sugars and is also used in skincare, cosmetics etc.

    Molasses is a mixture which is usually about 50% sugar and 50% impurities. It is separated from the sugar by centrifuging, as it is denser than sugar, it falls to the bottom. This is then used to make rum, animal feed, fertiliser and processed to make ethanol and other bio-fuels

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