ethanol Q (1 Viewer)

[Sirius Black]

hmm, I am getting confused on the production of ethanol now. My initial idea was that, cellulose obtained from sugarcane and then throuh acid hydrolysis/cellulase-->glucose --fermentation-->enthanol mixture--distillation-->ethanol
My question is when we say "ethanol is produced from the fermentation of glucose"
is this "glucose" obtained from decomposition of cellulose or directly from photosynthesis?

 

[lozabella]

about ethanol

at the moment there is no simple chemical way to decompose cellulose into its glucose constituents to be able to ferment it to ethanol! ethanol can be formed through the hydration of ethene which needs heat and a catalyst and is CH2=CH2 + H2O under dilute H2SO4 gives CH3-CH2-OH or through fermentation.

In fermentation enzymes in yeast convert starch or sucrose to glucose, or u can start with just glucose and its broken down by the enzymes in the year to ethanol and carbon dioxide. Only 15% ethanol contents can be produced that way, anything more needs to be distilled.

There are also conditions which promote fermentation;
low oxygen concentration
microrganisms being present-yeast
suitable plant sugars such as starch or simple sugars being present
a suitable temperature -usually about 37 degrees!!

Hope this is of help and some clarification! all the best inyour exams!

 

[Slidey]

Plants do photosynthesis, we then do decomposition of cellulose.

Find a way to do efficient, cheap photosynthetic production of ethanol and you're rich.

 

[Sirius Black]

So does that mean the actual glucose we referred in the fermentation process is from decomposition of cellulose?

 

[funking_you]

Yes.

This method of attaining ethanol (fermentation of glucose) is only really used in the real work as a source of ethanol for beverages.

The point here, it to understand that the fermentation process is a real way of obtaining ethanol from natural compounds, the fermentation of starch and other sugars and carbohydrated are much more common industrially than the fermentation of glucose.

Fermentation of natural substances (constituants of biomass) is a huge industry wordwide, what the BoS Syllabus is trying to do, is just take one of the most simple fermentation process (that of glucose) and make you learn it.

Yes, the decomposition of cellulose to yield glucose is a not easy (for humans that is), never the less, it does occur.

Hope that helps.

george

 

[jarro_2783]

I was under the impression you could just mash up some plants and add yeast and it would produce ethanol. Is that wrong? Does it need to be in the form of sucrose or glucose before it can ferment to make ethanol?

 

[xiao1985]

i believe so... yeast woudl only have the ability to work on sucrose or glucose...
i would very much think cellose yeast can't work on.. as only a few bacteria can break up the b - 1,4 glycosidic bond of cellulose...

 

[BlackJack]

That is so; sugar content of plants is rather minimal (in the millimolar). Almost all herbivores use bacteria in their intestines to break down cellulose and yeast has nothing to do with it.

A note for biomass industry, they currently use plants with high sugar content to make ethanol. Starch goes to fermenting, the rest is byproduct.