Liquid that dissolves any kind of solute.
* Butyl alcohol
* Glycerol etc..
Dry cleaning (tetrachloroethylene)
Paint thinner (toluene, turpentine)
Nail polish removers & glue solvents( acetone,
ethyl acetate, methyl acetate)
Spot removers(hexane, petrol ether)
Detergents( citrus terpenes)
Perfumes (ethanol) &
Petrochemical – hydration of ethylene
Biological – fermenting sugars with yeast
Chemical ethylene hydration :
Raw materials: petrochemical feedstocks
Process : acid- catalyzed hydration of ethylene
Reaction : C₂H₄ + H₂O CH₃CH₂OH
Catalyst : phosphoric acid – adsorbed onto a
porous support(diatomaceous earth/charcoal)
Biological fermentation :
Dry mill process or wet mill process.
DRY MILL PROCESS
Overall reaction involved
fermentation of starch portion of corn into sugar
distillation into alcohol
Steps involved in dry mill process
Cooled mash + glyco amylase - Liquefied sugars to fermentable sugars (dextrose)
Meal + water +alpha amylase -Cookers (120 -150)˚c & 95˚C – starch is liquefied
Feed stocks passed through Hammer mill - Fine powder ( meal)
Sugars ethanol & CO₂
Continuous flow of mash through several fermenter–fully fermented & leaves the tank
Batch process – mash in one fermentor for 48 hrs (beer) before distillation is started
Ethanol used for fuel must be denatured or made unfit for human consumption, with
a small amount of gasoline (2-5%) This is done at ethanol plant
Alcohol from top of the column – dehydration system (remaining water removed)
Most ethanol plants use molecular sieve to capture last bit of water in the ethanol
Alcohol product at this stage (anhydrous ethanol – pure, without water) – 100% proof
Fermented mash(beer)–10% alcohol & all non-fermented solids from corn & yeast cells.
Mash – pumped into continuous flow, multi-column distillation system – alcohol
Alcohol leaves the top of final column at 96% strength & residue mash (stillage)
transferred from base of the column to the co-product processing area
Distillers grain :
used wet or dry – highly nutritious livestock feed
Given off in great quantities during fermentation
Many ethanol plants collect ,compress & sell it for use in other
Most ethanol from microbial fermentation-preparation of beverages.
Ethanol production from sugary substrates-expensive than naturally
Microbial conversion of sugar to alcohol is limited by the toxicity of
alcohol which cannot accumulate in the fermenter beyond a limit.
The recovery process which involves distillation requires energy input.
Ethanol production by bacteria
Bacteria which can ferment sugar faster than yeast have
eg. Zygomonas mobilis &
Thermophilic Thermobacter ethanolicus.
As sugary substrates are expensive & are used for food, it
may be possible to use cellulosic materials & photosynthetic
1. Cellulose Sugar
2. Sugar Alcohol
Zygomonas mobilis (or)
The anaerobic bacterium Clostridium ljungdahlii, (in
commercial chicken wastes) can produce ethanol from
single carbon sources including
* synthetic gas,
* a mixture of CO and H
that can be generated from the partial combustion of
either fossil fuels or biomass.
If these techniques coupled with genetic engineering
techniques - possible to produce cheap ethanol to meet
the organic solvents & automative fuel requirements of the
Advantages of Z.mobilis over S.cerevisiae
Higher sugar uptake & ethanol uptake
Lower biomass production
Higher ethanol tolerance
Doesn’t require controlled addition of oxygen during the
Amenability to genetic manipulations
Limitations compared to yeast
Difficulties in converting large amount of complex CHO
polymers like cellulose, hemicelluloses and starch to ethanol.
Its utilizable substrate range is restricted to glucose, fructose and
Its resulting in by-products such as sorbitol, acetoin, glycerol
and acetic acid.
Formations of extracellular levan polymer.
ACETONE & BUTYL ALCOHOL
Chaim Weizmann, England in the early part of this
acetone: production of explosives &
butanol: making synthetic rubbers.
N-butanol is used in brake fluids, urea-formaldehyde
resins & in lacquers used as protective coatings in
1. Clostridium acetobutylicum – 1st organism – industrial
production of acetone from starch.
2. Clostridium saccharoacetobutylicum – convert molasses
into acetone & butanol.
Substrate: sterile diluted molasses or cooked corn meal.
pH : 7.2
Type of fermentation: anaerobic
By-products : CO₂( preparation of dry ice) & H (fuel)
Product recovery : fractional distillation
Main uses :
solvent in food colouring agents
Lubricant in toothpastes, candies, cake icings
Cosmetic & pharmaceutical industries
Production of explosives & propellants.
organism : yeast - Saccharomyces cerevisiae or
bacteria – Bacillus subtilis