6. Organic Solvents

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ORGANIC SOLVENTS
Ethanol, acetone, butanol, glycerol
Petrochemical industries
Due to scarcity of oil and natural gas alternatives for commercial
production
Use of low cost raw materials (wood, cellulose, starch)
ALCOHOL
Chemically manufactured by hydration of ethylene (C2H4)
In developing countries microbial fermentation is preferred to
cheap raw material available.
Now other countries also realize the potential due to political and
economic analysis.
AS A MOTOR FUEL
Green petrol produced using sugar based plants like sugarcane and cassava.
The pioneers are Brazil, with several fermentation and distillation plants
the 90% of new cars are run on alcohol as a fuel.
BioAlcohol from Plant Biomass
•Fermentation produces alcohol
•Raw materials are
1. STARCHy materials (wheat, rice, maize and potato)
2. CELLULOSic material (wood, agricultural wastes)
Brazil: first country to produce ethanol by large scale yeast fermentation by using sugarcane
and cassava
Advantages of ethanol as motor fuel:
less envtal. Pollution, 60%less CO2 as compared to petrol, 65% less Hydrocarbon
and 15% less nitric oxide
Flash point (temp. at which substance ignites) is higher (45oC)
than
petrol (13oC)
Disadvantages
Costlier than petrol
Starting engines in cold difficult
Ethanol may react with Al and Mg to damage containers
Should not pick H2O from air (i.e. highly pure) can cause
corrosion of engines and tanks and will not burn
Gasohol: 20% ethanol (has to be highly pure) and 80% petrol (used in USA)
Ethanol by Fermentation of Micro-organisms
Yeasts: Saccharomyces cerevisae
Bacteria: Zymomonas mobilis
Raw material:
Sugary material (molasses, whey, glucose, sucrose)
Starchy materials (wheat, rice, maize, potato, cassava)
Cellulosic material (wood, agricultural wastes)
Pretreatment of raw material:
Depends on type of raw material.
Sugary materials : mild
Cellulosic: extensive acidic or enzyme hydrolysis to release
monosaccharide units
PRE TREATMENT: Hydrolysis, clarification, filtration
RAW MATERIAL
PRE TEATMENT
Milled grain
steam
Gelatinized material
cool
a-amylase
Bacillus amyloliquefaciens
Liquefied material
Glucoamylase
Saccharified material
Glucose isomerase
Fructose
FERMENTATION
Yeast
Fermentation
Alcohol
Industrial production of alcohol and fructose from starch
ETHANOL FERMENTATION
RAW MATERIAL
PRETREATMENT
STERLIZATION
Molasses
pH 4-4.5
21-26oC---30oC
O2 initially
Anaerobic conditions
after CO2 produced
STARCH
Hydrolysis
GLUCOSE
Glycolysis
PYRUVATE
pyruvate
decarboxylase, TPP, Mg, CO2
ACETALDEHYDE
Alcohol
dehydrogenase, NADH+H+
ETHANOL
FERMENTATION
SEPARATION
DISTILLATION
DEHYDRATION
STILLAGE
(wastes
concentration)
Ethanol at high conc inhibits its own
synthesis
Eg. Yeasts at 5% alcohol, growth ceases
Zymomonas mobilis tolerate 13%
1g glu to 0.511g ethanol (theory)
Pure substrates (glu, lac, suc): 95%
conversion rate
Corn starch (industrial grade): 90%
100g pure glucose: 48.5g of ethanol
produced, 46.5g CO2, 3.3g glycerol and
1.3g biomass
USED FOR FUEL,
FEED OR FERTILIZER, SCP, METHANOL
Biofuel
Biofuel is defined as solid, liquid or gas fuel derived from recently dead
biological material and is distinguished from fossil fuels, which are
derived from long dead biological material. Theoretically, biofuels can
be produced from any (biological) carbon source
Two common strategies of producing biofuels
One is to grow crops high in sugar (sugar cane, sugar beet, and sweet
sorghum) or starch (corn/maize), and then use yeast fermentation to
produce ethyl alcohol (ethanol).
The second is to grow plants that contain high amounts of vegetable oil,
such as oil palm, soybean, algae, or jatropha. When these oils are heated,
their viscosity is reduced, and they can be burned directly in a diesel
engine, or they can be chemically processed to produce fuels such as
biodiesel.
Wood and its byproducts can also be converted into biofuels such as
woodgas, methanol or ethanol fuel. It is also possible to make cellulosic
ethanol from non-edible plant parts, but this can be difficult to
accomplish economically.
Agricultural products specifically grown for biofuel
Corn, switchgrass, and soybeans, primarily in the United States;
rapeseed, wheat and sugar beet primarily in Europe;
sugar cane in Brazil;
palm oil and miscanthus in South-East Asia;
sorghum and cassava in China;
jatropha in India.
Hemp has also been proven to work as a biofuel.
Biodegradable outputs from industry, agriculture, forestry and households
can be used for biofuel production, either using anaerobic digestion to
produce biogas, or using second generation biofuels; examples include
straw, timber, manure, rice husks, sewage, and food waste.
Biomass can come from waste plant material. The use of biomass fuels
can therefore contribute to waste management as well as fuel security
and help to prevent climate change, though alone they are not a
comprehensive solution to these problems.
Bioethanol
Can be used as a replacement to petrol for automobiles
1930s in USA ethanol was produced from maize at 20% conc to produce
gasohol called AGROL
In UK gasoholwas markted by Cleaveland Oil Company undr name DISCOL till
1960s until petrol became available and cheaper.
Large scale production was started in 1975 in Brazil follwed by USA in 1978
Ethanol producing microorganisms
Glucose
Yeast
Saccharomyces cerevisiae
Glycolysis
S. carlsbergensis
Kluyeromyces fragilis
TCA cycle
CO2
Bacteria
Candida tropicalis
Zymomonas mobilis
Clostridium thermocellum
Pyruvate
Acetaldehyde
NADH
NAD+
Ethanol
Vegetable oil
Plant with sugar
(sugarcane)
Plant with starch
(maize, potato,
cassava)
Plant with lignocellulose
treatment
Esterification
PURIFIED OIL
BIODIESEL
Hydrolysis
Gasification
Dehydration
Synthetic
catalysis
BIOETHANOL
BIOMETHANOL
Bioethanol from LignoCellulosic waste
Clostridium acetobutylicum
C. butyricum
ACETONE AND BUTANOL
Acetone used in manufacture of nitrocellulose for explosives
wood hydrolysates, molasses, starch, sucrose
Glucose
Acetyl COA
Pyruvate
Acetyl CoA
Acetyl PO4
Acetic acid
Acetoacetyl CoA
Acetyl COA
b-hydroxybutyl CoA
Crotonyl CoA
Butyryl CoA
Butyric Acid
b-hydroxyb-methyl glutaryl
CoA
Acetyl COA
Acetoacetic acid
Acetone
Isopropanol
Butanol
Nowadays acetone and butanol are by products of petroleum industry
Fermentation is discontinued
PRODUCTION
Raw material: molasses, ammonium sulphate, Ca CO3, corn steep
liquor, gassed with CO2, starting pH 5.8-6.0, 34oC, 36h
Phase I:
rapid growth, acetic acid, butyric acid, titratable
acidity, pH5.2
Phase II:
incr in acetone, butanol decr in acidity (acid break)
Phase III: decr in solvent production and no incr in pH
Contamination: absolute sterile conditions are required, bacteriophages
and Lactobacilli cn be contaminants
Product yield: 30% carbohyd. Gets converted. With molasses 7:3
butane acetone and corn medium 6:3. Production of butanol is influened
by its toxicity…more than 13.5% conc is toxic.
Recovery: acetone and butanol recovered by continuous distillation and
fractionation. Leftover residue is used as animal feed after drying.
GLYCEROL
• Starting material for manufacture of explosives
• Produced by saponification of fats and oils.
• Chemically synthesized from propylene or propane
Produced by yeast during alcoholic fermentation
Sodium bisulfite blocks blocks alcohol production and
large scale glycerol production
PRODUCTION
2-3 days
50% yield
Glucose
Fructose 1,6 bisPO4
Glyald 3 PO4
Pyruvate
Acetaldehyde
ACETALD.
SULFITE
COMPLEX
Sodium
bisulfite
blocks
Ethanol
Sodium sulfite +CO2 ---> Sod bisulfite
DHAPO4
DHAP
dehydrogenase
Glyald 3 PO4
CH2-OH GLYCEROL
CH-OH
CH2-OH
PRODUCTION from alga and bacteria
Dunalielia salina in Israel, lives in high salt envt and synthesizes
glycerol to balance osmotic pressure of hypersaline lakes.
When surrounding salt is more more intracellular solutes (glycerol)
When surrounding salt conc is reduced, glycerol is exxcreted out
into medium
Bacillus subtilis capable of converting glucose to glycerol, ethanol,
Lactic acid, butanediol
Produces high yield at anaerobic conditions despite being an aerobic MO
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