12. Long answer question III

Ethanol is generally referred to as carboxylic acidketonesalcoholaldehyde. All alcoholic liquids and some cough syrups contain ethanol. The molecular formula for ethanol is \(C_2H_5OH\).

 

Ethanol is prepared in industries via the fermentation of biomassfermentation of yeastfermentation of grapesfermentation of molasses, obtained through sugar from sugarcane. Molasses is a dark coloured syrupy liquid left after the crystallisation of sugar from the concentrated sugarcane juice. Molasses contain approximately \(30\) % of maltosesucrosegalactoselactose, which cannot be separated by using crystallisation.

 

 

Molasses is first diluted with etheralcoholacidwater to decrease the concentration of sugar to approximately \(8-10\%\).

 

 

During the fermentation process, the nitrogenous matter that is present in molasses acts as food for yeast. Ammonium sulphate or aluminium nitrideAmmonium sulphate or nitrogen phosphateAmmonium sulphate or ammonium phosphateAluminium sulphate or ammonium phosphate is added if the nitrogen content of the molasses is poor.

 

 

The solution extracted in addition of hydrogennitrogenammoniumoxygen source is collected in large ‘fermentation tanks’, and yeast is mixed. The aggregate is preserved at \(303K\) for some days. All through this period, the enzymes invertase and amylaselipaseszymasemaltase found in yeast result in the conversion of sucrose into ethanol.

 

i. \(Sugar + Water \xrightarrow{invertase} Glucose + Fructose\)

 

\(C_{12}H_{22}O_{11} + H_2O \xrightarrow{invertase} C_6H_{12}O_6 + C_6H_{12}O_6 \)

 

ii. \(Glucose or Fructose \xrightarrow{zymase} Ethanol + Carbon dioxide\)

 

\(C_6H_{12}O_6 \xrightarrow{zymase} 2C_2H_5OH + 2CO_2\)

 

The fermented liquid from this process is called as 'Wast''Wash''Mud''Spirit''.

 

The fermented liquid (i.e.wash), containing \(15\)% to \(18\)% alcohol, is now subjected to fractional distillation. The primary fraction drawn is an aqueous solution of ethanol  \(95.5\)% of ethanol and \(4.5\)% of water. This proportion of ethanol and water is known as fortified spiritrectified spiritdistilled spiritfermented spirit.

Rectified spirit is then refluxed over quicklime for about \(5\) to \(6\) hours and then allowed settling for \(12\) hours. Pure alcohol (\(100\)) % is obtained on the distillation of the above mixture. This is known as fortified alcoholdistilled alcoholabsolute alcoholfermented alcohol.