InterviewSolution
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InterviewSolution
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How is ethanol manufactured from sugarcane ? |
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Answer» Solution :Ethanol Manufacture : (i) Ethanol is manufactured in industries by the fermentation of molasses, which is a by-product obtained during the manufacture of sugar from sugarcane. (ii) Molasses is a DARK coloured syrupyliquid left after the crystallization of sugar from the concentratedsugarcanejuice . (iii) Molassescontain about 30% of sucrose , whichcannot be separatedby crystallization .It is converted into ethanol by the following steps : a) Dilution of molasses : Molassesis firstdiluted with waterto bringdown the concentration of sugar to about 8 to 10% . b) Addition of Nitrogen source : (i) Molassesusually containsenough nitrogeneous matterto act as food for yeast during the fermentationsprocess. (ii) If the nitrogen contentof the molasses is pooer , it may be fortified by the addition of ammonium sulphate or ammonium phosphate . (C) Addition of Yeast : The solution obtained in step . Is collectedin large ' fermentation tanks' and yeastis added to it . The mixtureis kept at about 303 K for a few days . During this period , the enzymes invertase and zymasepresent in yeast , BRING about the conversion of sucrose into ethanol . `underset("sugar")(C_(12)H_(22)O_(11))+H_2O overset("invertase")to underset("GLUCOSE")(C_6H_(12)O_6)+ underset("fructose")(C_6H_(12)O_6)` ` underset("glucose or fructose ")(C_6H_(12)O_6) overset("zymase")to underset("ethanol")(2C_2H_5OH)+2CO_2 ` The fermentedliquidis technicallycalled wash . d) Distillation of 'Wash' : (i) The fermented liquid (i.e. wash) , containing15 to 18 percent ALCOHOL , is now subjected to fractional distillation. (ii) The main fraction drawn in an aqueoussolutionof ethanol which contain 95.5% of ethanoland 4.5% of water . This is called rectified spirit . |
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