Fermentation Distillation process in the Making Bio Ethanol

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Fermentation in the Making Bio Ethanol 

The second stage is the fermentation process to convert glucose (sugar) into ethanol and CO2. Fermentation ethanol is a change in a mole of glucose into 2 moles of ethanol and 2 moles of CO2. In the ethanol fermentation process, yeasts will mainly 

metabolize glucose and fructose to form pyruvic acid through the stages of the reaction pathway Embden-Meyerhof-Parnas, whereas pyruvic acid generated would be decarboxylated to acetaldehyde which then experienced 

dehydrogenation to ethanol (Amerine et al., 1987). 

Yeasts are often used in alcoholic fermentation is Saccharomyces cerevisiae, because it can produce high tolerance to alcohol is quite high (12-18% v / v), resistant to high sugar levels and remain active in the fermentation at a temperature of 4-32o C. 

After fermentation was completed, a distillation to separate ethanol. Distillation is the separation of components based on boiling point. Boiling point of pure ethanol is 78o C while the water is 100o C (standard conditions). 

By heating the solution at a temperature range of 78 - 100o C will result in most of the ethanol evaporated, and the condensing units will be produced with a concentration of 95% ethanol by volume. 

The fermentation process is intended to convert glucose into ethanol / bio-ethanol (alcohol) by using yeast. Alcohol obtained from this fermentation process, usually alcohol with levels 8 to 10 percent by volume. Meanwhile, when the fermentation is used raw sugar (molasses), ethanol-making process can be faster. Making ethanol from molasses also has another advantage, ie require a smaller fermentation tanks. Ethanol is produced by the fermentation process needs to be enhanced by cleaning it of substances that are not needed. 

Alcohol produced from the fermentation process is usually still contain gases - gases such as CO2 (resulting from the conversion of glucose into ethano l / bio-ethanol) and the aldehyde that need to be cleaned. CO2 gas in the fermentation is usually reached 35 percent by volume, so as to obtain ethanol / bio-ethanol are good quality, ethanol / bio-ethanol must be cleaned from the gas. The process of cleaning (washing) of CO2 

done by filtering the ethanol / bio-ethanol which is bound by the CO2, so it can be obtained by ethanol / bio-ethanol is cleaner than CO2). Levels of ethanol / bio-ethanol produced from the fermentation process, usually only reaches 8 to 10 percent of it, so as to obtain an alcohol content of ethanol required 95 percent of other processes, namely the process of distillation. Distillation process is carried out through two levels, namely first degree with a beer column and the second level with a rectifying column.Definition of alcohol, or ethanol / bio-ethanol in% (percent) volume is 

"Volumes of ethanol at a temperature of 15o C contained in 100 unit volume of ethanol solution at a given temperature (measurement)." Based on BKS Alcohol Spiritus, a standard measurement temperature was 27.5 ° C and 

levels are 95.5% at a temperature of 27.5 o C or 96.2% at a temperature of 15o C (Wasito, 1981). 

In general, fermentation is the result of bio-ethanol or alcohol having a purity of about 30-40% and yet dpat categorized as ethanol-based fuel. In order to achieve the purity above 95%, then lakohol fermented must go through the process of distillation. 

   

Distillation process (refining) Making Bio Ethanol 

There are two types of distillation processes are widely applied, namely continuous-feed distillation column system and a pot-type distillation system. In addition to that type, also known as the type of vacuum distillation using low pressure 

and lower temperatures to produce a higher alcohol concentration.Pressure used for distillation is 42 mm Hg or 0.88 psi. With these pressures, the temperature used in the bottom of the column is 35o C and 20o C at the top. FGE production process of starchy material is presented in Figure 49, while Figure below shows the production process of cassava FGE. 

As mentioned above, to purify bioethanol to yield more than 95% that can be used as fuel, alcohol fermentation results that have a purity of about 40% had to pass through the distillation process to separate the alcohol with water taking into account the differences in boiling points of the two materials are then condensed again. 

In order to obtain bio-ethanol with a purity higher than 99.5% or commonly called the ethanol-based fuel, a problem that arises is the difficulty of separating the hydrogen bonded in the chemical structure of alcohol by ordinary distillation, therefore, to obtain fuel-grade ethanol purification implemented further by Azeotropic distillation.

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