Dehydration of Ethanol Water Solution Using Activated Starch
Chapter One
OBJECTIVES OF THE STUDY
The aim or objectives of the research work on the dehydration of ethanol water solution using activated starch is determined as follows:
- To identify polysaccharide compounds of starch materials which have the ability of adoption due to the removal of water by contact of the adsorbent either with vapor or liquid of ethanol solutions.
- To determine the adsorption of water from liquid solution 85 95%v/v ethanol onto starchy material.
- To determine the complication of a process for ethanol dehydration by the activated starch.
- To determine investigated water and adsorption efficiency of adsorbent prepared by the activated starch.
CHAPTER TWO
LITERATURE REVIEW
HISTORY OF ETHANOL
Ethanol is produced commercially by chemical synthesis and fermentation. Practically all industrial ethanol is manufactured synthetically from petroleum and natural gas while all beverage alcohol is produced by fermentation of cereal grains molasses, potatoes and other materials with high starch and sugar contents.
Potential sources of production of ethanol in Nigeria include millet, yam, sorghum, corn, cocoyam and cassava. Potato tuber (1poeme hatata) is the most potential candidate by virtue of the fact that this crop can be grown with low level of management and also varieties for industries production and presence of high yielding cultivation (potato 1poeme hatata) also called manioc of the spurge family (Euphorbia ceous) is native form south Africa but is now cultivated in most tropical and sub-tropical regions. It is a shrubby perennial about 9ft high and has terminal starchy tuberous root. The roots and tubers contain prussic acid and some are quite poisonous but heat expels the volatile acid and render the material harmless.
The hydrolysis of carbohydrate and utilization of an efficient low cost saccharifying agent factors of paramount importance in the production of food or alcohol from cassava, yam potato cereal grains starch since this polysaccharide must be broken down into fermentation sugar which can be utilized by the micro organism.
Ethanol (ethyl acohol) is produced by the anaerobic fermentation of the saccharifying starch (reducing sugar) by yeast through the embder meyerho pamas (EMP) path way of anaerobic fermentation.
Saccharomyces cerelisac was chosen for such characteristics as their ability to ferment rapidly and to tolerate higher ethanol concentration and to flocculate easily.
C6H12O6(aq) C2H5OH + 2CO2(g)
GELATINIZATION AND SACCHARIFICATION OF STARCH
The starch has to be gelatinized i.e cooking or dehydrated, saccharified i.e hydrolyzed and the saccharified work is then fermented into ethanol. The polysaccharified starch must be broken down or degraded into fermentable sugar for microbial action. This process of gelatinization is undertaken in order to release the starch granules and this facilitate the reaction of the substrate with the saccharifying agent.
Starch granules gelatinize in water when temperature is raised to about 71 – 74 0C range for carbohydrate; to the temperature raised further the granules swell progressively to form a paste or soil and shorter linear molecules dissolves. There is thus a distinguishing of the granules into molecules and starch granules fragment, the paste then forms gel cooling depending on the variety and concentration of starch present.
CHAPTER THREE
METHODOLOGY
APPARATUS/MATERIALS USED
APPARATUS
- Test tube
- Coffee grinder
- Screen filter paper
- Distilled water
- Oven driver
- Sieve
- Weighing balance
- Test tube rack
Materials
Sweet potato (Ipoemea hatata)
Sodium metabisulphite
METHOD OF STARCH EXTRACTION
Starch was extracted from the tubers using a slight modification of the method of whistler (1964) where sodium metasulphite was used with distilled water. Potato (ipoeme hatata) tubers were manually peeled and cut into 4 – 6cm pieces, soaked in 0.2% sodium metasulphite for some minutes and the juice was extracted at a low speed for some minutes. The resulting starch slurry was filtered through a screen (2.00 micron) and allowed to stand undisturbed for one hour. The white starch fraction was collected unsuspended in distilled water and allowed to settle. This process was repeated for three times to eliminate sulphite residues. The collected starch was dried at 400C for 24 hours and was finally grinded using a coffee grinders sieved through a 120mm mesh sieve, packed in polypropylene bags and stored at room temperature until further analyzed.
CHAPTER FOUR
RESULT ANALYSIS
The results
CHAPTER FIVE
DISCUSSION, CONCLUSION, RECOMMENDATION
DISCUSSION
The mixture containing ethanol and water form an azeotrope. The mixture contains a substantial amount of water which needs to be dehydrated in order to be put into diverse use. At atmospheric pressure, the azeotrope occurs at 351K (77 – 850C) where the purity of ethanol does not exceed to more than 90 mole%. Due to the formation of azeotrope the water mixture cannot be performed by using a single distillation column. The two most commonly applied processes for the dehydration of ethanol are azeotropic distillation and molecular sieve.
In azeotropic distillation a third component is usually employed, typically benzene or cyclohexane to break the azeotrope. When an azeotropic agent is added to a mixture of water and ethanol, it forms two liquids phases which are partially miscible. Benzene, ethanol and water form a ternary azeotrope with a ternary azeotrope with a boiling point of 64.90C. Since this azeotrope is more volatile than the ethanol – water azeotrope, it can be distilled out of the ethanol – water mixture, extracting all of the water in the process. The overhead product is then separated in a decanter into a water – rich layer and organic – rich layer.
The result obtained from the experiment was seen to be more palatable with the use of potato starch as the major absorbent. It was observed that the lower the concentration of ethanol –water mixture led to decrease in the refractive index of the water – ethanol mixture.
The dehydration of ethanol molecular sieve mostly uses modern ethanol plants. A molecular sieve column uses an adsorbent with a strong affinity for water and little affinity for ethanol and other impurity. When wet ethanol vapour passes through bed, the desiccant adsorbs the water molecules. synthetic zeolite [aluminosilicate minerals] are the most commonly used desiccant. Therefore, water – molecule are strongly attracted into the pore of the synthetic zeolite but ethanol molecules are excluded thereby leaving ethanol as the end product.
The dehydration process therefore entails that ethanol can be separable from a water- ethanol mixture using azeotropic distillation, extractive distillation, supercritical fluid extraction or molecular sieve.
The extraction method by fluid as observed in the small scale research experiment have proven to be more advantageous over prior art method, due to the fact that it can be conducted in liquid state below the vapourization temperature of the alcohols. The method is capable of removing water from mixture of alcohol and water by contacting such as mixture with a substantially dehydrated solid adsorbent which comprises particulate starch – containing vegetable such as potato. The substantially anhydrous adsorbent (activated starch) is then contacted with the aqueous alcohol mixture to remove water there from the dehydration procedure can be conducted in either a batch or continuous manner.
The small scale research experiment using activated starch from potato as the absorbent, when compared with other methods achieve the same aim of dehydration and the end product of quality ethanol. However the research experiment is cheaper viable and feasible unlike the other methods which imposed high cost of operation, energy and long time consumption in order to achieve result such as in the case of azeotropic distillation which is very costly and that of vapour dehydration procedure which involve high energy cost in order to accomplish and maintain the materials in vapour state and also present problem of efficient contact of the vapour with the absorption agent.
The end product of the ethanol obtained resulting from dehydration is also called ethyl alcohol purealchohol, grainalcohol or drunking alcohol which is a volatile, flammable, colourless liquid. It is a powerful psychoactive drug and one of the oldest recreational drugs. It is best known as the type of alcohol found in alcoholic beverages and thermometers. Ethanol can be used as an antiseptic to disinfect the skin before injections are given. Ethanol based soaps are becoming common in restaurants and are convenient because they do not require drying due to the volatility of the compound. Alcohol based gels have become as hand sanitizes.
CONCLUSION
Good quality of ethanol has been dehydrated from potato tuber. The intermediate products “activated starch” are equally useful products for textile, paper, dextrins, beverages industries. The use of potato as a source of starch for various industrial processes has long been of increasing interest. The starch content of cassava can be dehydration and turned into ethanol, a product that is of important use as a chemical feed stock. At present, there is no commercial dehydration of ethanol from potato in Nigeria. Huge sum of money is being spent to import ethanol for medical, pharmaceutical, research and industries.
Countries like Brazil, U.S.A are able to cope with their energy demand with ethanol as fuel and generally these countries produce their ethanol used as fuel from starchy materials. The final dehydration ethanol concentration of 50%(v/v) could be obtained using potato starch particles as packing materials. The effect of variables on the dehydrated ethanol concentration was optimized. The process conditions used were packing particles size, temperature, initial feed concentration feed rate and quantity of packing materials.
RECOMMENDATION
The research work although feasible and viable but tasting, in other to achieve high level of precision and accurate result, relevant equipment and facilities should be put in place. And it is recommended that non-functioning equipment and facilities should be refurblished so as to meet up with the standards and specifications accepted widely.
It is recommended that the research work should be carried out, using the school laboratories so as to reduce the cost of transportation outside the school premises and to increase or boost the participation of the student involved in the research work.
Finally, it is also recommended that more student should be involved due to the cost of the research work so as to relief or reduce much cost burden on the participating students.
REFERENCES
- Asheh A. ET AL (2004): Separation of ethanol water mixture, using molecular sieves and bio based Adsorbents ;trans/chem. E part A che. Engr Res Des vol 82 pp 855 – 864
- Benson T and George (2005): Cellulose based adsorption materials for the dehydration of ethanol using thermal swing adsorption, adsorption vol II, pp 697 – 701, 2005
- Kirrk Othmer (1967): Encyclopedia of chemical technology, 2nd edition interscience publisher, Newyork pp238
- Ladisch M. ET AL (1984): Cornmeal adsorber for dehydrating ethanol vapours, 1 SEC process design develop, vol 23 pp 437 – 443
