International Journal of Scientific Research in Chemistry (IJSRCH) © 2019 IJSRCH | Volume 4 | Issue 1 | ISSN : 2456-8457 Modelling and Optimization of Ethanol Production from Cassava (Manihot Esculenta) Otaraku I. J.*, Oji A., Obi C. L. Chemical Engineering Department, University of Port Harcourt, Port Harcourt, Nigeria ABSTRACT The need for ethanol optimization from locally sourced material like cassava informed the use of cassava samples to produce ethanol. Two sets of micro-organisms were used for cassava fermentation: Yeast (saccharomyces cerevisiae) obtained from fresh palm wine and zymomonasmobis obtained from decaying oranges. A combination of both the yeast and zymomonasmobis was also prepared as a single solution. The organisms were inoculated into the cassava starch substrate to enhance fermentation for six days. The quantities of starch that were fermented ranged from 5g -25g and the highest volume of ethanol produced was 25cm3 when 10g of starch was inoculated with zymomonasmobis. Distillation was used to determine the volume of ethanol that was produced. The densities obtained were compared to the density of standard ethanol and the results obtained agreed with the specification of standard ethanol. Design and model equations for ethanol production optimization were developed and the results obtained correlated with the experimental results. Keywords : Cassava, Ethanol Production, Microorganism, Fermentation, Starch, Yeast, Optimization. I. INTRODUCTION crop and for food security. When cooked, it is tasteless, odourless and has high degree of whiteness. Cassava (Manihot esculenta) that belongs to the Cassava starch when extracted can be modified into Family of Euphorbiaceae is a perennial crop. In food and non-food materials like textiles [2][3]. different geographical regions, it has other names Cassava and other carbohydrates has also been used for depending on where it is found. It is called Yaccu in Production of biofuel [4] e.g. bio-ethanol in adhesives central America, while in India it is called tapioca, such as Holt melt glues, envelopes etc, cosmetic Brazil calls it mandioca and most Africa countries call production like dusting powders and make-up and it cassava. In Africa it is cultivated mainly in the soap fillers, in pharmaceuticals as tablet binders, tropical region, while it is cultivated at the equatorial coatings and dispersant for medicine, in biomass fuels belt in Latin America and Asia. The crop serves as as briquette binders, in the construction industry as edible starch-reserving roots for human and animal concrete block material binder like binders in feed as staple food for millions [1] [Akande, 2009]. asbestos, clay/limestone binding, paint filler, Gypsum Cassava cultivation does not require much etc and in Paper industry for sizing. technicality as it is very easy to plant and requiring low input materials. Poor farmer are largely involved Fermentation in most process industry and laboratory in its cultivation on marginal lands, as it is often has been used for the chemical transformation of called the crop of the poor. Cassava plays an complex sugar and carbohydrate or organic substance important role in human’s life as income generation into simple sugars or compounds by the action of IJSRCH19411 | Received : 05 Jan 2019 | Accepted : 15 Jan 2019 | January-February-2019 [ 4 (1) : 01-06] 1 Otaraku I. J. et al. Int J Sci Res Chemi. January-February-2019; 4 (1) : 01-06 enzymes. This industrial process employs raw wheat crops, sorghum, millet, crop husk and peels, materials transformation by the controlled action of waste straw and sawdust are materials for bioethanol carefully selected strains of organism into definite production. Ethanol is also obtained by chemical products. Fermentation is classified as a biological process of reacting ethylene with hot steam. process of ethanol production [3], where sugar is broken down into alcohol and carbon (IV) oxide in This study shall focus on the raw material such as the presence of an enzyme as shown in equation 1 and cassava, decaying oranges and palm wine for 2. preparation of organisms and production of ethanol. The research is aimed at developing a model for the 2퐶2퐻5푂퐻(푎푞)) + 퐶푂2(푔) (1) production of ethanol and optimizes it with objectives of starch production from cassava and to identify Sugary juice including grapes, oranges, pineapple, microorganism that would give the maximum yield of paw-paw is extracted and fermented directly to ethanol ethanol using yeast. This may involve the conversion of the sugar to ethanol by the zymase, enzymes which II. METHODS AND MATERIAL are contained in the yeast. Ethanol is then collected by distillation at 78oC. 2.1 Preparation of organism Freshly tapped palm wine was taken to the 푍푦푚푎푠푒 microbiology laboratory to prepare the yeast called 퐶6퐻12푂6 → 2퐶2퐻5푂퐻(푎푞) + 퐶푂2(푔) (2) saccharomyces cerevisiae from palm wine. Decaying Other starch containing substances including potatoes, oranges were also taking to microbiological laboratory maize, rice, cassava, etc can also be used as feedstock. in the University of Port Harcourt to obtained zymomonasmobis. The starch (C6H10O5)n is first extracted, by crushing and pressure- cooking the material and then the malt (partially germinated barley) is then added at 50-60oC 2.2 Peeling and Grinding of Cassava for one hour. Diatase enzyme in malt converts the The freshly harvested cassava tubers were obtained from Okro market, Iriebe, in Port Harcourt, Nigeria. starch to maltose [n-(C12H22O11)] [5]. Zymomonasmobilis has also been used to ferment The tubers were peeled, washed and grinded with a cassava to ethanol. This process has shown higher grinder; thereafter blended with an electrical blender ethanol yield. in order to obtain the starch. The blended cassava mash was filtered to remove unwanted particles. Ethanol form biological sources also known as, Bio- ethanol is a product of “microbiological way of sugar 2.3 Hydrolysis A set of 5g, 10g, 15g, 20g and 25g of the starch was conversion into ethanol and carbon dioxide (CO2). weighed and sterilized. Distilled water was added to Ethanol is a high octane fuel and today has replaced make it up to the mark of 100ml for each set. The lead as an octane enhancer in petrol [6] and currently flasks were covered with sterile cotton wool wrapped adopted as principal fuel that can be used as petrol with aluminium foil to avoid contamination. substitute for vehicles [7]. This makes Bio-ethanol a renewable energy as a product of fermentation of 2.4 Sterilisation complex and simple sugar. Energy crops such as cane The mixtures were sterilized in an autoclave at 1210C sugar, cassava and cassava products are feedstock of for 20 minutes. The mixtures were also allowed to sugar required for ethanol production. Further, maize, International Journal of Scientific Research in Chemistry (www.ijsrch.com) | Volume 4 | Issue 1 2 Otaraku I. J. et al. Int J Sci Res Chemi. January-February-2019; 4 (1) : 01-06 cool again and sterilized distilled water was added to water has been added to make up the mark of 100ml. make up the mark of 100ml due to water loss by Also two drops of the mixtures of yeast and evaporation. zymomonasmobis were added to another set of the mixtures while one set of 5g of mixture was used as 2.5 Enzymes Hydrolysis and Fermentation the control. All the sets of the mixtures were shaken Two drops of freshly prepared yeast (saccharomyces to obtained homogeneous mixtures and they were cerevisiae) was inoculated into the set of 5g, 10g, 15g, inoculated at 26oC ± 2oC for six days. 20g and 25g of each substrate mixtures. Two drops of zymomonasmobis were added to another set of the substrate mixtures 5g, 10g, 15g, 20g and 25g after Figure 1: Process Block Flow Diagram International Journal of Scientific Research in Chemistry (www.ijsrch.com) | Volume 4 | Issue 1 3 Otaraku I. J. et al. Int J Sci Res Chemi. January-February-2019; 4 (1) : 01-06 2.6 Distillation 퐶6퐻10푂5 + 퐻2푂 → 퐶6퐻12푂6 (4) 퐶6퐻12푂6 → 2퐶2퐻5푂퐻 + 2퐶푂2 (5) 푑푁 The mixtures were taken to University of Port 푟푣 = (6) 푑푡 Harcourt Chemistry Laboratory for distillation. 푊ℎ푒푟푒 푐표푛푐푒푛푡푟푎푡표푛 (퐶) The fermented broth liquids were transferred = 푀표푙푒(푛)/푉표푙푢푚푒(푣) into round bottomed flasks and placed on a 푑퐶 푟 = (7) heating mantle fixed to a distillation column 푑푡 fitted to running water taps. Other flasks were For the irreversible kinetic reaction, fixed to the distillate at 780C (standard 2 2 [퐶2퐻5푂퐻] [퐶푂2] temperature for ethanol production).Anti- 푟 = 푘 (8) 퐶6퐻12푂6 bombing chips were dropped into the flasks to Neglecting the concentrating of 퐶푂2 avoid explosion of the flasks. This was done for all samples of the fermented broth. 푟 = 푘퐶2 (9) Where, C= ethanol concentration 2.7 Determination of Quantity of Ethanol 2 푑퐶 푘퐶 = ⁄푑푡 (10) Produced 푑퐶 푑푡 = ⁄ 2 (11) 푘퐶 Integrating Eqn (11) ⇒ ∫ 푑푡 = ∫ 푑퐶 Molecular seeds were added to the distillate 푘퐶2 collected to absorb water that would have 1⁄ − 1⁄ = 푘푡 (12) managed to escape with the distillate. The mass of 퐶 퐶0 −1 the distillates were weighed and the volumes ⁄퐶 = 푘푡 (13) were measured with a measuring cylinder. The process is summarized with the flow diagram in To determine the volume of ethanol, recall that Figure 1: 푚표푙푒 푛 퐶표푛푐. = , ⇒ 퐶 = (14) 푣표푙푢푚푒 푉 2.8 Modelling and optimization Substitute Equation (10) into Equation (9) thus, 푉 Assumptions = −푘푡 (15) 푛 (1) Unsteady state 푉 = −푘푛푡 (16) (2) Constant Temperature (3) Volume of CO2 was negligible Recall that (4) Initial concentration of starch is zero. 푚푎푠푠 푀표푙푒(푛) = (17) 푚표푙푎푟 푚푎푠푠 −푘푚푡 Thus, 푉 = (18) Modelling Equation 푚표푙푎푟 푚푎푠푠 표푓 푒푡ℎ푎푛표푙 (Input material)- (output material) + (rate of Unit of k which is slope is mol-1cm3min-1.It is reactant loss to chemical reaction) = Rate of obtain by plotting the graph of (-1/C) against time.