Effect of Acid Concentration on the Yield of Bio-ethanol Produced from Corncobs (original) (raw)
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Journal of Biotechnology & Bioresearch, 2018
Scarcity of non-renewable energy sources has paved need for sustainable and renewable biofuels from biomass. Of all natural resources used for production of biofuel, lignocellulosic biomass (producing second generation biofuel) are most attractive as they are highly abundant and easily available throughout the year. Various measures for maximal and efficient utilization of these lignocellulosic biomass for production of biofuels (bioethanol, biodiesel and biogas) have been taken including pretreatment, saccharification and fermentation process. In the present chapter we have consolidated relevant applications for bioethanol production, which includes a brief overview of the current status and biochemical route towards bioethanol production. Various approaches like tailoring of hydrolytic enzymes to increase the specific activity of particular enzymatic reaction and contributions by prominent scientists for effective utilization of celluloses and hemicelluloses for bioethanol production have been discussed. We have also highlighted the comparison on utilization of simple sugars (hexoses and pentoses) by bacteria and fungi and described the recent advanced techniques utilized for the production of ethanol.
Acid Hydrolysis of Lignocellulosic Materials for The Production of Second Generation Ethanol
2021
Brazil is one of the countries with the largest agricultural production in the world. Therefore, it is capable of generating large amounts of agro-industrial waste that can be used as biomass for the production of biofuels. Second generation ethanol is a renewable energy alternative, capable of replacing fossil fuels. Within this context, the objective of the present work was to study the effect of diluted acid hydrolysis in different types of lignocellulosic residues and the consequent production of 2G ethanol from these hydrolysates using different fermenting microorganisms. The acid concentration that released the highest content of fermentable sugars from the acid hydrolysis of lignocellulosic materials was 5.0% of sulfuric acid and the contact time with the biomass was 15 min. while heating in autoclave. The material that showed the highest sugar release after acid hydrolysis was cassava residues, with 131.09 g.L− 1 of reducing sugars. The fermentations were carried out with mi...
Challenges and opportunities in improving the production of bio-ethanol
Progress in Energy and Combustion Science, 2015
Bio-ethanol, as a clean and renewable fuel, is gaining increasing attention, mostly through its major environmental benefits. It can be produced from different kinds of renewable feedstock such as e.g. sugar cane, corn, wheat, cassava (first generation), cellulose biomass (second generation) and algal biomass (third generation). The conversion pathways for the production of bio-ethanol from disaccharides, from starches, and from lignocellulosic biomass are examined. The common processing routes are described, with their mass and energy balances, and assessed by comparing field data and simulations. Improvements through 5 possible interventions are discussed, being (i) an integrated energy-pinch of condensers and reboilers in the bio-ethanol distillation train; (ii) the use of Very High Gravity (VHG) fermentation; (iii) the current development of hybrid processes using pervaporation membranes; (iv) the substitution of current ethanol dewatering processes to >99.5 wt% pure ethanol by membrane technology; and (v) additional developments to improve the plant operation such as the use of microfiltration of the fermenter broth to protect heat exchangers and distillation columns against fouling, or novel distillation concepts.
Lautech Journal of Engineering and Technology, 2021
In this study, corn stover was converted into ethanol using a locally-fabricated bioreactor and process conditions were optimized. The corn stover biomass used as substrate was milled, screened to 200 μm and hydrolyzed with between 0.1-0.5 M HCl. The hydrolysis experiment was carried out for substrate concentrations of 20, 25, and 30% (w/v) of milled bagasse prepared in a 1000 mL glass jar containing distilled water. For each substrate concentration, the time, temperature, and acid concentration were varied between 10-60 min., 80-97 °C, and 0.1-0.5 M, respectively to find the optimum glucose yield. Glucose concentration in the optimum hydrolysate sample was determined using glucose oxidase method. Fermentation experiment was conducted in the bioreactor using 700 ml of the hydrolysate and Saccharomyces cerevisiae supplemented with minerals to yield ethanol of 21.47 g/L after 48 hours. A linear regression model developed after analysis of variance was able to predict the concentration of glucose produced during the acid hydrolysis, and the optimum ethanol yield of 21.47 g/L compares well with previous reported yield values found in literature.
Trends in biotechnological production of fuel ethanol from different feedstocks
Bioresource Technology, 2008
Present work deals with the biotechnological production of fuel ethanol from different raw materials. The different technologies for producing fuel ethanol from sucrose-containing feedstocks (mainly sugar cane), starchy materials and lignocellulosic biomass are described along with the major research trends for improving them. The complexity of the biomass processing is recognized through the analysis of the different stages involved in the conversion of lignocellulosic complex into fermentable sugars. The features of fermentation processes for the three groups of studied feedstocks are discussed. Comparative indexes for the three major types of feedstocks for fuel ethanol production are presented. Finally, some concluding considerations on current research and future tendencies in the production of fuel ethanol regarding the pretreatment and biological conversion of the feedstocks are presented.
Carbohydrate Polymers, 2011
The current research investigates the use of acid and enzyme hydrolysis to produce glucose from pretreated rice straw, banana plant waste and corn cob, as a lignocellulosic materials, to be a source for ethanol production. The agricultural biomasses were first tested, then a laboratory experimental set-up was designed in order to perform the necessary conversions. The biomass materials were characterized to contain 57.46-85.28% holocellulose and 14.55-26.12% lignin. Conversion of the cellulose to glucose was achieved by pre-treatment method for the agricultural residues first applying chemical pulping and steam explosion method as well as microwave treatment then followed by two processes, namely acid hydrolysis and enzyme hydrolysis. Sulfuric acid, 5%, was used in acid hydrolysis and Trichoderma reesei cellulases in enzyme hydrolysis. These experiments demonstrated that glucose concentration differs according to the type of pre-treatment and type of hydrolysis. Conversion of the glucose to ethanol during fermentation was accomplished by the action of yeasts from Saccharomyces cerevisiae. Ethanol production in the culture sample was monitored using gas chromatography. The results indicate that ethanol can be made from the above mentioned residues in a different yield according to the pre-treatment and the glucose produced from the hydrolysis method.
Production of renewable fuels, especially bio-ethanol from lignocellulosic biomass, holds remarkable potential to meet the current energy demand as well as to mitigate greenhouse gas emissions for a sustainable environment. Present technologies to produce bioethanol largely depend on sugarcane and/or starch based grains and tubers (mainly corn, potatoes). This is partly due to ease of substrate handling and processing. On the other hand, use of sugarcane and food grains to produce bio-ethanol has caused significant stress on food prices and food security. Accordingly, the recent focus has been on lignocellulosic materials as a source for bio-ethanol. In fact, many countries are moving towards developing or have already developed technologies to exploit the potential of lignocellulosic materials for the production of bioethanol. This process of ethanol production generally involves hydrolysis of lignocellulosic biomass to fermentable sugars followed by fermentation of such sugars to ethanol. Achieving fermentable levels of sugars from lignocellulosic biomass requires relatively harsh pretreatment processes. The pretreatment process has pervasive impact on the overall operation because the process depends on the choice of lignocellulosic source, the size reduction via grinding, chemical treatment, acid hydrolysis, neutralization and fermentation. Recent advances in the process technologies have made it possible to use simultaneous saccharification and fermentation. In this process cellulase enzyme is the critical reagent as well as the cost determining factor. The advances in biotechnology as related to bioethanol have focused on engineering organisms that are capable of producing ethanol from cellulose, hemicellulose and lignocellulose. Such organisms are expected to be capable of not only degrading cellulose, hemicellulose and lignocellulose to fermentable sugars, but also are able to utilize both pentose and hexose sugars to produce ethanol at a relatively high yield. More recent and emerging approaches in bioethanol production are focused on reducing production costs. This approach uses consolidated bioprocessing schemes in which cellulase production, substrate hydrolysis, and fermentation are all accomplished in a single step. Countries, such as Nepal, that totally depend on the import of fossil fuels cannot ignore the potential of bioethanol derived from lignocellulosic biomass. Nepal is rich in biodiversity and posses variety of energy crops. Accordingly, developing policies and mechanisms that promote bioethanol will go a long-way in reducing the fuel crises in the countries lacking oil resources.
Proceedings of the National Academy of Sciences, 2009
Fiber Expansion (AFEX) as the pretreatment technology, and Saccharomyces cerevisiae 424A(LNH-ST) as the ethanologenic strain in Separate Hydrolysis and Fermentation was able to achieve 191.5 g EtOH/kg untreated CS, at an ethanol concentration of 40.0 g/L (5.1 vol/vol%) without washing of pretreated biomass, detoxification, or nutrient supplementation. Enzymatic hydrolysis at high solids loading was identified as the primary bottleneck affecting overall ethanol yield and titer. Degradation compounds in AFEX-pretreated biomass were shown to increase metabolic yield and specific ethanol production while decreasing the cell biomass generation. Nutrients inherently present in CS and those resulting from biomass processing are sufficient to support microbial growth during fermentation. This platform offers the potential to improve the economics of cellulosic ethanol production by reducing the costs associated with raw materials, process water, and capital equipment.
Ethanol fermentation from biomass resources: current state and prospects
Applied microbiology and biotechnology, 2006
In recent years, growing attention has been devoted to the conversion of biomass into fuel ethanol, considered the cleanest liquid fuel alternative to fossil fuels. Significant advances have been made towards the technology of ethanol fermentation. This review provides practical examples and gives a broad overview of the current status of ethanol fermentation including biomass resources, microorganisms, and technology. Also, the promising prospects of ethanol fermentation are especially introduced. The prospects included are fermentation technology converting xylose to ethanol, cellulase enzyme utilized in the hydrolysis of lignocellulosic materials, immobilization of the microorganism in large systems, simultaneous saccharification and fermentation, and sugar conversion into ethanol.