Showing 5 results for Bioethanol
H. Shokrkar, S. Ebrahimi,
Volume 10, Issue 1 (3-2019)
Abstract
Microalgae with stores of carbohydrates are introduced as a promising energy resource to produce In this study, a mixed culture was used for reducing the processing costs. Afterward, nitrogen starvation strategy was used to increase the storage in The application of mixed cultures enhances the economic feasibility of the process due to the elimination of culture sterilization. After harvesting and drying enzymatic hydrolysis of microalgal biomass for extraction Afterward, the enzymatic hydrolysate of microalgal biomass (25, 50, 100g/L) underwent fermentation with Saccharomyces cerevisiae and kinetic models for fermentation were studied. The inhibition of glucose substrate and product was considered in the kinetic model. AQUASIM 2.0 software was used as a tool to simulate the fermentation process. The estimated values of the maximum specific growth rate (μ) Monod constant (Ks) to be 0.281h −1 1.8g/L, respectively. Also, the results indicate that the kinetic model predicted the behavior of the system well.
F. Boshagh , Kh. Rostami , N. Moazemi ,
Volume 10, Issue 1 (3-2019)
Abstract
Introduction: Biofuel production from renewable resource has been extensively paid attention as a sustainable alternative for fossil fuel. As the feed of third-generation biofuels, microalgae can produce variety of lipids, proteins, and carbohydrates in large quantities and in a relatively short time. Regarding the compatibility of these microorganisms with culture diffrent conditions and independence from the seasons of the year, the rapid growth rate, absorbing carbon dioxide and improving air quality, renewablity, non-competing with food supplies, the existence of large quantities of lipid and carbohydrate inside their cells, and abillity of biofuels production, microalgae are known as one of the most suitable options for the biofuels production. Biofuel production from microalgae consists of several stages, including cultivation, harvesting, drying, cell disruption, extraction (lipids or carbohydrates), and the production of biofuels.
Conclusion: In the present study, by reviewing each stage of the biofuels production from microalgae, its importance and application for bioenergy production is discussed. Algal biofuel is not yet competitive with fossil fuels due to its high costs. Researchers are trying to produce economic algal biofuel by improving the growth of microalgae and enriching their reserves of oil and carbohydrates, creating genetic changes, improving the design of photobioreactros, developing harvesting and drying methods, improving methods of extracting lipid and carbohydrate, and producing valuable products.
Volume 10, Issue 3 (7-2008)
Abstract
Biofuels are the main substitute to fossil fuels. These fuels are less polluting in compari-son to fossil fuels and can be produced from agricultural material residues for use in die-sel engines. In this research work bioethanol was produced from potato waste. It was de-hydrated in a vapor phase using 3A zeolite and was used in combination with sunflower methyl ester oil and diesel fuel blending which was evaluated thereafter. The sunflower methyl ester was also produced using a transesterification method. Considering the labo-ratory conditions and fuel stability limits to be used, the suitable blending proportion of bioethanol and diesel fuel was determined to be 12 to 88 and then, for maintaining fuel stability at temperatures lower than 15oC, the sunflower methyl ester was added to the mixture. The pour point of the fuel and different fuel blends, the viscosity, cetane number, flash point, amount of fuel ash, sulfur content and copper corrosion were determined in the laboratory. Experiments show that ethanol plays an important role on the flash point of the blends. With the addition of 3% bioethanol to diesel and sunflower methyl ester, the flash point was reduced to 16oC. The viscosity of the blends was reduced with the in-crease in the amount of ethanol. The sulfur content of bioethanol and sunflower methyl ester is very low compared with that of diesel fuel. The sulfur content of diesel is 500 ppm whereas that for ethanol and sunflower methyl ester is 0 and 15 ppm, respectively. The lower amount of sulfur content facilitates the use of fuel blends in diesel engines. For the ethanol and sunflower methyl ester combination, this amount is less than 20 ppm.
Volume 15, Issue 4 (7-2013)
Abstract
This study suggests a new effective chemical pretreatment to hydrolyze rice straw for efficient ethanol production. It introduces a new yeast strain that ferments rice straw hydrolyzate more efficiently than Saccharomyces cerevisiae. The results proved the effectiveness of alkali application before HCl to delignify rice straw and to make it more appropriate for hydrolysis. The application of the hydrolyzing enzymes (cellulase and pectinase) resulted in hydrolysis of pretreated rice straw up to 94.3%. The total sugars released due to pretreatment-enzyme system was about 624 mg g–1 dry mass and the glucose fraction was 198 mg g–1. The results indicated that Pichia guilliermondii is more effective to ferment rice straw hydrolyzate than S. cerevisiae. P. guilliermondii produced larger amounts of bioethanol (7.72 g L–1) than S. cerevisiae (6.13 g L–1)under the same conditions. Our results suggest an appropriate pretreatment system (the cold dilute alkali-acid) and a new effective yeast strain to ferment the rice straw hydrolyzate to produce large amounts of bioethanol.
Volume 19, Issue 127 (9-2022)
Abstract
In this study was investigated the possibility of converting agricultural lignocellulosic waste to sugar during the ultrasound-acid pretreatment, acid-thermal hydrolysis and cold plasma detoxification. For this purpose, after collecting wheat and rice straw, ultrasound-acid pretreatment (with three different treatments of bagasse load, sonicate time and acid concentration) and then acid hydrolysis (with three different treatments of hydrolysis time, acid concentration and temperature) on biomass were performed. The results of chemical data showed high sugar were released at 30 min time of sonication, bagasse load of 1% and acid concentration of 1.5% and soluble lignin was at its highest level. Also, during acid-thermal hydrolysis, hydrolysis time of 45 min, acid concentration of 1.5% and temperature of 120 ˚C caused further release of sugar and ASL. In addition to the chemical data, the results of FTIR, FESEM and thermal analysis proved that the structures are well disintegrated and the biomass is prepared for the conversion of sugar to bioethanol. Then, cold plasma detoxification method was used to remove such as acetic acid, formic acid and furfural and the results showed that after cold plasma detoxification, acid inhibitory compounds levels were 73, 58 and 78% decreased during 10 min of detoxification, jet distance of 0.5 cm and argon gas to air ratio 0.5. Finally, it can be said that lignocellulosic compounds can be broken down by ultrasonic pretreatment and acid-thermal hydrolysis of structural polysaccharides, and then the toxic inhibitory compounds can be eliminated by cold plasma method to achieve the best results.
