Bioethanol Concentration Research Articles

Effect of the Concentration of Bioethanol Mixed with Gasoline on the Energy and Environmental Performance of a Hybrid Vehicle in the Worldwide Harmonized Light Vehicles Test Cycle (WLTC)

Increasing the use of renewable biofuels in internal-combustion-engine (ICE) vehicles is a key strategy for reducing greenhouse gas emissions and conserving fossil fuels. Hybrid vehicles used in urban environments significantly reduce fuel consumption compared to conventional internal-combustion-engine cars. In hybrid vehicles integrating electric propulsion with biofuels offers even more significant potential to lower fuel consumption. One would like to think they should also be less polluted in all cases, but some results show that the opposite is true. This study’s aim was to evaluate a hybrid vehicle’s energy and environmental performance using different gasoline–bioethanol blends. A Worldwide Harmonized Light Vehicles Test Cycle (WLTC) study was conducted on a Toyota Prius II hybrid vehicle to assess changes in energy and environmental performance. During the WLTC test, data were collected from the chassis dynamometer, exhaust gas analyser, fuel consumption meter, and engine control unit (ECU). The collected data were synchronised, and calculations were performed to determine the ICE cycle work, brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), pollutant emissions (CO, HC, and NOx), CO2 mass emissions per cycle, and brake specific pollutant emissions per kilometre. The study shows that the performance of the hybrid vehicle’s ICE is strongly influenced by the utilisation of electrical energy stored in the battery, especially at low and medium speeds. As the bioethanol concentration increases, the engine’s ECU advances the ignition timing based on the knock sensor signal. A comprehensive evaluation using the WLTC indicates that increasing the bioethanol concentration up to 70% improves the energy efficiency of the hybrid vehicle’s internal combustion engine and reduces pollutant and CO2 emissions.

Optimization and modelling of bioethanol production by the fermentation of CCN‐51 cocoa mucilage using the sequential simplex method and the modified Gompertz model

AbstractThis work deals with the optimization of bioethanol production through a fermentation process of CCN‐51 cocoa mucilage, based on increased concentrations of the Saccharomyces cerevisiae yeast. Cocoa mucilage, considered biomass waste, was selected for its high productivity and the large volumes generated in the cocoa industrial chain in Ecuador. The optimization of the fermentation process was performed using the sequential simplex method with two variables, and the results were experimentally confirmed by quantifying bioethanol through the microdiffusion method. The best operational conditions corresponded to a temperature of 35°C and a pH of 4. Regarding the concentration of yeast, it was found that the optimal value was 8 g/L, since lower concentrations led to low productivities, while higher concentrations resulted in inadequate functioning of the bioreactor. The best results reached a productivity of 1.35 ± 0.04 g/L · h and a maximum bioethanol concentration of 28.3 ± 0.8 g/L for a processing time of 21 h. The production of bioethanol was modelled using the modified Gompertz equation and simulated in MATLAB®, yielding a bioethanol production rate of 2.42 g/L · h with a correlation coefficient (R2) of 0.95. These results contribute to the knowledge of bioethanol production using cocoa mucilage and seek to add a positive value to this residue, whose management and final disposition have both undesirable environmental and economic effects.

A Novel Modified ZIF-8 Nanoparticle with Enhanced Interfacial Compatibility and Pervaporation Performance in a Mixed Matrix Membrane for De-Alcoholization in Low-Concentration Solutions.

This study investigated the enhancement in bioethanol recovery from mixed matrix membranes (MMMs) by functionalizing zeolite framework-8 (ZIF-8) with imidazolate. This study focused on the separation of ethanol from low-concentration ethanol/water mixtures (typical post-fermentation concentrations of 5-10 wt%). Specifically, ZIF-8 was modified by the shell-ligand exchange reaction (SLER) with 5,6-dimethylbenzimidazole (DMBIM), resulting in ZIF-8-DMBIM particles with improved hydrophobicity, organophilicity, larger size, and adjustable pore size. These particles were incorporated into a PEBAX 2533 matrix to produce ZIF-8-DMBIM/PEBAX MMMs using a dilution blending method. The resulting membranes showed significant performance enhancement: 8 wt% ZIF-8-DMBIM loading achieved a total flux of 308 g/m2·h and a separation factor of 16.03, which was a 36.8% increase in flux and 176.4% increase in separation factor compared with the original PEBAX membrane. In addition, performance remained stable during a 130 h cycling test. These improvements are attributed to the enhanced compatibility and dispersion of ZIF-8-DMBIM in the PEBAX matrix. In conclusion, the evaluation of nanofiller content, feed concentration, operating temperature, and membrane stability confirmed that ZIF-8-DMBIM/PEBAX MMM is ideal for ethanol recovery in primary bioethanol concentration processes.

Study of Avian Colibacillosis and Antimicrobial Resistance in Escherichia coli from Chickens (Gallus domesticus) in Maiduguri, Borno State, Nigeria

Bioethanol is a renewable, colorless, less toxic, and readily biodegradable form of fuel from biological sources; that can be used for heat, electricity, and fuel. In this research study, an alternative feedstock known as microalgae was used. Bioethanol was produced from microalgae using enzymatic hydrolysis. The microalgae was pretreated with acid and alkaline. Hydrolysis was carried out by Aspergillus niger and Saccharomyces cerevisiae was used for fermentation. The concentration of the Bioethanol produced was determined using acid Potassium Dichromate. After hydrolysis, the reducing sugar concentration was determined using Dinitrosalicylic acid (DNS) colorimetric method. Results showed that there was significant difference at p<0.05 in the yields of the reducing sugar produced between acid and alkaline pretreated samples after microbial hydrolysis. Microbial hydrolysis of alkaline pretreated samples was higher in yield. Also, the results showed that the highest bioethanol yield of 0.142ml/l was obtained after alkaline pretreated hydrolysates were fermented with Saccharomyces cerevisiae at 40°C and pH of 6.0. The highest bioethanol yield of 0.116ml/l was obtained from the acid pretreated hydrolysates at 35°C and pH of 5.5. The volatile compounds produced by alkaline pre-treated samples using Gas Chromatography Mass Spectroscopy (GCMS) shows that Ethanol and Di-n-decylsulfone were the highest volatile compounds with peak areas of 30.70% and 41.87% respectively while 2-hydroxy-1-(hydroxymethyl) ethyl ester (linolenic acid) was found to be least volatile compound with peak area of 3.34%.Tthe volatile compounds produced by acid pre-treated samples shows that 2-ethyl-2-methyltridecanol was the highest volatile compound with peak area of 23.00% while Heptacosane was found to be the least volatile compound with peak area of 1.90%. Therefore bioethanol production using alkaline pretreated samples produced a large quantity of bioethanol and may be a preferred method. This study concluded that Microalgae is a suitable substrate for bioethanol production and hydrolyzing with Aspergillus niger and optimization of fermentation conditions at pH 6.0 and 40oC yielded higher bioethanol concentration.

Investigation of the effect of specific gravity and pH on the fermentation period of a single and combined algae species as a potential bioethanol feedstock

Algae has garnered significant attention as a promising biomass source for bioethanol production and as a solution to sustainability issues. Nevertheless, the disruption of complex carbohydrates required for yeast fermentation occurs during algae cultivation. The fermentation process, which is critical for producing bioethanol as a cost-effective and environmentally friendly alternative fuel, may be improved by meticulously managing the parameters that influence fermentation, such as specific gravity and pH. Bioethanol was produced from algae species (Navicula sp., Oscillatoria sp. and diatoms) using simultaneous saccharification and fermentation (SSF) processes. A control, single and combined algal species were prepared in the following formation: Oscillatoria sp. and Navicula sp. (sample A), Oscillatoria sp. (sample B), diatom and Oscillatoria sp. (sample C), Navicula sp. (sample D), and diatoms, Navicula sp. and Oscillatoria sp (sample E). The daily bioethanol concentrations in the fermentation medium were measured using a digital optical refractometer, and a Two-way ANOVA analysis (p < 0.05) was conducted to determine the differences between the period of fermentation and the bioethanol concentration. Additionally, the pH and specific gravity were assessed. The Two-way ANOVA analysis conducted indicated that the F-values surpassed the F-critical values and the p-values were all notably below 0.05, suggesting a statistically significant distinction between the samples in their fermentation periods and bioethanol concentration. The highest concentration was observed in sample E at 39.53 g/L, followed by samples C and D at 37.36 g/L, samples A and B at 35.10 g/L, and the control at 4.78 g/L. The findings showed that mixed cultures could potentially improve ethanol yield. The optimal fermentation period was determined to be 72 h. The pH levels in the control and algae samples varied between 6.5 and 6.7 and 7.06 to 8.42, respectively. The specific gravity in the control and algae samples ranged from 1.003 to 1.004 and 1.023 to 1.037, respectively. During algae fermentation, specific gravity initially increased, then stabilized before decreasing. pH levels correlated with fermentation duration. Understanding these factors is crucial for maximizing bioethanol production. This discovery could lead to exploring how different algae species interact to improve cultivation methods.

Analisis Penambahan Bioethanol dan Oktan Booster pada Bahan Bakar Pertamax terhadap Daya dan Torsi Sepeda Motor 4-Langkah

There are various methods to improve vehicle performance, including by blending fuels. In addition to bioethanol that can increase octane rating, there is the use of additives in vehicle fuels that are known to increase octane rating. With the addition of additives such as octane boosters and bioethanol, it is expected to increase the degree of ignition, reduce knocking, achieve more complete combustion, and automatically increase vehicle power.This study aims to analyze the power and torque of a four-stroke motorcycle by considering the addition of bioethanol and octane boosters to Pertamax fuel. Experimental method was used with variation of bioethanol concentration and octane booster in fuel as test parameters. This study provides insight into the potential for power improvement in the use of Pertamax fuel on four-stroke motorcycles through the addition of bioethanol and octane booster. The implications of these findings can serve as a basis for the development of more efficient and sustainable fuels for four-stroke motorcycles.

Hybrid pathway of bio-ethanol production employing empty fruit bunches co-gasified with charcoal and mixed culture fermentation: Optimization using response surface methodology

The research focuses on the synthesis of syngas from lignocellulosic biomass via co-gasification, employing response surface methodology. In addition, the study aims to optimize syngas fermentation efficiency for bioethanol production, utilizing two species of microorganisms – Saccharomyces cerevisiae and Clostridium butyricum – within an integrated biorefinery framework. The raw syngas was generated through the co-gasification of empty fruit bunches and charcoal mixtures (75:25). The optimal ratio of these components was determined via central composite design. The individual performances of S. cerevisiae and C. butyricum, as well as their co-fermentation, were thoroughly investigated, considering parameters such as colony forming units (CFU), pH, total organic carbon (TOC), and syngas flow rate. Morphological features of microorganisms during syngas fermentation were characterized using field emission scanning electron microscopy analysis. The results indicated that the highest bioethanol concentration, reaching 31.20 mmol, was achieved through co-fermentation as opposed to single-inoculum fermentation. Furthermore, a significant increase (3.08%) in bioethanol productivity was observed when the syngas flow rate was elevated from 50 to 1000 mL/min. Therefore, microbial co-fermentation emerges as a promising strategy to enhance bioethanol production from syngas derived from lignocellulosic biomass. Highlights Parametric optimization for co-gasification using response surface methodology Syngas was co-fermented using Saccharomyces cerevisiae and Clostridium butyricum Effects of syngas (CFU, pH, and TOC) were investigated during co-fermentation Bioethanol production increased 3.08% when syngas flowrate increased from (50 to 1000 mL/min)

Bioprospecting of Indigenous Microbial Species for Bioethanol Production from the Fruits of Some Selected Exotic Ornamental Plants

The study determined the ability of some selected indigenous microbial isolates, namely Bacillus subtilis, Zymomonas mobilis and Saccharomyces cerevisiae, in the production of bioethanol from the fruits of some exotic plants (i.e. Ixora coccinea, Duranta repens and Syzygium guineense). B. subtilis was isolated from soil, while Z. mobilis and S. cerevisiae were isolated from palm wine using cultural methods. The organisms were identified based on their colony characteristics and morphological features, which were observed by microscopic examination of the stained smears of the isolates. The identity of the organisms was confirmed through the molecular study of the 16S rRNA and 18S rRNA regions of the microbial genomes using Polymerase Chain Reaction – Denaturing Gradient Gel Electrophoresis (PCR - DGGE). The fruit samples were collected, washed, blended, filtered using a clean piece of cloth and pretreated using ultrasonication and autoclave. Concentrations of reducing sugars in the fruit filtrates were determined using DNSA-UV-visible spectrophotometry. Seven (7) conical flasks (500ml capacity) were arranged for each fruit sample in duplicate, and 250ml of the fruit filtrates were dispensed in the flasks accordingly. The fermenting organisms were inoculated in the flasks containing the fruit filtrates singly and in combination. Flasks were incubated in shaking incubator for seven days at 35oC. After incubation, the concentrations of bioethanol produced were determined using the UV-visible spectrophotometry. Highest reducing sugars concentrations of 43.7% and 43.6% were found in I. coccinea and S. guineense, respectively, while 36.4% was recorded for D. repens. Highest bioethanol yield of 27.5m/L was found in I. coccinea fermented by S. cerevisiae and Z. mobilis, while the lowest yield of 17.25m/L was found D. repens. The yield in bioethanol production was higher in samples containing a combination of fermenting organisms compared to ones with individual cells. It was recommended that the fruits of these exotic plants should be considered for commercial production of bioethanol.

Determination of Reducing Sugar Groups from Hydrolysis of Arthrospira platensis Microalgae using Microwaves

The depletion of fossil fuel sources and increasing carbon dioxide (CO2) emissions have encouraged research into renewable energy sources. Bioethanol is an environmentally friendly energy source with considerable potential for reducing dependence on gasoline. Bioethanol is produced from the fermentation process of monosaccharides. The first and second generations of bioethanol are derived from food crops, agricultural waste, and plantation waste, whereas the third generation is produced from microalgae. Arthrospira platensis is a carbohydrate-rich microalgae. This study attempts to determine the content of reducing sugar groups which are monosaccharides formed from a hydrolysis with microwaves. A total of 10 g of microalgae powder was added to 100 mL of 0.3 M H2SO4 solution. The hydrolysis process was carried out in a microwave reactor at a temperature of 100°C for 90 minutes. The hydrolysate obtained was then fermented with Saccharomyces cerevisiae anaerobically in a shaking water bath. The High Performance Liquid Chromatography (HPLC) test was performed to identify reducing sugar groups in the hydrolysate, and the Gas Chromatography (GC) test was performed to determine the concentration of bioethanol produced during the fermentation process. Meanwhile, the solid content of biochar that remained after hydrolysis was analyzed using Fourier-Transform Infrared Spectoscopy (FTIR). The HPLC test findings showed that the glucose concentrations before and after fermentation were 10.52 and 1.91 g/L, respectively, indicating that 81.8% of the glucose was converted to bioethanol. Furthermore, the distillation results from the fermented hydrolysate were analyzed using GC, yielding a bioethanol content of 3.90 g/L.

Conversion of Sweet Whey to Bioethanol: A Bioremediation Alternative for Dairy Industry

In many countries, whey from the dairy industry is an abundant waste that generates an important environmental impact. Alternative processes to use the whey and minimize the environmental impact are needed. This work considered six formulations with different ammonium sulfate and L-phenylalanine (L-Phe) concentrations to produce bioethanol in sweet whey fermentation by Kluyveromyces marxianus. The results showed a maximum bioethanol concentration equal to 25.13 ± 0.37 g L−1 (p &lt; 0.05) for formulation F6, with 1 g L−1 of L-Phe and 1.350 g L−1 of ammonium sulfate (96 h). For these conditions, the chemical oxygen demand removal percentage (CODR%) was 67%. The maximum CODR% obtained was 97.5% for formulation F3 (1 g L−1 of L-Phe) at 96 h; however, a significant decrease in bioethanol concentration (14.33 ± 2.58 g L−1) was observed. On the other hand, for formulation, F3, at 48 h of fermentation time, a bioethanol concentration of 23.71 ± 1.26 g L−1 was observed, with 76.5% CODR%. Based on these results, we suggest that the best conditions to obtain a significant bioethanol concentration and CODR% value are those used on the configuration F3 at 48 h.

PRODUKSI BIOETANOL DARI BONGGOL PISANG DENGAN PENAMBAHAN BIJI NANGKA SEBAGAI SUBSTRAT

Bioethanol is a type of bioenergy that can be used as an alternative fuel. One of the ingredients that can be used is banana stems and jackfruit seeds. Banana stems and jackfruit seeds are materials that contain considerable potential as basic ingredients for bioethanol based on the availability of certain components (starch and cellulose) they contain. The starch and cellulose content found in banana humps and jackfruit seeds can be converted into bioethanol through hydrolysis and fermentation processes. This research aims to synthesize bioethanol from banana humps and jackfruit seeds, determine the effect of the combination of a mixture of banana humps and jackfruit seeds on the concentration of glucose produced from the hydrolysis process and bioethanol produced from the fermentation process. This research began with pretreatment of raw materials (washing, cutting, drying) with variations in the components of banana humps and jackfruit seeds 100% : 0%, 75% : 25%, 50% : 50%, 25% : 75%, 0% : 100 % and variations in starch mass of 1%, 2%, 3%, 4% and 5%. Then the hydrolysis process uses H2SO4 for 1 hour at a temperature of 95˚C-100˚C. Then the hydrolysis results are fermented using Saccharomyces Cerevisiae. The fermentation process lasts for 24 hours, 48 hours, 72 hours, 96 hours and 120 hours. The research results showed that the largest concentration of bioethanol was obtained in the 50%: 50% component with a starch mass of 100 grams of 7% (v/v).

Availability and saccharification of starchy biowastes for bioethanol production in the Kingdom of Saudi Arabia

AbstractBioenergy has received a great interest because of increase in oil price, rapid depletion of fossil fuels, global climate change, and environmental pollution. However, cheap, and fermentable sugar-rich substrates represent a challenge that face production of biofuel on commercial scale. Therefore, this study offers a reliable solution for sustainability of biofuel production by recycling cheap resource (starchy biowaste) that is abundant in Kingdom of Saudi Arabia (KSA). To achieve the goal of this study, we applied different hydrolysis protocols to obtain a high quantity of fermentable sugars from starchy biowaste collected from restaurants as meal leftover. The results approved that starchy biowastes are abundant in the KSA; with the size of the residue per meal ranging from 149 to 5218 g, and starchy materials, mostly waste rice (WR), representing 72.5%. The saccharification of thermochemically pre-treated WR, carried out using an α-amylase and glucoamylase mixture for 4 h, was the most effective technique amongst all the pre-treatment methods, and produced the highest glucose concentration, i.e. 430.6 g/kg WR. Among five yeast isolates that were tested for their ability to produce ethanol from pre-treated WR via fermentation, Kluyveromyces marxianus KKU-RDI-11 and Pichia kudriavzevii KKU-RDI-18 produced the highest bioethanol concentrations, i.e. 15.44 g/L and 15.62 g/L, respectively. This study recommends application of our technique and the fermentative yeasts on the industrial and commercial scale in KSA, for production of biofuel and recycling of starchy waste materials from restaurants.

Impact of Bioethanol Concentration in Gasoline on SI Engine Sustainability

This study presents an experimental investigation into the impact of blending bioethanol (E100) with conventional gasoline (E0), incrementally increasing biofuel levels up to E10, E50, and E70. The test was carried out in two stages: Stage I assessed the engine’s performance under fixed speeds (n = 2000 rpm and n = 2500 rpm) and fixed throttle positions (15%, 20%, and 25%) to measure changes in engine torque, efficiency, and environmental metrics by varying the concentration of bioethanol in the fuel. Stage II aimed to enrich the initial findings by conducting an additional test, running the engine at a fixed speed (n = 2000 rpm) and braking torque (MB = 80 Nm) and varying the ignition timing. Results indicated slight improvements in engine brake torque and thermal efficiency (up to 1.7%) with bioethanol content increased to 70%, and a notable reduction in incomplete combustion byproducts—carbon monoxide and hydrocarbons emissions (up 15% and 43%). Nitrogen oxide emissions were reduced by up to 23%, but carbon dioxide emissions decreased by a mere 1.1%. In order to increase thermal efficiency by adding higher bioethanol blend concentrations, adjusting the ignition timing to counter the longer ignition delay is necessary; however, higher emissions of nitrogen oxides and hydrocarbons are a major drawback of such a strategy. The results of the research are important in determining the optimal concentration of bioethanol in the mixture with gasoline for the energy and environmental sustainability of a spark ignition engine.

Preliminary membrane screening and evaluation for the separation of bioethanol obtained from fermentation of oil palm empty fruit bunch (OPEFB)

This study evaluates the effectiveness of some commercial membranes (polytetrafluoroethylene [PTFE], polyvinylidene fluoride [PVDF], polyethersulfone [PES], and nitrocellulose [NC]) in concentrating a binary ethanol-water mixture under different conditions (volumes, temperatures, pressures, and concentrations). Then, the membrane was selected based on its performance for use in ethanol and by-product separation from OPEFB fermentation broth. The optimum result for the binary ethanol-water separation was found in the PVDF membrane with the highest separation factor of 3.03 and flux of 0.015 g.cm−2 s−1 under 10 ml permeate volume, 75 °C temperature, 60 psi pressure, and 20 % (v/v) ethanol concentration. Based on the membrane field emission-scanning electron microscope (FE-SEM) analysis, the PVDF membrane also had the lowest swelling degree. Utilization of the PVDF membrane to separate crude bioethanol resulting from OPEFB fermentation gave a separation factor of 3.66. The initial bioethanol concentration was 7.67 % (v/v), and the ethanol concentration in the permeate was 23.31 % (v/v). In addition, the separation factor of propanol from the crude mixture was 5.44, and the acetic acid rejection factor was 96.7 %. The S.cerevisiae suspension and the cellulase enzyme were also separated and recovered in the retentate phase. Hence, the PVDF membrane can be used to separate bioethanol from the yeast and enzyme suspension while pre-concentrating the bioethanol product. This could eventually help reduce the energy requirement to obtain industrial-grade bioethanol.

The Effect of Fermentation Time, pH and Saccharomyces Cerevisiae Concentration for Bioethanol Production from Ulva Reticulata Macroalgae

Research has been carried out on the effect of pH, fermentation time and yeast concentration on bioethanol production through hydrolysis using a CEM (Ceramic Elekctromagnetic Microwave) synthesizer and bioethanol production from Ulva reticulata seaweed. Ulva reticulata seaweed contains carbohydrates in the form of heteropolysaccharides such as glucose, arabinose, ramnose and xylose which are very abundant and suitable for conversion into bioethanol because the people of Timor Island do not use them as food. The carbohydrate content of Ulva reticulata seaweed can be converted into hexose and pentose sugars (glucose, arabinose, ramnose and xylose) through hydrolysis using 3 types of acid catalysts, namely hydrochloric acid (HCl), sulfuric acid (H2SO4) and nitric acid (HNO3). Fermentation was carried out with S. cerevisiae concentration variation of 6; 8; 10; 12 % (v/v) and fermentation time variation of 3; 5; 7; 9 days and a pH variation of 4; 4.5; 5; 5.5 at a temperature of 30 °C. Reducing sugar characterization used the Dinitrosalicylic acid (DNS) reagent, sample surface texture analysis was carried out using Scanning Electron Microscopy (SEM) and ethanol characterization used Gas Chromatography-Flame Ionization Detector (GC-FID). The results of surface texture analysis before and after hydrolysis experienced significant changes. Optimal conditions for hydrolysis of Ulva reticulata seaweed using sulfuric acid (H2SO4) combined with a CEM synthesizer at an acid concentration of 3 % (v/v) with irradiation power of 200 watts for 50 min at a temperature of 150 °C, produced reducing sugar of 97.06 g/L. The results of GC-FID analysis indicated that bioethanol concentration obtained at optimal conditions of pH 4.5 was 42.32 %, S. cerevisiae concentration was 12 % with a bioethanol content of 42.53 % at a fermentation time of 5 days. This research is expected to provide information for researchers and industry to overcome world energy problems and environmental pollution through Ulva reticulata waste. HIGHLIGHTS The results of surface texture analysis before and after hydrolysis experienced significant changes. Optimum conditions for hydrolysis of Ulva reticulata seaweed using sulfuric acid (H2SO4) combined with a CEM synthesizer at an acid concentration of 3 % (v/v) with irradiation power of 200 watts for 50 min at a temperature of 150 °C, producing reducing sugar of 97.06 g /L. GRAPHICAL ABSTRACT

Bioethanol Production from Marine Macroalgae Waste: Optimisation of Thermal acid Hydrolysis

Marine macroalgae waste, resulting from the accumulation of drifted algal biomass along the coastline, might be a relevant complementary raw material aiming sustainable bioethanol production. In the present study, the optimisation of thermal acid hydrolysis was performed using response surface methodology (RSM) considering the effect of three variables, namely, reaction time (10–60 min), acid concentration (0.1–2.5% (v/v) H2SO4) and biomass:acid ratio (5–15% (w/v)) on sugar concentration and yield. Under the best conditions, the resulting hydrolysates were fermented (7 days, 30 °C, 150 rpm, commercial yeast) to produce bioethanol. A statistically valid second-order model was obtained (r2 = 0.9876; Prob > F lower than 0.05), showing that sugar concentration is mostly influenced by the biomass:acid ratio while reaction time was not significant. The maximum predicted sugar concentration was 18.4 g/L, being obtained at 2.5% H2SO4 concentration and 15% (w/v) biomass:acid ratio, corresponding to a sugars yield of 12.5 g/100 g (less 36% than that obtained using 10% (w/v)). At the best conditions, the hydrolysates were fermented to obtain a bioethanol concentration up to 2.4 g/L and a 21 mgbioethanol/gbiomass yield, emphasizing the biomass potential for bioenergy production.Graphical

Microbial bioethanol production from Agave tequilana leaves juice sugars: Process variable optimization and kinetic modeling

This study focuses on the valorization of Agave tequilana leaves through bioethanol production from juice sugars. Optimal cultivation conditions were determined using a Taguchi orthogonal array design to maximize bioethanol production by Saccharomyces cerevisiae BEL6 61003. The optimal conditions included reducing sugars at 120 g/L, air flow at 0.5 vvm; agitation at 300 rpm, and pH at 4.5. Under these conditions, the maximum bioethanol concentration reached 43.26 ± 2.20 g/L, with a productivity (rP) of 2.4 ± 0.12 g/L·h and a yield of 43 %. A mathematical model was developed to describe the dynamics of the fermentation process under optimal conditions, comparing the kinetic equations of Moser-Boulton and Moser-Loung. The simulations strongly fit the experimental data, with coefficient of determination (R2) values reaching 0.96 for both models. The selection of the best model was assessed using the Akaike Information Criterion (AIC), favoring the Moser-Boulton equation as the more effective model.

Production of gasohol by azeotropic distillation

AbstractA new azeotropic distillation process is presented to produce gasohol in an adequate concentration of bioethanol and isooctane, which emulates the properties of gasoline ready to use in conventional combustion engines. Since the mixing step is eliminated, there are significant economic savings which imply a competitive price of bioethanol. A comparison is provided with the traditional bioethanol dehydration process, extractive distillation. Both processes were simultaneously designed and optimized with differential evolution with a Tabu list algorithm (DETL) in order to reduce the total annual cost (TAC). Results showed that when obtaining E10 biofuel, a blend of up to 10% ethanol and 90% unleaded isooctane, via azeotropic distillation, over 40% of the TAC is saved compared to obtaining pure alcohol dehydrating through extractive distillation. Moreover, the reduction in carbon dioxide emissions results in an average of 27%.

Response surface methodology based optimization studies about bioethanol production by Candida boidinii from pumpkin residues

For sustainable bioethanol production, the investigation of novel fermentative microorganisms and feedstocks is crucial. In this context, the goals of the current study are suggesting pumpkin residues as new raw material for bioethanol production and investigating the fermentative capacity of the Candida boidinii, which is a newly isolated yeast from sugar factory wastes. Response surface methodology was used to determine the effect of enzyme (cellulase and hemicellulase) concentration and enzymatic hydrolysis time. The maximum bioethanol concentration was 29.19 g/L when fermentation parameters were optimized. However, it is revealed that enzymatic hydrolysis and hydrolysis duration (48-72 h) have significant effects on reducing sugar concentration. The highest reducing sugar was 108.86 g/L when the 20% initial pumpkin residue was hydrolyzed at 37.5 FPU/g substrate cellulase and 37.5 U/mL hemicellulase at the end of 72 h. Under these optimized conditions, the bioethanol production of C. boidinii increased by 22.91% and reached 35.88 g/L. This study shows pumpkin residues are promising feedstocks and C. boidinii is a suitable microorganism for efficient bioethanol production.

Ethanol production from cassava peels using Saccharomyces cerevisiae via ethanologenic fermentation process

PurposeThis study aims to assess the effect of water variation on bioethanol production from cassava peels (CP) using Saccharomyces cerevisiae yeast as the ethanologenic agent.Design/methodology/approachThe milled CP was divided into three treatment groups in a small-scale flask experiment where each 20 g CP was subjected to two-stage hydrolysis. Different amount of water was added to the fermentation process of CP. The fermented samples were collected every 24 h for various analyses.FindingsThe results of the fermentation revealed that the highest ethanol productivity and fermentation efficiency was obtained at 17.38 ± 0.30% and 0.139 ± 0.003 gL−1 h−1. The study affirmed that ethanol production was increased for the addition of water up to 35% for the CP hydrolysate process.Practical implicationsThe finding of this study demonstrates that S. cerevisiae is the key player in industrial ethanol production among a variety of yeasts that produce ethanol through sugar fermentation. In order to design truly sustainable processes, it should be expanded to include a thorough analysis and the gradual scaling-up of this process to an industrial level.Originality/valueThis paper is an original research work dealing with bioethanol production from CP using S. cerevisiae microbe.HighlightsHydrolysis of cassava peels using 13.1 M H2SO4 at 100 oC for 110 min gave high Glucose productivityHighest ethanol production was obtained at 72 h of fermentation using Saccharomyces cerevisiaeOptimal bioethanol concentration and yield were obtained at a hydration level of 35% agitationHighest ethanol productivity and fermentation efficiency were 17.3%, 0.139 g.L−1.h−1