Bioethanol Samples Research Articles

Industrial crude bioethanol dehydration to ethylene: Doping ZSM-5 to enhance selectivity and stability

Although the conversion of bioethanol into light olefins is one of the most studied processes in biorefinery schemes, there is a need to develop materials more capable of operating at industrial conditions (WHSV > 20 h−1 crude bioethanol feed). Hence, in this study, we dehydrated crude bioethanol samples derived from sugarcane fermentation to produce ethylene over a series of H-ZSM-5 zeolites. Among them, H-ZSM-5 with different Si/Al ratios (26, 280, and 371) and doped with Ce and Cu were tested on the catalytic activity and stability. Accordingly, a 26 Si/Al ratio showed full conversion and ethylene selectivity at 300 °C with a WHSV of 30.2 h−1. When doping the zeolites, a decrease in relative crystallinity and a higher amount of acid sites were observed, which affected the interaction with reactants. This interaction was deeply analyzed by the in-situ DRIFTS, which showed that ethanol adsorption is lower for doped zeolites, but the desorption rate is higher, showing higher stability over longer reaction times. Therefore, the H-ZSM-5 with a Si/Al ratio of 26 and doped with Ce maintained its activity and improved its selectivity over 140 h under more drastic conditions of WHSV (42.3 h−1). These results elucidate that Ce-doped H-ZSM-5 zeolites can improve stability and represent a starting point for large-scale crude bioethanol conversion.

Assessment of total sample consumption infrared-heated system for minimization of matrix effects in ICP-tandem mass spectrometry

A total sample consumption infrared-heated system (IR-TSC) has been coupled to ICP-tandem mass spectrometry (ICP-MS/MS) for the first time. The objective of this study was to assess the analytical performance of the IR-TSC system, in terms of analytical figures of merit and mitigation of matrix effects. Twenty-seven elements have been determined: Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, V and Zn. Different operating conditions, including nebulization flow rate and spray chamber temperature, were optimized to improve sensitivity, signal stability, and plasma thermal conditions. The results showed that the infrared-heated sample introduction system improved the signal intensity by a factor of 2 to 4 compared to a conventional sample introduction system, whereas the limits of detection (LODs) improved by a factor going from 1.2 (Ba) to 3.3 (Cr) for a sample containing 2% HNO3. Meanwhile, for a 10% ethanol sample the improvement factor ranged from 1.4 (Ti) to 3.8 (Cr). Matrix effects for solutions containing inorganic acids or high content of sodium (2% HNO3, 10% HNO3, 20% HNO3, 10% HCl; 500 mg kg−1 Na, 500 mg kg−1 Na + 10% HNO3) were mitigated under optimum conditions (IR-TSC at 125 °C). Meanwhile, for solutions containing organic solvents (10% ethanol, 10% acetic acid, and 10% formic acid) it was not possible to eliminate matrix effects, even when applying an internal standard. For Se and As, elements spectrally interfered, the combination of IR-TSC sample introduction system with oxygen as reaction/collision gas mode in ICP-MS/MS provided accurate results. For 10% HNO3 and 10% HCl relative intensities values, calculated taking the signal intensity obtained for 2% HNO3 as reference, were close to the unity. Environmental and clinical control and certified reference materials were analyzed by means of an external calibration approach, with most of the elements showing concentrations not significantly different from the certified values. Finally, the IR-TSC was tested on twelve real samples, including seawater, surface water, peritoneal fluid, seminal plasma, wine, and bioethanol samples, demonstrating the system potential in different application fields.

Effect of chemical pre-treatment on bioethanol production from defoliated dried neem (Azadirachta Indica) leaves

In recent years, ethanol derived from biomass is grabbing attention due to incessant spike in petroleum prices along with increased green house gases. In this context, ethanol production from residual lignocellulosic biomass such as dried defoliated leaves which will not pose the menace food versus fuel has been gaining significant concern in the scientific community. In current study, lignocellulosic biomass derived from defoliated dried neem leaves (Azadirachta Indica) were used as a feedstock for bioethanol production. The powdered leaves were chemically pre-treated by adopting two types pre-treatment processes; (i) Single stage acid pre-treatment using three different concentrations of H2SO4 (0.1 M, 0.5 M and 1 M) and (ii) two-stage combined alkali and acid pre-treatment using three different concentrations of NaOH (0.1 M, 0.5 M and 1 M) followed by subsequent pre-treatment with 1 M H2SO4. FTIR study was adopted to characterize the biomass (neem leaves) samples before and after pre-treatmemt as well as produced bioethanol samples. The sugar content in the biomass sample and pre-treated solutions were carried out using Munson and Walker method. The ethanol concentration in the fermented broth was determined by UV–VIS spectroscopy. The FTIR studies of the neem leaves before and after pre-treatment showed breakdown in lignocellulosic biomass structure due to pre-treatment. The FTIR pattern of the produced bioethanol showed the characteristic peaks of ethanol. The study reveals that the two-stage combined alkali pre-treatment using 1 M NaOH and 1 M H2SO4 results highest quantity of recovered sugar (21 g/L) and ethanol (18.49 % (w/v)). The two-way ANOVA analysis with p < 0.05, suggests there is a significant variation in impact of two parameters i.e. concentration of pre-treating agents and nature of pre-treatment on bioethanol production. The study explored the possibility of using a residual biomass such as defoliated dried neem leaves that are abundantly available in Indian sub-continent as a potential feedstock for bioethanol production for consequent CO2 mitigation.

Bioethanol fuel quality assessment using dielectric spectroscopy

This study first aims to determine the physical characteristics of bioethanol from its dielectric properties during the production process. For this purpose, bioethanol samples were produced from sugarcane molasses under different fermentation conditions such as temperature and reaction time. The main permittivity properties, including dielectric constant and loss factor at various frequencies, were measured as the inputs, whereas flash point and octane number, as significant physical parameters, were considered as output variables. Linear regression (LR) models were developed to predict the relationships between predictors and targets. Next, four learning algorithms – multivariate regression splines (MARS), M5 tree, multilayer perceptron (MLP), and support vector regression (SVR) – were deployed to improve the models’ performance. The results from LR models revealed that the flash point had a direct relationship with the dielectric constant and loss factor. However, the octane number was indirectly proportional to the dielectric properties. Also, analysis of the testing data set of learning algorithms indicated that the best algorithm for predicting the responses was MARS, whereas the SVR model performed with the lowest accuracy. The findings from this paper suggest that dielectric spectroscopy is a valuable approach for estimating the physical features of bioethanol.

Bioethanol steam reforming over monoliths washcoated with RhPt/CeO2–SiO2: The use of residual biomass to stably produce syngas

Ethanol steam reforming of synthetic bioethanol (i.e., anhydrous ethanol plus water), as well as bioethanol obtained from glucose standards and sugarcane press-mud was evaluated on monoliths washcoated with RhPt/CeO2–SiO2. Tests with synthetic bioethanol indicated that the lower pressure drop favors higher ethanol conversion in the monoliths with respect to the powder samples. Also, two monoliths in series with 0.08 gcat/cm3 improved H2 yield compared to just one monolith with 0.16 gcat/cm3. Similarly, a decrease in the amount of carrier gas contributes to diffusion limitations in the monoliths, reducing the H2/CO ratio. Monoliths stability was also evaluated with “real” bioethanol samples (from glucose standards and sugarcane press-mud-SPM). In all cases, a syngas with >60% of H2 was produced. For SPM-bioethanol, 3.1 ± 0.2 mol H2/mol EtOH were obtained without evidence of deactivation for 120 h, at a cost of 6.9 $/kgH2, becoming a promising way to develop a technology for sustainable energy production.

Profiling of Organic Compounds in Bioethanol Samples of Different Nature and the Related Fractions.

Forty-one bioethanol real samples and related fractions, together with a biobutanol sample, have been analyzed with gas chromatography coupled to either mass spectrometry (GC–MS) or flame ionization detection (GC–FID). Bioethanol with different water contents, samples originated from several sources of biomass, first- as well as second-generation specimens, distillation fractions, samples stocked in containers made of four different materials, and, finally, a biobutanol sample have been analyzed. The number of the compounds found through GC–MS has been 130, including alcohols, aldehydes, ketones, esters, ethers, nitrogen compounds, organic acids, furane derivates as well as other species (e.g., limonene). Afterward, a quantitative determination of major components of bioethanol has been carried out. The achieved results have revealed that, besides ethanol and, in some cases, water, species such as acetaldehyde, methanol, and higher alcohols, as well as 1,1-diethoxyethane, may be present at concentrations above 500 mg L–1. While the source of bioethanol (nature of the raw material, ethanol generation, or water content) has a direct impact on its volatile organic compound (VOC) profile, the material of the container where the biofuel has been stored does not play a significant role. Finally, the results have demonstrated that, for a given production process, different distillation fractions contain unequal VOC profiles.

Effect of the Isopropanol Impurity in the Feed on Catalytic Dehydration of Bioethanol to Ethylene

Isopropanol is one of the main organic impurities present in bioethanol. Effect of the isopropanol impurity in the feed on catalytic dehydration of 92% ethanol to ethylene over an aluminum oxide catalyst was studied in a gradientless reactor under the conditions of kinetic control at 350–400°С. The maximum permissible concentration of isopropanol in ethanol was found to be 0.7 g L–1, which is equivalent to 0.05 mol % in the gaseous feed. Such isopropanol concentration in the feed does not decrease the catalyst activity and selectivity to ethylene but suppresses formation of acetaldehyde, hydrogen, and butylene, improving the quality of the ethylene product. A bioethanol sample with ~0.15 g L–1 isopropanol content, produced from miscanthus using nitric acid treatment of the biomass, was tested. The process characteristics and ethylene quality obtained by the bioethanol dehydration are slightly higher because of decreased formation of by-products, compared with the dehydration of commercially available pure ethanol.

Controlling sugarcane press-mud fermentation to increase bioethanol steam reforming for hydrogen production

Hydrogen (H2) production from sugarcane press-mud, a waste obtained from the non-centrifugal sugarcane agroindustry, was assessed by coupling hydrolysis, fermentation, purification, and ethanol steam reforming (ESR). Two culture media were employed on three different sugarcane press-mud samples to produce bioethanol by fermentation using Saccharomyces cerevisiae at 30 °C. One culture medium was supplemented with nutrients and the other without supplementation. The supplementation did not have a significant effect over ethanol production (∼82.1 g L−1) after 70 h fermentation, but the concentration of the impurities was always lower under supplemented conditions. Among tested impurities, differences in 3-methyl-1-butanol showed the effect of the supplementation on the ESR over RhPt/CeO2-SiO2 catalyst at 700 °C, where the H2 yield decreased significantly in the presence of 3-methyl-1-butanol (p < 0.05). The spearman correlation coefficient showed that the H2 yield was correlated with the 3-methy-1-butanol content (RHO = −0.929) and carbon deposits (RHO = −0.964). Therefore, supplemented bioethanol could deliver 3.0 g H2 kg−1 sugarcane press-mud, which is almost twice that of the non-supplemented samples, likely due to the reduction of harmful impurities in the bioethanol. Additionally, supplemented conditions allowed for energy savings in the process and improved catalyst stability. This study provides insights into the effect of supplementing culture media to produce purer bioethanol samples, which further deliver higher H2 yields by ESR.

Iron (III) determination in bioethanol fuel using a smartphone-based device

The presence of Fe(III) can catalyse fuel degradation processes, providing their inefficient burning and increasing the emission of harmful gases into the atmosphere. Thereby, Brazilian National Petroleum Agency establishes a strict limit for the maximum concentration of iron in fuel bioethanol (5 mg kg−1 that corresponds to 6.18 mg L−1), usually monitored by atomic absorption spectrometer. The main subject in this work was to determine the concentration of iron (Fe3+) in bioethanol fuel using the digital image method as a simple analytical methodology. Colorimetric determination was performed by Color Grab app in its RGB (red, green and blue) matrices, installed on a Smartphone. Fe(III) determination was based on its ability to complex with thiocyanate (SCN−) generating a red complex (Fe(SCN)2+). The correlation between Fe(III) concentration and color intensity was obtained after the transformation of RGB components into a grayscale model. A linear response was observed in the concentration range between 0.5 and 10 mg L−1 (R2 = 0.998) with a detection limit of 0.1 mg L−1. Recovery values between 97% and 105% were obtained for the analysis of spiked fuel bioethanol samples. The results agreed with those obtained by spectrophotometry. Repeatability (n = 10) of 2.1% and 1.3% was obtained for the determination of 1 and 4 mg L−1 of Fe3+, respectively. This work demonstrates that smartphone-based methods provide great promise for in-field fuel quality control.

Production of bioethanol from rice husk pretreated with alkalis and hydrolyzed with acid cellulase at pilot scale

Rice husk (RH) is the main biomass byproduct of the rice industry, so much that it corresponds to 20% of the total cereal production and is generally considered a waste. Due to its content of cellulose and hemicellulose, the RH has a great potential for its alternative use in the production of bioethanol, since it has a great advantage with respect to the conventional raw materials used (sugar cane, corn, beet and sweet sorghum, among others), given that this lignocellulosic material is abundant and does not compete with the food industry. The objective of this work was to obtain bioethanol from rice husk at a pilot scale, taking advantage of its cellulose and hemicellulose content. For this, a sample of 450g of RH was taken, which was pretreated with a 2.00% w/v NaOH solution and subsequently hydrolyzed with acid cellulase (CFB3S). The alcoholic fermentation of total reducing sugars (TRS) obtained in the enzymatic hydrolysis was carried out with Saccharomyces cerevisiae, finally, the fractional distillation of the must was carried out, by means of which four bioethanol samples were obtained with concentrations of 71.3% v/v, 30.0% v/v, 10.3% v/v, and 5.3% v/v of alcohol, which when mixed produced a sample of 95mL of solution with a concentration of 27% v/v alcohol (4.70g/100g of RH).

Evolution of the metal and metalloid content along the bioethanol production process

Metal and metalloid concentration has been determined through inductively coupled plasma - mass spectrometry (ICP-MS) in bioethanol samples, raw materials employed to obtain this biofuel and samples taken from different critical points of the manufacture method. In this way, it was possible to study the evolution of the metal and metalloid content all along the bioethanol production process, allowing to establish the origin of the elements determined in the final samples. Moreover, the steps of the production process where they were either removed from the biomass or accumulated in the biofuel were successfully identified.Four different acid assisted protocols were compared through the analysis of two biomass certified reference materials (CRMs). The results revealed that, for the most suitable method (nitric acid assisted MW digestion), recoveries for the analytes of interest went from 90% to 110%. Furthermore, good short-term and long-term precision and acceptable limits of detection (LODs) were obtained.Two different production lines were studied, and our results show that slight differences in terms of the minor elements concentration (Cd, Co, Sb, Pb and V) were identified. The most important source of metals and metalloids in the whole process can be attributed to the raw material. Meanwhile the distillation step caused 1000 to 10,000 times decrease in elemental concentration in the final bioethanol as compared to the initial biomass.

Thermodynamic and economic assessment of the production of light olefins from bioethanol

The production of light olefins from bioethanol was evaluated in terms of thermodynamics and economics using Aspen Plus and Aspen Hysys as process simulators. The conceptual design of two different plants were proposed: one for ethylene and another for propylene and butenes production. A bioethanol sample containing characteristic compounds after biomass fermentation (e.g., ethanol, water, and aliphatics) was used as raw material in the plants, which could handle 10% of the Colombian bioethanol market. The plants delivered streams of 99mol% ethylene, 90mol% propylene, and a mixture of butenes. A class-V-order economic assessment of both optimized, heated-integrated plants was carried out giving total investments of 5.37 USD million for the ethylene plant (459 USD/ton ethylene-year) and 10.27 USD million for the propylene plant (2100 USD/ton of propylene and butenes-year). Traditional production routes from petroleum have reported comparative investment costs of 1300 USD/ton-year for ethylene and 1450 USD/ton-year for propylene. This initial feasibility analysis shows the potential of olefin production, mostly ethylene, from real fermented bioethanol, as an interesting approach to the biorefinery concept that could make their production more sustainable and economic.

Analysis of bioethanol samples through Inductively Coupled Plasma Mass Spectrometry with a total sample consumption system

Bioethanol real samples have been directly analyzed through ICP-MS by means of the so called High Temperature Torch Integrated Sample Introduction System (hTISIS). Because bioethanol samples may contain water, experiments have been carried out in order to determine the effect of ethanol concentration on the ICP-MS response. The ethanol content studied went from 0 to 50%, because higher alcohol concentrations led to carbon deposits on the ICP-MS interface. The spectrometer default spray chamber (double pass) equipped with a glass concentric pneumatic micronebulizer has been taken as the reference system. Two flow regimes have been evaluated: continuous sample aspiration at 25μLmin−1 and 5μL air-segmented sample injection. hTISIS temperature has been shown to be critical, in fact ICP-MS sensitivity increased with this variable up to 100–200°C depending on the solution tested. Higher chamber temperatures led to either a drop in signal or a plateau. Compared with the reference system, the hTISIS improved the sensitivities by a factor included within the 4 to 8 range while average detection limits were 6 times lower for the latter device. Regarding the influence of the ethanol concentration on sensitivity, it has been observed that an increase in the temperature was not enough to eliminate the interferences. It was also necessary to modify the torch position with respect to the ICP-MS interface to overcome them. This fact was likely due to the different extent of ion plasma radial diffusion encountered as a function of the matrix when working at high chamber temperatures. When the torch was moved 1mm plasma down axis, ethanolic and aqueous solutions provided statistically equal sensitivities. A preconcentration procedure has been applied in order to validate the methodology. It has been found that, under optimum conditions from the point of view of matrix effects, recoveries for spiked samples were close to 100%. Furthermore, analytical concentrations for real samples following the preconcentration method and the direct determination were not significantly different. The quantification method was finally based on external calibration with standards containing 50% (v/v) ethanol content.

Hydrogen from glucose: A combined study of glucose fermentation, bioethanol purification, and catalytic steam reforming

A technical analysis of hydrogen (H2) production by coupling fermentation, distillation, and reforming is reported. A glucose solution (300 g/L glucose) was first fermented using a commercial Saccharomyces cerevisiae strain at 30 °C. The fermented samples were then distilled, giving bioethanol with a steam/ethanol ratio of 3:1. Several synthetic and real bioethanol samples were subjected to catalytic steam reforming (SR) over Rh0.4Pt0.4/CeO2. At 700 °C, real bioethanol samples produced the highest H2 yield (2.6 mol H2/mol inlet) compared to synthetic samples (0.8–1.6 mol H2/mol inlet), due to a synergistic effect between ethanol and fermentation byproducts, which increased H2 production. The catalyst was stable over 20 h during the SR of bioethanol at 700 °C with no appreciable carbonaceous deposition. Overall mass and energy balances confirmed that this process produced 8.2 mol H2/mol glucose, and could produce 5092 kJ/kg glucose as useful energy work output in fuel cell applications.

Enzymatic Hydrolysis of Lignocellulosic Materials in Aqueous Media followed by Microbiological Synthesis of Bioethanol

Enzymatic hydrolysis in aqueous media was studied using a lignocellulosic material (LCM) prepared from miscanthus and LCM prepared from oat covering (OC) as substrates to obtain bioethanol. LCM synthesis was a one-step processing of the feedstock with nitric acid (Pilot Plant of IPCET SB RAS). Commercially available enzymatic agents CelloLux-A and BrewZyme BGX were used for enzymatic hydrolysis in aqueous media at high initial concentrations (90 g/l) of the substrates. The yields of reducing substances (monosaccharides, mainly glucose) were established to equal 65,4 % and 73,3 % of the substrate weight for miscanthus LCM and OC, respectively. The composition of monosaccharides as products of biocatalytic decomposition of LCM was studied for the first time to show the predominant content of glucose. It was first time to synthesize bioethanol from LCM. The yield of bioethanol per unit of feedstock was 19,4 dal/t for miscanthus biomass and 16,2 dal/t for OC. A low methanol content (0,002–0,005 vol %) was characteristic of the experimental bioethanol samples.

Metal and metalloid determination in bioethanol through inductively coupled plasma-optical emission spectroscopy

A new method to carry out the elemental determination of metals in bioethanol through ICP-OES has been developed. The procedure is based on the use of a heated torch integrated sample introduction system (hTISIS) to directly introduce the vaporized sample into the plasma. Two injection modes (continuous liquid aspiration and air-segmented flow injection analysis) have been evaluated. In a first step, the matrix effects caused by several ethanol–water mixtures were removed by operating the hTISIS at 400°C in segmented injection. Meanwhile, the results also proved that the system could be operated in continuous mode at 200°C with the complete interference removal. Finally, twenty-eight real samples with bioethanol contents between 55% and 100% were analyzed with the methods previously developed. Regarding validation, recoveries from 80% to 120% were obtained for 18 analytes and the concentrations found with the proposed method were in agreement with those encountered with a preconcentration method, taken as a reference procedure. Limits of detection went from 3ngmL−1 for manganese to about 500ngmL−1 for calcium. This allowed to quantify Cr, Fe, Mg, Mn and Zn in segmented flow injection and Al, Cd, Cr, Cu, K, Mg, Mn, Na and Zn in continuous sample aspiration mode in bioethanol samples.

Batch-injection stripping voltammetry of zinc at a gold electrode: application for fuel bioethanol analysis

This article reports for the first time the anodic stripping voltammetric (ASV) detection of Zn at a gold disk macroelectrode for the analysis of fuel bioethanol. The accurate determination of Zn at gold macroelectrodes was only possible with the aid of batch injection analysis (BIA) associated with ASV; this statement was proved by comparison with a conventional three-electrode system. The BIA system consisted of injections of bioethanol sample plugs (up to 1mL) at 28.3μLs−1 directly onto a working (gold disc) electrode immersed in 0.04molL−1 Britton-Robinson buffer (pH 7) solution through an electronic micropipette and the Zn deposition occurs simultaneously. The highest analytical response for Zn was obtained for a deposition time of 90s, which indicated that Zn deposition also occurred from diffusion after the injection ended. The proposed method presented a low detection limit (5μgL−1), a linear range between 25 and 250μgL−1, and adequate recovery values (88–104%) for spiked samples, but no sample treatment was required. Such remarkable analytical features associated with the portability characteristics of BIA demonstrated the promising application of the proposed method for routine and on-site determination of metals in fuel bioethanol.

Thermal Conductivity and Thermal Diffusivity of Biodiesel And Bioethanol Samples

Abstract This article deals with thermal properties of selected biodiesel and bioethanol samples (biodiesel No 1, No 2 and bioethanol No 1, No 2). Biodiesel is renewable fuel that can be manufactured from vegetable oils, animal fats, or recycled restaurant grease for use in diesel vehicles. Biodiesel‘s physical properties are similar to those of petroleum diesel, but it is a cleaner-burning alternative fuel. Ethanol (CH3CH2OH) is a clear liquid. Also known as ethyl alcohol, grain alcohol, and EtOH, the molecules in this fuel contain a hydroxyl group (OH-) bonded to a carbon atom. Ethanol is made of the same chemical compound regardless of whether it is produced from starch and sugar-based feedstocks, such as corn grain, sugar cane, etc. The hot wire method was used for thermal parameters measurements. The experiment is based on measuring the temperature rise vs. time evaluation of an electrically heated wire embedded in the tested material. Thermal conductivity is derived from the resulting change in temperature over a known time interval. For two samples of biodiesel and two samples of bioethanol, there were determined basic thermophysical parameters - thermal conductivity and thermal diffusivity. Two series of measurements were made for each sample of biodiesel and bioethanol. In the first series, there were measured the thermal conductivity and thermal diffusivity at constant room temperature 20 °C. Every thermophysical parameter was measured 10 times for each sample. The results were statistically processed. In the second series of measurements, there were measured the relations of thermal conductivity and thermal diffusivity to temperature in temperature range 20-29 °C. It was evident from results that all measured dependencies are nonlinear. Polynomial functions described by polynomial coefficients were obtained for both thermophysical parameters. The type of function was selected according to statistical evaluation based on the coefficient of determination for every thermophysical parameter graphical dependency. All obtained results are presented in Figures 1-4 and in Tables 1-4. The results of thermophysical parameters measurements of biodiesel and bioethanol could be compared with the values presented in literature.

Batch-injection stripping voltammetry of metals in fuel bioethanol

This article reports for the first time the application of batch injection analysis (BIA) with anodic stripping voltammetry (ASV) for determination of metals in fuel bioethanol. An aliquot of bioethanol plug (up to 1mL) is directly injected onto a working (mercury-film) electrode immersed in electrolyte through an electronic micropippete and simultaneously metal deposition occurs. Stripping peaks for cadmium, lead, and copper were obtained at the same voltammetric scan under optimized conditions (electrolyte, deposition time and potential, injected volume, and dispensing rate). The proposed method presented low detection limit (⩽1μg L−1) for a 90 s deposition time, a linear range between 12.5 and 200μg L−1, and adequate recovery values (87–109%) for spiked samples. Estimation of the labile fraction of metals in bioethanol samples was also attained. Such remarkable analytical features associated with the portability characteristics of BIA attest the promising application of the proposed method for routine and on-site determination of metals in bioethanol.

Determination of Organic Impurities in Lignocellulosic Bioethanol Product by GC-FID

In recent, production of bioethanol in Indonesia is produced primarily from sugarcane molasses and cassava as the 1st generation. But related with its development, it is quite hard to be a major feedstock in bioethanol conversion because there is conflict in using between consumption food and energy resources. Due to abundant lignocellulose biomass resources in Indonesia, such as empty fruit bunch (EFB) of oil palm, sugarcane bagasse and other forrest residue, the research in the development of process for 2nd generation bioethanol production is being increase. This case can be a right solution to solve the problem because lignocellulose is unused material. Processing of lignocellulosic biomass into bioethanol consists of four major unit operations: pre-treatment, hydrolysis, fermentation and product separation/distillation. Although ethanol is the dominant alcohol produced in the fermentation of sugars process, there are some byproducts in bioethanol product, such as organic impurities, water and organic acid. Determination of the impurity is important to prove the quality of produced bioethanol. Some of the impurities is not allowed in the product, such as methanol and others organic, that should be limited to control the performance from bioethanol as substituted fuel. Organic impurities of the bioethanol product was analyzed by using GC-FID while the water content was analyzed by using Karl Fischer Coulometric Moisture Titrator. In this research, the lignocellulosic bioethanol analyzed for the moisture content and organic impurities was undenatured one. The water content of the bioethanol sample was analyzed in 7 replicates where the average was 0.1776%-w (% RSD 2.0460). There are eight compounds of organic impurities detected in GC-FID that are acetaldehyde (0.0217%-w), acetone (0.0102%-w), ethyl acetate (0.0368%-w), methanol (0.0224%-w), isopropyl alcohol (0.0035%-w), n-propyl alcohol (0.0188%-w), isobutanol (0.0437%-w) and isoamyl alcohol (0.0377%-w).