Physical and Chemical Pretreatment of Sugarcane Bagasse for Enhanced Acid Hydrolysis (original) (raw)
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Dilute mixed-acid pretreatment of sugarcane bagasse for ethanol production
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Alkaline Pretreatment on Sugarcane Bagasse for Bioethanol Production
Energy Procedia, 2014
Sugarcane bagasse is a lignocellulosic waste from sugar mills and agricultural processing. The aim of this research was evaluation of alkaline pretreatment on the chemical composition and structure of sugarcane bagasse. Pretreatment was conducted with cooking by sodium hydroxide. It was carried out at 12 L reactor with concentrations variation. Meanwhile, times variations were conducted for 15, 30, 40, and 45 minutes, respectively. Sugarcane bagasse characteristics before and after pretreatment have been analyzed by X-ray Diffraction and Fourier Transform Infra Red Spectrometer. The results showed that the lowest lignin content (7.16%) was the treatment by NaOH 1N for 30 minutes.
Biofuels in Brazil, 2014
Sugarcane juice-derived ethanol (1G ethanol) has been the major renewable energy source in Brazil after the inception of National Alcohol Program in 1970. The remaining part, after the processing of sugarcane and extraction of juice (sugarcane bagasse-SB and straw-SS), are the promising sugar feedstock for cellulosic ethanol (2G ethanol) due to their abundant availability round the year and high energy content. However, sugar recovery from lignocellulosic biomass is not easy and needs intensive processing. Pretreatment to overcome the recalcitrance of these feedstocks and sugar recovery constitute almost 30 % cost of 2G ethanol production. Several pretreatment methods have been studied recently aiming to either lignin removal or hemicellulose from SB/SS for the subsequent enzymatic hydrolysis for fermentable sugar production. However, steam explosion and dilute sulfuric acid have been emerged out as two successful options for the pretreatment of SB/SS. Pilot level studies at our institute (Laboratório Nacional de Ciência e Tecnologia do Bioetanol-CTBE, Campinas, Brazil), for the pretreatment of SB/SS considering steam explosion and dilute acid pretreatment, have shown the promising results. Both the pretreatment strategies are scalable and reproducible at the commercial level. This chapter deals with the experiments made on SB/SS for the steam explosion and dilute acid hydrolysis and the sugar recovery after enzymatic hydrolysis. Furthermore, process configurations for saccharification of pretreated biomass and the conversion of released sugars into ethanol have also been discussed.
Optimization of alkali concentration in the pretreatment of sugarcane bagasse for ethanol production
Bangladesh Journal of Scientific and Industrial Research, 2023
This study was aimed for the investigation of the effect of pretreatment procedure of alkaline, based on the chemical arrangement, surface morphology, structural composition and enzymatic assimilation of sugarcane bagasse for sugars and ethanol production. Alkali pretreatment (0 to 8% w/v of NaOH) assists to reduce the lignin portion (from 19.57±0.03% to 9.91±0.02%) and increase the cellulose content of the treated SB (from 34.66±0.05% to 63.58±0.05%) simultaneously. The optimal conditions for alkali pretreatment were 8% NaOH charge at 100 o C for 90 min. Enzymatic digestibility of alkali treated SB was significantly improved and hydrolysis yield reached to 89.59% glucose and 61.23% xylose at an prime level using Trichoderma viridae. Further hydrolysate of 8% (w/v) alkali treated SB sample was fermented by Saccharomyces cerevisiae to convert sugar into ethanol and yield was 16.81±0.32% in 24 h. Alkali pretreatment was found to be a treatment of choice for cellulose hydrolysis in SB and subsequent sugar acquired for the production of ethanol during fermentation.
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The production potential of cellulosic ethanol from sugarcane bagasse was studied. Chemical pretreatments were carried out by shaking bagasse with 1, 2 and 3% H2O2 (pH 10, 11.5 and 13) for 24, 48 and 72 h with subsequent saccharification of pretreated bagasse with H2SO4 (0.8 and 1.0 M) for 50 min for optimization of process. Acid hydrolysates were fermented with Saccharomyces cerevisiae var ellipsoideus for ethanol production. Maximum weight loss in alkaline pretreatment (52.30%), amount of reducing sugars (520.84 mg/g) and ethanol produced (27.94 ml/100 g pretreated bagasse) were found in 2% H2O2 (pH 11.5, 48 h) pretreated bagasse saccharified with 0.8 M H2SO4 after fermentation for 72 h. Pretreatment followed by acid saccharification decreased the time interval for ethanol fermentation.
Glucose production from sugarcane bagasse was investigated. Sugarcane bagasse was pretreated by four different methods: combined acid and alkaline, combined hydrothermal and alkaline, alkaline, and peroxide pretreatment. The raw material and the solid fraction of the pretreated bagasse were characterized according to the composition, SEM, X-ray and FTIR analysis. Glucose production after enzymatic hydrolysis of the pretreated bagasse was also evaluated. All these results were used to develop relationships between these parameters to understand better and improve this process. The results showed that the alkaline pretreatment, using sodium hydroxide, was able to reduce the amount of lignin in the sugarcane bagasse, leading to a better performance in glucose production after the pretreatment process and enzymatic hydrolysis. A good xylose production was also observed.
Bioresource Technology, 2011
An alternative route for bio-ethanol production from sugarcane stalks (juice and bagasse) featuring a previously reported low temperature alkali pretreatment method was evaluated. Test-tube scale pretreatment-saccharification experiments were carried out to determine optimal LTA pretreatment conditions for sugarcane bagasse with regard to the efficiency of enzymatic hydrolysis of the cellulose. Free fermentable sugars and bagasse recovered from 2 kg of sugarcane stalks were jointly converted into ethanol via separate enzymatic hydrolysis and fermentation (SHF). Results showed that 98% of the cellulose present in the optimally pretreated bagasse was hydrolyzed into glucose after 72-h enzymatic saccharification using commercially available cellulase and b-glucosidase preparations at relatively low enzyme loading. The fermentable sugars in the mixture of the sugar juice and the bagasse hydrolysate were readily converted into 193.5 mL of ethanol by Saccharomyces cerevisiae within 12 h, achieving 88% of the theoretical yield from the sugars and cellulose.
Assessment of Pre-Treatment Methods for Bio-ethanol Production from Sugarcane Bagasse
Chemical Engineering Transactions, 2015
Lignocellulosic biomass such as sugarcane bagasse is non-food biomass that can be used to produce ethanol. Lignocellulose is a complex network of cellulose, hemicellulose and lignin, which requires pre- treatment to improve access to cellulose for hydrolysis which produces glucose for fermentation. Lignin prevents access to cellulose thus delignification using alkaline is often included before hydrolysis. A variety of pre-treatment methods exist requiring different raw materials and operating conditions thus having different economics and environmental impacts. This paper aims to use computer modelling in an optimisation environment called GAMS (General Algebraic Modelling System) to screen a host of pre- treatment options of sugarcane bagasse for bio-ethanol production. The criteria to determine the best pre- treatment option evaluates both economic and environmental objectives. Pre-treatment options included steam explosion, with and without acid catalysis, and acid pre-treatment....
Biomass Conversion and Biorefinery, 2016
In lignocellulosic (LC) ethanol processes, to facilitate enzymatic hydrolysis of cellulose, a physical chemical pretreatment is vital. In this study, we explored a single as well as a two-step physical-chemical pretreatment involving steam and mixed acid on unwashed sugarcane bagasse at pilot-scale level in a continuous horizontal reactor. To serve as a largescale model, pretreatments were carried out at high solid levels of 18-20 % w/w. For the pretreatment, partial replacement of corrosive sulfuric acid with a milder acid-like oxalic acid was explored to derive possible advantages and synergies accruing by using a mixture of mineral acid and organic acid. The results of this work showed that first-step pretreatment carried out by the mixing of sulfuric acid (1.5 % w/w) and oxalic acid (1.5 % w/w) at 150°C followed by a second-step steam explosion pretreatment at 180°C gave significant synergies and advantages over other variants of pretreatments investigated, such as lower inhibitor levels and lower reaction severity. On post-pretreated bagasse, this study conducted comparative enzymatic hydrolysis study using a simple lab enzyme and a robust commercial enzyme. It was found that the addition of Tween 80 to the lab enzyme improved its performance to match the performance of the commercial enzyme. Scanning electron microscopy (SEM) studies were further carried out to correlate the morphology of pretreated samples with efficiency of enzyme hydrolysis. Besides morphological study, Fourier transform infrared (FTIR) studies of pretreated samples showed higher syringyl/guaiacyl ratio for all pretreatments, indicating lower levels of pseudo-lignins, which is beneficial for improved enzyme hydrolysis.
Investigation of Porosity, Wettability and Morphology of the Chemically Pretreated Sugarcane Bagasse
Enzymatic hydrolysis is one of the major steps involved in the conversion from sugarcane bagasse to ethanol production. This process shows a higher potential on yields and selectivity, a lower energy costs and a milder operating conditions in comparison to conventional chemical processes. However, the presence of some factors limit the digestibility of the cellulose present in the lignocellulosic biomasses, such as lignin content, degree of crystallinity of cellulose and particle sizes. Pretreatment aims to improve the enzyme access to the substrate. Differences in BET and BJH surface area, pores diameter and volume, structural and morphological changes were investigated by SEM images, X-Ray, FTIR and Wettability for sugarcane bagasse in natura and submitted to two pretreatments: diluted sulfuric acid (1% H 2 SO 4) and alkaline-solution concentrations (1, 2, 3 and 4% NaOH). Results showed that it was possible to observe morphological changes occurred after pretreatments. Acid and alkaline treatments had an increase for both BET and BJH surface areas about 9.2%, diameter and volume of pores also increased. Crystallinity index also increased about 3.6% in the amorphous cellulose and lignin regions degradation. Other experimental techniques, such as FTIR (functional groups, bands and vibrations) and wettability (hydrophobicity and hydrophilicity), were also confirmed the increase in these structural changes. In summary, the pretreatments employed were effective in chemical degradation of lignocellulosic materials for the bioenergy generation.