Highest Sugar Yield Research Articles

Screening of Ionic Liquids for Pretreatment of Taiwan Grass in Q-Tube Minireactors for Improving Bioethanol Production

In this study, a series of ionic liquids including conventional, protic and Bronsted acidic-type ionic liquids were evaluated as media for the pretreatment of Taiwan grass. The pretreatments were carried out in parallel format, for the first time, in a novel glass reactor known as Q-tube®. Based on the results, the Q-tube® was very efficient for the pretreatment of our lignocellulosic materials in comparison with the conventional equipment (round bottom flask). Pretreatments were completed in one hour with high yield of reducing and total sugars after enzymatic hydrolysis. Some protic and Bronsted acidic ionic liquids can depolymerize partially the cellulosic material in one step and after enzymatic hydrolysis the content of reducing sugars is up to 35 times higher in comparison with the material without pretreatment.

Dynamics in Carbohydrate Active Enzymes and Microbial Communities during Ensilage of Food Processing Residues

Abstract. Lignocellulosic food processing residues are suitable feedstocks for bioenergy generation, however, seasonal production of these materials requires storage, and their cell wall pectin and hemicellulose must be disrupted to improve enzymatic hydrolysis of cellulose. The objectives of this study were to examine ensilage as a method to facilitate preservation and pretreatment and to determine if these processes are influenced by the secretion of carbohydrate-active enzymes. Production of xylanase (Xase), endo-β-1,4-glucanase (EGase), and polygalacturonase (PGase) was monitored during ensilage of tomato pomace (TP) and sugar beet pulp (SBP). During two months of ensilage of TP, secreted Xase and EGase activities increased gradually with peak activities occurring at day 30. For SBP, Xase and EGase activities were detected only at day 14. Higher sugar yields were observed for ensiled feedstocks upon post-storage enzymatic saccharification, indicating ensilage had a pretreatment effect on these feedstocks. Lactic acid bacteria (LAB) were the dominant organisms in the ensilage community. , , and were detected at relatively high levels in SBP; while was the prominent LAB species in TP. Ensilage had a positive effect on the post-storage enzymatic treatment of SBP and TP. This may have been due to bacterial production of carbohydrate-active enzymes during ensilage. Incorporating ensilage as part of a bioconversion process will likely reduce necessary pretreatment severity and inputs for enzymatic hydrolysis.

Hydrothermal pre-treatment of oil palm empty fruit bunch into fermentable sugars

Presently oil palm empty fruit bunch (OPEFB) is one of the solid waste which is produced daily whereby it is usually left at plantation site to act as organic fertilizer for the plants to ensure the sustainability of fresh fruit bunch. The major drawback in biomass conversion technology is the difficulty of degrading the material in a short period of time. A pre-treatment step is required to break the lignocellulosic biomass to easily accessible carbon sources for further use in the production of fuels and fine chemicals. Therefore, this study investigated the effect of hydrothermal pre-treatment under different reaction temperatures (100 - 250°C), reaction time (10 - 40 min), solid to solvent ratio of (1:10 - 1:20 w/v) and particle size (0.15 - 1.00 mm) on the solubilization of OPEFB to produce soluble fermentable sugars. The maximum soluble sugars of 68.18 mg glucose per gram of OPEFB were achieved at 175°C of reaction temperature, 20 min of reaction time, 1:15 w/v of solid to solvent ratio for 30 mm of particle size. Results suggest that reaction temperature, reaction time, the amount of solid to solvent ratio and size of the particle are crucial parameters for hydrothermal pretreatment, in achieving a high yield of soluble fermentable sugars.

Genetic determination of high productivity in experimental hybrid combinations of sugar beet (Beta vulgaris L.)

Purpose. Creation of experimental sugar beet hybrid combinations of high sugar yield values and defining gene­tic determination of their heterotic effect. Methods. Diallel crossing and topcrossing, genetic analysis of quantitative traits. Results. The authors have studied the frequency of occurrence of sugar beet heterotic hybrid combinations for «sugar yield» trait created on the basis of two pollinator lines to be genetically valuable for productivity elements, CMS lines and single-cross sterile hybrids with the use of diallel and topcrossing system of controlled hybridization. The share of parental components’ effect and their interaction in CMS hybrids variability for productivity was determined. Expediency of heterotic forecasting based on high combining ability lines was substabtiated. Promising high-yielding sugar beet combinations were selected that exceeded the group standard by 4.1–16.3%. Conclusions. The theory of genetic balance by M. V. Turbin was confirmed. Such hybrids as [CMS 5  OT 4]  MGP 1 (116.3%), [CMS 1  OT 2]  MGP 1 (112.5%) and [CMS 3  OT 5]  MGP 1 (113.2%) were recognized as the best for their productivity, MGP 1 and MGP 2 lines – as the best for their combining ability.

Enhancing enzymatic hydrolysis and biogas production from rice straw by pretreatment with organic acids

Lignocellulosic biomass is recalcitrant to enzymatic and microbial degradation due to its chemical compositions and physical structures that inhibit the hydrolysis reactions. To obtain a high sugar yield for biofuel production, pretreatment process is generally needed to improve efficiency of hydrolysis. Here, organic acids were used to pretreat rice straw. Using Response Surface Methodology (RSM), the effect of three pretreatment parameters, including acid concentration, treatment time, and reaction temperature, on pretreatment efficiency were evaluated and used to generate mathematic optimization model. The hydrolysis results indicated that oxalic acid pretreatment led to the highest enhancement of enzymatic saccharification up to 213.4mg (starting from 500mg of pretreated sample) when using 5.01% oxalic acid concentration at 135.91°C for 30.86min, which was 2.68 times higher than the untreated rice straw. The structural changes in the pretreated biomass were investigated using FT-IR analysis. The results suggested that lignin composition was significantly removed from the pretreated biomass, and the crystalline cellulose was also modified to amorphous form during pretreatment. Both untreated and pretreated rice straw were subjected to anaerobic digestion to evaluate the influence of organic acid pretreatment on biogas production. The highest biogas yield was 322.1ml/g-rice straw when using citric acid pretreatment which was 7.40 times higher than untreated biomass. These results demonstrated that organic acids can be used for pretreatment of lignocellulosic materials to enhance hydrolysis and biogas production.

Careful selection of steaming and attrition conditions during thermo‐mechanical pretreatment can increase enzymatic conversion of softwood

AbstractBackgroundAn efficient pretreatment for softwoods prior to enzyme hydrolysis is pressurised steaming of the chips with successive attrition by disc refining and ball milling following removal of some hemicelluloses in a compression screw. For the process to be economical, thermal and mechanical energy inputs need to minimised and sugar yield maximised, so the aim of this study was to improve understanding of the behaviour of fibres during each stage of the pretreatment.ResultsRadiata pine wood chips were treated with steam at 173°C for between 3 and 144 min. The responses to refining and ball milling in terms of particle size reduction and sugar yield improved gradually as steaming time was increased to 36 min, but then an abrupt change in behaviour occurred resulting in more small particles during refining and much faster response to ball milling. This point coincides with an increase in cellulose degradation and fibre embrittlement. However, this higher steaming severity did not necessarily give highest sugar yields during saccharification as it limits the amount of energy that can be usefully applied during ball milling.ConclusionsThe results from this study can be utilised for optimisation of the pretreatment of softwoods like radiata pine. While effective in delivering high sugar yields, the steaming/refining/ball milling pretreatment is quite energy intensive but the results of this study show that significant savings in overall energy are possible by optimising relative energy inputs to the steaming and ball milling stages. © 2016 Society of Chemical Industry

VSI 434: New Sugarcane Variety Obtained Through Somaclonal Variation

VSI 434 is a somaclonal variant of sugarcane var. CoC 671 with high cane and sugar yield, high sucrose content and moderately resistant to smut, grassy shoot and red rot diseases. VSI 434 recorded 14.5 to 30.7 % higher cane yield and 22.9 to 30.1% higher commercial cane sugar over the donor and standard CoC 671 in different station and multilocation trials. This is the second sugarcane cultivar released in India through the use of somaclonal variation after var. Co 94012. A morphological variation was observed in number of traits for VSI 434 through somaclonal variation along with improvement in sucrose percent and moderately red rot resistant as compared to parent var. CoC 671. This variation was possibly due to complex genetic nature and existence of chromosomal mosaicism. Morphologically, these two varieties are distinct and also differentiated by using different molecular marker techniques. The study demonstrates that somaclonal variation can be utilized for improvement of sugarcane varieties.

Improved Ethanol Production Based on High Solids Fed-Batch Simultaneous Saccharification and Fermentation with Alkali-Pretreated Sugarcane Bagasse

Alkali-pretreated sugarcane bagasse fiber was subjected to fed-batch simultaneous saccharification and fermentation (SSF) with a pre-hydrolysis process to increase the solids loading and produce a high concentration of ethanol. The hydrolysis medium and yeast feeding modes were investigated to determine suitable conditions for high sugar yield and ethanol production. Batch addition resulted in a cumulative substrate concentration of up to 36% (w/v) and enhanced ethanol concentrations, while ethanol conversion efficiency gradually declined. Enzymatic pre-hydrolysis and fermentation with fed-batch mode contributed to the SSF process. The highest ethanol concentration was 66.915 g/L with the conversion efficiency of 72.89%, which was achieved at 30% (w/v) solids content after 96 h of fermentation. Hydrolyzed medium and yeast were added in batch mode at 24 h of enzymatic hydrolysis and fermentation, respectively. Thus, combining the fed-batch mode with pre-hydrolysis SSF produced a high yield of ethanol.

Evaluating the Effects of Chemical Ripening with Fluazifop-p-butyl on Sugarcane (Saccharum officinarum) Yield and Sugar Content

Ripening in sugarcane refers to an increase in sugar content on a fresh weight basis prior to commercial harvesting. Ripening is often prompted by use of chemicals and environmental cues such as moisture stress. The aim of this research was to determine the effects of Fluazifop- pbutyl, a chemical ripener on sugarcane yield and sugar content. The experiment was laid out as a Random Complete Block Design (RCBD) with five replications. Treatments were: Fluazifop- p- butyl (0.45 lha-1), drying off, Fluazifop- p- butyl (0.45 lha-1) + drying off and the control (no Dry off, no Fluazifop- p- butyl). The experiment was carried out at Triangle Estate which is located in the South East Lowveld of Zimbabwe from March 2012 to May 2012. Data on sugarcane yield, sugar quality (Pol % and ERC %) and sugar yield was collected 56 days after establishment of the experiment. Analysis of variance was done on yield and quality data using Genstat 14th edition. Results showed that there were significant differences (P = 0.05) among treatments on sugarcane yield, sugar yield, Pol% and ERC%. The sugarcane yield was highest for the control where no ripener was used. Fluazifop- p- butyl treatment attained 13.9% lower sugarcane yield relative to the control. Application of Fluazifop- p- butyl resulted in the highest sugar yield which was 35.6% higher than that of the control where no ripener was used. A combination of Fluazifop- p- butyl and Dry of resulted in the highest Pol % and highest ERC %. It can be concluded that Fluazifop- p- butyl is effective in increasing sugar yield although it results in a reduction in sugarcane yield. Combining Fluazifop- p- butyl with Dry off results in increased Pol% and ERC%. There is need for further studies to determine the optimum period from spraying Fluazifop- p-butyl to harvesting of sugarcane as this was only done at the end of the drying-off period.

Pretreatment of Oil Palm Empty Fruit Fiber (OPEFB) with Aquaeous Ammonia for High Production of Sugar

Corncob Oil Palm Empty Fruit Bunch (OPEFB) is an agricultural residue that has the potential to become a good source for renewable feedstock for production of sugar. This work evaluated the effectiveness of aqueous ammonia as pretreatment at low (soaking, SAA) and elevated temperature (Pressurized Chamber) to deconstruct the lignocellulosic feedstock, prior to enzymatic hydrolysis. The ammonia pretreatments were compared against the standard NaOH method. The best tested Pressurized Chamber method conditions were at 100°C with 3 hour retention time, 12.5% Ammonium hydroxide and 1:30 solid loading. The digestibility of the feedstock is determined with enzymatic hydrolysis using Cellic Ctech2 and Cellic Htech2. The sugars produced by Pressurized Chamber method within 24 hour of enzyme hydrolysis are similar to that produced by NaOH method which is 439.90mg/ml and 351.61mg/ml, respectively. Compared with optimum SAA method (24 hour, 6.25% of ammonium hydroxide at room temperature), Pressurized Chamber method was capable of producing enhanced delignification and higher production of sugar upon hydrolysis. These findings were supported by the disappearance peak at 1732, 1512 and 1243 on Fourier Transform Infrared (FTIR spectrum) of treated OPEFB by Pressurized Chamber method. XRD determination showed reduced crystallinity of OPEFB (37.23%) after treatment by Pressurized Chamber, suggesting higher accessibility toward enzyme hydrolysis. The data obtained suggest that the Pressurized Chamber pre-treatment method are suitable for OPEFB deconstruction to produce high yield of sugar.

Best suited fertigation schedule and its effect on growth, yield, quality and uptake of nutrients of sugarcane (Saccharum officinarum L.) under Sustainable Sugarcane Initiative method

A field experiment was conducted at experimental farm, Sugarcane Research Station, Cuddalore, Tamil Nadu during 2013 to 2014 in sugarcane cv. CoC (SC) 24 plant crop to standardize the fertilizer schedule with 100, 125 and 150% of the recommended NPK through surface and sub-surface drip fertigation on growth characters, yield and yield attributing characters, plant nutrient content and uptake pattern of nutrients by sugarcane under Sustainable Sugarcane Initiative (SSI) method. The results of the experiment revealed that sub-surface drip irrigation system increased the cane yield and uptake of nutrients than surface drip irrigation method. Maximum tiller population of 176520/ha was recorded with sub-surface drip irrigation with 150% recommended dose of fertilizers followed by sub-surface fertigation with 125% recommended dose of fertilizers (163320/ha). Application of 150% recommended levels of NPK produced maximum cane yield (132.69 t/ha) followed by 125% recommended NPK (129.69 t/ha) and on a par with each other. Irrigation and fertilizer did not significantly influence the CCS content. Fertigation of 125% recommended dose of NPK recorded higher sugar yield of 16.62 t/ha. The higher benefit: cost ratio of 3.01 per rupee invested was observed in treatment received 125% recommended NPK under sub-surface drip fertigation system. The highest NPK uptake of 193.92, 91.57 and 375.89 kg/ha was noticed by the 150% recommended NPK. The 125% recommended NPK @ 375: 125: 250 kg/ha was the suitable type and level of fertilizer for obtaining high yield and quality of sugarcane under SSI system of sugarcane planting. SSI is the first step towards standardization of sugarcane cultivation focusing on improving productivity while reducing the agriculture foot print on planet earth.

Molecular characterization of glycosyl hydrolases of Trichoderma harzianum WF5 – A potential strain isolated from decaying wood and their application in bioconversion of poplar wood to ethanol under separate hydrolysis and fermentation

Populous deltoides wood is a suitable raw material for ethanol production, since it has high cellulose content. Efficient degradation and subsequent conversion of lignocellulosic biomass to bio-ethanol, requires physico-chemical pretreatments followed by enzymatic hydrolysis to obtain high overall yields of sugars. Microbial hydrolytic enzymes are actively utilized for biomass degradation and bio-ethanol production. Four glycosyl hydrolases (GHs) namely; three subunits of cellulase, endoglucanase (ThWF5-endoglucanase), exoglucanase (ThWF5-exoglucanase) and β-glucosidase (ThWF5-glucosidase), and xylanase (ThWF5-xylanase), from fungal strain Trichoderma harzianum WF5 - isolated from decayed wood, were pulled out and subsequently characterized. Analysis of full length sequences and prediction of secondary and tertiary structure showed that these enzymes shared homology with the respective enzymes of other Trichoderma species and have comparatively evolved structure to express catalytic activity under broad range of environmental conditions. Respective GHs were partially purified and used for the enzymatic hydrolysis of P. deltoids wood after pretreatments. The pretreatment of P. deltoides wood with sulfuric acid and hydrogen peroxide (H2SO4 + H2O2) at 121 °C for 60 min was determined as the best condition to high recovery of reducing sugars after enzymatic hydrolysis. The overall high ethanol yield of 15.6 g/l and fermentation efficiency of 61.1% was obtained when fermentation was performed on pretreated poplar wood slurry followed by detoxification with calcium hydroxide. High bio-ethanol production from P. deltoides wood and molecular characterization of glycosyl hydrolases used, provide insights that this wood offers a potential source for biofuel production while T. harzianum WF5 is a treasure house of robust degrading enzymes.

Levulinic Acid as a Catalyst for the Production of 5‐Hydroxymethylfurfural and Furfural from Lignocellulose Biomass

AbstractLevulinic acid (LA) was used as a catalyst for the first time to produce 5‐hydroxymethylfurfural (5‐HMF) and furfural (FAL) from pinewood and eucalyptus sawdust in a mono‐ or biphasic solvent system. 2‐Methyltetrahydrofuran was used as a co‐solvent with water in different ratios and temperatures (140–200 °C). Highest yields of 5‐HMF and FAL were obtained at 180 °C and 2 h reaction time; however, at 160 °C, high yields of C6 and C5 sugars were obtained. Both hydrolysis and dehydration steps were accelerated in the MTHF/water biphasic system compared to pure aqueous phase. In particular, 1:2 w/w ratio of MTHF/water resulted in the highest yield of 5‐HMF and FAL, whereas 2:1 w/w ratio showed highest yield of C6 and C5 sugars. Increasing the ratio of MTHF/water resulted in a higher fraction of dehydrated products extracted into the organic phase. LA as a catalyst is beneficial because it is miscible in both the phases and the presence of LA favours the equilibrium towards 5‐HMF production.

Synergistic effects of mixing hybrid poplar and wheat straw biomass for bioconversion processes.

BackgroundLow cost of raw materials and good process yields are necessary for future lignocellulosic biomass biorefineries to be sustainable and profitable. A low cost feedstock will be diverse, changing as a function of seasonality and price and will most likely be available from multiple sources to the biorefinery. The efficacy of the bioconversion process using mixed biomass, however, has not been thoroughly investigated. Considering the seasonal availability of wheat straw and the year round availability of hybrid poplar in the Pacific Northwest, this study aims to determine the impact of mixing wheat straw and hybrid poplar biomass on the overall sugar production via steam pretreatment and enzymatic saccharification.ResultsSteam pretreatment proved to be effective for processing different mixtures of hybrid poplar and wheat straw. Following SO2-catalyzed steam explosion pretreatment, on average 22 % more sugar monomers were recovered using mixed feedstock than either single biomass. Improved sugar recovery with mixtures of poplar and wheat straw continued through enzymatic hydrolysis. After steam pretreatment and saccharification, the mixtures showed 20 % higher sugar yields than that produced from hybrid poplar and wheat straw alone.ConclusionsBlending hybrid poplar and wheat straw resulted in more monomeric sugar recovery and less sugar degradation. This synergistic effect is attributable to interaction of hybrid poplar’s high acetic acid content and the presence of ash supplied by wheat straw. As a consequence on average 20 % more sugar was yielded by using the different biomass mixtures. Combining hybrid poplar and wheat straw enables sourcing of the lowest cost biomass, reduces seasonal dependency, and results in increasing biofuels and chemicals productivity in a cellulosic biorefinery.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0414-9) contains supplementary material, which is available to authorized users.

Evaluation of lime and hydrothermal pretreatments for efficient enzymatic hydrolysis of raw sugarcane bagasse.

BackgroundEthanol production from sugarcane bagasse requires a pretreatment step to disrupt the cellulose-hemicellulose-lignin complex and to increase biomass digestibility, thus allowing the obtaining of high yields of fermentable sugars for the subsequent fermentation. Hydrothermal and lime pretreatments have emerged as effective methods in preparing the lignocellulosic biomass for bioconversion. These pretreatments are advantageous because they can be performed under mild temperature and pressure conditions, resulting in less sugar degradation compared with other pretreatments, and also are cost-effective and environmentally sustainable. In this study, we evaluated the effect of these pretreatments on the efficiency of enzymatic hydrolysis of raw sugarcane bagasse obtained directly from mill without prior screening. In addition, we evaluated the structure and composition modifications of this bagasse after lime and hydrothermal pretreatments.ResultsThe highest cellulose hydrolysis rate (70 % digestion) was obtained for raw sugarcane bagasse pretreated with lime [0.1 g Ca(OH)2/g raw] for 60 min at 120 °C compared with hydrothermally pretreated bagasse (21 % digestion) under the same time and temperature conditions. Chemical composition analyses showed that the lime pretreatment of bagasse promoted high solubilization of lignin (30 %) and hemicellulose (5 %) accompanied by a cellulose accumulation (11 %). Analysis of pretreated bagasse structure revealed that lime pretreatment caused considerable damage to the bagasse fibers, including rupture of the cell wall, exposing the cellulose-rich areas to enzymatic action.ConclusionWe showed that lime pretreatment is effective in improving enzymatic digestibility of raw sugarcane bagasse, even at low lime loading and over a short pretreatment period. It was also demonstrated that this pretreatment caused alterations in the structure and composition of raw bagasse, which had a pronounced effect on the enzymes accessibility to the substrate, resulting in an increase of cellulose hydrolysis rate. These results indicate that the use of raw sugarcane bagasse (without prior screening) pretreated with lime (cheaper and environmentally friendly reagent) may represent a cost reduction in the cellulosic ethanol production.

English

Sugarcane (Saccharum officinarum L.) is one of the most important crops in Kenya and has wide range of economic importance. The sugar industry contributes up to 15% to the country’s agricultural gross domestic product and an estimated 25% of the population depends on the industry for their livelihood. However, the industry has been facing several challenges including declining yields due to use of poor quality planting materials. There is an increasing pressure to enhance the productivity of sugarcane in order to sustain profitable sugar industries in Kenya, while there are several diseases attacking sugarcane and reducing its quality. Seed multiplication of newly released varieties of sugarcane is one of the major constraints in Kenya as it takes 6-7 years to produce sufficient quantity of improved seed material. In vitro culture offers a practical and fast method for mass propagation of disease-free clonal materials. Successful protocols for shoot tip culture, callus culture, embryo culture, virus free plant production and somatic embryogenesis have already been established. Thus, in vitro technology can be used to enhance productivity of sugarcane in Kenya. Despite several advantages of applying micro-propagation technique in sugarcane such as quick multiplication of newly released varieties, rejuvenation of old deteriorated varieties; production of disease free seed; easy transportation of seed material; elimination of viruses; high cane productivity and sugar yield etc., this technique is not gaining popularity up to the desired extent. There are several constraints like the high cost of production and appearance of some variants in micropropagated population among others. The present article describes the status, challenges and opportunities of in vitro technology for the sugar industry in Kenya. Though, some problems have now been resolved to considerable extents which have been described in this review however, some constraints still require intensive research work to be resolved so that a safe and efficient exploitation of this technique can be ensured in sugarcane seed production programmes for enhanced yields and quality. Key words: Sugarcane, somaclonal variation, in vitro culture, meristems, micro-propagation, callus.

Life cycle assessment of lignocellulosic biomass pretreatment methods in biofuel production

Purpose In converting lignocellulosic biomass into biofuel, a pretreatment stage is required in order to make the biomass more readily available for the transformation. There are numerous pretreatment techniques that can be chosen, which are broken down into four categories: chemical, physical, physicochemical, and biological. The aim of this work is to provide a new assessment for some of the emerging technologies using life cycle assessment (LCA) combined with an analysis of the overall product yield. Methods Using literature data, an LCA of four different pretreatment methods was carried out. Liquid hot water (LHW), steam explosion (SE), dilute acid (DA), and organosolv (OS) were chosen as the most common techniques with high scalability potential. Models were constructed using GaBi software. A cradle-to-gate analysis was selected with a common model of the corn stover growth and harvesting cycle being combined with the individual models for each pretreatment. Four impact categories were analyzed, and a selection has been discussed based on relevance to the biofuel production process. Results and discussion In nearly all of the impact categories, DA performs the worst due to the length of the process (12 h) and the amount of electricity required to elevate the temperature to 60 °C for that time period. In many of the other categories, the remaining three pretreatments perform comparably to each other with the exception of LHW which has significantly reduced CO2 emissions. LHW has slightly higher water depletion rates than both SE and OS, which is to be expected given the nature of the process. In terms of product yield, LHW produced twice as much total sugar than any of the other processes. Conclusions The project concluded that while LHW and SE are viable options for the pretreatment of biomass,LHWis the most suitable technique for the pretreatment of corn stover. Thispretreatmentwas environmentally friendly as it produced the lowest CO2 emissions, aligning with the main objective behind developing biofuels from agricultural residues. The process was also technically the most effective as it resulted in the highest sugar yields.

An integrated system for fractionation and hydrolysis of sugarcane bagasse using heterogeneous catalysts in aqueous biphasic system

Sugarcane bagasse fractionation and hydrolysis using heterogeneous catalysts in aqueous biphasic system was investigated. Carbon-based, polymer-based and metal-based catalysts were synthesized and tested for hydrolysis of sugarcane bagasse in a combination of solvent-based and polymer-based aqueous biphasic system at different polarities for sugar production. The results showed that acid density, functional groups and physical properties of catalysts influenced the catalytic activity on cellulose hydrolysis. From solvent screening study, nitrobenzene was the most promising solvent enhancing relatively high total reducing sugar (TRS) yield of 97.4% when hydrolysis took place at 140°C for 4h in the presence of carbon-based catalyst type 1(C-SO3H). Nevertheless in terms of recyclability, magnetic metal-based catalyst (SO42−/TiO2/Fe3O4) that yielded considerably high amount of glucose at elevated temperature and shorter time (180°C 1h) was suitable catalyst as it was easily separated from the solution. Kinetic study of cellulose hydrolysis reaction was performed, in which rate constant and activation energy of reaction catalyzed by active catalysts were compared. The results suggested an effective integrated system for cellulose fractionation and hydrolysis in which lignin-rich fraction was in solvent and polymer phases while cellulose fibers were remained in the aqueous phase and further hydrolyzed by heterogeneous catalyst.

English

Microbial inhibitors including weak acids, furan derivatives and phenolic compounds are key problems of cellulosic bio-fuels production by fermentation. Most of these inhibitors are sugars and lignin degradation compounds, which are almost unavoidable during pretreatment processes. While, most of the one stage pretreatment has been conducted at high severity factors of 3.5 or more to get high sugar yield, with increase in severity factor, high concentration of microbial inhibitors were formed and significantly affected downstream biofuel yield. Thus, a two-stage pretreatment of corn stalk, hydrothermal followed by oxalic acid, under low severity factor and its enzymatic degradability was investigated in this study to identify fermentable sugar production and corresponding microbial inhibitors formation. Additionally, effect of equivalent severity factors of 2 to 3.5 and particle sizes of 1 to 35 mm were also studied systematically. Particle size of 15 mm was found as an optimum size at an equivalent severity factor of 2.5. Sugars 61.99 ± 0.03 g and inhibitors 5.12 ± 0.01 g from 100 g of corn stalk were obtained at the optimum particle size and pretreatment condition. The highest glucan conversion and recovery at the optimum conditions were 92.95± 0.08 and 78.42± 0.07%, respectively. Overall, the two-stage pretreatment process with the larger particle size and low equivalent severity factor could be an alternative to reduce microbial inhibitors formation and excessive biomass processing cost. Key words: Bio-fuel, corn stalk, pretreatment, particle size, microbial inhibitors, fermentable sugars.

Organosolv Pretreatment of Slurry Composting and Biofiltration of Liquid Fertilizer-Treated Yellow Poplar for Sugar Production

ABSTRACT The present study examines the influence of slurry composting and biofiltration liquid fertilizer (SCBLF) treatment on the biomass characteristics of yellow poplar, and the optimization of organosolv pretreatment for sugar production. After SCBLF treatment, total exchangeable cation contents of yellow poplar was increased from 3.1 g kg -1 to 4.4 g kg -1 , and as a result, biomass production of yellow poplar was also enhanced by 82.3%. Organosolv pretreatment was conducted with three independent variables: 1) reaction temperature: 133.2℃ to 166.8℃; 2) acid concentration: 0.2% to 1.8%; and 3) reaction time: 1.6 min to 18.4 min. Reaction temperature was the most significant variable in water insoluble solid (WIS) recovery rate. High overall sugar yield was attained from pretreatment conditions approximately 50% of WIS recovery rate, and the highest overall glucose yield (44.0%) was achieved from pretreatment at 140℃ with 1.5% acid concentration for 5 min. Consequently, 21.1% of glucose and 5.8% of xylose were produced from the organosolv pretreatment of SCBLF-treated 8-year-old yellow poplar.Keywords : slurry composting and biofiltration, yellow poplar, organosolv retreatment, biomass production, sugar production