New Method for Carbohydrates Determination in Sugarcane Bagasse by HPAEC‐RPAD Using Glassy Carbon Electrode Modified with Carbon Nanotubes and Nickel Nanoparticles

Second generation ethanol can be produced from carbohydrates released from both sugarcane bagasse cell wall and sugarcane straw. The development of new method for the analysis of carbohydrates is, in this sense, seen as extremely relevant in the area of bioenergy. Based on the above considerations, the scope of this work encompasses the identification and quantification of carbohydrates composition in sugarcane bagasse without the need of sample derivatization, developing a novel analytical method using a glassy carbon electrode modified with multi‐walled carbon nanotubes containing nickel oxyhydroxide nanoparticles (GCE/MWCNT/NiOOH) and applying the modified electrode as a detector in HPAEC (High Performance Anion‐Exchange Chromatography) with reverse pulsed amperometric detection (RPAD) towards the determination of arabinose, galactose, glucose and xylose in hydrolyzed sugarcane bagasse. The carbohydrates concentrations determined in the hydrolyzed sugarcane bagasse were 6.1×10⁻⁴ mol L⁻¹, 1.0×10⁻² mol L⁻¹ and 2.8×10⁻³ mol L⁻¹ for arabinose, glucose, and xylose respectively. Our results showed that the present method is, in essence, attractive for analysis in the course of the production process of second generation ethanol production in that it does not require sample derivatization, has rapid run time, satisfactory separation, and can be used for the detection of carbohydrates without the interference of other electroactive species.     

Sugarcane Bagasse Mild Alkaline/Oxidative Pretreatment for Ethanol Production by Alkaline Recycle Process

In order to decrease the alkali and water consumptions in the sugarcane bagasse alkaline/oxidative pretreatment for ethanol production, an alkaline recycle process was carried out. Two recycles of NaOH/H₂O₂ pretreatment did not decrease the pretreatment and enzymatic hydrolysis efficiencies and the consumptions of NaOH and water would be saved by 26% and 40%, respectively. A simultaneous saccharification and fermentation (SSF) culture with pretreated bagasse as substrate was developed giving 25 g ethanol l⁻¹ with a yield of 0.2 g g⁻¹ bagasse and productivity of 0.52 g l⁻¹ h⁻¹.     

Characterization of Cellulolytic Extract from <Emphasis Type="Italic">Pycnoporus sanguineus</Emphasis> PF-2 and Its Application in Biomass Saccharification

The aim of this work was to evaluate the biochemical features of the white-rot fungi Pycnoporus sanguineus cellulolytic complex and its utilization to sugarcane bagasse hydrolysis. When cultivated under submerged fermentation using corn cobs as carbon source, P. sanguineus produced high FPase, endoglucanase, β-glucosidase, xylanase, mannanase, α-galactosidase, α-arabinofuranosidase, and polygalacturonase activities. Cellulase activities were characterized in relation to pH and temperature. β-Glucosidase and FPase activities were higher at 55 °C, pH 4.5, and endoglucanase activity was higher at 60 °C, in a pH range of 3.5–4.0. All cellulase activities were highly stable at 40 and 50 °C through 48 h of pre-incubation. Crude enzymatic extract from P. sanguineus was applied in a saccharification experiment using acid-treated and alkali-treated sugarcane bagasse as substrate, and the hydrolysis yields were compared to that obtained by a commercial cellulase preparation. Reducing sugar yields of 60.4% and 64.0% were reached when alkali-treated bagasse was hydrolyzed by P. sanguineus extract and commercial cellulase, respectively. Considering the glucose production, it was observed that P. sanguineus extract and commercial cellulase ensured yields of 22.6% and 36.5%, respectively. The saccharification of acid-treated bagasse was lower than that of alkali-treated bagasse regardless of the cellulolytic extract. The present work showed that P. sanguineus has a great potential as an enzyme producer for biomass saccharification.     

Production and Characterization of Violacein by Locally Isolated Chromobacterium violaceum Grown in Agricultural Wastes

The present work highlighted the production of violacein by the locally isolated Chromobacterium violaceum (GenBank accession no. HM132057) in various agricultural waste materials (sugarcane bagasse, solid pineapple waste, molasses, brown sugar), as an alternative to the conventional rich medium. The highest yield for pigment production (0.82?g?L^?1) was obtained using free cells when grown in 3?g of sugarcane bagasse supplemented with 10% (v/v) of l-tryptophan. A much lower yield (0.15?g?L^?1) was obtained when the cells were grown either in rich medium (nutrient broth) or immobilized onto sugarcane bagasse. Violacein showed similar chemical properties as other natural pigments based on the UV?CVis, Fourier transform infrared spectroscopy, thin-layer chromatography, nuclear magnetic resonance, and mass spectrometry analysis. The pigment is highly soluble in acetone and methanol, insoluble in water or non-polar organic solvents, and showed good stability between pH?5?C9, 25?C100?°C, in the presence of light metal ions and oxidant such as H₂O₂. However, violacein would be slowly degraded upon exposure to light. This is the first report on the use of cheap and easily available agricultural wastes as growth medium for violacein-producing C. violaceum.     

Evaluation of the Sorptive Capacity of Sugarcane Bagasse and Its Coal for Heavy Metals in Solution

Recycling of sugarcane bagasse and its coal as metal sorbents to capture metal ions from wastewater is the aim of this study. Thus, stability of sugarcane bagasse and its coal, in addition to the solubilities of metal ions in synthetic solution, were determined in this study at different pH values. Also, sorption of Fe, Mn, Cd, and Pb ions with different concentrations (10‐100 mg L^?1) on different grain size fractions of sugarcane bagasse (< 150 > μm) and its coal (< 80 > μm) was carried out under different pH values (2, 4 and 6), dosage (2, 6, and 10 g L^?1), time intervals (15‐300 min.) and temperature (20‐50 °C). The results indicated that the sugarcane bagasse and its coal were more stable at pH 6, and the solubilities of metal ions in the synthetic solution exhibited high values at pH 2 more than pH 4 and 6, respectively. Generally, removal of metal ions using the sorbents increased with the decreasing of grain size fractions and with increasing of pH values (6 > 4 > 2), sorbent doses (10 > 6 > 2 g L^?1) and initial concentrations of metal ions (10‐100 mg L^?1). Coal of sugarcane bagasse was more effective than the sugarcane bagasse for removal of the metal ions from solution. Positive values of ΔH° suggest the endothermic nature of sorption in all cases. The negative Gibb's free energy values indicate the feasibility of the process and spontaneous nature of sorption (Fe‐bagasse coal system), while the positive value of ΔG° suggests the non‐spontaneous character of adsorption of all metals. The negative values of entropy change ΔS° (Pb‐bagasse system) indicate the highly ordered adsorption process in this case, while the positive values of ΔS° show the increased randomness at solid/solution interface during the sorption metal ion on bagasse. The results of activation energy values indicate the order of sorption feasibility is: Pb > Fe > Cd > Mn in the case of bagasse and Fe > Pb > Cd > Mn in the case of coal. Generally, the results of this study suggest that the sugarcane bagasse and its coal might provide an economical method for the removal of metal ions from wastewater.     

Aspergillus fumigatus Thermophilic and Acidophilic Endoglucanases

This study evaluated the production of cellulolytic enzymes by an Aspergillus fumigatus strain, isolated from sugar cane bagasse, according to its ability to grow on microcrystalline cellulose as the sole carbon source. The effect of the carbon source (brewer’s spent grain, sugarcane bagasse, and wheat bran) and of the nitrogen source (corn steep liquor and sodium nitrate) on cellulase production was studied using submerged and solid state cultivations at 30 °C. The highest levels of endoglucanase (CMCase) corresponded to 365 U L^-1 and was obtained using sugarcane bagasse (1%) and corn steep liquor (1.2%) in submerged fermentation within 6 days of cultivation. This supernatant was used to run a sodium dodecyl sulfate polyacrylamide gel electrophoresis that showed six bands with endoglucanase activity. CMCase activity was higher at 65 °C and pH 2.0, indicating that this microorganism produces a thermophilic and acid endoglucanase. Solid state cultivation favored FPase production, that reached 47 U g^-1 of dry substrate (wheat bran and sugarcane bagasse) within 3 days.     

Analysis of the role of various biochar in the remediation of heavy metals in contaminated water and its kinetics study

Biochar prepared from agricultural wastes has gained great attention as a cost-effective treatment for metal-contaminated water. In this study, the effectiveness of corn cob and sugarcane bagasse-derived biochar for metals (Pb, Ni, and Cu) removal from an aqueous medium was examined following their physical, chemical, and structural characterization. Batch sorption experiments were carried out by employing the Langmuir and Freundlich equations. The results indicated that separation factor (R_L) values lay in the range of 0 and 1 representing the productive adsorption. The optimum dosage for metal adsorption can be recommended as 30 g L^?1. The optimum adsorption conditions were found at 6.5 and 5.5 pH, 1.5 g adsorbent dose, and at 180 min equilibrium time, for both corn cob and sugarcane bagasse biochars. At pH 6.5, adsorption capacities of Pb, Ni, and Cu were found maximum i.e., 11.34, 15.71, and 11.96 mg kg^?1 for corn cob and 8.96, 15.46, and 12 mg kg^?1, for sugarcane bagasse biochars, respectively. The metal adsorption kinetics was analyzed via four different types of the pseudo-second-order kinetic model. Moreover, the corn cob biochar showed a more pronounced activity in the removal of metals compared to sugarcane bagasse biochar. Hence, it was concluded that corncob and sugarcane bagasse-derived biochars could be utilized as economical bio-adsorbents for the heavy metals removal from wastewater.     

Synthesis of Quinoline/Phenanthroline Impregnated Sugarcane Bagasse for Recovering Uranium(VI) and Thorium(IV) from their Solutions

This present research aims to synthesize and investigate the adsorption potential of sugarcane bagasse (SCB) impregnated with 8 hydroxy quinolone 8-(HQ) and 1,10 phenethroline (phen) to prepare impregnated sugarcane bagasse (ISCB) for removal U^VI and Th^IV. The effects of the operating parameters, including pH of the solution, contact time, initial concentration, temperature, dose and interfering ions on the adsorption efficiency were investigated to identify an optimal condition. The characterization of SEM-EDX and FTIR analyses shows that ISCB has a porous structure and carbon-containing functional groups. The adsorption result revealed that ISCB removed 98 % for both U^VI and Th^IV. The result obtained fitted well for Langmuir isotherms model with 185.19 mg · g^–1 and 250 mg · g^–1 as theoretical capacity for U^VI and Th^IV respectively. The adsorption process followed the pseudo-second-order kinetic model. In conclusion, this study proved that ISCB has the potential to be used as an effective and low-cost adsorbent to remove U^VI and Th^IV. Finally we obtain products from thorium as ThO₂ and uranium as Na₂U₂O₇ from Abu Rushied leach liquor.     

Atmospheric Pressure Plasma Pretreatment of Sugarcane Bagasse: the Influence of Biomass Particle Size in the Ozonation Process

Atmospheric pressure O₂ plasma was used to produce ozone in order to treat sugarcane bagasse as a function of particle sizes. The fixed bagasse moisture content was 50 %. The delignification efficiency had small improvement due to ozonation process as a function of particle size, varying from 75 up to 80 %. Few amounts of hemicellulose were removed, but the ozonation has not been affected significantly with particle size variance as well (from 30 up to 35 %). The cellulose presented some losses below 1.0 mm size (8–15 %) which was an unexpected result. The conversion of cellulose content into free sugar has shown a significant increase as the particle size has diminished as well. The best condition of the bagasse particle size was for 0.08 mm. For this case, a great quantity of cellulose (78.8 %) was converted into glucose. Optical absorption spectroscopy was applied to determine ozone concentrations in real time where the samples with typical bagasse particle sizes equal or below to 0.5 mm had shown a better absorption of ozone in comparison with greater particle size samples.     

Inhibitors Compounds on Sugarcane Bagasse Saccharification: Effects of Pretreatment Methods and Alternatives to Decrease Inhibition

Considering bioethanol production, extensive research has been performed to decrease inhibitors produced during pretreatments, to diminish energy input, and to decrease costs. In this study, sugarcane bagasse was pretreated with NaOH, H₂SO₄, and water. The higher concentration of phenols, 3.3 g/L, was observed in biomass liquid fraction after alkaline pretreatment. Acid pretreatment was responsible to release considerable acetic acid concentration, 2.3 g/L, while water-based pretreatment was the only to release formic acid, 0.02 g/L. Furans derivatives were not detected in liquid fractions regardless of pretreatment. Furthermore, washing step removed most of the phenols from pretreated sugarcane bagasse. Saccharification of alkali-pretreated biomass plus polyethylene glycol (PEG) at 0.4% (w/v) enhanced 8 and 26% the glucose and the xylose release, respectively, while polyvinylpyrrolidone (PVP) also at 0.4% (w/v) increased the release by 10 and 31% of these sugars, respectively, even without washing and filtration steps. Moreover, these polymers cause above 50% activation of endoglucanase and xylanase activities which are crucial for biomass hydrolysis.

     

Evaluation of organic molecules originated during composting process

The composting process using sugarcane bagasse, animal manure, and urea as source of organic matter, microorganism, and nitrogen, respectively, were evaluated regarding the thermal behavior considering the maturation period: 0 (raw), 15, 22, 30, and 60 days. Thermogravimetric and differential thermal analysis curves were obtained in a synthetic air atmosphere and heating rate of 10 °C min⁻¹ in the range of 30–600 °C. The raw compost showed 80% organic matter, which was reduced up to 58% to 60 days compost. Two main mass losses were verified, corresponding to characteristics exothermic peak in differential thermal analysis curves depending on the maturation period. The variation in organic composition was evaluated by Fourier transform infrared spectroscopy verifying the structures (lignin, cellulose, and hemicelluloses) changes with composting process, and the gas chromatography–mass spectrometry was used to identify substance soluble in hexane.     

Pretreatment of sugarcane bagasse by acidified aqueous polyol solutions

Pretreatments of sugarcane bagasse by three high boiling-point polyol solutions were compared in acid-catalysed processes. Pretreatments by ethylene glycol (EG) and propylene glycol solutions containing 1.2 % H₂SO₄ and 10 % water at 130 °C for 30 min removed 89 % lignin from bagasse resulting in a glucan digestibility of 95 % with a cellulase loading of ~20 FPU/g glucan. Pretreatment by glycerol solution under the same conditions removed 57 % lignin with a glucan digestibility of 77 %. Further investigations with EG solutions showed that increases in acid content, pretreatment temperature and time, and decrease in water content improved pretreatment effectiveness. A good linear correlation of glucan digestibility with delignification was observed with R² = 0.984. Bagasse samples pretreated with EG solutions were characterised by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, which confirmed that improved glucan enzymatic digestibility is mainly due to delignification and defibrillation of bagasse. Pretreatment by acidified EG solutions likely led to the formation of EG-glycosides. Up to 36 % of the total lignin was recovered from pretreatment hydrolysate, which may improve the pretreatment efficiency of recycled EG solution.     

Xylooligosaccharides Production from Alkali-Pretreated Sugarcane Bagasse Using Xylanases from Thermoascus aurantiacus

Sugarcane bagasse hemicellulose was isolated in a one-step chemical extraction using hydrogen peroxide in alkaline media. The polysaccharide containing 80.9% xylose and small amounts of l-arabinose, 4-O-methyl-d-glucuronic acid and glucose, was hydrolyzed by crude enzymatic extracts from Thermoascus aurantiacus at 50?°C. Conditions of enzymatic hydrolysis leading to the best yields of xylose and xylooligosaccharides (DP 2-5) were investigated using substrate concentration in the range 0.5–3.5% (w/v), enzyme load 40–80 U/g of the substrate, and reaction time from 3 to 96 h, applying a 2² factorial design. The maximum conversion to xylooligosaccharides (37.1%) was obtained with 2.6% of substrate and xylanase load of 60 U/g. The predicted maximum yield of xylobiose by a polynomial model was 41.6%. Crude enzymatic extract of T. aurantiacus generate from sugarcane bagasse hemicellulose 39% of xylose, 59% of xylobiose, and 2% of other xylooligosaccharides.     

Clean energy from sugarcane bagasse: quality evaluation by neutron activation analysis

The energy from sugarcane is one of the most important in Brazil’s energy matrix and the efficiency of extraction and processing is fully dependent on the quality of the raw material. The soil present in sugarcane was investigate here as a factor that can affect the production of energy. Chemical elements (Fe, Hf, Sc and Th) determined by instrumental neutron activation analysis were used for tracing soil in sugarcane and its derived bagasse. The lower calorific value (LCV) of bagasse demonstrated a good negative correlation (r = ?0.9727) with the ash content of the bagasse, which in turn was positively correlated to the amount of soil in the sugarcane. Therefore, the presence of soil reduces the production of energy from burning bagasse. The proportion of loss in the LCV was just slightly higher than the soil content, i.e. for an soil content of 10 % a reduction of 12.7 % was observed in the LCV.     

Optimization of lignin recovery from sugarcane bagasse using ionic liquid aided pretreatment

Ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]oAc) was employed for the pretreatment of sugarcane bagasse (SCB) and extraction of lignin, a potentially valuable by-product of the biofuel industry. Response surface methodology based on central composite design was exploited and thereby an empirical model, exhibiting a coefficient of determination, R², of 0.9890, was established to optimize lignin recovery. In particular, a maximum lignin yield, equal to 90.1%, was calculated at the optimal pretreatment conditions, namely time: 120 min, temperature: 140 °C, and ionic liquid to bagasse ratio equal to 20:1 (wt/wt). The presence of guaiacyl and syringyl rings in lignin was confirmed by Fourier transform infrared spectroscopy (FTIR); whereas UV–Vis spectrophotometry showed that both p-coumaric acid and ferulic acid were contained in the lignin. Thermal analysis indicated a maximum decomposition rate of 2%/°C at 265 °C while Gel permeation chromatography analysis revealed that the molecular weight (M_w) of recovered lignin was equal to 1769 g/mol. Comparison of FTIR spectra of pretreated and untreated bagasse showed a negligible presence of lignin in the pretreated samples. Maximum delignification of bagasse after pretreatment was thus ensured. Thermal stability of the ionic liquid towards recyclability was proven by thermogravimetric analysis. The present study established adequate performance of neat and recycled ([EMIM]oAc) with regard to lignin recovery from SCB.     

Characterization and thermal behavior of residues from industrial sugarcane processing

The increase in sugarcane production and processing in order to obtain important products such as sugar and ethanol has the negative aspect of also increasing industrial residues. The most important residues originated during processing are bagasse, hydrolyzed bagasse, filter cake, vinasse, and ash. Thermal analysis revealed that these residues have peculiar properties, such as the presence of lignocellulosic material, except in the ash. The amount of organic matter decreases during the treatment process, due to the addition of chemical products to the residues, which are responsible for some alteration in their thermal properties. Colorimetric analysis showed considerable K and P concentrations in the vinasse and filter-cake residues. EDX and infrared spectroscopy showed the presence of Si in the residues. A higher percent of Si in ash sample was also observed, as a product of the thermal decomposition, by TG, FTIR, and X-ray diffractometry.     

Oxidation in Acidic Medium of Lignins from Agricultural Residues

Agricultural residues as sugarcane straw and bagasse are burned in boilers for generation of energy in sugar and alcohol industries. However, excess of those by-products could be used to obtain products with higher value. Pulping process generates cellulosic pulps and lignin. The lignin could be oxidized and applied in effluent treatments for heavy metal removal. Oxidized lignin presents very strong chelating properties. Lignins from sugarcane straw and bagasse were obtained by ethanol–water pulping. Oxidation of lignins was carried out using acetic acid and Co/Mn/Br catalytical system at 50, 80, and 115 °C for 5 h. Kinetics of the reaction was accomplished by measuring the UV-visible region. Activation energy was calculated for lignins from sugarcane straw and bagasse (34.2 and 23.4 kJ mol⁻¹, respectively). The first value indicates higher cross-linked formation. Fourier-transformed infrared spectroscopy data of samples collected during oxidation are very similar. Principal component analysis applied to spectra shows only slight structure modifications in lignins after oxidation reaction.     

THE SYNTHESIS OF DISODIUM O-n-ALKYLTHIOPHOSPHATES

Abstract

The disodium O-alkylthiophosphates were synthesized by reaction of PSCl₃ with the corresponding alcohols to the O-alkylphosphorodichloridothioates (1), which were hydrolyzed in aqueous triethylamin–sodium acetate solution.¹ The O-alkylthiophosphates (2) were isolated as barium salts and converted to the disodium salts by Na₂SO₄.

Because the barium salts of O-ethyl- and O-n-propyl-thiophosphate were soluble in water, the corresponding dichlorido compounds were hydrolyzed directly to the disodium salts in aqueous sodium hydroxide plus dioxane according to Gray and Hamer.²

Further purification was achieved by column chromatography on Sephadex LH20 using water as an eluant. Pure products, which were not contaminated by either inorganic thiophosphate or O-alkylphosphates, were thus obtained.     

Utilization of Agricultural Residues of Pineapple Peels and Sugarcane Bagasse as Cost-Saving Raw Materials in Scenedesmus acutus for Lipid Accumulation and Biodiesel Production

The aim of this study is to optimize the lipid accumulation in microalgae by using two agricultural residues of pineapple peels and sugarcane bagasse as low-cost organic carbon sources. Green microalgae Scenedesmus acutus was isolated and selected for cultivation. Effects of three initial sugar concentrations and the stage for adding sugar during cultivation on biomass and lipid production were investigated. The results clearly showed that two-stage cultivation is more suitable than one-stage. The maximum biomass concentration and productivity were obtained at 3.85 g/L and 160.42 mg/L/day when sugarcane bagasse was used. The highest lipid content and lipid yield was reached at 28.05 % and 0.93 g/L when pineapple peels were used, while in the case of sugarcane bagasse, 40.89 % and 1.24 g/L lipid content and yield were obtained. Lipid content was found in normal condition (autotrophic) at 17.71 % which was approximately 2.13-fold lower than when sugarcane bagasse was used (40.89 %). Biodiesel production via in situ transesterification was also investigated; the main fatty acids of palmitic acid and oleic acid were found. This work indicates that using agricultural residues as organic carbon sources could be able to increase lipid content and reduce the cost of biofuel production.     

Xylose reductase and xylitol dehydrogenase activities of Candida guilliermondii as a function of different treatments of sugarcane bagasse hemicellulosic hydrolysate employing experimental design

The sugarcane bagasse hydrolysate, which is rich in xylose, can be used as culture medium for Candida guilliermondii in xylitol production. However, the hydrolysate obtained from bagasse by acid hydrolysis at 120°C for 20 min has by-products (acetic acid and furfural, among others), which are toxic to the yeast over certain concentrations. So, the hydrolysate must be pretreated before using in fermentation. The pretreatment variables considered were: adsorption time (15,37.5, and 60 min), type of acid used (H2So4 and H3Po4), hydrolysate concentration (original, twofold, and fourfold. concentrated), and active charcoal (0.5, 1.75 and 3.0%). The suitability of the pretreatment was followed by measuring the xylose reductase (XR) and xylitol dehydrogenase (XD) activity of yeast grown in each treated hydrolysate. The response surface methodology (2⁴ full factorial design with a centered face) indicated that the hydrolysate might be concentrated fourfold and the pH adjusted to 7.0 with CaO, followed by reduction to 5.5 with H₃PO₄. After that it was treated with active charcoal (3.0%) by 60 min. This pretreated hydrolysate attained the high XR/XD ratio of 4.5.