Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by mercerized cellulose and mercerized sugarcane bagasse chemically modified with EDTA dianhydride (EDTAD)

This work describes the preparation of new chelating materials derived from cellulose and sugarcane bagasse for adsorption of Cu²⁺, Cd²⁺, and Pb²⁺ ions from aqueous solutions. The first part involved the mercerization treatment of cellulose and sugarcane bagasse with NaOH 5 mol/L. Non- and mercerized cellulose and sugarcane bagasse were then reacted with ethylenediaminetetraacetic dianhydride (EDTAD) in order to prepare different chelating materials. These materials were characterized by mass percent gain, X-ray diffraction, FTIR, and elemental analysis. The second part consisted of evaluating the adsorption capacity of these modified materials for Cu²⁺, Cd²⁺, and Pb²⁺ ions from aqueous single metal solutions, whose concentration was determined by atomic absorption spectroscopy. These materials showed maximum adsorption capacities for Cu²⁺, Cd²⁺, and Pb²⁺ ions ranging from 38.8 to 92.6 mg/g, 87.7 to 149.0 mg/g, and 192.0 to 333.0 mg/g, respectively. The modified mercerized materials showed larger maximum adsorption capacities than modified non-mercerized materials.     

Removal of Ca(II) and Mg(II) from aqueous single metal solutions by mercerized cellulose and mercerized sugarcane bagasse grafted with EDTA dianhydride (EDTAD)

In a previous work, chemically modified cellulose (EMC) and sugarcane bagasse (EMMB) were prepared from mercerized cellulose (MC) and twice-mercerized sugarcane bagasse (MMB) using ethylenediaminetetraacetic dianhydride (EDTAD) as modifying agent. In this work we described in detail the modification of these materials in function of reaction time and EDTAD amount in the reaction media. The resistance of ester bond at pH 1, 2, 11, and 12 was also evaluated by FTIR. The results were used to model the hydrolysis process and a kinetic model was proposed. The modified materials (EMMB and EMC) were used to adsorb Ca²⁺ and Mg²⁺ ions from aqueous single solutions. The adsorption isotherms were developed at two pH values. These materials showed maximum adsorption capacities for Ca²⁺ and Mg²⁺ ions ranging from 15.6 to 54.1 mg/g and 13.5 to 42.6 mg/g, respectively. The modified material from sugarcane bagasse (EMMB) showed larger maximum adsorption capacities than modified material from cellulose (EMC) for both metals.     

Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by succinylated mercerized cellulose modified with triethylenetetramine

This study describes the preparation of two new chelating materials derived from succinylated mercerized cellulose (cell 1). Cell 1 was activated through two different methods by using diisopropylcarbodiimide and acetic anhydride (to form an internal anhydride) and reacted with triethylenetetramine in order to obtain cell 2 and 4. New modified celluloses were characterized by mass percent gain, concentration of amine functions, elemental analysis, and infrared spectroscopy. Cell 2 and 4 showed degrees of amination of 2.8 and 2.3 mmol/g and nitrogen content of 6.07% and 4.61%, respectively. The capacity of cell 2 and 4 to adsorb Cu²⁺, Cd²⁺, and Pb²⁺ ions from single aqueous solutions were examined. The effect of contact time, pH, and initial concentration of metal ions on the metal ions uptake was also investigated. Adsorption isotherms were well fitted by the Langmuir model. The maximum adsorption capacity of cell 2 and 4 were found to be 56.8 and 69.4 mg/g for Cu²⁺; 68.0 and 87.0 mg/g for Cd²⁺; and 147.1 and 192.3 mg/g for Pb²⁺, respectively.     

Decomposition of sugarcane bagasse with lignocellulose-derived thermotolerant and thermoresistant Penicillia and Aspergilli

To promote the decomposition of sugarcane bagasse (SCB) for conversion into value-added products and to reduce waste, the capability of fungal mixes (FMs) to degrade SCB was examined. A total of 169 isolates from SCB and non-SCB were categorized as thermotolerant and thermoresistant. Thirty-six fungal candidates were screened for the presence of polyphenol oxidase, endoglucanase (EDN) and xylanase (XLN) activities, and EDN and XLN activities were quantitated. Five identified isolates (Aspergillus flavus AG10; Aspergillus niger AG68 & NB23; and Penicillium citrinum AG93 & AG140) were selected as the best enzyme producers, and 15 moderately to highly xylolytic, cellulolytic and ligninolytic isolates were added to construct FMs. Using a Taguchi design, the top ten reducing sugar-producing FMs (no. 12 showed the maximum amount of reducing sugar, at 2.11 mg g⁻¹, followed by no. 7, 15, 2, 16, 11, 13, 6, 4, & 8) were selected as potential agents for decomposition durations of 1, 2 and 3 months. The maximum decrease in SCB materials compared with the control was generated by FM 6 (9.08% cellulose reduction); FM 13 (21.03% hemicellulose reduction); and FM 16 (9.21% lignin reduction). These results indicate the potential use of SCB as a substrate for synergistic FMs. These FMs could be applied to the large-scale composting of SCB and other related agricultural residues, thus improving the biological pretreatment of lignocellulose.     

Fermentation of hexoses and pentoses from sugarcane bagasse hydrolysates into ethanol by Spathaspora hagerdaliae

The present study evaluated 13 strains of yeast for ethanol and xylitol production from xylose. Among them, Spathaspora hagerdaliae UFMG-CM-Y303 produced ethanol yields (Y_P/S) of 0.25 g g^− 1 and 0.39 g g^− 1 under aerobic and microaerophilic conditions, respectively, from a mixture of glucose and xylose in flasks. A pH of 5.0 and an inoculum of 3.0 × 10⁸ cells mL^− 1r resulted in the highest ethanol yields. These conditions were tested in a bioreactor for fermenting a medium containing an enzymatic hydrolysate of sugarcane bagasse with 15.5 g L^− 1 of glucose and 3 g L^− 1 of xylose, and achieved a Y_P/S of 0.47 g g^− 1, in relation to total available sugar. These results suggest that S. hagerdaliae UFMG-CM-Y303 has potential for use in second-generation ethanol studies.

     

Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by cellulose and mercerized cellulose chemically modified with succinic anhydride

This work describes the preparation of new chelating material from mercerized cellulose. The first part treats the chemical modification of non-mercerized cellulose (cell 1) and mercerized cellulose (cell 2) with succinic anhydride. Mass percent gains (mpg) and degree of succinylation (DS) of cell 3 (from cell 1) and cell 4 (from cell 2) were calculated. Cell 4 in relation to cell 3 exhibited an increase in mpg and in the concentration of carboxylic functions of 68.9% and 2.8 mmol/g, respectively. Cells 5 and 6 were obtained by treatment of cells 3 and 4 with bicarbonate solution to release the carboxylate functions and characterized by FTIR. The second part compares the adsorption capacity of cells 5 and 6 for Cu2+, Cd2+, and Pb2+ ions in an aqueous single metal solution. Adsorption isotherms were developed using Langmuir model. Cell 6 in relation to cell 5 exhibited an increase in Qmax for Cu2+ (30.4 mg/g), Cd2+ (86.0 mg/g) and Pb2+ (205.9 mg/g).     

Anaerobic thermophilic fermentation for carboxylic acid production from in-storage air-lime-treated sugarcane bagasse

Wet storage and in situ lime pretreatment (50 °C, 1-atm air, 56 days, excess lime loading of 0.3 g Ca(OH)₂/g dry biomass) of sugarcane bagasse (4,000 g dry weight) was performed in a bench-scale pile pretreatment system. Under thermophilic conditions (55 °C, NH₄HCO₃ buffer, methane inhibitors), air-lime-treated bagasse (80 wt.%) and chicken manure (20 wt.%) were anaerobically co-digested in 1-L rotary fermentors by a mixed culture of marine microorganisms (Galveston, TX). During four-stage countercurrent fermentation, the resulting carboxylic acids consisted of primarily acetate (average 87.7 wt.%) and butyrate (average 9.0 wt.%). The experimental fermentation trains had the highest yield (0.47 g total acids/g volatile solids (VS) fed) and highest selectivity (0.79 g total acids/g VS digested) at a total acid concentration of 28.3 g/L, which is equivalent to an ethanol yield of 105.2 gal/(tonne VS fed). Both high total acid concentrations (>44.7 g/L) and high substrate conversions (>77.5%) are predicted for countercurrent fermentations of bagasse at commercial scale, allowing for an efficient conversion of air-lime-treated biomass to liquid transportation fuels and chemicals via the carboxylate platform.     

Acid hydrolysis of sugarcane bagasse for lactic acid production

In order to use sugarcane bagasse as a substrate for lactic acid production, optimum conditions for acid hydrolysis of the bagasse were investigated. After lignin extraction, the conditions were varied in terms of hydrochloric (HCl) or sulfuric (H₂SO₄) concentration (0.5–5%, v/v), reaction time (1–5 h) and incubation temperature (90–120 °C). The maximum catalytic efficiency (E) was 10.85 under the conditions of 0.5% of HCl at 100 °C for 5 h, which the main components (in g l⁻¹) in the hydrolysate were glucose, 1.50; xylose, 22.59; arabinose, 1.29; acetic acid, 0.15 and furfural, 1.19. To increase yield of lactic acid production from the hydrolysate by Lactococcus lactis IO-1, the hydrolysate was detoxified through amberlite and supplemented with 7 g l⁻¹ of xylose and 7 g l⁻¹ of yeast extract. The main products (in g l⁻¹) of the fermentation were lactic acid, 10.85; acetic acid, 7.87; formic acid, 6.04 and ethanol, 5.24.     

Optimization of pretreatment and fermentation conditions for production of extracellular cellulase complex using sugarcane bagasse

Sugarcane bagasse (SCB), a lignocellulosic byproduct of juice extraction from sugarcane, is rich in cellulose (40-42%). This could be used as a substrate for the production of cellulase complex. Fermentation conditions were optimized for production of cellulase complex (CMCase, Cellulobiase and FPase) by wild type Trichoderma sp. using sugarcane bagasse as sole carbon source. Alkaline treatment (2% NaOH) of bagasse (AlSCB) was found suitable for the production of reducing sugar over the acidic pretreatment method. After 5 days of incubation period, 5% substrate concentration at pH 5.0 and 400C resulted in maximum production of CMCase (0.622 U), while maximum (3.388 U) production of cellulobiase was obtained at 300C. The CMCase was precipitated and purified to the extent of 59.06 fold by affinity chromatography with 49.09% recovery. On 12% SDS-PAGE, a single band corresponding to 33 kDa was observed. The Km and Vmax for CMCase from Trichoderma was found 507.04 mg/ml and 65.32 mM/min, respectively. The enzyme exhibited maximum activity at 300C at pH-5.0 (0.363 U) and was stable over range of 20-60°C and pH 5.0-7.5.     

Effect of alkaline pre-treatment on enzyme synergy for efficient hemicellulose hydrolysis in sugarcane bagasse

This aim of this study was to investigate the effect of ammonium hydroxide (NH₄OH) and sodium hydroxide (NaOH) pre-treatment on the digestibility of sugarcane bagasse (SCB) by hemicellulase action. It was found that pre-treatment of SCB with NH₄OH removed a larger percentage of the SCB lignin and effectively increased SCB digestibility 13.13 fold. The greatest amount of reducing sugar (1194.88 μmol/min) and largest degree of synergy (2.85) was obtained using a combination of two enzymes (25% ManA and 75% XynA) with NH₄OH pre-treated SCB. In this study, NH₄OH therefore appeared to be a more effective pre-treatment step for subsequent hydrolysis by hemicellulases.     

Utilization of sugarcane bagasse for bioethanol production: sono-assisted acid hydrolysis approach

In this study, the production of sugar monomers from sugarcane bagasse (SCB) by sono-assisted acid hydrolysis was performed. The SCB was subjected to sono-assisted alkaline pretreatment. The cellulose and hemicellulose recovery observed in the solid content was 99% and 78.95%, respectively and lignin removal observed during the pretreatment was about 75.44%. The solid content obtained was subjected to sono-assisted acid hydrolysis. Under optimized conditions, the maximum hexose and pentose yield observed was 69.06% and 81.35% of theoretical yield, respectively. The hydrolysate obtained was found to contain very less inhibitors, which improved the bioethanol production and the ethanol yield observed was 0.17 g/g of pretreated SCB.     

Enzymatic hydrolysis of sugarcane bagasse and straw mixtures pretreated with diluted acid

Abstract

In Brazil, sugarcane biomass is generated in large amounts. Sugarcane bagasse and straw are considered as an important feedstock for renewable energy and biorefinery. This paper aims to study the generation of monosaccharides (C5 and C6) from sugarcane biomass via processing bagasse or straw and mixtures of both materials (bagasse:straw 3:1, 1:1 and 1:3). Samples were pretreated with sulfuric acid which resulted in approximately 90% of hemicellulose solubilization, corresponding to around 58 g L^{? 1} of xylose. Pretreated straw showed greater susceptibility to enzymatic hydrolysis in comparison to bagasse, as shown by glucose yields of 76% and 65%, respectively, whereas the mixtures showed intermediate yields. Thus, one strategy to balance sugarcane biomass availability and possibly increasing 2G ethanol production would be to use bagasse–straw mixtures in appropriate ratios according to market fluctuations. Untreated and pretreated samples were analyzed using X-ray diffraction, but there was no relationship to enzymatic hydrolysis.     

Production of bioethanol from sugarcane bagasse using NH<Subscript>4</Subscript>OH-H<Subscript>2</Subscript>O<Subscript>2</Subscript> pretreatment and simultaneous saccharification and co-fermentation

In this study, we investigated the production of bioethanol from sugarcane bagasse (SCB) using an NH₄OH-H₂O₂ pretreatment and simultaneous saccharification and co-fermentation (SScF). Response surface methodology and a 2³ Box-Behnken design were used to evaluate the effect of different liquid mixture concentrations, liquid-to-solid ratios (LSRs) and pretreatment temperatures on the production of ethanol. The liquid mixture concentration and LSR significantly influenced the fermentation efficiency. Based on ridge max analysis, the following pretreatment conditions resulted in a fermentation efficiency of 95.79 ± 0.01%: liquid mixture concentration 53%, LSR 28, and a temperature of 63°C. A morphological analysis performed using scanning electron microscopy (SEM) and chemical characterization revealed that these pretreatment conditions were effective in disrupting the sugarcane fibers and removing lignin. Ethanol fermentation with the pretreated SCB using SScF in yeast SHY 07-1 resulted in an ethanol concentration of 14.65 ± 0.17 g/L, an ethanol yield of 0.48 ± 0.01 g/g, and an ethanol productivity of 0.12 ± 0.01 g/(L/h), which represents increases of 106.02, 89.98, and 107.02%, respectively, over the values obtained from SScF with untreated SCB.     

Fermentation of cellulosic hydrolysates obtained by enzymatic saccharification of sugarcane bagasse pretreated by hydrothermal processing

This work aims to evaluate the fermentability of cellulosic hydrolysates obtained by enzymatic saccharification of sugarcane bagasse pretreated by hydrothermal processing using Candida guilliermondii FTI 20037 yeast. The inoculum was obtained from yeast culture in a medium containing glucose as a carbon source supplemented with rice bran extract, CaCl₂·2H₂O and (NH₄)₂SO₄ in 50 mL Erlenmeyer flasks, containing 20 mL of medium, initial 5.5 pH under agitation of an orbital shaker (200 rpm) at 30°C for 24 h. The cellulosic hydrolysates, prior to being used as a fermentation medium, were autoclaved for 15 min at 0.5 atm and supplemented with the same nutrients employed for the inoculum, except the glucose, using the same conditions for the inoculum, but with a period of 48 h. Preliminary results showed the highest consumption of glucose (97%) for all the hydrolysates, at 28 h of fermentation. The highest concentration of ethanol (20.5 g/L) was found in the procedure of sugarcane bagasse pretreated by hydrothermal processing (195°C/10 min in 20 L reactor) and delignificated with NaOH 1.0% (w/v), 100°C, 1 h in 500 mL stainless steel ampoules immersed in an oil bath.     

Extracellular L-asparaginase production in solid-state fermentation by using sugarcane bagasse as support material

Abstract

L-asparaginase is an important enzyme used in the pharmaceutical and food industry, which can be produced by different microorganisms using low cost feedstocks. In this work, sugarcane bagasse (SCB) was used as support for enzyme production in solid-state fermentation (SSF) by A. terreus. Initially, the influence of the variables carbon and nitrogen sources on the enzyme production was studied following an experimental design carried out in Erlenmeyer flasks. Statistical analysis indicated the use of 0.54% of starch, 0% of maltose, 0.44% of asparagine, and 1.14% of glutamine in the medium, resulting in enzyme activity per volume of produced extract of 120.723?U/L. Then, these conditions were applied in a horizontal column reactor filled with SCB, producing 105.3?U/L of enzyme activity. Therefore, the potential of extracellular L-asparaginase enzyme production in the column reactor using sugarcane bagasse as support was demonstrated and it represents a system that can favor large scale production.     

Characterization of commercial cellulases and their use in the saccharification of a sugarcane bagasse sample pretreated with dilute sulfuric acid

This study aimed to correlate the efficiency of enzymatic hydrolysis of the cellulose contained in a sugarcane bagasse sample pretreated with dilute H₂SO₄ with the levels of independent variables such as initial content of solids and loadings of enzymes and surfactant (Tween 20), for two cellulolytic commercial preparations. The preparations, designated cellulase I and cellulase II, were characterized regarding the activities of total cellulases, endoglucanase, cellobiohydrolase, cellobiase, β-glucosidase, xylanase, and phenoloxidases (laccase, manganese and lignin peroxidases), as well as protein contents. Both extracts showed complete cellulolytic complexes and considerable activities of xylanases, without activities of phenoloxidases. For the enzymatic hydrolyses, two 2³ central composite full factorial designs were employed to evaluate the effects caused by the initial content of solids (1.19–4.81%, w/w) and loadings of enzymes (1.9–38.1 FPU/g bagasse) and Tween 20 (0.0–0.1 g/g bagasse) on the cellulose digestibility. Within 24 h of enzymatic hydrolysis, all three independent variables influenced the conversion of cellulose by cellulase I. Using cellulase II, only enzyme and surfactant loadings showed significant effects on cellulose conversion. An additional experiment demonstrated the possibility of increasing the initial content of solids to values much higher than 4.81% (w/w) without compromising the efficiency of cellulose conversion, consequently improving the glucose concentration in the hydrolysate.     

Effect of antioxidant extraction on the enzymatic hydrolysis and bioethanol production of the extracted steam-exploded sugarcane bagasse

Ethyl acetate extraction (EAE) of the steam exploded sugarcane bagasse may be an effective and economic way to extract antioxidants as well as enhance the enzymatic hydrolysis and bioethanol yield from the extracted residue. Therefore, the effects of EAE on steam-exploded sugarcane bagasse (SESB) were studied. Under boiling solvent extraction (BSE), the efficiency of EAE for obtaining phenolics from SESB was approximately 20%. EA extracts obtained under BSE showed an H₂O₂ scavenging activity (210 μL) of 99%. The IC₅₀ values for 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power of BSE40 were 50.89 and 256.38 μg/mL, respectively, while those of vitamin C were 24 and 112 μg/mL, respectively. EAE improved the glucose yield by 30% but had no significant effect on the xylose yield during the enzymatic hydrolysis obtained using Celluclast 1.5L and Novozym 188. EAE also increased the ethanol yield by 8.78% by employing simultaneous saccharification and fermentation. The present study may be of great importance in industrial bioethanol production from steam-exploded biomass environmentally friendly and economically.     

Optimization of amylase production by Aspergillus niger in solid-state fermentation using sugarcane bagasse as solid support material

Synthesis of amylase by Aspergillus niger strain UO-01 under solid-state fermentation with sugarcane bagasse was optimized by using response surface methodology and empirical modelling. The process parameters tested were particle size of sugarcane bagasse, incubation temperature and pH, moisture level of solid support material and the concentrations of inoculum, total sugars, nitrogen and phosphorous. The optimum conditions for high amylase production (457.82 EU/g of dry support) were particle size of bagasse in the range of 6–8 mm, incubation temperature and pH: 30.2°C and 6.0, moisture content of bagasse: 75.3%, inoculum concentration: 1 × 10⁷ spores/g of dry support and concentrations of starch, yeast extract and KH₂PO₄: 70.5, 11.59 and 9.83 mg/g of dry support, respectively. After optimization, enzyme production was assayed at the optimized conditions. The results obtained corroborate the effectiveness and reliability of the empirical models obtained.     

Fungal rock phosphate solubilization using sugarcane bagasse

The effects of different doses of rock phosphate (RP), sucrose, and (NH₄)₂SO₄ on the solubilization of RP from Araxá and Catal?o (Brazil) by Aspergillus niger, Penicillium canescens, Eupenicillium ludwigii, and Penicillium islandicum were evaluated in a solid-state fermentation (SSF) system with sugarcane bagasse. The factors evaluated were combined following a 2³?+?1 factorial design to determine their optimum concentrations. The fitted response surfaces showed that higher doses of RP promoted higher phosphorus (P) solubilization. The addition of sucrose did not have effects on P solubilization in most treatments due to the presence of soluble sugars in the bagasse. Except for A. niger, all the fungi required high (NH₄)₂SO₄ doses to achieve the highest level of P solubilization. Inversely, addition of (NH₄)₂SO₄ was inhibitory to P solubilization by A. niger. Among the fungi tested, A. niger stood out, showing the highest solubilization capacity and for not requiring sucrose or (NH₄)₂SO₄ supplementation. An additional experiment with A. niger showed that the content of soluble P can be increased by adding higher RP doses in the medium. However, P yield decreases with increasing RP doses. In this experiment, the maximal P yield (approximately 60?%) was achieved with the lower RP dose (3?g?L^?1). Our results show that SSF can be used to obtain a low cost biofertilizer rich in P combining RP, sugarcane bagasse, and A. niger. Moreover, sugarcane bagasse is a suitable substrate for SSF aiming at RP solubilization, since this residue can supply the C and N necessary for the metabolism of A. niger within a range that favors RP solubilization.     

Production of ethanol and xylanolytic enzymes by yeasts inhabiting rotting wood isolated in sugarcane bagasse hydrolysate

Yeasts associated with rotting wood from four Atlantic Rain forest sites in Brazil were investigated using a culture medium based on sugarcane bagasse hydrolysate. A total of 330 yeast strains were isolated. Pichia manshurica, Candida pseudolambica, and Wickerhamomyces sp. 3 were the most frequently isolated species. Fourteen novel species were obtained in this study. All isolates were tested for their ability to ferment d-xylose and to produce xylanases. In the fermentation assays using d-xylose (30 g L⁻¹), the main ethanol producers were Scheffersomyces stipitis (14.08 g L⁻¹), Scheffersomyces sp. (7.94 g L⁻¹) and Spathaspora boniae (7.16 g L⁻¹). Sc. stipitis showed the highest ethanol yield (0.42 g g⁻¹) and the highest productivity (0.39 g L⁻¹h⁻¹). The fermentation results using hemicellulosic hydrolysate showed that Sc. stipitis was the best ethanol producer, achieving a yield of 0.32 g g⁻¹, while Sp. boniae and Scheffersomyces sp. were excellent xylitol producers. The best xylanase-producing yeasts at 50 °C belonged to the species Su. xylanicola (0.487 U mg⁻¹) and Saitozyma podzolica (0.384 U mg⁻¹). The results showed that rotting wood collected from the Atlantic Rainforest is a valuable source of yeasts able to grow in sugarcane bagasse hydrolysate, including species with promising biotechnological properties.