Search Results (60)

The influence of the autohydrolysis temperature of sunflower stems (SSs) and sunflower inflorescence (SI) on the changes in the composition of the pyrolysis products of their hydrochars (HCs) was investigated. This research was carried out using a TG/FT-IR analytical device, the semi-quantitative ATR technique, the quantitative XRD technique, and the SEM (EDS) technique. It was found that a rise in autohydrolysis temperature alarmingly increases the contribution of undesirable hydrocarbons in the volatile pyrolysis products of HCs calculated with respect to the emitted CO₂ and substantially decreases the yield of pyrolyzed solid products. The rise in autohydrolysis temperature not only changes the content of inorganics in HCs but also influences the migration of inorganics in these samples during pyrolysis: intensifies the migration of Mg and Ca and reduces the migration of K. This affects the secondary reaction between the volatile pyrolysis products. The addition of 2 wt% of paracetamol to pyrolyzed HCs inhibits the migration of Mg and Ca and increases the migration of K with volatile products, which positively influences the reduction in undesirable compounds in the composition of emitted volatile products. The addition of paracetamol decreases the yield of pyrolyzed SSHCs by circa 2% and increases the yield of pyrolyzed SIHC₁₈₀ by almost 5%. Full article

Olive trees cultivated in the Viseu region (Portugal) were used in the present work. This study investigates the compositional characteristics and hydrothermal behavior of olive branches (OB) and olive leaves (OL) under autohydrolysis, aiming to assess their potential for biorefinery applications. Chemical analysis revealed that during autohydrolysis (140–180 °C, 15–30 min), OL exhibited greater solubilization than OB, consistent with their higher extractive content. Increasing the temperature promoted selective hemicellulose removal and partial cellulose degradation, leading to a relative enrichment of lignin in the solid residues. Nevertheless, the cellulose content of olive branches for 180 °C and 30 min hydrolysis increased. Fourier transform infrared spectroscopy confirmed progressive structural rearrangements, including enhanced hydroxyl exposure, carbonyl formation, and lignin condensation, indicating the transformation of the solid phase toward more aromatic and thermally stable structures. Autohydrolysis slightly increased the higher heating value of the solid residues while acid-catalyzed liquefaction markedly increased, exceeding those of both native and technical lignins. These results suggest extensive carbon enrichment and oxygen removal during liquefaction. Overall, autohydrolysis proved effective for hemicellulose solubilization and sugar recovery, while liquefaction favored energy densification and lignin condensation. The distinct behaviors of OB and OL highlight the importance of tailoring processing conditions to each feedstock type. Both materials show strong potential as renewable resources for bioenergy and value-added carbon-based products within an integrated olive biomass biorefinery framework. Full article

The production of biobutanol from lignocellulosic biomass is a promising route toward sustainable biofuels, but current research is limited due to the use of commercial simulation tools, incomplete process modeling, and insufficient variation in available feedstock. The current work addresses these gaps by developing and evaluating a complete process simulation for biobutanol production using the open-source software DWSIM. A process flow diagram was established based on a comprehensive literature review, and relevant experimental data were collected to guide simulation inputs and validate results. Six process configurations were developed, using dilute acid and autohydrolysis as pretreatment methods, and assessed based on parameters such as feedstock composition, conversion efficiency, and enzymatic hydrolysis performance. Simulation results show that DWSIM effectively models key stages of biobutanol production and accommodates variations in pretreatment and hydrolysis conditions. Processing solid fractions of pretreated biomass yields higher biobutanol concentrations than using liquid prehydrolysate alone, and the efficiency of enzymatic hydrolysis strongly influences the final output. This work demonstrates that DWSIM is a viable platform for simulating biofuel processes and offers a flexible, cost-effective alternative for early-stage process development, followed by process design with implications for future biorefinery integration and technology scaling. Full article

Sugarcane is a popular crop whose cultivation generates a wide range of by-products. The aim was to optimize the hydrothermal extraction of hemicellulose from sugarcane straw using response-surface methods with a two-factor composite design and to assess its functional qualities. Three process parameters were subject to optimization: solid/liquid ratio (1:6–1:18), temperature (143–186 °C), and extraction time (20–60 min). A xylooligosaccharide (XOS)-enriched extract was characterized regarding its chemical composition, molecular weight, and antioxidant and antimicrobial potential. The optimized extraction yield was 24.46 g/100 g of straw with a polymerization degree of 17.40. Both hemicellulose and XOS demonstrated notable antioxidant properties, with antioxidant effects of 73% and 85%, respectively. Regarding skin enzyme activity, hemicellulose inhibited elastase by more than 50%, while XOS showed no significant effect. However, both extracts exhibited collagenase (MMP1) inhibition comparable to the positive control. In terms of production feasibility, the estimated costs were 130.5 EUR/kg for hemicellulose and 272.5 EUR/kg for XOS. Overall, the optimized XOS-enriched sugarcane straw extract demonstrated promising anti-aging, antioxidant, and preservative properties, highlighting its potential for cosmetic applications. Full article

A hemicellulose-first approach can offer advantages for biorefineries utilizing wheat straw as it combines lignocellulose fractionation and potentially higher added value from pentose-based hemicellulose. Therefore, a tailored hydrothermal concept for the production of xylooligosaccharides and xylan was investigated. The focus was on assessing the energy requirements and potential improvements based on experimental results. The wheat straw pretreatment and the downstream processing of hemicellulose hydrolysate were modeled at a scale of 30,000 tons of wheat straw dry mass per year. The results confirmed that the hydrothermal concept can be implemented in an energy-efficient manner without the need for additional auxiliaries, due to targeted process design, heat integration and a high solids loading during hydrolysis. The resulting specific energy requirements for pretreatment and hydrolysate processing are 0.28 kWh/kg and 0.13 kWh/kg of wheat straw dry mass, respectively. Compared to thermal hydrolysate processing alone, the combination of a multi-effect evaporator and pressure-driven ultrafiltration can reduce the heating and cooling energy by 29% and 44%, respectively. However, the ultrafiltration requirements (e.g., electrical energy, membrane area and costs) depend heavily on the properties of the hydrolysate and its interactions with the membrane. This work can contribute to the commercially viable ramp-up of wheat straw multi-product biorefineries. Full article

Pretreatment is an essential step for breaking the recalcitrant structure of lignocellulosic biomass and allowing conversion to high-value-added chemicals. In this study, coconut fiber was subjected to three pretreatment methods to compare their impacts on the biomass’s structural characteristics and their efficiency in fractionating the biomass. This comparative approach was conducted to identify mild biomass pretreatment conditions that efficiently extract lignin and recover cellulose-rich pulp for the production of bioproducts. To this end, autohydrolysis, alkaline, and organosolv pretreatments were performed under different experimental conditions, and the physicochemical properties of the samples were evaluated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and chemical characterization of the cellulose, hemicellulose, and lignin fractions. Therefore, efficient experimental conditions were identified to pretreat coconut fibers with an extended understanding of the methods to process lignocellulose. Great delignification efficiency and pulp yield were obtained with organosolv > alkaline extraction > autohydrolysis under the selected conditions of 2 h at 185 °C in the presence of a catalyst, namely, 0.5 M NaOH, for 2 h at 55 °C and 20 min at 195 °C, respectively. FT-IR revealed a predominance of hydroxyl groups in fibers obtained from alkaline and organosolv pretreatment, showing higher lignin degradation and cellulose concentration in these samples. TGA revealed mass loss curves with similar behaviors but different patterns and intensities, and MVE analysis showed differences on the surfaces of each sample. The comparison of experimental parameters allowed the identification of suitable conditions for each extraction method, and structural analyses identified the specific characteristics of the fibers that could be obtained according to the method used. Therefore, the results are of great importance for developing sustainable and effective industrial processes. Full article

Posidonia oceanica balls (POB), a kind of seagrass, are a significant environmental issue since they are annually discharged onto beaches. Their current usefulness limits interest in their management and enhances the environmental problem. Therefore, in this research, the potential of this lignocellulosic biomass was studied from a holistic biorefinery point of view. To this end, an in-depth study was carried out to select the best pathway for the integral valorization of POBs. First, an autohydrolysis process was studied for the recovery of oligosaccharides. Then, a delignification stage was applied, where, in addition to studying different delignification methods, the influence of the autohydrolysis pre-treatment was also investigated. Finally, cellulose nanofibers (CNFs) were obtained through a chemo-mechanical treatment. The results showed that autohydrolysis not only improved the delignification process and its products, but also allowed the hemicelluloses to be valorized. Acetoformosolv delignification proved to be the most successful in terms of lignin and cellulose properties. However, alkaline delignification was able to extract the highest amount of lignin with low purity. CNFs were also successfully produced from bleached solids. Therefore, the potential of POB as a feedstock for a biorefinery was confirmed, and the pathway should be chosen according to the requirements of the desired end products. Full article

Lignocellulosic biomass is a powerful approach to produce sustainable biofuels and the further achievement of the goal of biomass conversion into a second-generation clean energy that can cope with the depletion of fossil reserves and rising energy requirements. In the conversion process, a pretreatment is essential to overcome the recalcitrance of the lignocellulosic biomass; accelerate its disintegration into cellulose, hemicellulose, and lignin; and, in turn, obtain an optimal yield of fermentable sugars in the enzymatic hydrolysis. In addition to this, it should be industrially scalable and capable of enhancing fuel properties and feedstock processability. Here, steam explosion technology has stood out due to its results and advantages, such as wide applicability, high efficiency in the short term, or lack of contamination despite its conventionality. This gentle and fast pretreatment incorporates high temperature autohydrolysis and structural alteration by explosive decompression. The steam explosion method has been one of the most effectual, especially for the hydrolysis of cellulose from agricultural wastes due to the lower quantity of acetyl groups in the composition of hemicellulose. In this aspect, sugarcane bagasse is a promising feedstock for bioethanol production due to its high cellulosic content and elevated availability. The objective of this review has been to compile the latest information on steam explosion pretreatment, stages, equipment, variables involved, by-products generated, as well as the advantages and disadvantages of the technique. At the same time, its feasibility and viability using sugarcane bagasse as feedstock has been discussed. Finally, the effectiveness of the technique with different feedstocks has been evaluated. Full article

Halomonas elongata 1H9^T is a moderate halophilic strain able to produce poly(3-hydroxybutyrate) (P(3HB)), a biodegradable plastic, and gluconic acid, a valuable organic acid with wide industrial applications. In this work, the green alga Ulva rigida was used as platform to produce cultivation substrates for microbial conversion as well as functional ingredients, targeting its full valorization. The liquor obtained by autohydrolysis presented the highest concentration of oligosaccharides and protein, being an interesting feedstock to produce functional ingredients. The acid and/or enzymatic hydrolysis liquors are adequate as substrates for microbial processes. Shake flask assays with H. elongata revealed that the N-rich liquor produced after acidic treatment was the best suited for cell growth while the N-poor liquor produced by the enzymatic treatment of acid-pretreated algae residues produced the highest P(3HB) titers of 4.4 g/L. These hydrolysates were used in fed-batch cultivations as carbon and protein sources for the co-production of gluconic acid and polymer achieving titers of 123.2 g/L and 7.2 g/L, respectively. Besides gluconic acid, the Krebs cycle intermediate 2-oxoglutaric acid, also called alpha-ketoglutaric acid (KGA), was produced. Therefore, the co-production of P(3HB) and acids may be of considerable interest as an algal biorefinery valorization strategy. Full article

Inspired by the principles of the circular economy, using vineyard pruning residues as a source of raw materials for producing nanocellulose is a promising approach to transforming vineyard resources into value-added products. This study aimed to obtain and characterize cellulose and cellulose nanofibers from such sources. The cellulose collected from different fractions of micronized stems (500, 300, 150 μm, and retain) of vines was submitted to autohydrolysis and finally bleached. Soon, it underwent treatment via (2,2,6,6-tetrametil-piperidi-1-nil)oxil (TEMPO) oxidation and ultrasonic to obtain nanocellulose fibers. The cellulose films were obtained at a microscale thickness of 0.05 ± 0.00; 0.37 ± 0.03; 0.06 ± 0.01 e 0.030 ± 0.01 mm, with the following particle size: 500 µm, 300 µm, 150 µm, and retain (<150 µm). The bleaching efficiency of the cellulose fibers of each particle size fraction was evaluated for color through a colorimeter. In addition, the extraction of cellulose fibers was assessed by infrared with Fourier transform, and size and shape were assessed by microscopy. Differential scanning calorimetry and X-ray diffraction were performed to confirm the thermal and crystalline properties. Combining autohydrolysis with a bleaching step proved to be a promising and ecological alternative to obtain white fractions rich in cellulose. It was possible to perform the extraction of cellulose to obtain nanocellulose fibers from vine pruning residues for the development of coatings for the conservation of heritage buildings from environmental conditions through an environmentally friendly process. Full article

In the current investigation, the woody stem of Moringa oleifera was processed by chipping and milling and was subsequently exposed to a combination of pretreatments involving a 3% v/v solution of nitric acid and autohydrolysis. The simultaneous saccharification and fermentation (SSF) of the pretreated hydrolysate of M. oleifera was conducted using Zymomonas mobilis and Kluyveromyces marxianus in occurrence of commercial cellulase enzyme, Tween 80, and sodium azide. The fermentation process parameters for Z. mobilis were optimized individually, including a substrate concentration of 5% (w/v), concentration of inoculum 5% (v/v), pH 5.4, and temperature 34 °C. Similarly, for K. marxianus, the process parameters were optimized individually, with a substrate concentration of 5% (w/v), an inoculum concentration of 3% (v/v), a pH of 5.1, and a temperature of 41 °C. The highest cellulosic ethanol concentration was achieved by the micro-organism K. marxianus after a fermentation period of 96 h. Full article

This study proposes an efficient strategy for co-producing high-value-added xylooligosaccharides (XOS) and humic-like acid (HLA) from vinegar residue based on two-step hydrothermal pretreatments. During the first-step hydrothermal pretreatment (170 °C, 50 min), 29.1% of XOS (X₂-X₆) was obtained. The XOS yield was further improved to 36.2% with endoxylanase hydrolysis, thereby increasing the value of (X₂-X₄)/XOS from 0.8 to 1.0. Subsequently, the second-step hydrothermal pretreatment was investigated to produce HLA from the solid residue of the first-step hydrothermal pretreatment. The highest HLA yield was 15.3% in the presence of 0.6 mol/L of KOH at 210 °C for 13 h. In addition, 31.7% of hydrochar by-product was obtained. The mass balance results showed that 1000 g of vinegar residue produced 67.9 g of XOS, 91.6 g of HLA, and 189.5 g of hydrochar. Therefore, this study provides a promising pathway for comprehensive use of lignocellulosic biomass in producing XOS and HLA. Full article

The purpose of this study was to assess the extraction of cellulose from stalks of vines using auto-hydrolysis and characterize it. As the results obtained, the colorimeter readings displayed a final yellow color of the fiber, demonstrating that the bleaching process was insufficient and that multiple bleaching processes might be required. According to the FTIR (Fourier-transform infrared spectroscopy) data, there were stretching and deformation vibrationsof characteristic peak that represent cellulose (2900, 1500, and 1200 cm⁻¹). Although lignin and hemicellulose were partially removed according to the FTIR, distinct cellulose yields were achieved for each fraction, including fractions 500, 300, 250, 150 µm, and retain, with values of 21.98, 12.70, 7.20, 5.74, and 3.11%, respectively. In sum, we were able to extract cellulose from the stalk vine, although the last step still needs to be optimized for better whitening. Full article

Avocado seeds represent the chief waste produced in avocado processing, leading not only to environmental problems regarding its elimination but to a loss of economic profitability. In fact, avocado seeds are known as interesting sources of bioactive compounds and carbohydrates, so their utilization may reduce the negative effect produced during the industrial manufacture of avocado-related products. In this sense, deep eutectic solvents (DES) are a novel greener alternative than organic solvents to extract bioactive polyphenols and carbohydrates. The study was based on a Box–Behnken experimental design to study the effect of three factors, temperature (40, 50, 60 °C), time (60, 120, 180 min) and water content (10, 30, 50% v/v) on the responses of total phenolic (TPC) and flavonoid content (TFC), antioxidant capacity (measured as ABTS and FRAP) and xylose content in the extract. The DES Choline chloride:glycerol (1:1) was used as solvent on avocado seed. Under optimal conditions, TPC: 19.71 mg GAE/g, TFC: 33.41 mg RE/g, ABTS: 20.91 mg TE/g, FRAP: 15.59 mg TE/g and xylose: 5.47 g/L were obtained. The tentative identification of eight phenolic compounds was assayed via HPLC-ESI. The carbohydrate content of the solid residue was also evaluated, and that solid was subjected to two different processing (delignification with DES and microwave-assisted autohydrolysis) to increase the glucan susceptibility to enzymes, and was also assayed reaching almost quantitative glucose yields. These results, added to the non-toxic, eco-friendly, and economic nature of DES, demonstrate that these solvents are an efficient alternative to organic solvents to recover phenolics and carbohydrates from food wastes. Full article

Lignocellulosic biomass is a powerful material for producing sustainable biofuels because it can be converted into second-generation clean energy capable of coping with the depletion of fossil reserves and rising energy demands. However, pretreatment is required in the conversion process to overcome the recalcitrance of the lignocellulosic biomass; accelerate its disintegration into cellulose, hemicellulose, and lignin; and obtain an optimal yield of fermentable sugars in the enzymatic hydrolysis. Steam explosion technology has stood out due to its results and advantages, such as broad applicability, high efficiency in the short term, and lack of contamination. This gentle and quick pretreatment combines high-temperature autohydrolysis and structural alteration via explosive decompression. So, steam at high pressure (1–3.5 MPa) and temperature (180–240 °C) is pressed into the cell walls and plant tissues for a duration of seconds (30 s) to several minutes (20 min). In this aspect, sugarcane bagasse is a promising feedstock for bioethanol production due to its high cellulosic content and availability. Finally, the pretreatment of sugarcane bagasse by applying steam explosion seems to be a feasible economic option for bioethanol production. Full article