Search Results (754)

It is necessary to find sustainable alternatives to the conventional fossil fuels used by the transportation sector today. For the hard-to-abate aviation and heavy transport, liquid hydrocarbon fuels derived from biomass via pyrolysis are a viable option. Biomass pyrolysis oils need upgrading by hydroprocessing before they can be further processed into fuels at a refinery. Due to reactor plugging and catalyst deactivation in one-step hydroprocessing, it has been proposed to add a stabilization step at a lower temperature to convert the most reactive compounds in pyrolysis oil, such as carbonyls, to less reactive species such as alcohols. Three different catalysts, Ni/Al₂O₃, sulfided NiMo/Al₂O₃, and Pt/Al₂O₃, were studied for stabilizing three different model compounds, furfural, guaiacol, and octanoic acid, alone and as a mixture in a batch reactor at 90 bar initial H₂ pressure and 180 °C. The order of performance was determined to be Ni/Al₂O₃ > Pt/Al₂O₃ > sulfided NiMo/Al₂O₃ in these conditions. The Ni/Al₂O₃ catalyst showed both the highest overall conversion, the most fully hydrogenated compounds, and the highest carbonyl conversion. The effect of adding 1172 wt-ppm sulfur to the feed was also investigated, which showed that Ni/Al₂O₃ was the most sensitive catalyst to sulfur poisoning. Full article

5-Methoxymethyl-2-furfural (MMF) serves as a crucial biobased platform molecule that can be transformed into various high-value chemicals and biobased polyester monomers. However, the current production of MMF still faces several challenges, such as low yield and prolonged reaction time. In this study, we prepared a series of amide-modified strongly acidic resin catalysts and discovered that they have a higher efficiency in converting fructose to prepare MMF in 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) and methanol. Among the synthesized catalysts, DB757-NMP demonstrated superior performance, achieving an MMF yield of approximately 61.5% under the optimized conditions, with a combined yield of HMF and MMF reaching about 66.6%. The catalyst formation mechanism was analyzed using FTIR, and NMR, confirming the transformation of proton between NMP and the sulfonic acid groups of the resin, which collectively promoted the conversion of fructose to MMF. In addition, we investigated main reasons for catalyst deactivation and successfully restored catalytic activity through regeneration. The regenerated catalyst could be reused for three times with only a slight decrease in MMF yield. The results suggested that DB757-NMP is a more sufficient and recyclable catalyst for the production of MMF from fructose. This work presented a simple and environmentally benign approach for the synthesis of MMF. Full article

Thermal modification is widely applied to improve the durability and dimensional stability of wood; however, it alters the emission profile of volatile organic compounds (VOCs), which may affect indoor air quality. This study evaluated the effect of accelerated aging on VOC emissions from thermally modified Norway spruce (Picea abies) wood. Untreated and thermally treated samples (160, 180, and 210 °C) were subjected to accelerated aging in a xenon test chamber for 600 h. VOC emissions were analyzed using headspace gas chromatography–mass spectrometry (HS-GC-MS), and total VOC emissions (TVOC) were calculated from peak areas. Thermal modification significantly reduced TVOC compared to untreated wood, with samples treated at 210 °C showing up to a 376-fold decrease. Increasing modification temperature reduced the amount and variability of emitted VOCs and altered their chemical composition. Terpenes dominated in untreated wood, particularly α-pinene (51%), whereas thermally treated samples showed lower terpene content and higher proportions of carbonyl compounds such as furfural. Accelerated aging further affected VOC emissions, including a 42% decrease in TVOC for the 160 °C sample and compositional shifts characterized by the disappearance or formation of specific compounds. Thermal modification and subsequent aging substantially modify VOC emission profiles and improve emission stability of thermally treated spruce wood. Full article

Background: Pityriasis versicolor (PV) is a common superficial mycosis caused by Malassezia species. To describe the clinical and epidemiological characteristics of PV in Acapulco, Mexico, and to identify the associated Malassezia species using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). Methods: A cross-sectional study was conducted in 2024 at Acapulco General Hospital and a private dermatology clinic. Patients with clinically suspected PV and no recent antifungal or immunosuppressive treatment were enrolled. Skin scales were examined microscopically and cultured on modified Dixon agar. Isolates were identified using conventional methods and PCR-RFLP with HhaI and BstCI enzymes. Results: Sixty-nine patients were included; 68.1% were male, and the most affected age group was 11–20 years (34.8%). The hypochromic variant predominated (63.8%). PCR-RFLP identified M. globosa (33.3%) and M. furfur (31.9%) as the most frequent species, followed by M. restricta, M. sympodialis, and M. slooffiae. Species identification was unsuccessful in 11.6% of isolates. No statistically significant associations were found between clinical variants, gender, or species distribution. Conclusions: M. globosa and M. furfur were the predominant species in this tropical Mexican cohort. PCR-RFLP is a practical option for species-level identification, highlighting the diversity of Malassezia in PV. Full article

Dried okara (DOK), a lignocellulosic byproduct from tofu production, was evaluated as both a carbon source and culture medium to enable cost-effective polyhydroxybutyrate (PHB) production. Hydrolysis with either HCl or H₂SO₄ generated 48–51 g/L reducing sugars with peak values reaching 60.2 g/L using 3% acid at 121 °C. Analysis of monosaccharides indicated pentoses, especially xylose, as the main sugars present. A novel strain, Burkholderia sp. EP10 exhibited direct growth and PHB accumulation in DOK hydrolysate without requiring detoxification, tolerating inhibitory compounds such as furfural and 5-hydroxymethylfurfural. In shake flask experiments, the strain achieved 6.9 g/L biomass and 26.3 wt% PHB, while in fermentor studies, biomass reached 10.9 g/L and PHB content was 29.3 wt% at a C/N ratio of 5.7. Notably, these outcomes were achieved without pH control, constituting a key benefit for operational simplification and cost minimization. The biopolymer was verified as PHB using gas chromatography, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The PHB displayed melting transitions at 163.5 and 172.4 °C, a degradation onset at 268 °C, and high molecular weight (4.66 × 10⁵ Da). Burkholderia sp. EP10 for sustainable PHB production via direct bioconversion of lignocellulosic hydrolysates, without the need for pH adjustment, detoxification, or complex medium development. Full article

In recent years, the sustainable production of bio-based platform chemicals from non-lignocellulosic biomass has garnered increasing attention. In this study, Stevia rebaudiana residues were evaluated via hydrothermal liquefaction (HTL) to produce key furan derivatives, namely 5-hydroxymethylfurfural (5-HMF) and furfural. The effects of reaction temperature (160–240 °C) and pressure (0–8 MPa) on product yields were systematically investigated and statistically evaluated using Analysis of Variance (ANOVA) and regression modeling. The highest 5-HMF (93.1 mg/L) and furfural (51.2 mg/L) yields were obtained at 200 °C, while pressure was found to have no statistically significant effect on product formation. To elucidate the physicochemical transformations occurring during hydrothermal processing, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy were used to analyze the morphological and functional group evolution of the biochar and bio-oil fractions. SEM images revealed gradual structural degradation, pore formation, and carbonization with increasing temperature, while FT-IR analysis confirmed dehydration, hydrolysis of glycosidic bonds, aromatization, and the formation of carbonyl groups directly related to furan production. A validated High-Performance Liquid Chromatography (HPLC-UV) method providing analytical efficiency for the precise determination of 5-HMF and furfural in complex biomass matrices was developed. This study provides a comprehensive understanding of the thermochemical behavior of Stevia rebaudiana biomass by integrating morphological characterization, molecular-level spectroscopy, and statistical process modeling and establishes a predictive framework for optimizing furan production under hydrothermal conditions. The findings highlight the potential of Stevia rebaudiana residues as a sustainable feedstock within circular bioeconomy strategies and offer a scalable approach for converting agricultural waste into high-value platform chemicals. Full article

Royal jelly, a nutrient-rich bee product characterized by high water content and active components, is particularly susceptible to quality deterioration during storage. While temperature effects have been extensively documented, the specific role of light exposure in quality degradation remains largely unexplored. despite its relevance during production, handling, transportation, and display. This study systematically investigated the volatile organic compounds (VOCs) of royal jelly under different storage conditions using gas chromatography-ion mobility spectrometry (GC-IMS) combined with fingerprint analysis. Results from dual-column validation demonstrated that even short-term light exposure at 25 °C induced pronounced alterations in VOC profiles, triggering the accumulation of off-flavor aldehydes (e.g., hexanal, nonanal) and ketones, along with 2-furfural generated via Maillard reaction. Concurrently, characteristic fresh-aroma esters and alcohols were significantly depleted. Multivariate statistical analysis confirmed light exposure as the predominant factor driving quality deterioration, with temperature variation under dark conditions producing comparatively minor effects within the same short timeframe. This work provides the first systematic evidence establishing insights into early volatile changes in royal jelly and identifies key VOC markers that offer valuable insights for optimizing storage strategies and developing rapid quality monitoring protocols. Full article

Paired electrolysis represents a more environmentally sustainable and efficient approach for converting agroforestry biomass-derived 5-hydroxymethylfurfural (HMF) and furfural (FUR) into valuable fine chemicals and fuel additives. A critical challenge in developing paired electrolysis systems for furanal compounds is finding the optimal potential matching between the anode and the cathode. One solution is to reduce the potential sensitivity of the anode so that the paired electrolysis system can be regulated only by the cathode potential. In this study, we employed the homogeneous catalyst 4-acetamido-TEMPO (ACT) to facilitate oxidation reaction at the anode, enabling the potential sensitivity of the anode to be reduced. The results displayed the furanal substrates oxidation proceeds through a non-electrochemical chemical reaction with the active oxoammonium cation (ACT⁺), rather than being directly governed by the anode potential. The paired electrolysis system exhibited enhanced catalytic performance, with a total faradaic efficiency of 190.69% and 189.11% in the FUR and HMF paired electrolysis setup, respectively. Furthermore, this system demonstrated excellent stability, maintaining a total faradaic efficiency of over 167.64% after multiple successive cycles. Additionally, the solar-driven paired electrolysis system showed commendable substrate conversion capabilities, achieving a total faradaic efficiency of 187.89%, comparable to that of the electrically driven system. The mechanisms of the ACT electro-oxidation of furanal compounds and the construction of paired electrolysis systems for furanal compounds were proposed and discussed. This work aims to enhance electrical energy efficiency and underscore the potential of paired electrochemical catalysis for sustainable biomass conversion in the green economy. Full article

The development of sustainable biorefining processes is essential for increasing the value of lignocellulosic resources and reducing the environmental footprint of the forest-based industry. Birch wood is one of Latvia’s most abundant renewable feedstocks, yet current catalytic technologies for furfural production—primarily based on sulfuric acid (H₂SO₄)—cause extensive cellulose degradation and generate sulfur-containing residues that hinder further valorization. This study proposes an integrated biorefining approach in which orthophosphoric acid (H₃PO₄) is utilized as an alternative catalyst to selectively convert hemicellulose into furfural and acetic acid while preserving cellulose in birch veneer chips (BVC). The experimental plan was based on a full central composite circumscribed (CCC) response surface methodology (RSM) design, which consists of factorial points, axial (star) points, and centre points. In total, 26 experimental runs were performed, including 24 non-centre points (comprising both factorial and axial points (±α)) and two centre points. The optimized conditions enabled high acetic acid yields (6.29–6.48% o.d.m., corresponding to 98–100% of theoretical), furfural yields of 8.75–10.41% o.d.m. (57–68% of theoretical), and exceptional glucan preservation (38.84–40.92% o.d.m., 94–99% of theoretical). Compared with sulfuric acid pretreatment, the H₃PO₄-based process significantly reduced cellulose degradation and improved the suitability of the resulting lignocellulosic residue for subsequent 5-hydroxymethylfurfural (5-HMF) production and other biorefining routes. The findings demonstrate that orthophosphoric acid catalysis is a promising pathway for integrating furfural extraction with cellulose-retentive pretreatment, thereby enhancing the sustainability, efficiency, and circularity of birch veneer chips’ biomass utilization. Full article

The effective utilization of biomass components in the pre-hydrolysis liquor (PHL) of lignocellulose is a crucial way for traditional pulp and paper mills converting into biomass refining facilities. In the present work, separation technologies are summarized and reviewed—including acidification, ethanol precipitation, flocculation and coagulation, adsorption, solvent extraction, enzyme treatment, and oxidation—with regard to component separation and impurity removal. The utilization of hemicelluloses from PHL for the production of furfural, adhesive and biofuel, as well as the application of lignin separated from PHL and the full components utilization of PHL without separation is reviewed and analyzed. Full article

The sustainable synthesis of valuable noncanonical amino acids from renewable raw materials holds significant importance. This research developed a viable chemical–biological coupling process, leveraging the synergistic effect of a solid acid catalyst and the whole cell of E. coli PpLTA to selectively synthesize β-(2-furanyl) serine from corncob. Initially, a novel magnetic solid acid catalyst, Fe₃O₄/C-SO₃H, was successfully fabricated and employed to catalyze the degradation of corncob in a toluene–water biphasic system for furfural production. Under the optimal conditions (catalyst loading of 2.0% w/w and reaction at 170 °C for 20 min), the furfural yield could attain 62.3%. After ten cycles of use, the yield of furfural remained at 44.7% and the retention rate of catalytic activity was 71.7%. Furthermore, the biocompatibility verification results demonstrated that the furfural derived from corncob could be completely transformed by E. coli PpLTA at a concentration of 50 mM, and this furfural system did not generate any by-products that hindered the biotransformation process. This chemical–biological coupling approach offers a technical solution for the efficient production of noncanonical amino acids from biomass resources. Full article

2,5-Furandicarboxylic acid (FDCA) is an important bio-based platform compound that can be synthesized through the biotransformation of 5-hydroxymethylfurfural (HMF). However, the limited availability of safe microbial strains is a major constraint in the whole-cell catalysis of HMF to FDCA. In this study, a strain capable of catalyzing the conversion of HMF to FDCA, Bacillus subtilis J8M8, was identified. Under optimized whole-cell catalytic conditions, the wild-type strain produced 33.1 mM FDCA with a yield of 41.4%. To enhance FDCA production, HMF/furfural oxidoreductase (HmfH), PQQ-dependent alcohol dehydrogenase (ADH), and aryl-alcohol oxidase (MaAAO) were co-expressed in B. subtilis J8M8. As a result, FDCA production increased to 72.3 mM, with a yield of 90.4%. Further optimization of the engineered strain improved FDCA production to 83.3 mM and yield to 92.6%, representing a 2.52-fold increase over that of the wild-type strain. This study establishes a foundation for the safe and sustainable production of FDCA from HMF. Full article

Efficient co-utilization of mixed sugars from lignocellulosic hydrolysates is often hindered by carbon catabolite repression and pretreatment-derived inhibitors. In this study, a co-fermentation strategy using Saccharomyces cerevisiae (S. cerevisiae) and Enterococcus mundtii (E. mundtii) was developed to simultaneously produce ethanol and lactic acid from non-detoxified corncob hydrolysate. Co-fermentation performed at 39 °C significantly improved substrate utilization compared with monoculture systems, achieving pentose and total sugar utilization percentages of 67.1% and 83.7%, respectively. S. cerevisiae preferentially consumed glucose and effectively detoxified furfural and 5-hydroxymethylfurfural (5-HMF), thereby alleviating inhibitory stress and carbon catabolite repression on E. mundtii. By optimizing the inoculation sequence, a 3 h delayed inoculation of E. mundtii significantly enhanced pentose utilization from 68.6% to 80.2% and increased total sugar utilization to 90.4%. This synergistic co-fermentation strategy provides an effective approach for improving mixed-sugar utilization and multi-product bioconversion efficiency in lignocellulosic biorefineries. Full article

Chemical looping combustion (CLC) has been recognized as a promising CO₂ capture technology, in which oxygen carriers (OCs) transport lattice oxygen to the fuel instead of the air. This study aims to evaluate a newly developed perovskite OC for biomass CLC and to clarify the role of staged fuel conversion in improving gas–solid redox efficiency. This is the first application of perovskite OC CaMn_0.625Ti_0.125Fe_0.125Mg_0.125O₃ in biomass CLC using a dual-stage fluidized bed. The perovskite OC was synthesized via a solid-phase synthesis method, and its performance in a dual-stage fluidized bed reactor was evaluated using pine wood chips and furfural residues as model solid fuels. The in situ conversion of volatile compounds and gasification products derived from the two biomass types was comprehensively studied. The effects of operational parameters, including temperature, OC-to-biomass ratio, and gas flow rate, on the combustion efficiency and CO₂ yield were examined. Results showed that separated gasification–combustion enhanced the combustion efficiency and CO₂ yield. At 950 °C, an OC-to-pine chip ratio of 100:1, and a gas flow rate of 0.7 L/min, the maximum combustion efficiency and CO₂ yield of 79% and 82% were obtained, respectively. Moreover, under the optimal gasification conditions (gasification rate > 99%), increasing the fuel concentration resulted in an increase in the oxygen release from 0.21 g to 0.40 g. Concurrently, the corresponding total oxygen demand increased from 4.34% to 10.56%, indicating the suitability of CaMn_0.625Ti_0.125Fe_0.125Mg_0.125O₃ in the CLC of biomass. Full article

Furfural extraction oil (FEO) is rich in polycyclic aromatic hydrocarbons (PAHs) and is hard to convert under mild conditions. To address this upgrade challenge, this study proposed a co-aquathermolysis process with corn stalk and a Ni/Mo hydrofining catalyst. Key parameters, including reaction temperature, time, catalyst dosage, and corn stalk dosage, were systematically evaluated for their impact on upgrade performance. Under optimized conditions (oil-to-water mass ratio 2:1, 280 °C, 18 h, 8 wt% catalyst, 8 wt% corn stalk), a viscosity reduction rate of 19.96% was achieved, significantly exceeding the 12.69% rate obtained without corn stalk. Meanwhile, the average molecular weight decreased from 430.0 to 353.3 g·mol⁻¹ and the aromatic ring index declined from 3.049 to 2.593. The H/C ratio increased to 1.568, and the sulfur content decreased to 0.09210%. ¹H NMR analysis revealed that corn stalk promotes long-chain scission and inhibits aromatic condensation, leading to a reduced aromatic carbon fraction. A detailed hydrocarbon composition analysis corroborated the conversion of tricyclic and tetracyclic aromatic hydrocarbons to monocyclic and bicyclic aromatic hydrocarbons. These findings offer valuable insights for the modification of FEO via aquathermolysis and establish biomass utilization as a practical strategy for FEO upgrades. Full article