Search Results (723)

Residual avocado biomass, primarily peel and seed generated during industrial processing of Persea americana Mill., represents an abundant agro-industrial residue with considerable potential for sustainable valorization. This review critically examines the biotransformation of residual avocado biomass into humic substances (HS) through composting, integrating current knowledge on substrate composition, microbial succession, biodegradation kinetics, humification mechanisms, and process-control strategies. A systematic literature review was conducted following the PRISMA framework, enabling the identification and critical evaluation of recent advances in composting technologies, kinetic modeling, and humification processes specific to avocado residues. Particular emphasis is placed on the influence of key operational variables—including temperature, moisture, aeration, C/N ratio, pH, and microbial activity—on organic matter degradation, nitrogen conservation, compost stability, and HS formation. The review also discusses maturity and quality indicators, including the humification index, E4/E6 ratio, germination index, and leachate management, together with the role of vermicomposting and cascade biorefinery approaches in maximizing resource recovery. Current evidence indicates that residual avocado biomass constitutes a promising feedstock for producing stable humified organic amendments while contributing to nutrient recycling, soil fertility, carbon sequestration, and circular bioeconomy strategies. Finally, major research gaps are identified, particularly regarding avocado-specific biodegradation kinetics, integrated process monitoring, predictive modeling, and intelligent process-control systems, providing future directions for the optimization and industrial implementation of composting technologies for sustainable agro-industrial waste valorization. Full article

As a renewable aromatic carbon reservoir, lignin exhibits great potential for the synthesis of sustainable fuels and high-value chemicals. Nevertheless, its intricate skeletons, irregular bond distribution, and abundant oxygenated functional groups complicate hydrodeoxygenation (HDO), resulting in inferior product selectivity and limited catalytic durability. Centered on structure–activity relationships, this review systematically correlates lignin structural features, catalytic performance, hydrogen supply modes, and HDO mechanisms. Impacts of linkage types, functional group distribution, and pretreatment-induced structural evolution on substrate adsorption and C–O bond cleavage are analyzed. The structure-performance rules of monometallic, bifunctional, atomic-scale, and carbon-based catalysts are clarified. Regulatory effects of various hydrogen supply strategies on active hydrogen generation and competitive direct deoxygenation/hydrogenation deoxygenation (DDO/HYD) pathways are elaborated. Critical bottlenecks restricting practical lignin conversion are summarized, and prospects for rational catalyst design and green biorefinery development are proposed. Full article

Agricultural and food-processing residues represent abundant renewable feedstocks for the sustainable production of functional oligosaccharides through biocatalytic conversion. Valorization of these underutilized biomass resources represents a promising strategy for producing high-value bioactive oligosaccharides while improving resource efficiency and supporting the circular bioeconomy. This review discusses current developments in the biocatalytic synthesis of functional oligosaccharides from agro-food residues, with emphasis on residue-specific biocatalytic techniques and carbohydrate-active enzymes (CAZymes). Along with new transglycosylation and glycosynthase-based methods for the synthesis of structurally defined oligosaccharides, the catalytic mechanisms and substrate specificity of hydrolytic enzymes involved in the synthesis of xylo-, cello-, pectic-, and chitooligosaccharides are critically discussed. Recent advances in biocatalytic platforms, such as multi-enzyme cascade systems, whole-cell biocatalysis, and immobilized enzyme technologies, are highlighted as promising strategies for improving catalytic efficiency, product selectivity, and operational performance, together with future opportunities in enzyme engineering and computationally assisted biocatalyst development. This review offers a biocatalyst-centered perspective for the sustainable production of functional oligosaccharides and provides insights into the development of effective biomass valorization strategies for future industrial biorefineries by linking residue-specific biomass resources with current biocatalytic approaches. Full article

Wood vinegar (WV), also known as pyroligneous acid, is the aqueous condensate produced during lignocellulosic biomass pyrolysis, generated alongside biochar and non-condensable gases. In forest biorefineries, it represents a promising value-added coproduct capable of transforming forestry and agroforestry residues into a multifunctional bioproduct. Its composition, dominated by water, organic acids, phenolic compounds, aldehydes, and ketones, confers antimicrobial, antioxidant, biostimulant, herbicidal, and preservative properties. This review critically examines WV production, chemical composition, purification strategies, mechanisms of action, and applications, explicitly distinguishing evidence-based uses from prospective ones. Current evidence supports applications in agriculture, wood preservation, environmental management, and forestry, including forest nursery production and clonal propagation of Eucalyptus and Pinus. However, the literature remains fragmented by compositional variability, non-standardized terminology, limited mechanistic understanding, and scarce long-term toxicological and techno-economic assessments. WV holds significant potential for sustainable biomass valorization and circular bioeconomy strategies. Realizing this potential requires harmonized analytical protocols, standardized formulations, rigorous mechanistic studies, life-cycle assessments, and regulatory frameworks that support the transition of this heterogeneous pyrolysis byproduct into a reliable commodity within integrated forest biorefineries. Full article

This research proposes an approach based on a circular economy principle for the integral valorization of Sargassum from the Mexican Caribbean. The biomass was characterized through proximal and elemental analyses, and then an oxidative pretreatment was carried out to enhance a sequential processing scheme to extract sodium alginate and use the solid waste as a substrate for biogas production via anaerobic digestion. The oxidative pretreatment successfully reduces the recalcitrant content and the concentration of heavy metals. The sodium alginate extracted from treated biomass achieves a yield higher than 20%; the characterization of the polymer via nuclear magnetic resonance showed that the mannuronic-to-guluronic ratio was between 0.34 and 0.62, indicating the potential for its use for environmental and biomedical applications. The highest yield in methane production was 328 mL CH₄/g of volatile solids, with a purity of 90%, and was achieved using the waste from alginate extraction with an inoculum-to-substrate ratio of 1:1. The experimental data presented an excellent fit to a Gompertz model (R² > 0.99). The proposed valorization pathway improves the sustainability of Sargassum management, prioritizing the recovery of high-value compounds before energy production. This circular approach provides a framework for converting environmental challenges into opportunities in the Caribbean. Full article

Sustainable aviation fuel (SAF) deployment requires simultaneous coordination of spatially distributed biomass supply chains and nonlinear conversion technologies. This study develops an integrated multiscale optimization framework for SAF production in Mexico using second-generation sugarcane bagasse as the lignocellulosic resource for alcohol-intermediate production, followed by an intensified Alcohol-to-Jet (ATJ) upgrading stage targeting Mexico City Airport. A multi-period mixed-integer linear programming model optimizes harvest-area selection, biorefinery location, biomass allocation, inventory, production, and distribution, while an Aspen Plus model of an intensified Alcohol-to-Jet (ATJ) process with reactive distillation is optimized using Differential Evolution with Tabu List. In this framework, the ATJ block is not modeled as direct biomass-to-jet conversion. In the base case, ethanol is used as the representative alcohol intermediate. Therefore, the upstream biomass-to-alcohol section is represented through an effective bagasse-to-ethanol coefficient, whereas the Aspen Plus–DETL model explicitly describes the downstream ethanol-to-ATJ-range hydrocarbon blendstock upgrading section through dehydration, ethylene oligomerization, hydrogenation, and fractionation. Process yield, production cost, environmental impact, and feasible capacity are fed back into the supply chain model, making process performance endogenous rather than fixed. Results show that the decoupled supply chain baseline favors large production capacities, reducing TAC from approximately 1010 to 340 USD/tSAF and system-level EI99 from 1.110 to 1.059 kPt EI99/tSAF as capacity increases from 80,000 to 490,000 tSAF/year. This corresponds to an environmental reduction of approximately 5.2%. In contrast, isolated ATJ optimization exhibits nonlinear scale-dependent behavior, with process-only EI99 decreasing from approximately 1.70 to 0.55 kPt EI99/tSAF. The integrated framework identifies an intermediate capacity region of 120,000–300,000 tSAF/year, with TAC values of approximately 3400–6800 USD/tSAF and total EI99 values of approximately 0.78–1.31 kPt EI99/tSAF. The integrated base case at 200,000 tSAF/year has an EI99 value of approximately 1.063 kPt EI99/tSAF. Full article

Fungal cellulases are key biocatalysts for lignocellulosic biomass valorization and the development of sustainable biorefineries. This review examines recent advances in the production of endoglucanase (EGL), exoglucanase (EXG), and β-glucosidase (BGL) by fungi of the genera Trichoderma, Aspergillus, and Penicillium under solid-state fermentation (SSF) and submerged fermentation (SmF). Emphasis is placed on fermentation strategies, substrate selection, process optimization, and emerging chemometric and artificial intelligence-based approaches. The literature reveals a predominance of SSF systems, especially when agri-food residues such as wheat bran, sugarcane bagasse, rice-derived residues, fruit-processing wastes, and cocoa by-products are employed as low-cost substrates. Among the evaluated genera, Aspergillus was among the most frequently investigated genera and exhibited broad substrate versatility, whereas Trichoderma reesei remains the principal industrial production host for cellulase-rich enzyme preparations used mainly in the saccharification of lignocellulosic biomass for cellulosic ethanol and other biorefinery applications. In contrast, Penicillium stands out as an important source of BGL, complementing cellulase systems derived from other fungi. Temperature, pH, moisture content, and fermentation time were consistently identified as the main factors affecting cellulase biosynthesis, with optimal production generally occurring under mildly acidic conditions and mesophilic temperatures. CCD and BBD were the predominant optimization strategies, while artificial neural network-based models are emerging as promising alternatives. The complementary characteristics of these fungi genera support their application in integrated biomass conversion and future lignocellulosic biorefineries. Full article

The transition towards a circular economy of agri-food wastes requires innovative strategies for transforming them into value-added products. This study evaluates the environmental and economic sustainability of a laboratory-scale process that converts 100 g of pomegranate waste, experimentally processed and defined as functional unit (FU), into a cosmetic emulsion. Primary data were collected from laboratory activities carried out in an Italian university, including material and reagent consumption, equipment operating times and energy use. A cradle-to-gate Life Cycle Assessment was performed in SimaPro according to ISO 14040 and 14044 using the Environmental Footprint 3.1 method, while Life Cycle Costing was developed in Microsoft Excel using the same system boundaries. The process valorized the three main pomegranate fractions (arils, mesocarp and exocarp) to obtain a cosmetic emulsion. The exocarp treatment was identified as the main impactful phase. The overall climate change impact reached 328 g CO₂ eq/FU, while fossil resource use amounted to 5.3 MJ/FU. The total production cost was estimated at 189 €/FU, mainly due to labor, reagents, enzymes and equipment costs. Although laboratory-scale operation results in relatively high impacts and costs, the study identifies the main hotspots and provides a baseline for future process optimization and industrial scale-up. Full article

Water hyacinth leaves (WHL) are an inexpensive renewable fuel resource that can be employed for energy creation through hydrolysis of simple fermentable reducing sugars. In this work, a hybrid microwave irradiation (MWI)–ternary deep eutectic solvent (TNDES) system involving choline chloride (ChCl) as a hydrogen bond acceptor (HBA), triethanolamine (TEOA) as an amine-based hydrogen bond donor (HBD), monoethylene glycol (MEG), diethylene glycol (DEG), or triethylene glycol (TEG) as polyol-based HBD components was employed as an efficient and green material for pretreatment of WHL for further transformation of the polysaccharide portion. The results showed that hybrid MWI/TNDES (ChCl-TEOA-MEG, ChCl-TEOA-DEG, and ChCl-TEOA-TEG) pretreatments were very efficient for lignin removal from WHL, with efficacy ranging from 80.4 ± 3.2 to 87.7 ± 3.8% compared with pretreatment using hybrid MWI/binary NDES (ChCl-TEOA) (75.6 ± 2.4%). The higher efficacy of the hybrid MWI/TNDES pretreatment was attributed to the impacts of MWI on extracting biological materials and the lower viscosity, higher pH, and lower density associated with the TNDESs. The results indicate that WHL pretreated using hybrid MWI and ChCl-TEOA-MEG, ChCl-TEOA-DEG, and ChCl-TEOA-TEG resulted in significantly boosting cellulose digestibility (4–5 times that of pristine WHL and 1.5 times that of hybrid MWI/ChCl-TEOA-treated WHL). The effect of MWI/TNDES pretreatment was confirmed by scanning electron microscope (SEM) pictures, and lignin and hemicellulose elimination were clearly observed in Fourier transform infrared (FTIR) spectra. The lignin-rich material separated by the hybrid MWI/TNDES pretreatment was analyzed using thermogravimetric analysis (TGA) to obtain the thermal behaviors of this hybrid, pretreated WHL material. In our experimentation with hybrid MWI/TNDES, under optimum circumstances of MWI time of 6 min, MWI power of 300 W, and a temperature of 90 °C, 43–49 g/L TRS yield was achieved by acid-catalyzed hydrolysis employing WHL substrate after being optimized by the single-factor experiments (SFE) approach, while the optimized TRS for untreated WHL and hybrid MWI/binary ChCl-TEOA were estimated to be 12 g/L and 32 g/L, respectively. The hybrid MWI/ChCl-TEOA-TEG pretreated WHL resulted in a high ethanol yield (ca. 22.3 g/L) by Saccharomyces cerevisiae after 72 h of fermentation. This work demonstrates the potential of WHL as a sustainable bioenergy feedstock for bioethanol production in industrial biorefineries. The research establishes effective and green solvent pre-treatment materials and methods (based on hybrid MWI/TNDES) for the efficient removal of lignin and hemicellulose from WHL and cellulose recovery. In general, the research contributes to the development of environmentally friendly and cost-effective hybrid MWI/TNDES processes for WHL biomass conversion and offers strong evidence that hybrid MWI/TNDES processes represent a high-potential method for managing WHL infestations while generating useful products. Future studies should further investigate ways to enhance the efficacy of acid-catalyzed hydrolysis processes and assess the scalability of the technology for industrial applications. Full article

The urgent need for bio-based functional materials has driven a shift away from fossil-fuel-sourced materials toward renewable lignocellulosic biomass (LCB). This comprehensive review explores the advancements in LCB carbonization between 2020 and 2026, marking a shift from traditional, low-yield combustion processes toward highly selective and sustainable thermochemical conversion pathways. The primary objective of this review is to evaluate the integration of green pretreatment strategies, conversion technologies, and efficient valorization of the aqueous effluents and by-products. The goal of green pretreatment is to overcome the inherent recalcitrance of LCB without the use of harsh chemicals and reaction conditions, specifically highlighting the effectiveness of deep eutectic solvents (DESs) and ionic liquids (ILs). The review also evaluates the emerging conversion technologies, including hydrothermal carbonization (HTC), microwave-assisted pyrolysis (MAP), and the synergistic co-pyrolysis of LCB with synthetic polymeric wastes. Another novel concept in preparing hard carbon and other related materials is the “lignin-first” biorefinery strategy, which facilitates the subsequent production of high-value aromatic monomers, platform chemicals, and biofuels. The engineered carbon materials are increasingly utilized well beyond their traditional use as solid fuels. The products have been proven to be excellent for use in high-performance energy conversion and storage, serving as renewable bio-based electrode materials for supercapacitors and carbon electrodes in next-generation batteries. Full article

Pyroligneous liquor (PL) is a by-product of charcoal production with potential applications in agriculture, forestry, and industry. This study evaluated the influence of carbonization temperature on the yield, chemical composition, and physicochemical properties of PL obtained from Eucalyptus spp. in a sustainable kiln-furnace system. PL fractions were collected at four temperature intervals: T1 (60–170 °C), T2 (171–270 °C), T3 (271–350 °C), and T4 (351–400 °C). The recovery of condensable gases did not affect the quality of the charcoal and minimized pollutant emissions. Gas chromatography–mass spectrometry (GC-MS) identified 78 organic compounds, mainly carboxylic acids, phenolic compounds, alcohols, carbohydrates, and aromatics. The highest PL yield was obtained in T3 (271–350 °C), accounting for 27% of the recovered liquor and showing high phenolic content, including syringol and catechol. In contrast, T1 (60–170 °C) showed the lowest yield and was dominated by carboxylic acids, particularly acetic acid. Carbonization temperature affected both PL composition and physicochemical properties, resulting in higher electrical conductivity and vegetable tar content at higher temperatures. Hierarchical cluster analysis revealed distinct compound groups according to their concentration patterns across the evaluated temperature intervals. These results reinforce the notion that the evolution of pyrolysis vapors is not a continuous or homogeneous process, but rather occurs through discrete and chemically distinct stages driven by the sequential decomposition of hemicellulose, cellulose, and lignin—a behavior that directly justifies the temperature-based fractionation approach adopted. It was found that temperature-controlled fractionation effectively yields pyrolysis liquid (PL) fractions with distinct chemical profiles, facilitating the selective recovery of value-added compounds for forest biomass biorefineries and specific end-use applications, in addition to offering environmental benefits. Full article

The transition toward sustainable biorefinery processes requires efficient strategies for lignocellulosic biomass deconstruction and valorization. In this study, an integrated enzymatic system combining fungal holocellulases and laccases with a bacterial galactolipase was developed and evaluated. The consortium, composed of Trametes hirsuta GMA-01, Mycothermus thermophilus CBS 619.91, and Burkholderia lata BL02, was produced using agro-industrial substrates and applied to the hydrolysis of different lignocellulosic biomasses. The incorporation of galactolipase activity enhanced the saccharification yields for leaf-derived substrates, reaching up to 292.0 mg/g for spinach leaves and 236.0 mg/g for corn straw, compared to fungal systems alone. This effect is associated with the selective hydrolysis of membrane-associated galactolipids, improving substrate accessibility to holocellulolytic enzymes. Proteomic analysis confirmed the partial identification of the BL02 enzyme as an ester hydrolase, while structural modeling based on homologous Burkholderia lipases provided preliminary insights into features that may be compatible with the accommodation of bulky polar substrates. In addition, the enzyme catalyzed the synthesis of sugar fatty acid esters with conversion yields above 50% for glucose and xylose in binary solvent systems. These findings support the role of galactolipases as accessory enzymes and highlight their potential application in integrated and sustainable biorefinery processes. Full article

Agricultural residues represent an abundant renewable resource for sustainable lignocellulosic biorefineries, offering opportunities to produce value-added biopolymers while mitigating the environmental impacts associated with conventional disposal. This study evaluated the technical feasibility of using sorghum stubble as a feedstock for the recovery of cellulose, hemicellulose, and lignin through an ethanol–water organosolv process. Specifically, the study aimed to separate the main structural polymers of sorghum stubble and evaluate the performance of the proposed fractionation system. The biomass was treated at 180 °C and approximately 30 bar, followed by chlorine-free peroxide bleaching. The hemicellulose fraction was obtained by extracting the holocellulose (Wise method) and precipitating the dissolved hemicellulose using a 3:1 (v/v) ethanol-to-liquor ratio. The lignin fraction was isolated from the black liquor through vacuum distillation and drying. This approach yielded a cellulose fraction (23.66 wt%), a hemicellulose fraction (36.22 wt%), and a lignin fraction (30.35 wt%), corresponding to an overall polymer recovery of approximately 90 wt%. Structural and physicochemical characterization (FTIR, SEM, XRD, and TGA) supported the fractionation of the lignocellulosic matrix and identified characteristic structural and physicochemical features of the recovered cellulose, hemicellulose, and lignin fractions. SEM revealed substantial structural breakdown following the organosolv treatment, while TGA demonstrated distinct degradation behaviors among the components. Notably, the crystallinity index increased from 38% in the raw material to 71% in the cellulose fraction, indicating effective removal of amorphous components. A preliminary mass–energy analysis showed that approximately 96% of the initial energetic content of the biomass was retained in the polymers. Furthermore, approximately 70% of the ethanol used was recycled, highlighting the potential for solvent reintegration under the evaluated laboratory conditions. Overall, these findings demonstrate the potential of sorghum stubble as a renewable feedstock for the recovery of lignocellulosic polymers and provide a technical basis for the future optimization of organosolv-based biorefineries. Full article

The global oil-processing industry generates substantial quantities of by-products and secondary streams, including oilseed cakes, pomaces, hulls, and wastewaters, which remain largely underutilized despite being rich sources of high-value bioactive compounds. The development of sustainable strategies for the valorization of these residues is increasingly recognized as a key component of circular bioeconomy and biorefinery frameworks. In this context, deep eutectic solvents (DESs) have attracted considerable attention as a new generation of designer solvents owing to their tunable physicochemical properties, low vapor pressure, ease of synthesis, and potential environmental compatibility. This review critically discusses the current state of knowledge regarding the application of DESs in the processing and valorization of oil industry by-products. Particular emphasis is placed on the relationship between DES composition, physicochemical characteristics, and extraction performance. Recent advances in the recovery of phenolic compounds, proteins, saccharides, and tocopherols from oilseed-derived residues are comprehensively examined, including the integration of DESs with intensified extraction techniques such as microwave-, ultrasound-, and ohmic-assisted extraction. Furthermore, the role of DESs in oil purification processes and the treatment of technological waste stream is evaluated. Emerging evidence indicates that DES-based systems not only enhance extraction efficiency and selectivity but may also improve the stability, bioaccessibility, and purity of the recovered compounds. Finally, the opportunities and challenges associated with the implementation of DES-based technologies within integrated biorefinery schemes are discussed, including solvent recovery, product scalability, sensory acceptability, and regulatory considerations. The available literature demonstrates that DESs constitute a versatile platform for the sustainable valorization of oil-processing residues, supporting the transition from conventional waste management approaches toward resource-efficient and circular production systems. Full article

The enzymatic conversion of lignocellulosic biomass (LB) into fermentable sugars is important for the development of sustainable biorefineries. This study investigated the immobilisation of Trichoderma reesei (T. reesei) cellulase on amine-functionalised magnetic nanoparticles (MNPs) and evaluated the resulting biocatalyst for the hydrolysis of pretreated hemp hurd (HH) biomass. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) provided evidence consistent with cellulase association with the nanoparticles, with the estimated dry-state particle diameter increasing from 22.4 ± 0.4 to 27.8 ± 0.3 nm after immobilisation. The selected immobilised catalyst loading produced approximately 89% of the total filter-paper assay response obtained with the selected free-enzyme loading, although this comparison was not normalised to protein content. During 7 h hydrolysis experiments, glucose production increased progressively for both enzyme forms. Across the tested enzyme dilutions, immobilised cellulase generated approximately 88–91% of the glucose produced by free cellulase. The immobilised enzyme also retained approximately 64% of its initial hydrolysis performance after five reuse cycles. These findings demonstrate the potential of magnetic cellulase nanobiocatalysts for recoverable and reusable hydrolysis of lignocellulosic biomass. However, further studies are required to determine protein-normalised activity, immobilisation efficiency, longer-term stability, process economics and industrial scalability. Full article