Search Results (1,768)

The maritime transport sector’s reliance on fossil-based fuels remains a major contributor to global greenhouse gas emissions, underscoring the urgent need for sustainable alternatives such as marine biofuels. Thermochemical pyrolysis of biomass and plastic waste represents a promising route for producing renewable and recycled marine fuel feedstocks. This review provides an integrated analysis of the full production and upgrading chain, encompassing pyrolysis of lignocellulosic biomass and polymer-derived resources, catalytic upgrading, and qualitative evaluation of product distribution and yield trends. Particular emphasis is placed on montmorillonite-based catalysts as naturally abundant, low-cost, and environmentally benign alternatives to conventional zeolites. The review systematically examines the influence of key montmorillonite modification strategies, including acid activation, pillaring, and ion-exchanged, on acidity, textural properties, and catalytic performance in catalytic cracking and hydrodeoxygenation processes. The analysis shows that catalyst modification strongly governs the yield, selectivity, and reproducibility of biofuels. By adopting this integrated perspective, the review extends beyond existing works focused on isolated upgrading steps or zeolitic catalysts. Key research gaps are identified, particularly regarding long-term catalyst stability, deep deoxygenation of real bio-oils, and compliance with marine fuel standards. Full article

Potassium (K) fertilization plays a key role in regulating stem morphology, particularly stem diameter, yet the influence of different K fertilizer formulations on stem structure and tensile strength remains insufficiently understood. Cereal straw is a key lignocellulosic by-product with growing importance in the circular bioeconomy. Thus, the aim of this study was to determine the links between potassium nutrition, stem structure, and mechanical behavior for four cereal species: wheat, barley, rye, and oats. There were three potassium fertilization levels (0, 60, and 120 kg K ha⁻¹) conducted in a field experiment in eastern Croatia (2021/2022). At maturity, stem morphology, macroelements (Ca, K, P, C, N), acid detergent fiber (ADF), neutral detergent fiber (NDF), and uniaxial tensile properties (maximum force, tensile strength, Young’s modulus) were determined. Cereal species was the dominant source of variation (p < 0.0001) for all traits, whereas the main effect of K was generally weak and significant only for stem diameter at the midpoint and N concentration, although K × species interactions were frequent. Oats and rye showed the most vigorous biomass production, whereas wheat exhibited by far the highest tensile strength (about 120 MPa) and stiffness (6.23 GPa), together with the highest ADF, while barley had the greatest NDF. Oat stems had the lowest ADF and NDF, indicating less lignified, more digestible tissues but mechanically weaker straw. Mechanical traits were tightly and positively correlated with ADF, NDF, and CN ratio, whereas P showed weak or negative associations with plant size and strength. Therefore, for targeted straw valorization, cereal species selection is paramount, with potassium fertilization playing a secondary, species-dependent role. Full article

Driven by the energy transition within the framework of the United Nations Framework Convention on Climate Change, second-generation (2G) ethanol stands out as a technical and sustainable alternative to fossil fuels. Although first-generation ethanol, produced from saccharine and starchy feedstocks, represents an advance in mitigating emissions, its expansion is limited by competition with areas destined for food production. In this context, 2G ethanol, obtained from residual lignocellulosic biomass, emerges as a strategic route for diversifying and expanding the renewable energy matrix. Thus, this work discusses the current state of 2G ethanol technology based on the gradual growth in production and the consolidation of this route over the last few years. Industrial second-generation ethanol plants operating around the world demonstrate the high potential of agricultural waste as a raw material, particularly corn straw in the United States, which offers a lower cost and significant yield in the production of this biofuel. Similarly, in Brazil, sugarcane by-products, especially bagasse and straw, are consolidating as the main sources for 2G ethanol, integrated into the biorefinery concept and the valorization of by-products obtained during the 2G ethanol production process. However, despite the wide availability of lignocellulosic biomass and its high productive potential, the consolidation of 2G ethanol is still conditioned by technical and economic challenges, especially the high costs associated with pretreatment stages and enzymatic cocktails, as well as the formation of inhibitory compounds that compromise the efficiency of the process. Genetic engineering plays a particularly important role in the development of microorganisms to produce more efficient enzymatic cocktails and to ferment hexoses and pentoses (C₆ and C₅ sugars) into ethanol. In this scenario, not only are technological limitations important but also public policies and tax incentives, combined with the integration of the biorefinery concept and the valorization of (by)products, which prove fundamental to reducing costs, increasing process efficiency, and ensuring the economic viability and sustainability of second-generation ethanol. Full article

High-density aviation fuels and diesel-range cycloalkanes are in high demand for the transportation sector, but the development of sustainable and high-efficiency synthesis routes from biomass-derived platform chemicals remains a key challenge. High-density aviation fuel and diesel-grade cycloalkanes were successfully synthesized from biomass-derived isophorone and furfural through a continuous process of selective hydrogenation, aldol condensation, and hydrodeoxygenation reaction. (E) 2-(Furan-2-methylene)-3,5,5-trimethylcyclohex-1-one (1A) was obtained by selective hydrogenation of isophorone to obtain 3,3,5-trimethylcyclohexanone (TMCH), which was then subjected to aldol condensation with furfural. The system studied key reaction parameters such as solvent type, temperature, catalyst type, catalyst loading, and reaction time that affect the aldol condensation of TMCH and furfural. The yield of 1A reached 98.69%, under optimized conditions using NaOH as the catalyst at a molar ratio of 3,3,5-trimethylcyclohexanone:furfural = 1:1, NaOH 0.15 g, anhydrous ethanol as the solvent, and a reaction temperature of 313 K for 1 h. A series of nickel-based catalysts supported on porous materials, including SiO₂, CeO₂, Al₂O₃, Hβ, and HZSM-5, were prepared and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These catalysts were evaluated for the hydrodeoxygenation of 1A. Among them, the 10% Ni-SiO₂ catalyst exhibited the highest catalytic activity, affording a C₉–C₁₄ cycloalkane yield of 88.32% and a total carbon yield of 99.6%. This work demonstrates a promising and sustainable strategy for producing branched cycloalkanes in the diesel and jet fuel range from lignocellulosic biomass-derived platform chemicals. Full article

The production of essential oils generates substantial quantities of solid post-distillation residues, a largely unutilized waste stream rich in bioactive compounds (e.g., phenolics, flavonoids) as well as polysaccharides. Managing this organic waste presents both environmental and economic challenges. This review critically examines environmentally friendly green innovations and resource-efficient technologies within circular bio-economy strategies for valorizing these residues, focusing on four primary conversion pathways: physico-mechanical, thermochemical, biological, and chemical methods. We highlight their potential for practical applications, including the extraction of active compounds for food, cosmetic, and pharmaceutical industries, utilization in agriculture, incorporation into construction materials and wastewater treatment. Despite these opportunities, wider industrial adoption remains limited by high processing costs and the lack of scalable, cost-effective technologies. Key research gaps included the need for methods applicable at the farm level, optimization of the residue-specific conversion process, and life-cycle assessments to evaluate environmental and economic impacts. Addressing these gaps is crucial to fully exploit the economic and ecological potential of post-distillation solid residues and integrate them into sustainable circular bio-economy practices through various processes. Full article

Fruit shrubs’ lignocellulosic biomass remaining as waste after harvesting and/or after pruning is an underutilized, little-explored bioresource. Sea buckthorn (Hippophae rhamnoides L.), aronia (Aronia melanocarpa) and blackcurrant (Ribes nigrum) berries are rich in biologically active compounds, so these shrubs’ woody biomass derivatives are prospective investigation objects. The influence of pre-treated biomass, extracts, and purified proanthocyanidins on the oxidative stability of lipid-based systems was studied by accelerated oxidation method. Emulsion stability, antimicrobial activity against bacteria that causes acne—Cutibacterium acnes; contaminating wounds; skin care products—Streptococcus pyogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus; cytotoxicity and phototoxicity of extracts and proanthocyanidins on HaCaT human keratinocytes were tested. The study established that biomass, lipophilic extracts obtained using liquefied hydrofluorocarbon, and hydrophilic extracts obtained by aqueous ethanol increased oxidative stability of lipid-based formulations. Compounds with skin-protecting properties were detected. Sea buckthorn and aronia hydrophilic extracts and proanthocyanidins had the highest antimicrobial activity. Low phototoxicity was revealed, emphasizing safety and applicability in topical formulations; human HaCaT keratinocyte viability was the best with aronia extracts, but none of the other samples decreased cell viability by more than 50%. It was proven that agro-waste biomass is a prospective source of multifunctional ingredients for cosmetic and pharmaceutical topical formulations. Full article

Faced with the depletion of fossil resources and the need to promote a circular economy, lignocellulosic biomass represents a solution for energy transition and bioeconomy. However, wood sawdust, which contains bioactive compounds (secondary metabolites), is often burned in the open by many sawmills. This study aims to valorize Framiré wood sawdust by extracting its secondary metabolites through maceration and infusion, then converting the depleted residue into combustible briquettes. The yellowness index of the extracts ranged from 73.490 ± 0.021 (maceration) to 81.720 ± 0.014 (infusion). The total phenolic content varied from 0.097 ± 0.001 to 0.63 ± 0.049 gGAE/100 g dry matter for maceration and infusion, respectively. The extraction of bioactive compounds did not significantly affect the energy or mechanical properties of the fuels. Their higher heating value ranged from 26,153 ± 92 to 26,201 ± 90 kJ/kg for fuels with and without secondary metabolites, respectively. The Shock Resistance Index ranged from 139.33 ± 7.51% (without metabolites) to 153.00 ± 5.20% (with metabolites). A significant difference was observed in the specific consumption of the fuels, decreasing from 1.400 ± 0.100 to 0.861 ± 0.001 kg/L for fuels without and with secondary metabolites, respectively. These results open promising prospects, particularly for the use of Framiré extracts to develop flame-retardant products for wood and its derivatives. Full article

Microbial lipid production from renewable carbon sources, particularly lignocellulosic hydrolysates, is a promising alternative to plant-derived oils and fats for food applications, as it can minimize the land use by utilizing agricultural wastes and byproducts from food production. In this context, a standard approach to prevent oxygen limitation at reduced air gassing rates during long-term aerobic microbial processes is to operate bioreactors at increased pressure for elevating the gas solubility in the fermentation broth. This study investigates the effect of absolute pressures of up to 2.5 bar on the conversion of the carbon sources (glucose, xylose, and acetate), growth, and lipid biosynthesis by Cutaneotrichosporon oleaginosus converting a synthetic nutrient-rich lignocellulosic hydrolysate at low air gassing rates of 0.1 vessel volume per minute (vvm). Increasing pressure delayed xylose uptake, reduced acetic acid consumption, and reduced biomass formation. Lipid accumulation decreased with increasing pressure, except for fermentations at 1.5 bar, which achieved a maximum lipid content of 83.6% (±1.6, w/w) (weight per weight in %). At an absolute pressure of 1.5 bar, a lipid yield from glucose, xylose, and acetic acid of 38% (w/w) was reached after 6 days of fermentation. The pressure sensitivity of C. oleaginosus may pose challenges on an industrial scale due to the dynamic changes in pressure when the yeast cells pass through the bioreactor. Increasing liquid heights in full-scale bioreactors will result in increased hydrostatic pressures at the bottom, substantially reducing lipid yields, e.g., to only 23% (w/w) at 2.0–2.5 bar, as shown in this study. However, further scale-up studies with dynamic pressure regimes (1–2.5 bar) may help to evaluate scale-up feasibility. Full article

The synthesis of sodium carboxymethylcellulose (NaCMC) from lignocellulosic pineapple stubble provides a renewable alternative to conventional cellulose sources for pharmaceutical applications. This study aimed to obtain NaCMC from pineapple biomass, characterize it according to pharmacopoeial specifications, and formulate hydrogels as a physicochemical proof-of-concept for future drug delivery and tissue regeneration applications. NaCMC was successfully synthesized and met the requirements of the Mexican Pharmacopoeia. Hydrogels were prepared by blending NaCMC with gelatin and crosslinking with citric acid. Spectroscopic, morphological, and thermal analyses confirmed the structural equivalence between pineapple-derived NaCMC (NaCMC-Pi) and commercial NaCMC (NaCMC-Co). Swelling and gel fraction studies showed that NaCMC-Pi hydrogels exhibited a higher gel fraction, indicating a more crosslinked network, which corresponded to lower swelling capacity but higher thermal stability compared to NaCMC-Co hydrogels. Overall, these results demonstrate that pineapple stubble is a viable source of pharmaceutical-grade NaCMC and that the resulting hydrogels provide a robust physicochemical basis for future biomedical validation. The use of agro-industrial residues additionally offers a complementary sustainability benefit without compromising pharmaceutical performance. Full article

This study assessed the production and characterisation of biochars derived from the pyrolysis and co-pyrolysis of urban biosolids (BSs) combined with two lignocellulosic biomasses: rice husk (RH) and pruning waste (PW). The treatments were conducted at 300, 400, and 500 °C to evaluate the influence of temperature and mass ratio on the physicochemical, structural, and biological properties of the material. Co-pyrolysis significantly improved the material’s properties, enhancing carbon content, surface area, porosity, and pH, while reducing ash and heavy metal concentrations. RH promoted greater porosity and alkalinity, whereas PW increased carbon content and improved maize germination. Biochars produced at 400–500 °C met the stability criterion (H/C < 0.7) set by the International Biochar Initiative (IBI) and the European Biochar Certificate (EBC). However, zinc (Zn) remained the most limiting element for certification. Overall, the findings demonstrate that the co-pyrolysis of BSs with agroforestry biomasses is an effective and sustainable strategy for generating stable and environmentally safe biochars, suitable for use as soil amendments and for the sustainable valorisation of BSs. Full article

Alkaline pretreatment of wheat straw could significantly augment enzymatic hydrolysis for producing fermentable sugars, which is a pivotal process for the conversion of lignocellulosic biomass into advanced biofuels, biomaterials, or biochemicals. Yet, the enzymatic conversion process system is complex and multivariate, and study on the interaction mechanism of the key parameters in enzymatic hydrolysis is still lacking. Therefore, in this work, multivariate data analysis (MDA) (i.e., principal component analysis (PCA) and partial least square (PLS)) was conducted to reveal the inherent relationship and the significance of these factors in a modified alkali pretreatment system. A robust model, developed from 140 enzymatic hydrolysis datasets, was validated with an additional 20 datasets, demonstrating the predictive prowess of the PLS model. MDA identified that cellulase dosage, mechanical refining, dye adsorption value, and solid content were paramount variables. The integration of cellulase and xylanase notably elevated sugar yields and the conversion rates of carbohydrates, surpassing those of single enzyme treatments. The model’s predictive accuracy, reflected in the close alignment between observed and predicted data, underscores its suitability for optimizing and controlling the enzymatic hydrolysis process. This study paves a way for data-driven strategies to enhance industrial bioprocessing of lignocellulosic feedstocks. Full article

The growing demand for sustainable and renewable materials has intensified interest in agro-industrial waste as an alternative source of cellulose. This review critically examines current approaches to cellulose production from major agro-industrial residues, including cereal straw, corn residues, rice waste, sugarcane bagasse, and oilseed by-products. Emphasis is placed on the relationship between feedstock composition and extraction efficiency, highlighting how lignin distribution, hemicellulose content, and mineral impurities influence pretreatment severity, cellulose yield, and process sustainability. The review systematically analyzes chemical, enzymatic, and mechanical processing routes, with particular attention being paid to pretreatment strategies, fibrillation intensity, and yield variability. Beyond cellulose recovery, key sustainability indicators—such as energy demand, water and chemical consumption, waste generation, and chemical recovery—are evaluated to provide a system-level perspective on process efficiency. The analysis demonstrates that cellulose yield alone is an insufficient criterion for sustainable process design and must be considered alongside environmental and techno-economic metrics. Advanced applications of agro-waste-derived cellulose are discussed using a feedstock-driven approach, showing that high functional performance can often be achieved with moderately processed cellulose tailored to specific end uses. Finally, the review addresses challenges related to feedstock heterogeneity, mineral management, standardization, and industrial scale-up, underscoring the importance of biorefinery integration, closed-loop resource management, and harmonized quality descriptors. These insights provide a foundation for the development of scalable and sustainable cellulose production pathways based on agro-industrial waste. Full article

The global floriculture industry generates massive organic residues that pose environmental risks but offer untapped bioenergy potential. This review evaluates the feasibility of valorizing flower waste through anaerobic digestion (AD) by synthesizing experimental data on substrate characterization, pretreatment efficacy, and reactor performance. Results indicate that biochemical methane potentials (BMP) vary significantly, ranging from 89 to 412 mL_CH4·g⁻¹_VS, depending on plant species and tissue composition. Major bottlenecks include high lignocellulosic recalcitrance (lignin content up to 0.28 g·g⁻¹_TS) and the presence of inhibitory phenolic compounds. Analysis reveals that while alkaline pretreatments effectively disrupt lignocellulosic structures, co-digestion strategies are essential to mitigate inhibition and balance nutrient ratios. However, current research is predominantly limited to laboratory-scale batch assays, leaving a critical knowledge gap regarding long-term process stability and inhibition dynamics in continuous systems. To transform this laboratory concept into a scalable technology, future efforts must focus on pilot-scale continuous reactor trials, standardized testing protocols, and comprehensive techno-economic and life cycle assessments. Full article

Agricultural biomass has potential as a renewable and versatile carbon feedstock for developing eco-friendly and biodegradable polymers capable of replacing conventional petrochemical plastics. To address the growing environmental concerns associated with plastic waste and carbon emissions, lignocellulosic residues, edible crop by-products, and algal biomass were utilized as sustainable raw materials. These biomasses provided carbohydrate-, lipid-, and lignin-rich fractions that were deconstructed through optimised physical, chemical, and enzymatic pretreatments to yield fermentable intermediates, such as reducing sugars, organic acids, and fatty acids. The intermediates were subsequently converted through tailored microbial fermentation processes into biopolymer precursors, primarily polyhydroxyalkanoates (PHAs) and lactate-based monomers. The resulting monomers underwent polymerization via polycondensation and ring-opening reactions to produce high-performance biodegradable plastics with tunable structural and mechanical properties. Additionally, the direct extraction and modification of naturally occurring polymers, such as starch, cellulose, and lignin, were explored to develop blended and functionalized bioplastic formulations. Comparative evaluation revealed that these biomass-derived polymers possess favourable physical strength, thermal stability, and biodegradability under composting conditions. Life-cycle evaluation further indicated a significant reduction in greenhouse gas emissions and improved carbon recycling compared to fossil-derived counterparts. The study demonstrates that integrating agricultural residues into bioplastic production not only enhances waste valorization and rural bioeconomy but also supports sustainable material innovation for packaging, farming, and consumer goods industries. These findings position agriculture-based biodegradable polymers as a critical component of circular bioeconomy strategies, contributing to reduced plastic pollution and improved environmental sustainability. Full article