Search Results (284)

Lignin valorization is a central objective of modern biorefinery research. This study investigates the catalytic depolymerization of two technical lignins, kraft lignin from beech hardwood and natron lignin from annual plants, via two complementary routes: analytical catalytic pyrolysis (Py-GC/MS, 300–600 °C) and hydrogenolysis (250–310 °C, Ru/C, isopropanol/H₂). In Py-GC/MS experiments, noble-metal catalysts on carbon supports (Ru/C, Pd/C, RuPd/C) were screened. Relative compound distributions revealed phenolic derivatives as the dominant products, with Ru/C yielding the highest conversion for lignin from annual plants at 500 °C and Pd/C proving most selective for hardwood lignin at 400 °C. Hydrogenolysis was optimized through a five-level, three-factor central composite design, varying temperature, residence time, and catalyst loading. Lignin conversion ranged from 64 to 83 wt% and bio-oil yield from 69 to 89 wt%. A regression model identified optimal conditions at 295 °C, 32 min, and 17 wt% Ru/C. Catalyst regeneration via solvent washing, H₂O₂ oxidation, and controlled thermal treatment resulted in only an 8% decrease in lignin conversion. The results demonstrate that lignin origin, catalyst type, and depolymerization pathway jointly govern product selectivity, highlighting clear strategies for targeted phenolic compound production. Full article

We evaluated the effect of ammonium sulfate, a major component of airborne particulate matter, in the quantification of airborne micro- and nanoplastics (AMNPs) by analytical pyrolysis–gas chromatography-mass spectrometry (Py-GC/MS). Analytical pyrolysis has shown promising potential in providing mass-based information on AMNPs, which are compatible with established standard protocols to monitor airborne particulate matter. Py-GC/MS can be performed with little to no sample preparation, minimizing the risk of polymer loss or sample contamination. However, reactive components of particulate matter, such as inorganic salts, can interfere with the Py-GC/MS measurement of polymers, leading to over/underestimation of the polymer content and instrument contamination. In this study, we have shown that ammonium sulfate can generate matrix interference in the quantification of AMNPs in PM_2.5. We have provided a solution to this issue based on water rinsing of the particulate matter directly inside the pyrolysis crucible, avoiding sample loss and preventing instrument contamination. Full article

The iconic Dali’s painting The Temptation of St. Anthony dated 1946, housed in the Royal Museums of Fine Arts of Belgium since 1965, displays worrying surface conditions in specific areas, notably the figure of St. Anthony. The problematic paint layers similarly exhibit uneven transparency and a rugged surface irrespective of their color, raising questions about whether these features reflect deliberate artistic intent or material degradation. To evidence potential degradation mechanisms and to identify the associated painting materials, Dali’s picture has been investigated through a large panel of imaging and analytical techniques, including digital microscopy, MA-XRF, Raman and FT-IR spectroscopies, XRD and Py-GC–MS. The obtained results were subsequently assessed against the material and technical information collected from Dali’s 50 Secrets of Magic Craftsmanship, as well as against archival photographs. By combining historical and multi-analytical approaches, it was possible to diagnose the altered condition of the artwork, but above all to determine when and how the deterioration patterns took place. Visible changes of appearance occurred prior to 1965 and were most probably already initiated during the curing and drying processes of the paint films. The present study tends to demonstrate the key roles of mobile resin acids from amber, reactive zinc oxide pigment suspected of containing crystal defects, uncured lead-white-rich underlayers, and chlorine environmental contamination, regarding the early and peculiar degradation behavior observed on Dali’s masterpiece. Full article

The widespread use of conventional plastic mulch films in agriculture contributes significantly to soil pollution due to their non-biodegradable nature. This study explores the potential of novel bio-based mulch films composed of chitosan, carboxymethyl cellulose, and sodium alginate, formulated in different ratios (1:1 and 17:3), with or without enrichment with monoammonium phosphate (MAP), to serve as biodegradable films with potential nutrient-releasing functionality as alternatives to conventional plastics. A multi-analytical approach, including elemental and isotopic analysis (EA-IRMS), biodegradation assays, and pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS), was employed to assess their chemical properties, degradation behavior, and environmental compatibility. The results demonstrated that the 1:1 films, both with and without MAP, achieved over 90% biodegradation within 120 days under controlled soil conditions, in agreement with international criteria for soil biodegradability. In contrast, the 17:3 films showed reduced degradation, especially without MAP enrichment, highlighting the influence of polymer composition on microbial degradation. Isotopic tracing confirmed MAP integration and revealed composition-dependent fractionation effects. Py-GC-MS provided structural fingerprints of film components and putatively annotated nitrogen-containing compounds indicative of chitosan presence. Overall, these results demonstrate that the 1:1 films can be considered viable, multifunctional, and soil-friendly alternatives to conventional plastic mulches for sustainable agriculture. Full article

Cellulose has received significant attention, given its high demand for the transition to sustainable fuels and renewable energy, addressing the environmental challenges of fossil fuels. Fast pyrolysis is a process that can transform cellulose into bio-oil. Although the bio-oils produced contain considerable amounts of oxygen and water, they are highly corrosive and highly viscous, which limits their utility as biofuels. Pyrolysis bio-oils require upgrading to remove oxygen and corrosive components, thereby enhancing their stability for use as biofuels and their environmental sustainability. This study investigates the catalytic pyrolysis of cellulose without a catalyst and with Ga/HZSM-5 catalysts with various gallium loadings (0.3, 3 and 9 wt%) and bulk Ga₂O₃ catalysts using pyrolysis/gas chromatography–mass spectrometry (Py/GC-MS). The catalytic influence of different gallium loadings on HZSM-5 in cellulose pyrolysis reactions is discussed using a range of characterisation techniques, including ICP, XRD, N₂ porosimetry, DRIFTS, and TPRS. The main production of oxygenated compounds (furan, sugar, ketone and phenol) and hydrocarbon products, including total aromatic and monocyclic and polycyclic aromatics, as well as benzene, toluene, xylene (BTX) and naphthalene compounds, using a family of Ga-doped HZSM-5 catalysts for cellulose pyrolysis is investigated for making sustainable cellulose-derived fuel. Ga(3)/HZSM-5 formed the highest amount of aromatics, displaying that aromatic yield depends on the Brønsted-to-Lewis acid balance (2.3 ratio) and total acidity (1.03 mmol·g⁻¹), rather than on gallium loading alone. Full article

Acrylate-based self-polishing copolymer antifouling paint particles (SPC-APPs) are persistent micropollutants that act as carriers for biocidal heavy metals, posing significant ecological hazards to aquatic ecosystems. Despite their toxicity, the occurrence, characterization, and metal-leaching risks of SPC-APPs in estuarine environments remain largely understudied. This study investigated the contamination characteristics of SPC-APPs in surface sediments from the Yangtze River Estuary, a hotspot of shipping activity. A multi-technique analytical protocol was employed, combining density separation with scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), inductively coupled plasma mass spectrometry (ICP-MS), and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) to characterize the morphology, quantify particle abundance, and assess the correlation between SPC-APPs and sedimentary heavy metals. SPC-APPs were ubiquitously detected across all sampling sites, with abundances ranging from (0.82 ± 0.15) × 10³ to (3.65 ± 0.42) × 10³ particles g⁻¹ dry sediment. A distinct distribution property (South Branch > North Branch > offshore shoal) was identified, primarily driven by shipping density and hydrodynamic sorting. Morphologically, particles exhibited irregular, abraded surfaces, with EDS confirming Cu (1.76~5.63 wt%) and Zn (0.27~3.65 wt%) as major metallic components. Py-GC/MS analysis identified specific mass fragments (m/z 41, 69, 87) as diagnostic markers. Strong positive correlations were observed between SPC-APP abundance and sediment Cu (r = 0.82, p < 0.01) and Zn (r = 0.76, p < 0.01) concentrations, indicating that these particles are a primary source of metal contamination. Ecological risk assessment based on sediment quality benchmarks showed that Cu in the South Branch reached 82~91% of the probable effect concentration (PEC), highlighting potential risks to benthic organisms. This study provides critical baseline data on the distribution and speciation of SPC-APPs, underscoring their role as vectors for toxic metals and the need for targeted pollution control in high-shipping-intensity estuarine regions. Full article

Biomass is characterized by its diversity and wide availability. Co-pyrolysis technology is considered a promising approach for high-quality conversion and high-value utilization of biomass, representing a critical pathway toward environmental sustainability. This study selected rice husk and pine as representative herbaceous and woody biomass materials. Using a thermogravimetric analyzer (TGA) and Py-GC/MS, we systematically investigated the synergistic effects during co-pyrolysis, examined their underlying mechanisms, and analyzed changes in product distribution. The results indicate that the blend containing 30% rice husk exhibited the most pronounced synergistic effect. Specifically, the experimental char yield and pyrolysis activation energy were 9.7% and 10.5% lower than the theoretically calculated values, respectively. Both the blending ratio and heating rate were found to significantly influence these synergistic interactions. The observed synergy is attributed to the migration of alkali metals from rice husk ash, which enhances reaction rates and promotes specific pathways such as cellulose ring-opening cleavage and hemicellulose deacetylation. Consequently, the product distribution shifts toward lighter compounds, including aldehydes, ketones, and alcohols. This study clarifies the central catalytic role of herbaceous biomass ash and highlights the critical function of alkali metal migration in regulating product selectivity, thereby providing theoretical support for efficient pyrolytic conversion. Full article

Catalytic pyrolysis is a crucial technology for lignin valorization, where the catalyst support itself can play a pivotal role in influencing the catalytic process. This study systematically investigates and compares the distinct catalytic effects of two commonly used catalyst supports, HZSM-5 zeolite and activated carbon (AC), during lignin pyrolysis. Macrokinetic analysis was conducted using TGA coupled with the Friedman kinetic model to determine the apparent activation energies (Ea) and coke yields. The evolution of functional groups was analyzed using Py-GC/MS coupled with quantitative functional group indexing. Additionally, the evolution of small-molecule gases during catalytic pyrolysis was monitored using TGA-FTIR. The results demonstrate differences in the catalytic pathways promoted by HZSM-5 and AC. HZSM-5 effectively deoxygenated lignin by removing methoxy and hydroxyl groups, resulting in a reduction in Ea by 83 kJ/mol at 80% conversion and suppression of coke formation. In contrast, AC, exploiting its large specific surface area as a reaction platform, promoted the conversion of methoxy groups into methyl and hydroxyl functional groups, rather than directly removing them. Moreover, the use of AC led to a marked increase in Ea, and the coke yield increased by 2.5%. This study provides valuable insights for the rational design of efficient catalyst systems for biomass conversion. Full article

The carved lacquer horse-hoof-shaped box excavated from Yulin, Shaanxi Province, represents a typical example of lacquerware preservation in the arid environment of northern China, exhibiting multiple deterioration phenomena, including substrate deformation, lacquer film peeling, and pigment fading. To systematically analyze its structural composition and craftsmanship features, this study employed multiple analytical techniques, including ultra-depth microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), confocal laser micro-Raman spectroscopy (Raman), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Based on these analyses, a targeted conservation protocol was developed. Results revealed that the carved lacquer horse-hoof-shaped box has a wooden substrate structure, with the lacquer ash layer composed of mixed materials, including calcium carbonate (CaCO₃), quartz (SiO₂), and hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂). The lacquer film layer contains Chinese lacquer and plant oils, with cinnabar applied as surface decoration. Based on these findings, a stratified reinforcement conservation strategy was proposed: under dynamic monitoring with optical fiber sensors and three-dimensional scanning, the wooden substrate was reinforced with moisture-curable polyurethane (MCPU), the lacquer ash layer was strengthened with acrylic emulsion (Primal AC33), aged areas were restored with nano calcium hydroxide (Ca(OH)₂) aqueous dispersion, and polyethylene glycol (PEG 400) poultice application was implemented to restore the flexibility of the lacquer film. This research significantly enhanced the integrity and stability of the carved lacquer horse-hoof-shaped box, providing practical evidence and technical references for the scientific conservation of lacquerware excavated from arid regions of northern China. Full article

The aim of this study is to investigate the impact of layered nanomodifiers with distinct chemical structure and morphology, namely graphene nanoplates (GnP) and sodium montmorillonite (Na-MMT), on thermal degradation of polylactic acid (PLA). The exploration was performed with thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and pyrolytic gas chromatography–mass spectrometry (PyGCMS). The findings revealed a catalytic effect of Na-MMT on PLA thermal destabilization, manifested in accelerated degradation and the notable change in the composition of pyrolysis products. In contrast, the incorporation of graphene nanoplates into the PLA matrix induced a “barrier effect”: it imposed diffusion limitations on the emission of volatile degradation products during pyrolysis, which enhanced the thermal stability of the PLA/GnP composite and led to quantitative alterations in the distribution of major pyrolysis products. To elucidate the underlying degradation pathways, authors proposed a model kinetic analysis of thermal degradation for both PLA/GnP and PLA/Na-MMT composites. The analysis clearly distinguished the mechanistic differences between the two systems: while Na-MMT promotes catalytic decomposition, GnP primarily acts as the physical barrier retarding mass transport and delaying the thermal degradation development. Good alignment of theoretical model–kinetic predictions with Pyrolysis–GC/MS observations confirms the robustness of the suggested kinetic modeling method. Full article

The anaerobic thermal decomposition of plant biomass produces raw materials such as wood charcoal, wood oil, or biogas, which can be used to replace conventional fossil fuels. This enables the development of environmentally friendly alternatives to traditional fuels without the need to develop new technologies, such as engines. The aim of the study was to verify the substances produced during the anaerobic thermal decomposition process of wheat straw. Measurement was carried out by pyrolysis at eight selected temperatures between 350 °C and 1050 °C, with an increase of 100 °C. The analysis was performed on a pyrolyzer coupled to a gas chromatograph (PY/GC-MS). An ANOVA test was used to detect the significance of the results. Based on the ANOVA analysis, the distribution of compound classes in the three temperature regimes was statistically significant. Phenolic compounds reached their highest relative abundance (or relative content) at 650 °C, while PAHs (polycyclic aromatic hydrocarbons) were absent below 550 °C and increased sharply above 850 °C. The results illustrate the thermal decomposition pathway of straw biomass: low-temperature pyrolysis favors the formation of oxygen-rich bio-oils, while higher temperatures increase aromatic condensation and PAH production. Full article

Microplastics (MPs) and Antifouling Paint Particles (APPs) are pervasive anthropogenic pollutants that threaten global ecosystems, with distinct yet overlapping environmental behaviors and toxic impacts. MPs disperse widely in aquatic systems via runoff and wastewater; their toxicity stems from physical, chemical, and synergistic effects. APPs are concentrated in coastal zones, estuaries, and shipyard areas, and are acutely toxic due to their high metal and biocide content. This study systematically characterized the composition, concentration, and size distribution of common MPs and APPs in ship-hull derusting wastewater produced by ultra-high-pressure water jetting, using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) coupled with particle size analysis. The wastewater exhibited a total suspended solids (TSS) concentration of 20.04 g·L⁻¹, within which six types of MPs were identified at 3.29 mg·L⁻¹ in total and APPs were quantified at 330.25 mg·L⁻¹, representing 1.65% of TSS. The residual fraction primarily consisted of algae, biological debris, and inorganic particles. Particle size distribution ranged from 3.55 to 111.47 μm, with a median size (D50) of 31 μm, while APPs were mainly 5–100 μm, with 81.4% < 50 μm. Extrapolation to the annual treated ship-hull surface area in 2024 indicated the generation of ~57,440 m³ wastewater containing ~0.2 tons of MPs and ~19 tons of APPs. These findings highlight the magnitude of pollutant release from ship maintenance activities and underscore the urgent need for targeted treatment technologies and regulatory policies to mitigate microplastic pollution in marine environments. Full article

Changes in preservation conditions act as an important environmental filter driving shifts in microbial communities. However, the precise identities, functional traits, and ecological mechanisms of the dominant agents driving stage-specific deterioration remain insufficiently characterized. This study investigated microbial communities and dominant fungal degraders in waterlogged versus dried bamboo slips using amplicon sequencing, multivariate statistics, and microbial isolation. Results revealed compositionally distinct communities, with dried slips sharing only a small proportion of operational taxonomic units (OTUs) with waterlogged slips, while indicating the persistence of a subset of taxa across preservation states. A key discovery was the dominance of Fonsecaea minima (92% relative abundance) at the water-solid-air interface of partially submerged slips. Scanning electron microscopy (SEM) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) indicate that this fungus forms melanin-rich, biofilm-like surface structures, suggesting enhanced surface colonization and stress resistance. In contrast, the fungal community isolated from dried slips was characterized by Apiospora saccharicola associated with detectable xylanase activity. Meanwhile, the xerophilic species Xerogeomyces pulvereus dominated (99% relative abundance) the storage box environment. Together, these results demonstrate that preservation niches select for fungi with distinct functional traits, highlighting the importance of stage-specific preservation strategies that consider functional traits rather than taxonomic identity alone. Full article

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive pollutants across different aquatic systems on a global basis, yet integrated assessments linking wastewater, riverine, and marine environments remain scarce. The present study provides the first comprehensive evaluation of MPs in three interconnected aquatic matrices of Northern Greece, namely surface seawater from the Thermaic Gulf, surface freshwater from the Axios River, and influent and effluent wastewaters from the Thessaloniki WWTP (Sindos). During two sampling periods spanning late 2023 and spring 2024, suspected MPs were isolated, morphologically classified by stereomicroscopy, and chemically characterized through pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). MPs were ubiquitously detected in all substrates, exhibiting distinct spatial and compositional patterns. Seawater samples displayed moderate concentrations (1.5–4.8 items m⁻³) dominated by fibers and fragments, while riverine samples contained slightly higher levels (0.5–2.5 items m⁻³), enriched in fibrous forms and polyolefins (PE, PP). Wastewater influents showed the highest MP abundance (78–200 items L⁻¹; 155.6–392.3 µg L⁻¹), decreasing significantly in effluents (11–44 items L⁻¹; 27.8–74.3 µg L⁻¹), corresponding to a removal efficiency of 81–87.5%, being the first indicative removal efficiencies in a Greek WWTP. Among the different polymers detected, polyethylene, polypropylene, and poly(ethylene terephthalate) were identified as the most prevalent polymers across all matrices. Interestingly, a shift toward smaller size classes (125–500 µm) in effluents indicated in-plant fragmentation processes, while increased concentrations during December coincided with increased rainfall, highlighting the influence of hydrological conditions on MP fluxes. The combined morphological and polymer-specific approach provides a holistic zunderstanding of MP transport from inland to marine systems, establishing essential baseline data for Mediterranean environments and reinforcing the need for integrated monitoring and mitigation strategies. Full article

Waste valorization is a necessary activity for the development of the circular economy. Pyrolysis as a waste valorization pathway has been extensively studied, as it allows for obtaining different fractions with diverse and valuable applications. The joint analysis of results generated by thermogravimetry (TGA) and analytical pyrolysis (Py-GC/MS) allows for the characterization of waste materials and the assessment of their potential as sources of energy, value-added chemicals and biochar, as well as providing awareness for avoiding potential harmful emissions if the process is performed without proper control or management. In the present study, these techniques were employed on three greenhouse plant residues (broccoli, tomato, and zucchini). Analytical pyrolysis was conducted at eight temperatures ranging from 100 to 800 °C, investigating the evolution of compounds grouped by their functional groups, as well as the predominant compounds of each biomass. It was concluded that the decomposition of biomass initiates between 300–400 °C, with the highest generation of volatiles occurring around 500–600 °C, where pyrolytic compounds span a wide range of molecular weights. The production of organic acids, ketones, alcohols, and furan derivatives peaks around 500 °C, whereas alkanes, alkenes, benzene derivatives, phenols, pyrroles, pyridines, and other nitrogenous compounds increase with temperature up to 700–800 °C. The broccoli biomass exhibited a higher yield of alcohols and furan derivatives, while zucchini and tomato plants, compared to broccoli, were notable for their nitrogen-containing groups (pyridines, pyrroles, and other nitrogenous compounds). Full article