Search Results (141)

The effects of pyrolysis temperature (400–500 °C) and time (30–90 min) on the yield and chemical and physical properties of biochar produced from almond and pistachio shells were studied using a fixed-bed pyrolyzer. Thermogravimetric analysis (TGA) was employed to characterize the kinetics of thermal degradation of the shells. This study compared the thermal behavior observed by TGA with biochar yields obtained from a fixed-bed pyrolyzer, providing insight into the agreement between laboratory-scale thermogravimetric measurements and fixed-bed pyrolysis performance. Fourier transform infrared spectroscopy (FTIR) was performed for each type of biochar. Results showed higher biochar yields from almond shells (35.0–41.3% dry basis) than from pistachio shells (26.8–36.7% dry basis). Shell type, pyrolysis temperature, pyrolysis time, and their interactions had significant effects on biochar yield. The Derivative Thermogravimetric (DTG) profiles showed distinct thermal decomposition patterns for almond and pistachio shells. Almond shells exhibited broader decomposition regions, while pistachio shells showed more distinct decomposition stages. FTIR analysis of both shell biochars indicated reduced O–H and oxygen-containing groups with increasing pyrolysis temperature and residence time, suggesting greater carbonization, aromatic enrichment, and formation of carbonaceous compounds. Greater biochar yields were obtained from the fixed-bed pyrolyzer than from TGA. A first-order kinetics model adequately described the thermal decomposition of both shell types. Apparent activation energies were 41.83–44.99 kJ mole⁻¹ for almond shells and 58.19–63.58 kJ mole⁻¹ for pistachio shells. Model validation showed a good agreement between the experimental and predicted conversion values. The results provide a basis for evaluating the potential of TGA-derived thermal behavior to inform biochar production conditions in fixed-bed pyrolysis. Full article

Coptotermes formosanus is an economically significant termite species with a highly organised caste system, in which division of labour underpins colony function. Although gut microbiota is widely recognised for its roles in host nutrition and adaptation, much less is known about how these microbial communities are structured across castes. To explore caste-related gut bacterial variation in C. formosanus, we analysed the community structure of both workers and soldiers using high-throughput amplicon sequencing targeting the bacterial 16S rRNA gene. Although both castes were dominated by Bacteroidota and Spirochaetota, which together accounted for 78.87% to 85.78% in workers and 63.31% to 84.38% in soldiers, significant caste-associated differences were evident. Workers showed significantly higher bacterial richness, as indicated by observed ASVs, Chao1 indices, and Faith’s PD. Further clear caste-associated bacterial community was revealed by beta-diversity analysis. Differential taxonomic analysis revealed distinct caste-associated enrichment patterns. In addition, co-occurrence network analysis indicated a caste-associated interaction structure, with soldier-biased taxa forming a dense, highly connected module while worker-biased taxa contributed to local structure and bridging positions. Furthermore, chemoheterotrophy and fermentation were predicted to be enriched in workers, whereas nitrate reduction, aerobic chemoheterotrophy, aromatic compound degradation, and phenotypes related to biofilm formation, stress tolerance, and mobile elements were predicted to be relatively enriched in soldiers. Moreover, qPCR analysis further showed caste-associated differences in dominant gut protists, with Pseudotrichonympha in workers significantly higher than in soldiers and positively correlated with Azobacteroides. These results provide clear evidence of caste-associated differentiation in gut microbial composition and offer a foundation for identifying novel microbial targets for termite pest management. Full article

The photocatalytic degradation of Acid Orange 7 (AO7) in aqueous solution in the presence of exfoliated C₃N₄ (n-C₃N₄) as a photocatalyst was investigated under simulated solar light irradiation. The n-C₃N₄ photocatalyst was synthesized by polymerization of urea as a precursor and characterized by UV/Vis and FTIR spectroscopy, and transmission electron microscopy. Degradation products were identified by high-performance liquid chromatography with high-resolution mass spectrometry (LC–HRMS). It was found that AO7 undergoes a series of oxidation steps mediated by radicals generated during light absorption by n-C₃N₄, as well as through a photosensitization process initiated by light absorption by AO7. This results in decolorization and the formation of aromatic and aliphatic intermediates, which undergo further oxidation to simpler compounds. Full article

The catalytic pyrolysis of post-consumer polystyrene (PS) offers a potential route to obtain styrene-rich liquid fractions from plastic waste. In this study, natural zeolites were modified by thermal activation (AT-ZN), acid treatment (AA-ZN), and protonic ion exchange (H-ZN), and their performance was evaluated under different pyrolysis temperatures (400–500 °C), heating rates (10–20 °C min⁻¹), and catalyst loadings (5–10 wt.%). Thermogravimetric analysis indicated that zeolite incorporation shifted the apparent PS degradation profile toward lower temperatures, suggesting that the modified solids altered the polymer’s thermal conversion behavior. Product-yield analysis showed that H-ZN provided the most favorable phase distribution, producing high liquid fractions while limiting solid-residue formation. AT-ZN exhibited an intermediate, comparatively stable response. In contrast, AA-ZN promoted greater solid formation and lower liquid recovery, suggesting that more severe catalytic conditions may favor secondary reactions and the accumulation of carbonaceous residues. Targeted GC–MS analysis revealed that styrene was the dominant aromatic compound among the quantified products, with H-ZN consistently showing the highest styrene proportion in the analyzed liquid fraction. Correlation analysis and ANOVA further indicated that the influence of temperature, catalyst loading, and their interactions depended strongly on the zeolite modification route. Overall, the results demonstrate that the route of modification of the natural zeolite strongly affected its composition, textural properties, acidity distribution, thermal behavior, and catalytic performance during PS pyrolysis. XRF, N₂ adsorption–desorption, NH₃-TPD, TGA/DTG, and FTIR characterization showed that AA-ZN exhibited the highest Si/Al ratio and BET surface area, whereas H-ZN presented the highest total acidity and the largest contribution of medium- and strong-acid sites. The combined characterization and pyrolysis results indicate that the preservation of styrene-rich liquid products was governed by the balance between acid-site distribution and pore accessibility, rather than by surface area or total acidity considered in isolation. Full article

Lignin, one of the most abundant renewable aromatic biopolymers on earth, represents a promising feedstock for producing high-value chemicals capable of replacing fossil-derived resources, yet its structural complexity poses significant barriers to efficient valorization. In recent years, photocatalytic transformation has emerged as an attractive strategy to overcome these limitations, employing heterogeneous catalysts to harness solar energy for the selective cleavage and functionalization of lignin under mild and sustainable conditions. This review provides a comprehensive overview of recent progress in heterogeneous photocatalysts designed for lignin degradation, emphasizing how material composition, morphological features, surface properties, and band-gap engineering influence catalytic efficiency and selectivity. Key reaction pathways and mechanistic insights are discussed to elucidate the roles of photo-generated charge-carriers, reactive oxygen species, and catalyst–lignin interactions in driving depolymerization and upgrading processes. Furthermore, we analyze current challenges—including low reaction selectivity, catalyst deactivation, and limited scalability—and highlight emerging strategies aimed at improving catalyst stability, enhancing visible-light utilization, and promoting targeted product formation. By critically examining these advancements and limitations, this review outlines future opportunities for the development of efficient, robust, and economically viable photocatalytic systems to enable the sustainable and large-scale valorization of lignin. Full article

Chlorinated benzoquinones such as 2,6-dichlorobenzoquinone (DCBQ) are toxic disinfection by-products that may persist in treated waters, requiring post-treatment strategies. In this study, the photo-Fenton process was evaluated for DCBQ degradation, with a focus on the influence of pH on kinetics, oxidation behavior, and water quality evolution. Experiments were conducted using 50.0 mg/L DCBQ, 1.0 mg/L Fe²⁺, and 2.0 mM H₂O₂ under UV irradiation (150 W) within a pH range of 3.0–12.0. Degradation followed apparent second-order kinetics, with maximum rates at acidic pH. At initial pH 3.0–5.0, rapid pollutant removal was accompanied by efficient aromaticity (UV₂₅₄) and color elimination, intense dissolved oxygen consumption, transient turbidity peaks due to intermediate formation, and increases in total dissolved solids, indicating extensive oxidation and a high degree of organic matter transformation, as inferred from indirect physicochemical indicators. At near-neutral pH, oxidation was slower, with delayed aromatic and chromophoric decay and moderate accumulation of intermediates. Mildly alkaline conditions exhibited limited radical activity, stable turbidity, and reduced mineralization. Under strongly alkaline conditions, oxidation was largely inhibited, with persistent aromaticity and negligible oxygen consumption. These findings highlight the importance of integrating advanced oxidation processes with adsorption-based systems for efficient and sustainable water treatment of emerging contaminants. Full article

Conventional composting struggles with slow fermentation and low humification efficiency in managing global food waste. While hyperthermophilic composting (HTC, >80 °C) can enhance efficiency, the microbial and metabolic drivers of accelerated humification remain unknown. Multi-omics analysis revealed that microbial restructuring during the HTC cooling stage (30–80 °C) triggers metabolic reprogramming. Enriched thermophiles (e.g., Gordonia, Cryptosporangium, Limnochordia) redirect carbon flux toward anabolism via upregulated glycolysis/gluconeogenesis and aromatic amino acid biosynthesis, while suppressing the TCA cycle. This redirected carbon flux accelerated lignocellulose degradation (2.6–3.7-fold), boosted humic acid synthesis (by 50%), and increased the humification index (by 76%). Critically, it promoted the condensation of lignin-derived phenolics with amino acids and Maillard-mediated polymerization, increasing aromatic precursors by 161%. Structural equation modeling demonstrated a strong association between microbial restructuring and humic substance formation, explaining 96% of the total variance through metabolic regulation. These mechanistic insights enable the design of high-efficiency composting systems for simultaneous waste valorization and stable humic substance production. Full article

An inevitable decrease in oil production from reservoirs all over the world necessitates the application of microbial enhancement of oil recovery (MEOR) technologies. The high total salinity of formation water is a factor strongly suppressing the growth of most industry-applicable strains of hydrocarbon-oxidizing bacteria. The halotolerant strain Ectopseudomonas guguanensis G3 isolated from an oil reservoir (Republic of Kazakhstan) has demonstrated high efficiency of oil degradation and presumable biosurfactant production. The ability of the strain to utilize crude oil, n-alkanes, toluene, and xylene and its resistance to NaCl concentrations up to 6% were shown, as well as a high decrease in the interfacial tension of the culture liquid. Genomic analysis of the strain confirmed its ability to oxidize aromatic oil compounds and a wide range of n-alkanes (with a chain length up to C₃₀) and revealed its potential capabilities to produce alginate, consume nitrate and urea as nitrogen sources, and synthesize betaine as an osmoprotectant. These findings demonstrate the high potential of E. guguanensis strain G3 to be used in oil reservoirs with high-salinity formation water in the biotechnology of oil displacement through oil degradation and in situ microbial metabolite production. Full article

This study investigates the bio-inspired photocatalytic degradation of humic acids using TiO₂-functionalized clinoptilolite (C–TiO₂) and Ag-doped TiO₂ (C–TiO₂/Ag) under UV irradiation. TiO₂ acts as an artificial analogue of naturally occurring photoactive mineral phases, while clinoptilolite provides a biomimetic scaffold mimicking mineral–organic interfaces. Ag doping enhances charge separation and promotes reactive oxygen species formation, accelerating degradation. The effects of pH and catalyst composition were evaluated over a range of conditions, including the native pH of the humic solution. Degradation was monitored via changes in UV₂₅₄ absorbance, VIS₄₃₆ absorbance, and COD values, revealing a multistage pathway: rapid decolorization of chromophoric groups, slower breakdown of aromatic structures, and final mineralization. Acidic conditions further enhanced performance through increased adsorption and ROS (reactive oxygen species) generation, while measurable activity persisted at near-natural pH values. Kinetic analysis indicated pseudo-first-order behavior, with the highest apparent rate constants obtained for VIS436 removal under C–TiO₂/Ag at pH 3 (k = 0.0166 min⁻¹), followed by COD₁ (k = 0.0190 min⁻¹), confirming faster oxidation of labile fractions and slower mineralization of recalcitrant intermediates. Therefore, the results demonstrate that semiconductor–mineral hybrid systems can serve as biomimetic platforms that reproduce and accelerate natural self-purification processes, providing mechanistic insights into nature-inspired pathways for water treatment. Full article

The removal of persistent pharmaceutical compounds such as carbamazepine (CBZ) by advanced oxidation processes (AOPs) remains a major challenge in water treatment, particularly in relation to understanding the operating conditions governing reaction kinetics and transformation pathways. In this context, this study aims to evaluate the effect of ozone concentration on the kinetics and mechanistic regimes of CBZ ozonation in aqueous solutions. Ozonation experiments were conducted in an aqueous solution at an initial CBZ concentration of 50.0 mg/L, using inlet ozone concentrations between 1.9 and 58.5 g/m³ under controlled conditions. CBZ degradation followed apparent pseudo-first-order kinetics under the studied conditions, with the corresponding apparent rate constant increasing linearly with the inlet ozone concentration. At ozone concentrations ≥ 15.7 g/m³, rapid CBZ removal was observed, together with high dissolved ozone levels, accelerated loss of aromaticity, and transient formation of colored oxidation intermediates, which were subsequently degraded. In contrast, low ozone concentrations led to ozone-limited kinetics and slower aromatic breakdown. The pH evolution revealed two distinct kinetic regimes, transitioning from oxidant-limited to reaction-controlled behaviour and stabilizing at pH 4.3. These findings may provide guidelines for optimizing ozone-based treatment processes. The insights gained may be applied to the design, scale-up, and operation of advanced and hybrid oxidation systems. Full article

This study aims to systematically investigate the combined effect of chemical activation of açaí seeds (Euterpe oleracea Mart.), with an aqueous sodium hydroxide (NaOH) solution at 2 mol·L⁻¹, and process temperature by pyrolysis of alkaline activated açaí seeds on the yield of reaction products (bio-oil, gas, H₂O, and biochar), physicochemical properties (acid value, density, and kinematic viscosity) and chemical composition (hydrocarbons and oxygenates) of bio-oil. Catalytic pyrolysis was carried out in a 143 L reactor at temperatures of 350 °C, 400 °C, and 450 °C, 1.0 atmosphere, operating in batch mode. The NaOH activation played a crucial role in modifying the thermal degradation pathway of the biomass, promoting the formation of specific chemical structures and altering the product yields. NaOH acted as a catalyst, enhancing the deoxygenation of the biomass and stimulating the formation of hydrocarbons. As a result, the yields of bio-oil, water, biochar, and gas varied from 5.77 to 7.20% (by mass), 14.90 to 19.77% (by mass), 41 to 54% (by mass), and 25.33 to 32.03%, respectively, influenced by the increase in temperature. FT-IR analyses indicated the presence of characteristic chemical functions of hydrocarbons (alkanes, alkenes, and aromatics) and oxygenated compounds (phenols, cresols, ketones, esters, carboxylic acids, aldehydes, and furans), with an intensification of hydrocarbon signals at higher temperatures. GC-MS analysis identified hydrocarbons and oxygenated compounds as the main chemical classes in the bio-oil, showing a strong dependence on pyrolysis temperature. It was observed that hydrocarbon concentration in bio-oil increased from 49.7% to 57.88% (area) with increasing temperature, while the concentration of oxygenated compounds decreased from 13.88% to 6.69% (area), demonstrating that NaOH activation, combined with temperature elevation, favors the formation of hydrocarbons and the reduction of oxygenated compounds, thereby improving the quality of the produced bio-oil. Full article

This study investigates the oxidative degradation of polystyrene (PS) through a synergistic framework integrating UV-C-accelerated aging with Reactive Molecular Dynamics (ReaxFF) simulations. To bridge the gap between experimental and computational timescales, shock compression was employed in the simulations as an accelerator of degradation reactions. ATR-FTIR spectroscopy revealed the emergence of carbonyl (1717 cm⁻¹) and peroxyester (1760 cm⁻¹) bands, alongside dominant ether-type oxygen bridges (1260, 1209 cm⁻¹). These experimental data, particularly the depletion of native aromatic bands (1492, 1451 cm⁻¹), provide direct empirical validation of the ring-ring cross-linking and radical-mediated oxidation pathways predicted by the ReaxFF model. The results demonstrate that theory-guided diagnostics offer a robust mechanism for understanding the atomic-level restructuring of the polymer matrix. Significantly, the formation of hydrophilic oxygenated groups increases the bioavailability and environmental hazard potential of fragmented PS microplastics, providing critical insights into their long-term ecological fate. Full article

This study investigated the influence of hydrocarbon feedstock composition evolved from slow pyrolysis of polypropylene (PP) and polystyrene (PS) and plasma gas flow rate on the carbon black and hydrogen production yields and quality. The temperature distribution and feedstock flow within the carbon black formation zone with plasma were supplementarily modeled using computational fluid dynamics. TG-FTIR-GC/MS was employed to analyze thermal degradation patterns of plastics and to estimate the composition of volatile intermediates of plastics’ slow pyrolysis. Produced CB was characterized, encompassing physical, structural, and compositional properties using thermogravimetric analysis, CHNS analysis, scanning electron microscopy–energy dispersive spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and Raman spectroscopy. The results revealed that both feedstocks yield CB with comparable structural characteristics; however, PS-derived (aromatic-rich) volatiles produce significantly higher CB yields, whereas PP-derived (aliphatic) volatiles favor hydrogen formation. Differences in carbon structure were also observed, with PP-derived CB exhibiting a higher degree of graphitic ordering compared to the more disordered CB obtained from PS. The optimal flow rate of plasma gas was identified as 6.1 L/min. Increasing the flow rate to 7.2 L/min led to reduced conversion efficiency for PP-derived long-chain hydrocarbons. Overall, the findings demonstrate the potential of this approach for the co-production of high-quality carbon black and hydrogen from plastic waste. Full article

This study evaluates the pH-dependent ozonation of 2,6-dichloro-1,4-benzoquinone to optimize sustainable oxidation strategies for water treatment. Experiments were conducted over a wide pH range under controlled temperature and ozone dosage. DCBQ was fully degraded within minutes following first-order kinetics, regardless of pH. Acidic to neutral systems experienced a progressive pH decrease due to the formation of oxygenated transformation products, whereas strongly alkaline conditions remained stable due to buffering effects. Aromaticity removal followed a second-order kinetic and increased with pH, reflecting enhanced aromatic ring cleavage under alkaline conditions. Color was rapidly eliminated for all tested pH values, while turbidity remained low at pH ≤ 10 but increased under extreme alkalinity due to colloidal aggregation. While previous studies have examined the influence of pH on ozone reaction pathways, its combined effect on ozonation performance and gas–liquid mass transfer remains largely unexplored. Dissolved ozone measurements enabled estimation of the gas–liquid mass transfer coefficient, which decreased linearly with increasing pH, revealing a direct coupling between pH-controlled ozone reactivity and transfer efficiency. Overall, pH 9–10 was identified as the optimal operational range, balancing effective aromaticity removal, ozone stability, and minimal turbidity, thus providing practical strategies for the treatment of chlorinated quinones in water. Full article

This study reports the synthesis and evaluation of diclofenac-derived organotin(IV) complexes as photostabilizing additives for poly(vinyl chloride) (PVC). Diclofenac was selected as a ligand due to its aromatic structure and heteroatom-rich framework, enabling the formation of stable tin-based complexes with potential UV-absorbing and radical-scavenging properties. The synthesized di- and tri-organotin complexes were incorporated into PVC films at 0.5 wt.% and exposed to UV irradiation (365 nm) for up to 300 h to assess their stabilizing efficiency. Photodegradation was monitored by tracking changes in carbonyl, polyene, and hydroxyl indices, as well as weight loss and surface deterioration. Compared with blank PVC and ligand-containing films, the organotin-modified samples exhibited significantly slower growth of degradation indices, reduced mass loss, and improved surface integrity after irradiation. Among the evaluated additives, the tributyltin complex demonstrated the highest photostabilizing performance, showing superior retention of chlorine content and lower surface roughness parameters. Overall, the results indicate that diclofenac-based organotin(IV) complexes are effective photostabilizers for PVC, with the tributyltin derivative emerging as the most promising candidate for enhancing the durability of PVC materials under UV exposure. Full article