Aliphatic Research Articles

Synthesis of hydroxytyrosol analogs with enhanced antioxidant and cytostatic properties against MG-63 human osteoblast-like cells and their potential implications for bone health.

Sixteen novel hydroxytyrosol (HT) analogs with substitutions at the C-1 position of the HT aliphatic side chain were synthesized and evaluated for their cytostatic activity against MG-63 human osteoblast-like cells and for their antioxidant properties. The results revealed that these analogs exhibited significantly higher inhibitory activity compared with HT, which served as the positive control. Among these, the cyclo-substituted compounds stood out as particularly potent, demonstrating strong radical scavenging abilities and notable cytostatic effects against MG-63 cells. These findings suggest that the cyclo-substituted HT analogs hold considerable promise for the development of novel antioxidants with potential applications in bone physiology.

Metallaphotocatalytic triple couplings for modular synthesis of elaborate N-trifluoroalkyl anilines.

The integration of trifluoromethyl groups and three-dimensional quaternary carbon moieties into organic molecules has emerged as a prominent strategy in medicinal chemistry to augment drug efficacy. Although trifluoromethyl (hetero)aromatic amines and derivatives are prevalent frameworks in pharmaceuticals, the development of trifluoromethyl-embedded, intricately structured alkyl amine scaffolds for medicinal research remains a significant challenge. Herein, we present a metallaphotoredox multicomponent amination strategy employing 3,3,3-trifluoropropene, nitroarenes, tertiary alkylamines, and carboxylic acids. This synthetic pathway offers notable advantages, including the accessibility and cost-effectiveness of starting materials, high levels of chemo- and regioselectivity, and modularity. Furthermore, this approach enables the synthesis of a broad spectrum of aniline compounds featuring both trifluoromethyl group and distal quaternary carbon motifs along the aliphatic chains. The accelerated access to such elaborate N-trifluoroalkyl anilines likely involves three sequential radical-mediated coupling events, providing insightful implications for the retrosynthesis of potential compounds in organic synthesis and drug discovery.

Locations of Functional Groups in the Aliphatic Chains of Lipids and the Arrangement of Aliphatic Chains within Acylglycerolipids by the Methods of Mass Spectrometry

Locations of Functional Groups in the Aliphatic Chains of Lipids and the Arrangement of Aliphatic Chains within Acylglycerolipids by the Methods of Mass Spectrometry

Performance of co-composting Pholiota nameko spent mushroom substrate and pig manure at different proportions: Chemical properties and humification process.

Co-composting is the controlled aerobic degradation of organics, using more than one feedstock. By combining the spent mushroom substrate of Pholiota nameko (SMS) and pig manure (PM), the benefits of each could be used to optimize the composting process and the final product. This study introduced a comprehensive evaluation strategy aimed at identifying the optimal co-composting ratio for these two substrates. A 120-day composting trial was conducted, blending SMS and PM in various ratios to evaluate the benefits of co-composting SMS-PM. The results indicated that dissolved organic matter (DOM) in SMS-derived compost primarily originated from plants, whereas PM-derived compost predominantly consisted of microbial metabolic products, and co-composting combined both sources. An increase in aromaticity and humification degree of DOM occurred during the composting process itself rather than being derived from autochthonous origin. Carbohydrates like phenols and alcohols broke down during composting, and microbes utilized polysaccharides as an energy source for humus formation. As co-composting progressed, the treatments with varying mass ratios of SMS to PM, including 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 were observed to result in a decline in aliphatic hydroxylated chains alongside an enhancement in aromaticity within the compost. Additionally, there was a conversion from organic carbon (C) to carboxyl C within humic acid (HA) due to oxidation and dehydrogenation processes that facilitated the formation of stable nitrogen-containing compounds characterized by condensed aromatic structures. Following thorough evaluation, it was determined that optimal composting efficacy occurred at a mass ratio of SMS to PM equal to 6:4. Post-compost analysis revealed increases in nutrient content; specifically, germination index (GI) value reached 132.7%, while organic matter content attained 45.3%. Conversely, electrical conductivity (EC), C contents of water-soluble substances and humin (Cwss and CHu) decreased by approximately 11.8%, 73.4%, and 29.8% respectively; meanwhile, C contents of humic-extracted acid and HA (CHE and CHA), along with degree of polymerization (DP), increased by 17.3%, 20.3% and 9.9% respectively. The proposed co-compost formula not only facilitated simultaneous recycling of both SMS and PM waste but also transformed them into high-quality organic fertilizers suitable for soil enrichment-effectively addressing challenges faced by both edible fungi cultivation and livestock industries while augmenting organic fertilizer sources for Black land protection.

Comprehensive Overview of the Amide Linker Modification in the Succinate Dehydrogenase Inhibitors.

Succinate dehydrogenase inhibitors (SDHIs) have become one of the most important classes of agrochemical fungicides. According to the data from FRAC, the resistance risk for SDHIs had reached up to medium and even to high. In general, the chemical structure of SDHIs mainly contained three fragments: an acid core, a hydrophobic tail, and an amide linker, corresponding to three modification directions for each fragment. Among them, amide linker modification (ALM) has become a research hotspot for the design of novel SDHIs fungicides in recent years. We presented here a detailed review on the ALM strategy in the past decade, and some of them had entered the market. According to their chemical structures, ALM strategy were classified into four parts: (1) linked aliphatic chain between amide bond and hydrophobic tail, (2) introducing substituents to replacing hydrogen atom in the amide bond, (3) reverse extending the amide linker, and (4) changed with other bioisosteres. Moreover, the structure-activity relationship and the interaction mechanism of ALM-SDHI with SDH were discussed. This review aims to provide a global perspective on research and development of novel SDHIs, as well as suggestions for food safety management.

Comparative volatiles profiling of two marjoram products via GC-MS analysis in relation to the antioxidant and antibacterial effects.

Marjoram (Origanum majorana L.), also known as "sweet marjoram" or "sweet oregano" is a Mediterranean herbaceous perennial herb cultivated in Egypt and widely consumed as an herbal supplement for treatment of several ailments. The main goal of this study was to assess volatiles' variation in marjoram samples collected from two different widely consumed commercial products using two different extraction techniques viz. head space solid phase microextraction (HS-SPME) and petroleum ether using gas chromatography mass spectrometry (GC-MS) analysis and multivariate data analysis. A total of 20 major aroma compounds were identified in samples extracted with HS-SPME found enriched in monoterpene hydrocarbons and oxygenated compounds. The major volatiles included β-phellandrene (20.1 and 14.2%), γ-terpinene (13.4 and 11.7%), 2-bornene (12.3 and 11.5%), p-cymene (9.8 and 4.6%) terpenen-4-ol (16.4 and 7.5%), sabinene hydrate (16.02 and 8.8%) and terpineol (4.2 and 3.2%) in MR and MI, respectively. Compared with HS-SPME, 51 aroma compounds were identified in marjoram samples extracted with petroleum ether, found more enriched in aliphatic hydrocarbons (42.8 and 73.8%) in MR and MI, respectively. While a higher identification score was observed in the case of solvent extraction, SPME appeared to be more selective in the recovery of oxygenated terpenes to account more for marjoram aroma. Multivariate data analysis using principal component analysis (PCA) revealed distinct discrimination between volatile composition of both marjoram samples. The total phenolic and flavonoid contents in marjoram samples were at (111.9, 109.1µg GA/mg) and (18.3, 19.5µg rutin eq/mg) in MR and MI, respectively. Stronger antioxidant effects were observed in MR and MI samples with IC50 at 45.5 and 56.8µg/mL respectively compared to IC50 6.57µg/mL for Trolox as assayed using DPPH assay. Moderate anti-bacterial effect was observed in MR and MI samples and expressed as a zone of inhibition mostly against Bacillus subtilis (16.03 and 15.9mm), B. cereus (12.9 and 13.7mm), Enterococcus faecalis (14.03 and 13.97mm), and Enterobacter cloacae (11.6 and 11.6mm) respectively.

Optimizing Na2EDTA Concentration for Enhanced Properties of SILAR - Deposited CTS Thin Films

Abstract This study investigates the impact of varying Na2EDTA concentrations on the properties of copper tin sulfide (CTS) thin films deposited on soda lime glass substrates using the successive ionic layer adsorption and reaction (SILAR) method. The aim is to optimize CTS thin film growth for photovoltaic technology applications. CTS thin films were prepared using SILAR with Na2EDTA concentrations of 0.01M, 0.04M, and 0.07M, resulting in samples CTS01, CTS04, and CTS07. Characterization techniques included XRD, SEM, EDAX, FTIR, I-V curves, transmittance spectra, and Tauc plots. The results reveal significant variations in film properties with changing Na2EDTA concentration. XRD patterns indicate polycrystalline films with an orthorhombic CTS phase. SEM images show smooth, dense films with localized clusters. FTIR spectra detect hydrocarbon chains, aromatic rings, and hydroxyl or ether groups. The I-V curves of three samples (CTS01, CTS04, and CTS07) show a voltage-dependent transition from semiconducting to ohmic behavior. The CTS01 exhibits superior conductivity (3.13x10-5/Ωm), while the samples' resistance and conductivity values show an inverse relationship. Transmittance curves display low UV transmittance and high visible transmittance,suggests that the samples are highly absorptive in the UV range and become more transparent in the visible range, indicating potential applications in optical filtering and photovoltaic devices. Tauc plots estimate band gap energies of 3.66, 3.89, and 3.23 eV, indicating high band gap energies suitable for buffer layers in solar cells. The correlation between band gap energy and crystallite size as a function of Na2EDTA concentration is also observed. The study demonstrates the importance of optimizing Na2EDTA concentration for achieving high-quality CTS thin films with desirable properties for photovoltaic applications. The findings highlight the potential of CTS thin films for solar cells, optical filtering, and photonic devices.

Regulation of Glass Transition Temperature in Thermo‐Responsive Epoxy Shape Memory Polymers: The Roles of Chemical Crosslinking Density and Chain Flexibility

ABSTRACTShape memory polymers (SMPs) are novel kinds of smart materials whose shape can be changed in external conditions such as heat stimulus. Due to their excellent structural versatility and high elastic strain, they have important applications in the field of biomaterials. Here, a series of amorphous shape memory polymer materials are prepared and their shape memory properties and glass transition temperature (Tg) are also investigated. A special kind of epoxy polymer, whose shape can be changed at around physiological temperature, is synthesized by regulating the crosslinking density and introducing flexible aliphatic epoxy chains. The shape memory function of this epoxy polymer is studied by deformation test. In addition, to explore their application in the field of biomedical materials, the biocompatibility of the materials are evaluated, including the effects on the erythrocyte hemolysis rate and cell activity. The experimental results show that this kind of epoxy polymer has good shape memory function and biocompatibility.

Study on Microstructure Evolution Characteristics of Coal in Low Temperature Oxidation Stage in Goaf of Longfeng Coal Mine

ABSTRACT Low temperature oxidation of coal is the nature of oxidation of coal with oxygen molecules at temperatures below its oxidation critical point or ignition point, usually from ambient temperature to about 200°C. Air leakage and uneven oxygen distribution significantly impact coal spontaneous combustion in goaf. Understanding the changes in free radicals and functional groups during low-temperature oxidation of coal under different oxygen concentrations is crucial for preventing and controlling residual coal self-ignition. This study employs Fourier transform infrared spectroscopy to analyze the effects of varying oxygen concentrations (3%, 5%, 9%, 15%, 21%) on functional groups and structural parameters during coal’s low-temperature oxidation. Results indicate that increasing oxygen concentration promotes the consumption of oxygen-containing functional groups, reducing their content from 71.9% to 52%. Concurrently, the activity and content of aromatic hydrocarbon functional groups rise rapidly from 4.8% to 52.6%. The aliphatic hydrocarbon structure shows a downward trend, indicating its minimal presence. Aromatic ring condensation increases coal sample aromaticity, suggesting higher maturity and weaker hydrocarbon generation potential, with minimal effect from oxygen concentration. Early-stage reactions show little change in coal’s basic structure, and coal-oxygen reactions remain low in low oxygen environments. This study provides an important basis for understanding the mechanism of coal spontaneous combustion in goaf and formulating effective prevention measures for coal spontaneous combustion.

Unraveling the Potential of Yarrowia lipolytica to Utilize Waste Motor Oil as a Carbon Source

This study evaluated the potential of Y. lipolytica (CBS 2075 and DSM 8218) to grow in waste motor oil (WMO) and produce valuable compounds, laying the foundation for a sustainable approach to WMO management. Firstly, yeast strains were screened for their growth on WMO (2–10 g·L−1) in microplate cultures. Despite limited growth, the CBS 2075 strain exhibited comparable growth to control conditions (without WMO), while DSM 8218 growth increased 2- and 3-fold at 5 g·L−1 and 10 g·L−1 WMO, respectively. The batch cultures in the bioreactor confirmed the best performance of DSM 8218. A two-stage fed-batch strategy–growth phase in aliphatic hydrocarbons, followed by the addition of WMO (one pulse of 5 g·L−1 or five pulses of 1 g·L−1 WMO), significantly increased biomass production and WMO assimilation by both strains. In experiments with five pulses, CBS 2075 and DSM 8218 strains reached high proteolytic activities (593–628 U·L−1) and accumulated high quantities of intracellular lipids (1.3–1.7 g·L−1). Yeast lipids, mainly composed of oleic and linoleic acids with an unsaturated/saturated fraction > 59%, meet the EU biodiesel standard EN 14214, making them suitable for biodiesel production.

Fluorinated Squareimines for Molecular Sieving of Aromatic over Aliphatic Compounds

The development of more energy‐efficient separation technologies is essential. Especially the separation of cyclic aliphatic hydrocarbons from their aromatic counterparts remains a significant challenge due to azeotrope formation and similar physical properties, often requiring energy‐intensive processes. Herein, we introduce a novel class of electron‐deficient macrocycles with a unique rectangular structure to optimise π···π interactions within the pore, enabling the highly selective molecular sieving of aromatic compounds from mixtures. Utilising dynamic covalent imine chemistry, the squareimine NDI2F42‐based crystalline functional material is directly obtained from the reaction mixture in a single self‐assembly step in high yields of 84%, alongside the larger NDI2F82 congener, which can be obtained in 69% yield. In vapour sorption and diffusion experiments, NDI2F42 demonstrates rapid adsorption kinetics with selectivities of 97:3 for benzene over cyclohexane and 93:7 for toluene over methylcyclohexane, while single‐crystal and powder X‐ray diffraction studies confirm that the selectivity is primarily governed by directed π···π interactions.

Fluorinated Squareimines for Molecular Sieving of Aromatic over Aliphatic Compounds.

The development of more energy-efficient separation technologies is essential. Especially the separation of cyclic aliphatic hydrocarbons from their aromatic counterparts remains a significant challenge due to azeotrope formation and similar physical properties, often requiring energy-intensive processes. Herein, we introduce a novel class of electron-deficient macrocycles with a unique rectangular structure to optimise π···π interactions within the pore, enabling the highly selective molecular sieving of aromatic compounds from mixtures. Utilising dynamic covalent imine chemistry, the squareimine NDI2F42-based crystalline functional material is directly obtained from the reaction mixture in a single self-assembly step in high yields of 84%, alongside the larger NDI2F82 congener, which can be obtained in 69% yield. In vapour sorption and diffusion experiments, NDI2F42 demonstrates rapid adsorption kinetics with selectivities of 97:3 for benzene over cyclohexane and 93:7 for toluene over methylcyclohexane, while single-crystal and powder X-ray diffraction studies confirm that the selectivity is primarily governed by directed π···π interactions.

Synthesis of biobased poly(ether-ester) from potentially bioproduced betulin and p-coumaric acid

For a more sustainable future, innovative polymer materials synthesized from biobased molecules are currently a key trend, in the frame of the bioeconomy. In this study, new renewable macromolecular architectures poly(ether-esters) has been synthesized from betulin and para-coumaric acid, two plant-based building blocks, poorly valorized till now, and potentially bioproduced by white biotechnologies. To date, these are the first synthesized polymers with such a reported architecture. In a first step, different chemical modifications were carried out on these biomolecules to increase their reactivities. Betulin hydroxyl groups were esterified with aliphatic acids of carbon chain lengths C6, C8 and C10 terminated by a bromine, with good yields (79–85%). P-coumaric acid was dimerized by [2 + 2] cycloaddition, and then esterified with ethanol, butanol or isobutanol with excellent yields (92–96%). These modified building blocks were finally copolymerized by Williamson polyetherification reaction, leading to various analogous materials with molar masses ranging from 9700 to 15500 g mol−1. Different thermal characterizations have been then performed. TGA results show that these poly(ether-esters) displayed high thermal stabilities (up to 336 °C). Besides, DSC analyses revealed Tg ranging from 38 to 81 °C, depending on the length of the aliphatic carbon chain and the nature of the pendant ester groups for a large range of potential applications.

Atmospheric Pressure Photoionization with Halogen Anion Attachment for Mass Spectrometric Analysis of Hydrocarbons and Hydrocarbon-Based Polymers.

Aliphatic hydrocarbons and hydrocarbon-based synthetic polymers are of interest in many fields, but their characterization by mass spectrometric methods is generally limited due to their poor ionizability. Recently, atmospheric pressure photoionization (APPI), combined with halogen anion attachment in negative-ion mode, has drawn attention as a potential method for ionizing various polymers without extensive fragmentation or other unwanted side reactions. In this work, the applicability of halogen anion attachment with APPI was studied using several synthetic polymers, including polyethylene, polypropylene, polyisoprene, and polystyrene, as well as simple n-alkanes of various chain lengths. For hydrocarbon-based polymers, the method produced clear distributions of intact polymer adduct ions when different halogen anions were used. It was found that increasing the halogen anion size decreased ionization efficiency, particularly in the absence of π-bonds in the polymer structure. Testing with simple n-alkanes showed that only molecules containing fifty or more carbon atoms formed detectable halogen adducts, possibly due to the low gas-phase stabilities of the lighter n-alkane adduct ions. In conclusion, halogen anion attachment with negative-ion APPI appears to be a highly promising method for polymer analysis, providing structural data and clean polymer mass spectra with minimal fragmentation, which can be useful for the identification of unknown samples.

Wastewater biotreatment and bioaugmentation for remediation of contaminated sites at an oil recycling plant

ABSTRACT This work focused on the biotreatment of wastewater and contaminated soil in a used oil recycling plant located in Bizerte. A continuous stirred tank reactor (CSTR) and a trickling filter (TF) were used to treat stripped and collected wastewater, respectively. The CSTR was started up and stabilized for 90 days. Over the following 170 days, the operational organic loading rates of the TF and the CSTR were around 1,200 and 3,000 mg chemical oxygen demand (COD) L−1 day−1, respectively. The treatment efficiency was 94% for total petroleum hydrocarbons, 89.5% for COD, 83.34% for biological oxygen demand (BOD5), and 91.25% for phenol. Treated industrial wastewater from the TF was used for bioaugmentation (BA) of contaminated soil. The assessment of the soil took 24 weeks to complete. The effectiveness of the soil BA strategy was confirmed by monitoring phenolic compounds, aliphatic and polycyclic aromatic hydrocarbons, heavy metals, and germination index. The biodegradation rate of contaminants was improved and the time required for their removal was reduced. The soil bacterial communities were dominated by species of the genera Mycobacterium, Proteiniphilum, Nocardioides, Luteimicrobium, and Azospirillum, which were identified as hydrocarbon and phenol-degrading bacteria.

In Silico Structural Comparison of Aromatic and Aliphatic Chiral Peptoid Oligomers.

Atomistic simulations of peptoids have the capability to predict structure-property relationships, depending on the accuracy of the associated force field. This work presents an addendum to the CGenFF-NTOID peptoid force field for aliphatic side chains. We develop parameters for two aliphatic side chains, RN1-tertiary butylethyl glycine (r1tbe) and SN1-tertiary butylethyl glycine (s1tbe). Enhanced sampled (well-tempered metadynamics) atomistic simulations are performed using CGenFF-NTOID to determine the monomer structural preferences for these side chains. The free energy minima attained through these simulations are compared with structural observations obtained from experiments. We also compare the structural preferences of aliphatic s1tbe and aromatic SN1-naphthylethyl glycine (s1ne). This is done through parallel bias metadynamics on monomers and pentamers of s1tbe and s1ne. The structural observations through simulations are also compared with available experimental metrics of the dihedral angles and pitch. The pentamer minima structures are also compared with ab initio optimized structures, which show excellent agreement. This comparison illustrates alternatives to aromatic side chains that can be used to stabilize peptoid secondary structures. The developed parameters help to increase the diversity of peptoid side chains available for materials discovery through computational studies.

Research on the Influence of Fault Structure on Physical and Chemical Structure of Coking Coal During Spontaneous Combustion

ABSTRACT The spontaneous combustion tendency and oxidation combustion properties of coking coal in fault fracture zone and primary coking coal are different. Accordingly, this study uses Thermogravimetric analysis, in-situ Fourier transform infrared spectroscopy, Scanning electron microscope, low-temperature N2 adsorption and Electron spin resonance techniques were used to study the difference of macroscopic and microscopic structural characteristics between coking coal and primary coking coal in fault fracture zone. The results show that: The oxygen absorption capacity of coking coal in fault fracture zone is enhanced and the thermogravimetric characteristic temperature is advanced, and the ignition point temperature is advanced by 5.36°C; the maximum weight loss temperature of coking coal in fault fracture zone is 3.32°C lower than that of primary coking coal. The apparent activation energy of coking coal in oxidation stage and pyrolytic combustion stage decreased by 4.88 and 5.03 kJ/mol, respectively. Compared with primary coking coal, the pore structure of coking coal in fault fracture zone is more complex, which increases the roughness of coal surface and is conducive to oxygen adsorption. In addition, fault tectonics promotes the separation and cracking of oxygen-containing functional groups into small molecules, and the polycondensation of aliphatic hydrocarbon structure promotes the formation of active free radicals, thus promoting spontaneous combustion. This study provides an important reference and theoretical support for further understanding of the structural evolution and oxidation kinetics of highly metamorphic coking coal induced by fault tectonics, which is helpful for fire prevention and control in fault structure-developed mining areas and safe production of coal industry.

Insight into the Antibacterial Activities of Pyridinium-Based Cationic Pillar[5]arene with Controllable Hydrophobic Chain Lengths against Staphylococcus aureus.

The increasing number of infections caused by pathogenic bacteria has severely affected human society. More and more deaths were originated from Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) infection each year. The potential and excellent bacteriostatic activity and resistance to biofilm formation of pillar[5]arene with different functional groups attract important attention to further study the relationship between antimicrobial activity and cytotoxicity by varying the length of the hydrophobic chain, the number of positive charges, and the hydrophobic/hydrophilic balance of the molecule. In this work, four pyridinium-based cationic pillar[5]arene (PPs) with linear aliphatic chains of different lengths were synthesized. After systematic characterization, their inhibition activities against S. aureus were investigated. It revealed that PP6 (six methylenes in each linker) exhibited excellent inhibition activity against S. aureus (ATCC 6538) with a minimum inhibitory concentration (MIC) of 3.91 μg/mL and a minimum bactericidal concentration (MBC) of 62.50 μg/mL. As expected, PP6 exhibited the strongest antibiofilm ability and negligible antimicrobial resistance even after the 20th passage. A study of the action mechanism of selected PPs on the bacterial membrane depolarization and permeability by transmission electron microscopy (TEM) disclosed that the cationic pyridine groups of PPs inserted into the negatively charged bacterial membranes, thereby leading to membranolysis, cytoplasmic content leakage, and cell death. Importantly, PPs all showed very low toxicity to mammalian cells (L929 and HBZY-1), which provided a significant reference for the construction of hypotoxic antibacterial biomaterials for multiple drug-resistant bacteria based on pyridinium-grafted cationic macrocycles with controllable hydrophobic chain lengths.

Olive pomace waste conversion to bio-fuel by application of integrated configuration of pyrolysis/hydrodeoxygenation process

Bio-oil obtained from non-catalytic pyrolysis of biomass, consists of a large number of oxygenated compounds. Hence, it is essential for the bio-oil to go through upgrading processes such as hydrodeoxygenation (HDO) to reform these compounds to aliphatic and aromatic hydrocarbons. This study works towards this purpose by initially deriving raw bio-oil from olive pomace waste biomass in a non-catalytic pyrolysis process at temperature of 400–700 ºC. Then for reducing the oxygen content of derived bio-oil, HDO of the raw bio-oil over NiMo/Al2O3 catalyst was performed in a batch reactor, in varying operational parameters: temperature of 200–250 °C, reaction time of 1–3 h, hydrogen pressure of 2–6 bar and catalyst: bio-oil ratio of 1:20, 1:10, 1:5. The results revealed that the catalytic HDO is an appropriate procedure, as fatty acids as the main oxygenated components in bio-oil were reduced from 81.8 % to 56.7 %, aldehydes and ketones were entirely removed, and there was a noticeable rise in aliphatic hydrocarbons from 2.8 % to 33.9 % at temperature of 250 ºC, hydrogen pressure of 6 bar and reaction duration of 3 h. In addition, by raising the catalyst to bio-oil ratio to 1:5, the content of fatty acids reached 47.6 %. Furthermore, a comparison was made between the O/C and H/C ratios of the obtained biofuels and the raw bio-oil, which results exhibited that this method worked successfully in substituting oxygen atoms of the raw bio-oil with hydrogen atoms.

Contrasting molecular structures and photooxidation behaviors between dissolved organic sulfur released from rice straw-biochar and aerobically decomposed rice straw

Photooxidation of dissolved organic sulfur (DOS) in soils and natural waters plays an important role in the sulfur biogeochemical cycle. However, the structural-dependent photoliabilities of DOS from different sources remain unclear. Here, the molecular structures and photooxidation behaviors of DOS in pyrogenic dissolved black matter (PyDOM) derived from rice straw-pyrolyzed biochar (referred to as PyDOM-S and considered to be representative of black carbon from prairie fires) were thoroughly characterized and compared with those of DOS in leached dissolved organic matter (LDOM) derived from aerobically decomposed rice straw (referred to as LDOM-S and considered to be generally representative of organic-rich horizons in soils and peats). The Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis revealed that both PyDOM-S and LDOM-S were, respectively, dominated by aliphatic (60.4 % and 41.1 %) and lignin-like compounds (35.1 % and 40.1 %), followed by minimal aromatic and polyaromatic compounds (2.8 % and 11.9 % in total). As demonstrated by the sulfur K-edge X-ray absorption near-edge structure (S-XANES) analysis, PyDOM-S consisted mainly of organosulfate (80.4 %) contrasting to the diversified and mingled reduced sulfurs (62.7 %) and oxidized sulfurs (37.3 %) of LDOM-S. Under simulated sunlight irradiation, 74 % of sulfur in PyDOM-S was photomineralized to sulfate within 24 h and totaling 89 % after 168 h, but only 9 % and 42 % for LDOM-S given the same periods of time, confirming the much faster photomineralization of PyDOM-S. After 168-h irradiation, almost all molecules in PyDOM-S disappeared, whereas a large proportion (44.2 %) of LDOM-S molecules (mainly aliphatic and lignin-like compounds) were photo-resistant. Furthermore, the photomineralization of PyDOM-S was mainly contributed by the final and complete oxidation of organosulfate to sulfate; however, the photooxidation of LDOM-S was dominated by the sequential oxidation of exocyclic sulfur and heterocyclic sulfur to organosulfate prior to releasing sulfate. These results highlight that pyrogenic-sourced PyDOM-S and diagenesis-derived LDOM-S exhibit contrasting photooxidation behaviors due to the associated distinct molecular structures.