Aliphatic Groups Research Articles

Effect of different extraction solvents on bioactive phenolics and antioxidant potential of Illicium griffithii fruit

The fruits of Illicium griffithii are of medicinal and economic importance. In this study, five solvents viz. methanol, ethanol, acetone, ethyl acetate and water at 20–100% concentration analyzed for phenolic content (TPC and TFC) and antioxidant activities (DPPH and ABTS) of I. griffithii fruit. TPC was highest (40.06±0.48 mg GAE/g dw) in 80% MeOH, and TFC was highest (6.58±0.12 mg QE/g dw) in 100% EtOAc extracts. The antioxidant activities were higher in extract(s) with 100% of each solvent (93.35–94.27% inhibition) and highest in 100% EtOAc extracts. A total of 7 phenolic compounds, viz. gallic acid, catechin, chlorogenic acid, p-hydroxybenzoic acid, vanillic acid, ferulic acid, and phloridzin, were identified in different solvent extracts. 100% MeOH extracted the highest content of gallic acid (2.54 mg/g) and catechin (2.59 mg/g). The ATR-FTIR spectra showed the presence of aliphatic, aromatic, and phenolic groups. The TGA analysis exposed volatile matter, cellulose, hemicellulose, and lignin content. The FESEM analysis also revealed the morphological changes in treated samples. The extraction efficacy of phenolic compounds was better in extracts with higher concentration of solvents (60% −100%). The fruit is a rich source of phenolics and antioxidants; thus, it can provide multiple industrial benefits.

Understanding the hydrocarbon‒generation potential on jurassic coal-measure source rocks in the Junggar Basin: From the perspective of hydrogen-rich molecular structure

The Jurassic coal-measure source rocks in the Junggar Basin have drawn considerable attention in recent years. In our hydrocarbon thermal simulation experiments of these rocks, we found that the dark mudstone evaluated as good source rock, had a much lower hydrocarbon generation capacity than the coal and carbonaceous mudstone, evaluated as poor source rock. Based on this background, we performed Fourier transform infrared spectroscopy (FTIR) and combined the results of semi‒open thermal simulation experiments to explore the association between the molecular structure and hydrocarbon production capacity, with the aim of obtaining a new understanding of hydrocarbon potential of Jurassic coal‒measure source rocks from the perspective of molecular structure. The results indicate that coals exhibit lower condensation of aromatic structures and higher relative abundance of aliphatic structures with a higher degree of branched chaining than mudstones and carbonaceous mudstones. Apparent aromaticity (fa), aromatic abundance parameter I, and degree of condensation (DOC) are negatively correlated with organic matter abundance. The aliphatic structural parameter H demonstrates a substantial positive correlation with organic matter abundance. Furthermore, aliphatic relative abundance factor A is associated with the type of organic matter; the better is the type of the organic matter, the larger is the A value. The combination of the molecular structures with the thermal simulation results shows that the aliphatic hydrogen enrichment of selected carbonaceous mudstone is similar to that of coal. However, the relative abundance of the aliphatic group of it is high, and the DOC of the aromatic structure is low, making the hydrocarbon generation base stronger and easier to crack. Thus, the hydrocarbon generation capacity of carbonaceous mudstone is slightly higher than that of coal. Mudstone has low H and I values, and the DOC is high, indicating that its hydrocarbon base is low, so it has low hydrocarbon generation capacity. Therefore, the molecular structure is closely associated with the hydrocarbon potential of coal‒measure source rocks. When evaluating the qualities of coal-measure source rocks, the influence of molecular structure on these rocks should be considered.

In Vitro Activity of Ethanol Extract of Rimbang Fruit (Solanum ferox) as an Active Ingredient in Sunscreen Preparations

Solanum ferox is a typical Central Kalimantan plant widely used by Dayak’s community as a vegetable. The study aims to determine the ethanol extract of sour eggplant activities by measuring its SPF in vitro and identifying secondary metabolite contents. The sour eggplant is extracted by maceration using 96% ethanol solvent and then bound with an evaporator. The secondary metabolite groups of ethanol extract were identified using phytochemical screening. The identification results indicate the presence of flavonoid, terpenoid, steroid, and phenolic compounds. Then, the ethanol extract was fractionated with a water solvent, and its functional cluster was identified using the IR spectrum. IR spectral identification results indicate the presence of OH, C-O, C=C olefin, C -O ether, and aliphatic CH functional groups. (CH2 and CH3) SPF values were determined by measuring the absorption of ethanol and water extracts in vitro using UV-Vis spectrophotometry at UV-B wavelengths of 290-320 nm. In vitro testing has been conducted as a preliminary test in developing a sunscreen product (active substance). The SPF values of ethanol extract and water from weighted fruit extract in sequence are 40 and 23 at a 10% concentration with ultra-category.

Synthesis of Fe3O4-Mn2O3 and Fe3O4-graphene oxide hybrid nanocatalyst and their effects on the electromagnetic properties and their performance on heavy hydrocarbons upgrading

In this research for the first time, the hybrid nanocatalysts with various ratios were syntheses and the impact of the type and ratio of nanocatalyst on heavy oil upgrading was examined. For this purpose, at first, Fe3O4 was synthesized, and then 4 types of hybrids nanocatalysts using Fe3O4, Mn2O3, and reduced Graphene oxide were synthesized (with various ratios, 3:1, 2:1), and characterized. The hybrid nanocatalyst Fe3O4-Mn2O3 (ratio 2:1) was extremely efficient in reducing viscosity and heavy oil upgrading and declined the viscosity of heavy oil by 31%. Additionally, at the optimal result, a sample of crude and upgraded heavy oil was investigated and compared by FTIR and GC analysis. In the optimum sample, the aromatic and sulfoxide functional groups decreased by 21% and 72%, respectively, while the index of aliphatic groups of the alkane branch increased by 15%. In addition, Hexadecane, Nonadecane, and Octadecane compounds have experienced a 77%, 65%, and 56% decrease, respectively. Also, heavy and long chains such as C15-C20 cracked and transformed into light compounds such as C4-C7, which were not present in the heavy crude oil.

Investigation of an Antifouling Compound from Sponge Siphonodictyon coralliphagum

Marine fouling is attaching organisms to objects floating or submerged in seashores, such as ships, docks, and offshore structures. The impact caused is the reduced lifespan of the thing attached to the biofouling. In addition, there was a spread of invasive species. The government and industries in the United States spend over 6.5 million dollars annually on their budget to overcome this problem. So far, the prevention of marine biofouling is using antifouling paint on ships and submerged structures. One of them is organotin tributyltin (TBT) proven effective for preventing fouling; however, it is not environmentally friendly. Sponge Siphonodictyon coralliphagum growing in Salibabu Island waters, Talaud Islands, with previously shown activities against prokaryotes, was collected and extracted by maceration using ethanol as a solvent. The extract was then added to the base paint with several compositions of 5%, 10%, and 25% applied to the paving block surface. Positive control uses paint with copper additives. The objects are then immersed in the seashore below subtidal depths. The observation was carried out every seven days until day 28. The paving block was observed on day 90 after immersion. Significant results were obtained where macrofouling was only able to grow in negative control and positive control. The extract sponge S. coralliphagum has vigorous antifouling activity against marine biofouling. Furthermore, the extract was fractionated using liquid chromatography and continued by testing their activity against Gram-positive and negative bacteria. Further investigation of NMR spectra from the active fraction to prokaryotic cells shows a cyclic aliphatic compound with several keto-enol functional and methyl aliphatic groups on their chain.

Adsorption of lead and chromium ions from electroplating wastewater using plantain stalk modified by amorphous alumina developed from waste cans

Waste beneficiation is key to environmental protection and the realisation of a circular economy. Herein, amorphous alumina (a-Al2O3) derived from aluminium waste cans (AWC) was used to modify plantain stalk as an adsorbent for sequestration of lead (II) and chromium (VI) ions from electroplating wastewater. Raw plantain-stalk (RPS) and amorphous-alumina modified plantain stalk (APS) developed as adsorbents were characterised using various equipment such as x-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The FTIR revealed that the adsorbents are rich in functional groups that could promote the adsorption process which includes carboxyl, hydroxyl, and aliphatic groups. Also, the BET analysis showed a substantial increase in the surface area of APS (174.448 m2/g) compared to that of RPS (40.531 m2/g) which could be due to the effect of modification by the a-Al2O3. The batch adsorption studies revealed that the APS achieved 99.38% and 98.33% removal of Cr(VI) and Pb(II), respectively, which is superior to RPS adsorption efficiency. Also, the estimated and experimental data for the APS compared well under all the kinetic models studied with R2 > 0.88. This suggested that chemisorption is the most plausible adsorption mechanism of Cr(VI) and Pb(II) onto the APS. Further analysis showed that the Cr(VI) and Pb(II) adsorption followed the Langmuir model with the RL value of 0.038 and 0.999, respectively, which indicated that the two metal ions were effectively adsorbed onto the APS. Therefore, this work demonstrated that the modification of plantain-stalk with amorphous-alumina derived from AWC enhanced the characteristics of the APS and favoured its adsorption of the selected heavy metals.

Development of Curcumin Composite Gel Inhibitor for Preventing Spontaneous Combustion of Coal

ABSTRACT To improve their whole-stage inhibition effects on the spontaneous combustion of coal, curcumin (CCM) and chitosan (CTS) were grafted, and the natural nanomaterial montmorillonite (MMT) was used for intercalation to prepare the composite gel inhibitor CTS-CCM/MMT. Its macro effect and micro mechanism of inhibition were studied. SEM analysis revealed a significant increase in the surface folds and pores of CTS-CCM, suggesting enhanced mechanical properties and thermal stability. XRD and DSC experiments demonstrated a reduction in the diffraction angle 2θ from 21.148° to 20.011° for CTS-CCM/MMT, along with a 21.3% increase in glass transition temperature. This supports the effective improvement of thermal stability through intercalation treatment. Thermogravimetric analysis indicated a higher characteristic temperature point for the inhibitor composite. Infrared diffuse reflection experiments showed deactivation of oxidation activity for the hydroxyl and aliphatic groups through combined inhibition treatment. These findings collectively suggest that the gel exhibits heightened stability and flame retardancy, and can effectively inhibit the entire spontaneous combustion reaction of coal.

Co(O)4(N)‐type single‐atom‐based catalysts and ligand‐driven modulation of electrocatalytic properties for reducing oxygen molecules

AbstractSingle‐atom‐based catalysts are intriguing electrocatalytic platforms that combine the advantages of molecular catalysts and conductive carbon‐based materials. In this work, hybrids (Co‐NrGO‐1 and Co‐NrGO‐2) were generated by wet‐reactions between organometallic complexes (Co(CH3COO)2 and Co[CH3(CH2)3CH(C2H5)COO]2, respectively) and N‐doped reduced graphene oxide at 25°C. Various characterizations revealed the formation of atomically dispersed Co(O)4(N) species in Co‐NrGO‐2. Density functional theory (DFT) calculations explained the effect of the aliphatic C7 group in Co2 on the formation processes. The Co‐NrGO‐2 hybrid showed excellent catalytic performance, such as onset (0.94 V) and half‐wave (0.83 V) potentials, for electrochemical oxygen reduction reaction (ORR). Co‐NrGO‐2 outperformed Co‐NrGO‐1, which was explained by more back donation to the antibonding orbitals of O2 from electron‐rich aliphatic groups. DFT calculations support this feature, with mechanistic investigations showing favored ORR reactions and facile breakage of double bonds in O2.

Spectroscopic and microscopic characterization of humic acids from composts made by co-composting of green waste, spent coffee and OMWW sludge

ABSTRACT Due to its important role in the formation of humic acids (HA), improving lignin degradation during composting has usually been considered a challenge. One practice that could stimulate the biodegradation of this recalcitrant molecule is inoculation with exogenous lignolytic fungal strains. Two composts (C1) and (C2) from piles (H1) and (H2) were evaluated. H1 was the control pile and H2 was inoculated at maturity with Trametes trogii, resulting in a 35% increase in lignin degradation rate compared to H1. The aim of this study was to show the main effects of this increase on the humification process in the co-composting of green waste, coffee grounds and olive mill wastewater sludge (OMWWs). Microstructure of HA1 and HA2 extracted from C1 and C2, respectively, was also investigated by scanning electron microscopy (SEM) and SEM coupled with energy-dispersive X-ray spectroscopy (X-EDS). The results showed that there were several similarities between the compost samples tested. These included the mineral content, the degree of polymerization (PD)> 1 and the compact and rigid surface of the extracted HA. However, C2 was characterized by a higher humic content (HC), degree of polymerization (PD), humification index (HI) and percentage of humic acids (PHA) than C1. Carbon-13 nuclear magnetic resonance (13C-NMR) and Fourier transmission-infrared spectroscopy (FTIR) analysis showed that aliphatic groups such as hydroxyls, alcohols and carboxyls were predominant in both composts. SEM analysis in conjunction with X-EDS analysis of HA2 showed a higher proportion of carbon and potassium (18 and 7.93%) than in HA1 (14 and 0.95%).

Trapping and reversing neuromuscular blocking agent by anionic pillar[5]arenes: Understanding the structure-affinity-reversal effects

Selective relaxant binding agents (SRBA) have great potential in clinical surgeries for the precise reversal of neuromuscular blockades. Understanding the relationship between the structure-affinity-reversal effects of SRBA and neuromuscular blockade is crucial for the design of new SRBAs, which has rarely been explored. Seven anionic pillar[5]arenes (AP5As) with different aliphatic chains and anionic groups at both edges were designed. Their binding affinities to the neuromuscular blocking agent decamonium bromide (DMBr) were investigated using 1H NMR, isothermal titration calorimetry (ITC), and theoretical calculations. The results indicate that the capture of DMBr by AP5As is primarily driven by electrostatic interactions, ion-dipole interactions and C-H‧‧‧π interactions. The optimal size matching between the carboxylate AP5As and DMBr was ∼0.80. The binding affinity increased with an increase in the charge quantity of AP5As. Further animal experiments indicated that the reversal efficiency increased with increasing binding affinity for carboxylate or phosphonate AP5As. However, phosphonate AP5As exhibited lower reversal efficiencies than carboxylate AP5As, despite having stronger affinities with DMBr. By understanding the structure-affinity-reversal relationships, this study provides valuable insights into the design of innovative SRBAs for reversing neuromuscular blockade.

Congested C(sp3)-rich architectures enabled by iron-catalysed conjunctive alkylation.

Catalytic cross-coupling by transition metals has revolutionized the formation of C-C bonds in organic synthesis. However, the challenge of forming multiple alkyl-alkyl bonds in crowded environments remains largely unresolved. Here, we report the regioselective functionalization of olefins with sp3-hybridized organohalides and organozinc reagents using a simple (terpyridine)iron catalyst. Aliphatic groups of various sizes are successfully installed on either olefinic carbon, furnishing a diverse array of products with congested cores featuring C- or heteroatom-substituted stereocenters. The method enables access to valuable but synthetically challenging C(sp3)-rich molecules, including alicyclic compounds bearing multiple contiguous stereocenters through annulation cascades. Mechanistic and theoretical studies suggest a stepwise iron-mediated radical carbometallation pathway followed by outer-sphere C-C bond formation, which potentially opens the door to a broader scope of transformations and new chemical space.

Contrasting Effects of Nitrogen Deposition and Phosphorus Addition on Soil Organic Carbon in a Subtropical Forest: Physical Protection versus Chemical Stability

Soil organic carbon (SOC) not only contributes to maintain soil health, but is also important in regulating global climate change. How atmospheric nitrogen (N) deposition and phosphorus (P) addition affects SOC dynamics remains unclear, especially in subtropical forests. The response of SOC in three layers to N deposition and P addition in this study is estimated by analyzing the soil aggregates and C chemical stability composition fertilized with N (100 kg N hm−2 a−1) and/or P (50 kg P hm−2 a−1) over 9 years in a Chinese fir (Cunninghamia lanceolata) plantation. Treatments involving N deposition increased the SOC concentration, while P addition alone decreased the SOC concentration in soil layers above 10 cm. The addition of N significantly increased the mean diameter of topsoil aggregates, macroaggregates SOC concentration, and the contribution of N to total SOC. P addition decreased the relative abundances of aromatic and aliphatic functional groups while decreasing the chemical stability of SOC in the topsoil. A structural equation model indicated that N deposition promoted SOC concentration by mainly improving the physical protection of soil aggregates, while P addition reduced SOC sequestration by decreasing the chemical stability of SOC. Our research suggested that elevated N deposition might promote the soil C sink, while P fertilization would not be recommended under increased N deposition to protect soil C storage in subtropical forests.

Cross-linking lignin and cellulose with polymers using siloxane compounds

Siloxanes are a group of substances characterized by Si-O-Si functional group. Siloxanes can react with alcohols to form Si-O-C bond. Siloxanes have been widely used as crossing linking agents and graft copolymers as well as additives for plastics. Lignin contains both phenolic and aliphatic hydroxy groups which have the potential to instigate bonding with siloxane compounds. However, there has not been any attempt to apply siloxanes as crosslinking agents for biobased composite formation. This manuscript presents the first study of applying siloxanes compounds to lignin and Cellulose nanofibers (CNF) with respective PLA, PETG, and HDPE to prepare biocomposites. Both Tetramethyl Tetraphenyl Trisiloxane (TTT) and Tetraethoxysilane (TEOS) were used as cross-linking agents. We have successfully incorporated 20 wt% lignin and 10 wt% CNF into the biocomposite filaments. The tensile properties of ensuing biocomposite were investigated. The objective of this work is to demonstrate the potential of lignin and CNF as a sustainable co-polymer to improve the properties of PLA/PETG/HDPE-based materials for 3D printing. This paper will also discuss the challenges and opportunities associated with the use of lignin in 3D printing, including the effect of lignin and CNF content on the mechanical and thermal properties, the compatibility of lignin and CNF with PLA/PETG/HDPE, and the potential for further optimization of the cross-linking chemistry using TTT and TEOS.

In-situ polymerization of a free-standing and tough gel polymer electrolyte for lithium metal batteries

In-situ polymerization of gel polymer electrolyte (GPE) is expected to be promising approach to solve the safety and interfacial problems of lithium ion battery, but it is still challenging ways to tradeoff the high electrochemical properties and mechanical toughness. Here, 30 μm thickness of free-standing GPEs with extremely high monomer conversion were obtained by in-situ UV approach on lithium metal anode within only few seconds. The coordination of amide and aliphatic carbonyl groups with lithium ion endows the tough mechanical properties, which tensile strength and elongation at break reach up to ∼1.0 MPa and ∼920 %. Furthermore, the inflammability of dry polymer matrix and a good degree of graphitization on the surface of burned polymer gel contribute to its flame resistance. The ionic conductivity and lithium ion transferance number are up to 1.03 mS/cm and 0.44 at room temperature, respectively. Finally, Li/LiFePO4 half cells assembled with the optimized GPEs exhibit stable cycle performance at 0.5C rate, delivering 77.44 % of capacity retention after 1000 cycles.

Molecular-level insights into the temperature-dependent formation dynamics and mechanism of water-soluble dissolved organic carbon derived from biomass pyrolysis smoke

Water soluble organic carbon (WSOC) derived from biomass pyrolytic smoke is deposited through atmospheric aerosols, negatively affecting aquatic ecological quality and safety. However, the temperature-dependent molecular diversity and dynamic formation of smoke-derived WSOC remain poorly understood in water. Herein, we explored the molecular-level formation mechanism of pyrolytic smoke-derived WSOC in water to explain the evolution, heterogeneous correlations, and sequential responses of molecules and functional groups to increasing pyrolysis temperature. Two-dimensional correlation spectroscopy was used to innovatively establish the characteristic correlations between spectroscopy and Fourier transform-ion cyclotron resonance mass spectrometry. Temperature-dependent formation of WSOC exhibited diversity in absorbance/fluorescent components, unique/common molecules, and their chemical parameters, showing the simultaneous formation and degradation reactions. The common WSOC molecules with lower and higher degrees of oxidation showed significant positive and negative correlations with the fluorescent components, respectively. The primary sequential response of WSOC molecules to increasing pyrolysis temperature (lignin-like molecules → unsaturated hydrocarbons, condensed aromatic molecules → lipid-like/aliphatic-/peptide-like molecules) corresponded to the temperature response of functional groups (carboxylic/alcoholic → polysaccharides → aromatics/amides/phenolic/aliphatic groups), demonstrating well synergistic relationships between them. These novel findings will contribute to the comprehensive understanding and assessments of potential environmental behavior or risks of WSOC in aquatic ecosystems.

The effect of co-pyrolysis of bamboo waste and polypropylene on biomass deoxygenation and carbonization processes

While numerous research studies have delved into the co-pyrolysis of biomass and plastic waste, limited attention has been devoted to comprehending the interaction mechanism that impacts biomass deoxygenation and carbonization. Therefore, this study explores the co-effect of temperature and polypropylene blending ratio on co-pyrolysis reaction kinetics, distribution of oxygenates/hydrocarbons, as well as the evolution of biochar structure. At a blending ratio of 0.5, the co-pyrolysis exhibits the lowest activation energy (146 kJ/mol), approximately 25.1 % lower than that required for individual pyrolysis. The interaction between bamboo waste with polypropylene increases the O-abstraction process, resulting in the creation of O-containing free radicals and hydrocarbon compounds. The peak proportion of aromatic compounds, reaching approximately 69.5 %, is observed at 700 °C when the blending ratio is 0.5. The H-abstraction process converts large-molecular alkanes into H free radicals and tiny-molecular unsaturated hydrocarbons. The aliphatic functional group content diminishes as the polypropylene ratio increases. The maximum specific surface area (7.70 m2/g) and pore volume (21.7 mm3/g) are achieved at a blending ratio of 0.75. Notably, polypropylene exerts minimal influence on the graphite crystallite size and graphitization degree of biochar. This research significantly contributes to advancing our understanding of the interaction mechanisms between biomass and plastic waste.

Effects of rock water with different acidity on microstructure and reburning ability of residual coal in goaf

To explore the influences of rock water acidity (PH = 4,5,7) over the microstructure and reburning behaviors of oxidized residual coal in the overlying goaf, the pore morphology, coal surface, functional group content and activity of pre-oxidized coal (O0) and water-immersed oxidized coal (OI) were analyzed by Low-temperature nitrogen adsorption and In-situ diffuse reflection experiments, combining with fractal dimension theory and functional group oxidation kinetics. The oxidation and reburning ability of coal samples has been analyzed by Thermogravimetric-Differential thermal analysis experiment. The results are as follows: Part of the type-III pores of pre-oxidized coal become type-II pores when immersed. The acidic solution has stronger corrosivity to O0 than distilled water, playing a role in smoothing coal and improving the uniformity of pore structure. The order of reburning ability of samples is OI7>OI4>O0>OI5 according to the ignition and stage average mass loss rate (RM). The reactivity of –OH may affect the reburning ability of coal more than its initial content. Soaking is beneficial to the decrease of activation energy of aliphatic groups, and the activity of –C=O- and -C-O- in acid-soaked coal molecules is stronger, so that they can take part in coal-oxygen composite reactions at low temperature.

Solvent effects on the Raman absorption spectrum of epinephrine and norepinephrine by Monte Carlo and QM computational methods

The Raman spectra of epinephrine (EP) and norepinephrine (NP) were obtained by computational simulation in gaseous phase and diluted in water by both PCM and Monte Carlo explicit molecules methods by four levels of theory: HF and DFT (B3LYP, CAM-B3LYP and M06-2X) in combination with 6-311++G(d,p) basis functions, as PCM solvation was applied directly in Gaussian/09 and the Monte Carlo output from DICE was then single point simulated to obtain vibrational data. Raman shifts related to hydrogen bonds were identified. For EP, red shifts were obtained in peaks near 750 cm−1, 950 cm−1, 1300 cm−1 and 1600 cm−1 wavenumbers assigned to both aliphatic and catechol groups, indicating decrease in system energy and tendency to solvation. For NP, shifts near 750 cm−1 were slighter due to the change in the aliphatic group, as red shifts near 1250 cm−1 and 1600 cm−1 were similar as in EP due to the analogous catechol group. A comparison between HF/DFT methods was done and the better description of solvation was obtained by the Monte Carlo explicit approach as it identifies local molecular effects.

Effect of water immersion pressure on oxidation characteristics and spontaneous combustion characteristics of long-flame coal

Coal seam water injection has an obvious effect on coal dust prevention. The high-pressure water environment of coal seam water injection changes the structure of coal which brings new effects on the characteristics of coal spontaneous combustion disaster. To reveal the effects of water immersion pressure on the oxidation characteristics of long-flame coal, coal samples immersed in water at 0.1 MPa, 2.5 MPa, 5.0 MPa, 7.5 MPa and 10.0 MPa were prepared. Four experiments were conducted to study the changes in oxidation characteristics and its main reasons. The results showed that elevated water immersion pressure promoted the spontaneous combustion tendency of coal, and the composite judgment index of coal decreased to 521.1. Coal immersed in pressurized water entered the stages of oxygen-absorbing oxidation and thermal decomposition earlier than coal immersed in atmospheric pressure water. The specific surface area and average pore diameter of coal immersed in high-pressure water increased, where the pore volume proportion of mesopores of the coal immersed in water at 10.0 MPa increased by 138.5 % compared with that of the coal immersed in atmospheric pressure water. The elevated water immersion pressure prompted coal to produce further aliphatic hydrocarbons and hydroxyl groups, which improved the low-temperature oxidation capacity.

Kraft Lignin-Derived Microporous Nitrogen-Doped Carbon Adsorbent for Air and Water Purification.

The study presents a streamlined one-step process for producing highly porous, metal-free, N-doped activated carbon (N-AC) for CO2 capture and herbicide removal from simulated industrially polluted and real environmental systems. N-AC was prepared from kraft lignin─a carbon-rich and abundant byproduct of the pulp industry, using nitric acid as the activator and urea as the N-dopant. The reported carbonization process under a nitrogen atmosphere renders a product with a high yield of 30% even at high temperatures up to 800 °C. N-AC exhibited a substantial high N content (4-5%), the presence of aliphatic and phenolic OH groups, and a notable absence of carboxylic groups, as confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Boehm's titration. Porosity analysis indicated that micropores constituted the majority of the pore structure, with 86% of pores having diameters less than 0.6 nm. According to BET adsorption analysis, the developed porous structure of N-AC boasted a substantial specific surface area of 1000 m2 g-1. N-AC proved to be a promising adsorbent for air and water purification. Specifically, N-AC exhibited a strong affinity for CO2, with an adsorption capacity of 1.4 mmol g-1 at 0.15 bar and 20 °C, and it demonstrated the highest selectivity over N2 from the simulated flue gas system (27.3 mmol g-1 for 15:85 v/v CO2/N2 at 20 °C) among all previously reported nitrogen-doped AC materials from kraft lignin. Moreover, N-AC displayed excellent reusability and efficient CO2 release, maintaining an adsorption capacity of 3.1 mmol g-1 (at 1 bar and 25 °C) over 10 consecutive adsorption-desorption cycles, confirming N-AC as a useful material for CO2 storage and utilization. The unique cationic nature of N-AC enhanced the adsorption of herbicides in neutral and weakly basic environments, which is relevant for real waters. It exhibited an impressive adsorption capacity for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at 96 ± 6 mg g-1 under pH 6 and 25 °C according to the Langmuir-Freundlich model. Notably, N-AC preserves its high adsorption capacity toward 2,4-D from simulated groundwater and runoff from tomato greenhouse, while performance in real samples from Fyris river in Uppsala, Sweden, causes a decrease of only 4-5%. Owing to the one-step process, high yield, annual abundance of kraft lignin, and use of environmentally friendly activating agents, N-AC has substantial potential for large-scale industrial applications.