C O Bond Research Articles

ATR-FTIR characterisation of daily-use plastics mycodegradation

Synthetic polymers, such as plastics, have permeated all aspects of modern life, and nowadays plastic pollution is a major environmental problem. Mycodegradation of these polymers could represent part of the solution to this problem since it calls on a broad toolbox of enzymes and applies non-enzymatic mechanisms to degrade and deteriorate recalcitrant materials. However, not enough is known about this ability for most of the representatives of the fungal kingdom. Another bottleneck is the harmonisation of technologies to analyse plastic degradation. This work involved the design of a biodegradation experiment, where the potential of four fungi representative of Dikarya and Penicillia (Funalia floccosa, Trametes versicolor, Pycnoporus cinnabarinus and Penicillium oxalicum) were tested on their ability to deteriorate the six most used plastics based on gravimetry and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The following correlation between changes in the band signals and the loss of mass after treatment was determined using polyethylene terephthalate, polypropylene, polyethylene, poly vinyl chloride, high density polyethylene, low density polyethylene and nylon. After treatment, the decrease in absorbance of the characteristic bands of the plastics was taken as an indication of the degradation of the corresponding bonds/functionalities. The four fungi used could transform CH, CH2, CH3, CO, CO, CN, NH and CCl bonds. The best result was obtained using the fungus F. floccosa with 90-day treatments for high density polyethylene (∼ 62.0 %), low density polyethylene (∼ 23.6 %) and nylon (∼ 35.6 %). Therefore, mycodegradation could open up new doors in the fight against plastic pollution.

Ferrate(Ⅵ) oxidative degradation of capecitabine in aquatic matrices: Degradation performance, mechanisms, and toxicity assessment

The growing utilization of anticancer drugs in recent years has resulted in their presence in surface water and sewage, which could have ecological consequences. In this work, ferrate (Fe(VI)) was utilized to oxidize capecitabine (CAP), a frequently used anticancer drug that has gained attention lately. The experiments have demonstrated that Fe(VI) was quite reactive with CAP at pH 7. The addition of humic acid (0.1–10 mg L−1) significantly inhibited the oxidation process. Then, four reaction pathways, mainly including hydroxyl substitution, direct oxidation and cleavage of CO and CN bond were proposed based on twelve products detected by high-resolution hybrid quadrupole time-of-flight mass spectrometer. These pathways were further validated by theoretical calculations. Experiments conducted in water matrices assessed the applicability of Fe(VI) technology. Toxicity assessments of CAP and its intermediates were performed using the TEST program, and predictions indicated that the intermediates were generally less toxic than CAP. Overall, this work revealed that Fe(VI) has great potential to solve the environmental pollution problems associated with capecitabine in water.

Mechanistic studies on phosphine-catalyzed [4 + 3] annulation of β′-acetoxy allenoate with 1C,3N-dinucleophile

The mechanism and role of catalyst on the PPh3-catalyzed [4 + 3] annulation reaction have been systematically investigated using density functional theory (DFT) method. Based on the calculations, the possible mechanism contains six steps: nucleophilic addition of PPh3 to allenoate to give Z-configured intermediate, cleavage of CO bond for forming phosphonium diene, nucleophilic addition of phosphonium diene with anionic 1C,3N-dinucleophile, intramolecular [1,5]-proton shift, ring-closure, and dissociation of catalyst. Non-covalent interaction (NCI) analysis shows that the O⋯P interaction would be the key for leading to the Z-configured pathway more favorable and electron localization function (ELF) analysis indicates that the implication of PPh3 can significantly lower the energy barrier involved in CO cleavage process, which mainly because the addition of PPh3 reduces the electron density of CO bond and thus facilities the cleavage of CO bond. This theoretical study would provide some clues for understanding the role of catalyst in a catalytic reaction.

Gold Meets Selenium: Dual Activation of Selenium-Containing Propargyl Alcohols Towards the Synthesis of 2H-Chromenes and Mechanistic Insights.

Herein, we report the synthesis of seleno-substituted chromenes from selenoalkynes and phenols. In this cascade reaction, the applied gold catalyst not only functions as a π-acid, but also as a Lewis acid, enabling the propargylic substitution in the first step to connect the oxygen carbon bond. Under the optimal reaction condition a total of 26 chromenes were accessible by this modular access. During scale up experiments, the hydrolysis of the vinylselenium substructure to the corresponding chromenones was observed. By revisiting the electron-rich starting materials, four chromenones were produced following a one-pot reaction using a single gold catalyst. To better understand the interaction of gold and selenium, a series of nuclear magnetic resonance studies and high-resolution mass spectrometry studies were performed, which led to the proposal of a mechanism for this transformation.

Hydrodeoxygenation of Glycerol to Propene Over Molybdenum and Niobium Phosphate Catalysts

AbstractIn single‐step conversion of glycerol to propene, the intricate catalytic pathways with molybdenum and niobium catalysts remain elusive. While these catalysts can effectively accelerate the hydrogenolytic cleavage of the glycerol CO bonds, resulting in a high selectivity to propene, the routes have not been thoroughly studied. This study explores the reaction routes and the role hydrogen plays in determining the product distribution. The hydrodeoxygenation (HDO) of glycerol was investigated using various glycerol purities in both batch and continuous reaction modes. Remarkably, Mo(PO4)x and Nb(PO4)x demonstrated catalytic performance with raw glycerol, indicating that impurities had no detrimental effect on the catalyst's activity. In batch mode, a propene selectivity of 53% was achieved over Mo(PO4)x as the catalyst, highlighting the catalyst's stability under these conditions. In continuous operation, the highest product selectivity to propene (12%) was observed at low temperatures (573 K), while more C2 to C6 alkanes were formed at increased temperatures (623 and 673 K). Whereas a hydrogen atmosphere promotes formation of 2‐propenol, as primary precursor to propene, an inert atmosphere leads to increased formation of propanal and dissociation products. Our work has elucidated new routes to upcycle biorenewable glycerol to propene over Mo(PO4)x and Nb(PO4)x catalysts.

Triple Catalysis for the Tandem Transformation of Cyclopropyl Ketones to SCF3-Substituted Dihydrofurans.

In this study, we have developed an effective and general strategy for synthesizing various 4-[(trifluoromethyl)thio]-2,3-dihydrofuran derivatives with high regioselectivity from easily prepared cyclopropyl ketone under mild reaction conditions. By the combination of photoredox, copper, and Lewis acid catalysis into a triple catalytic system, this methodology facilitates the selective cleavage of the carbon-carbon bonds and the formation of new carbon-oxygen and carbon-sulfur bonds. In addition, to enhance the synthetic feasibility of this protocol, we demonstrate its broad applicability across a wide range of substrates and its scalability for large-scale synthesis.

Computational Study of Carbon Dioxide Capture by Tertiary Amines.

The reaction mechanisms and corresponding structure-activity relationships of tertiary amines with respect to CO2 capture have been investigated using density functional theory (DFT) calculations. The reaction mechanism for CO2 capture via base-catalyzed hydration to form bicarbonate is proposed to proceed in a single step involving proton transfer and the formation of a carbon-oxygen bond. Based on the height of the reaction barriers, we suggest that amines containing side chains with the ethyl group, along with a single hydroxyl group, and cyclic structures, are especially active for CO2 capture. The activation barrier is shown to be a descriptor for predicting the experimental CO2 loading values. To enhance the prediction accuracy for CO2 loading, we employ the sure-independence screening and sparsifying operator (SISSO) method, which can scan a large pool of mathematical terms stemming from combining DFT-derived descriptors to select the superior ones. Thus, we can predict the CO2 loading with acceptable accuracy from the obtained mathematical expression. Since the computational workload of applying this expression is negligible, this facilitates high-throughput screening and accelerates the design of tertiary amines for CO2 capture.

Revealing the mechanism of bifunctional PtLa electrocatalyst for highly efficient methanol oxidation, hydrogen evolution, and coupling reaction

The development of clean energy solutions, such as fuel cells and hydrogen energy, is crucial for addressing the global energy shortage. Platinum (Pt)-based catalysts are widely used in fuel cells and hydrogen energy generation (for example, via water electrolysis). However, reducing the amount of Pt used while maintaining the catalytic performance of such catalysts is essential. Herein, PtLa catalysts (PtxLay/C) doped with rare earth element lanthanum (La) with different Pt/La atomic ratios were synthesized using a simple chemical reduction method, resulting in Pt65La35/C, Pt78La22/C, Pt97La3/C, and Pt100/C. These PtxLay/C catalysts exhibited excellent electrocatalytic activity and stability in methanol oxidation reaction (MOR), hydrogen evolution reaction (HER), and their coupling reaction as MOR||HER under alkaline conditions. The mechanism by which La doping enhances the electrocatalytic properties and stability of Pt-based catalysts was investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), aberration-corrected scanning transmission electron microscopy (AC-STEM), in-situ Fourier transform infrared (FTIR) and operando Raman spectroscopy. For HER, La doping facilitated the adsorption and activation of H2O at Pt sites, improving water dissociation and *OH desorption and reducing Pt poisoning by *OH. This enhances both the catalytic performance and stability of PtxLay/C for HER. Pt78La22/C exhibited a considerably lower overpotential of only 111 mV at 100 mA cm−2 compared to commercial 20 wt% Pt/C (Pt/C-Johnson Matthey (JM)), which requires 153 mV. For MOR, La promotes CO bond cleavage and reduces CO adsorption at the Pt sites, thereby enhancing both the performance and stability of the catalysts. The mass activity (MA) of Pt78La22/C for MOR is 4.44 A mg−1Pt, which is 12.33 times higher than that of Pt/C-JM (0.36 A/mgPt), and surpasses those of Pt65La35/C, Pt97La3/C, and Pt100/C (2.93, 0.24, and 2.91 A mg−1Pt, respectively). Additionally, Pt78La22/C exhibited outstanding catalytic performance for MOR||HER, with a current density of 20 mA cm−2 at 1.030 V, demonstrating good stability with negligible voltage changes after a 15 h chronoamperometry (CA) testing. This study provides a new strategy for synthesizing Pt-based catalysts with enhanced efficiency and low-energy input for HER||MOR.

Facile synthesis of vinyl sulfoxides via external oxidant-free oxidative condensation of phenylglycinols with DMSO

Oxidative activation of CO, CN and CC bonds has recently emerged as a powerful method for the synthesis of valuable organic compounds. However, these strategies have often required the metal catalysts and strong external oxidants. Herein, we report a new protocol for the convenient construction of vinyl sulfoxides from phenylglycinols and DMSO under basic conditions. Notably, DMSO was used not only as a methyl sulfoxide (−SOMe) reagent, but also as an oxidizing agent. The present system features mild metal- and external oxidant-free conditions, broad scope, and excellent functionality tolerance.

Tip-like copper sites on high curvature supports for non-covalent to covalent interaction tuning in CO2 photoreduction

Single-atom engineering offers a promising method to transform CO2 into high-value chemicals. The local coordination structure design of the metal-support is crucial for overcoming slow reaction kinetics. In this study, Cu single atoms are immobilized on curved Bi12O17Br2 surface to create a tip-like metal site structure named Cutip-Bi12O17Br2. Due to the high curvature Bi12O17Br2 surface with tensile strain, the tip Cu creates significant electronegativity differences between adjacent Bi atomic sites, creating the vigorous polarization centers. The strong charge redistribution character of tip asymmetric Cu-Bi site favor the polarization of CO bond in nonpolar CO2 and adjust the noncovalent to covalent interaction of reaction intermediates. Benefiting from these features, the optimized Cutip-Bi12O17Br2 enhance the CO production rate by a factor of 34 relative to bulk-Bi12O17Br2, reaching a rate of 96.99 μmol g−1 h−1. This work provides a comprehensive understanding of the structural regulation of single-atom on high curvature surface for CO2 photoreduction.

Effect of Electric Fields on the Decomposition of Phosphate Esters.

Phosphate esters decompose on metal surfaces and form protective polyphosphate films. For many applications, such as in lubricants for electric vehicles and wind turbines, an understanding of the effect of electric fields on molecular decomposition is urgently required. Experimental investigations have yielded contradictory results, with some suggesting that electric fields improve tribological performance, while others have reported the opposite effect. Here, we use nonequilibrium molecular dynamics (NEMD) simulations to study the decomposition of tri-n-butyl phosphate (TNBP) molecules nanoconfined between ferrous surfaces (iron and iron oxide) under electrostatic fields. The reactive force field (ReaxFF) method is used to model the effects of chemical bonding and molecular dissociation. We show that the charge transfer with the polarization current equalization (QTPIE) method gives more realistic behavior compared to the standard charge equilibration (QEq) method under applied electrostatic fields. The rate of TNBP decomposition via carbon-oxygen bond dissociation is faster in the nanoconfined systems than that in the bulk due to the catalytic action of the surfaces. In all cases, the application of an electric field accelerates TNBP decomposition. When electric fields are applied to the confined systems, the phosphate anions are pulled toward the surface with high electric potential, while the alkyl cations are pulled to the surface with lower potential, leading to asymmetric film growth. Analysis of the temperature- and electric field strength-dependent dissociation rate constants using the Arrhenius equation suggests that, on reactive iron surfaces, the increased reactivity under an applied electric field is driven mostly by an increase in the pre-exponential factor, which is linked to the number of molecule-surface collisions. Conversely, the accelerated decomposition of TNBP on iron oxide surfaces can be attributed to a reduction in the activation energy with increasing electric field strength. Single-molecule nudged-elastic band (NEB) calculations also show a linear reduction in the energy barrier for carbon-oxygen bond breaking with electric field strength, due to stabilization of the charged transition state. The simulation results are consistent with experimental observations of enhanced and asymmetric tribofilm growth under electrostatic fields.

Regulation of surface oxygen functional groups in starch-derived hard carbon via pre-oxidation: A strategy for enhanced sodium storage performance

During the process of sodium storage in hard carbon anodes, the significance of surface oxygen functional groups cannot be overlooked. In this work, we utilize starch as raw material to synthesize hard carbon by the process of pre-oxidation and two-step carbonization. XPS analysis reveals that pre-oxidation bolsters the presence of CO bonds, thereby providing more active sites. TEM analysis reveals that hard carbon with pseudo-graphite and graphite-like structure is obtained at relatively high carbonization temperature (1400 °C), and the formation of closed pores results in lower specific surface area. The introduction of appropriate oxygen-containing groups in pre-oxidation process can facilitate the cross-linking of starch chains, promoting the increase of defect sites and the sodium storage performance of hard carbon. A series of samples are prepared at various pre-oxidation temperature. Among them, P200-HC obtained after pre-oxidation at 200 °C and carbonization at 1400 °C exhibits the highest reversible specific capacity of 342.7 mAh g−1 at current density of 0.1 C with an initial Coulombic efficiency of 71.1 %, and capacity retention of 87.3 % at current density of 1 C. The work presents a viable approach for the synthesis of hard carbon derived from starch, thereby expanding the design tactic of sodium-ion batteries with improved performance.

Low-energy argon ion beam irradiation for the surface modification and reduction of graphene oxide: Insights from XPS

Developing environmentally friendly methods for reducing graphene oxide (GO) is essential. This study investigates the surface modification and reduction of GO films using 200 eV argon ion (Ar+) beam irradiation. X-ray Photoelectron Spectroscopy (XPS) analysis reveals significant chemical changes on the GO surface. GO was irradiated with a 200 eV Ar+beam for varying times (0–80 s). XPS survey spectra showed the presence of carbon and oxygen, with an increasing carbon atomic percentage over time. High-resolution XPS spectra of C 1s revealed peaks corresponding to sp2, C–OH, O–C–O, CO, and O–CO bonds. In the O 1s spectra, CO, O–C–O, and C–OH groups were observed. Upon irradiation, the CO peak consistently decreased, the O–C–O peak fluctuated, and the C–OH peak increased, indicating effective reduction of CO groups, dynamic changes in O–C–O functionalities, and the formation of additional C–OH groups. The C/O ratio increased from ∼2.4 to 2.7, underscoring the reduction process and enhanced carbon content. This method proves to be an efficient approach for producing reduced graphene oxide (rGO) with improved properties for advanced applications.

Selective switching hydrogenation products of 5-hydroxymethylfurfural at high substrate concentrations by regulating Pd-MgO interactions

Controlling the selective activation of one or some functional groups as desired is still a challenge in hydrogenation, especially at high substrate concentrations. Herein, Pd-MgO interfaces over Al2O3 were finely regulated for efficiently selective hydrogenation of furan ring in 5-hydroxymethylfurfural (HMF) to produce 5-hydroxymethyltetrahydro-2-furaldehyde (5-HMTHFF) or total hydrogenation to 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF), also inhibiting side reaction. The Pd-MgO/Al2O3 with 12.0 wt% of MgO selectively hydrogenates the furan rings with a 5-HMTHFF yield of 82.4 % while that with 2.0 wt% of MgO totally hydrogenates HMF with a DHMTHF yield of 96.2 % at high substrate concentrations (400 mM). Characterizations and DFT calculations demonstrated that oligomeric MgO species suppress the agglomeration of Pd nanoparticles and strengthen HMF adsorption, consequently promoting total hydrogenation. Furthermore, Pdδ+-MgO1-x sites between the crystallized MgO and Pd metal favored tilted adsorption on the interface and weakened the activation of the CO bond, consequently selectively producing 5-HMTHFF.

MIL-101(Cr) entrapped polyol-synthesized iron promoted platinum bimetallic nanoparticles system for synergistic selective hydrogenation of cinnamaldehyde

The interfacial characteristics of platinum (Pt) metal catalysts can be systematically regulated by interacting them with electropositive metals, leading to synergistic interactions for extensive catalytic applications. In this study, an evenly dispersed polyol-synthesized iron (Fe)-promoted Pt bimetallic nanoparticle (BNPs) system was embedded in MIL-101(Cr). The PtFe2@MIL-101(Cr) catalyst unveiled remarkable activity (86%) and selectivity (89%) for the superior hydrogenation of the targeted CO bond of cinnamaldehyde (CAL). The exceptional hydrogenation performance can be credited to the interplay of the geometric and electronic properties arising from charge shuttling between Fe and Pt within the homogenously distributed Pt–Fe bimetallic nanoparticle system. The experimental results indicate enhanced valence electrons in the Pt d-band through the mutual synergetic interface between the Pt and Fe BNPs. Consequently, these Fe–Pt sites functioned as interfacial electrophilic and nucleophilic (Lewis acid-base) sites, enhancing H2 activation and facilitating CO bond conversion to yield unsaturated cinnamal alcohols (COL). Additionally, the narrow pores of MIL-101(Cr) encapsulating the Pt–Fe BNPs induced steric hindrance, allowing only CO bond hydrogenation. Furthermore, the PtFe2@MIL-101(Cr) catalyst maintained its optimal hydrogenation performance over five cycles, demonstrating no substantial loss in either CAL conversion or COL yield, thus endorsing the universal practical applicability of the catalyst.

Enhancing the production of reactive oxygen species in the rhizosphere to promote contaminants degradation in sediments by electrically strengthening microbial extracellular electron transfer

The production of reactive oxygen species (ROS) in the rhizosphere is limited by the low extracellular electron transfer capacity of indigenous microorganisms. In the present study, electrical stimulation was used to promote the generation of rhizospheric ROS by accelerating extracellular electron transfer. The result showed that •OH concentrations in the electrically stimulated group (ES group) exceeded the control group by 15.76 %. Accordingly, the removal rate of the target pollutant (i.e., 2,4-dichlorophenol, and sulfamethoxazole) was 20.01 %−24.80 % higher in the ES group than in the control group. The sediment of the ES group had a higher capacity (30.55 %) and a lower electrical resistance (29.15 %) compared to the control group, which subsequently promoted the dissimilatory iron reduction to produce Fe(II) for triggering a Fenton-like process. The increased extracellular respiratory capacity under electrical stimulation could be attributed to the polarization of C-N and CO bonds, which provided more electron storage sites and thus participated in proton-coupled electron transfer. In addition, the concentration of ATP and co-enzymes (NADH/NAD+ and Complex I/Complex III), reflecting electron exchange within respiratory chains, increased distinctly under electrical stimulation. Applying electrical stimulation seemed feasible to increase ROS production and contaminant degradation in the rhizosphere, deepening the understanding of electrical stimulation to promote the production of ROS in the natural system.

Peroxydisulfate activation by copper nanoparticles doped highly graphitized hollow carbon spheres for thiocyanate degradation

Thiocyanate (SCN-) is a toxic and refractory inorganic pollutant commonly found in industrial wastewater. This paper proposes an innovative solution to enhance the activation of peroxydisulfate (PDS) by designing a highly graphitized hollow carbon nanosphere structure catalyst doped with copper nanoparticles, thereby achieving efficient and complete degradation of SCN-. Specifically, the active sites and electron transfer ability of the catalyst were improved by controlling the pyrolysis temperature and acid etching time during the catalyst preparation process, thereby optimizing the PDS activation rate and SCN- degradation rate. In the optimized Cu-NPs@C/PDS system, a low dose of Cu-NPs@C-650–6 catalyst (0.2 g/L) and PDS ([PDS]0: [SCN-]0 = 3: 1) was sufficient to achieve 100 % degradation of 100 mg/L SCN- within 20 min. The non-radical oxidation pathway combined with singlet oxygen (1O2) and direct electron transfer process was identified as the main degradation mechanism of SCN-. The unique oxidation mechanism provided a higher SCN- degradation reaction rate constant (k1 = 0.39 min−1) and stronger environmental ion resistance. Density functional theory (DFT) calculations show that the CO bond is the primary PDS active site for the formation of inside-out electron delocalization, and the S atom in SCN- is a vulnerable site. This work offers technological support for the treatment of water bodies holding emerging electron-rich pollutants in addition to fresh insights into the creation of efficient catalysts for metal-carbon composites.

Fe3 cluster-anchored monolayer MoS2 for direct deoxygenation of phenol: Catalyst design and activation mechanism

This study introduces a novel Fe3@MoS2 catalyst for the direct deoxygenation of phenol, key to lignin’s catalytic conversion into aromatic hydrocarbon bio-oil. Through density functional theory (DFT) calculations, we have dissected the electron transfer and activation barrier for the CO bond’s direct cleavage over the Fe3 cluster. A pivotal activation mechanism was uncovered, characterized by the formation and occupation of d-π* orbitals, which facilitates electron transfer from Fe3′s d orbital to phenol’s CO π* orbital. This enhanced catalytic activity is revealed to stem from the spin polarization and the reduced oxidation state of the Fe3 cluster, as corroborated by DOS and Bader charge analysis. Moreover, the study compares the performance of Fe3@MoS2 with that of heterogeneous active sites, such as 3Fe@MoS2 and Fe-3@MoS2, and finds that the homogeneous active site of Fe3@MoS2 is more favorable for phenol DDO in terms of both kinetic and thermodynamic aspects.

Preparation and characterization of FeZrB amorphous ferrofluids as magnetic sizing agents for basalt fibers coating

In this paper, FeZrB amorphous nanoparticles were prepared and used to obtain a magnetic fluid which can be used as a magnetic sizing agent for basalt fibers. Unmodified FeZrB nanoparticles (Unmodified FeZrB), citric acid-modified FeZrB nanoparticles (FeZrB@CA) and sodium oleate-modified FeZrB nanoparticles (FeZrB@NaOL) were synthesised by chemical reduction. Three kinds of FeZrB magnetic sizing agents were obtained by dispersing nanoparticles into the mixture consisting of PVA and KH-550. The magnetic basalt fibers were prepared by spraying the magnetic sizing agents in the process of drawing basalt fibers. The structure, morphology, surface state and magnetic properties of unmodified and modified FeZrB amorphous nanoparticles were characterized by XRD, SEM, TEM, FT-IR and VSM. The properties of magnetic basalt fibers were investigated by SEM, VSM and EDS. The results showed that the XRD spectra showed sharp diffraction peaks in both Unmodified FeZrB and FeZrB@NaOL nanoparticles, and the two groups of samples had different degrees of crystallinity. Only a single broad peak can be observed at around 45° in FeZrB@CA, which confirms the amorphous structure of FeZrB@CA. SEM and TEM images show that the FeZrB amorphous nanoparticles exhibit spherical with sizes ranging from 7 nm to 25 nm. Electron diffraction patterns showed that FeZrB@CA had a diffraction halo typical of an amorphous structure, and the remaining two samples displayed diffraction rings, indicating some degree of crystallinity. The FT-IR spectra confirm the formation of CO bonds in both FeZrB@CA and FeZrB@NaOL nanoparticles, suggesting the successful modification of FeZrB nanoparticles. The saturation magnetization of Unmodified FeZrB, FeZrB@CA, and FeZrB@NaOL nanoparticles were determined as 83.4 emu/g, 98.9 emu/g, and 60.3 emu/g, respectively. The SEM images showed that the surface of fibers was completely covered by the magnetic sizing agents. Moreover, the saturation magnetization of BF-Unmodified FeZrB, BF-FeZrB@CA, BF-FeZrB@NaOL (magnetic basalt fibers) could reach 47.9 emu/g, 63.5 emu/g, and 28.9 emu/g, respectively. The formation mechanism of magnetic basalt fibers was elucidated, which is attributed to the SiO bonds between basalt fibers and KH-550, as well as CONH bonds between KH-550 and FeZrB@CA. Consequently, the FeZrB magnetic sizing agents could adhere to the fiber surface. This study provides a simple method for developing magnetic sizing agents and offers a new perspective for imparting magnetism to basalt fibers and preparing magnetic fibers.

Insight into carbon structures and pyrolysis behaviors of coal from the 13C CP/MAS NMR spectra

Carbon structures play an important role in the pyrolysis behavior of coal. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy is a powerful nondestructive technique for characterizing the carbon skeleton structures in coal. In this study, the carbon type distribution, lattice parameters, and chemical bond concentrations of six coal samples with different Vdaf values were investigated using 13C CP/MAS NMR spectra. Typical TGA and Py-GC-MS methods were utilized to obtain information on weight loss and pyrolysis products of the coals. The aromaticity of coal was determined by an adjustment of the apparent area ratio in the 13C CP/MAS NMR spectra, which shows promising potential for predicting key temperatures, characteristic index, and tar quality in coal pyrolysis. Results from the carbon fractions indicated that the total concentrations of chemical bonds in coal are approximately 150 mmol/g, with more Car−Car and Car−H bonds present in highly mature coal samples, and fewer Cal−Cal, Cal−H, and CO bonds. The breaking behaviors of chemical bonds during coal pyrolysis depend on a combination of temperature and concentration. The breakage of Cal−Cal bond contributes significantly to the pyrolytic weight loss of coal, accompanied by the decrease of Cal−H bonds along with the removal of aliphatic groups. Furthermore, as coal maturity increases, tar from fast pyrolysis contains more polycyclic aromatic hydrocarbons with a higher average molecular weight. The average number of aromatic rings in tar components is notably lower than that of aromatic clusters in coal. These results will contribute to a better understanding of the relationship between coal structure and reactivity, and may provide valuable insights for the efficient and clean utilization of coal.