Carbon-containing Functional Groups Research Articles

Enhancing Soil Aggregation and Organic Carbon Retention in Greenhouse Vegetable Production through Reductive Soil Disinfestation with Straw and Fertiliser: A Comprehensive Study

In greenhouse vegetable production, reductive soil disinfestation (RSD) effectively mitigates soil-borne diseases, yet its impact on the dynamics of soil organic carbon (SOC) has not been adequately examined. This study investigated the distribution of soil aggregates and the organic carbon retention mechanism following intensive RSD treatment. Greenhouse experiments, including control (CK), wheat straw (RSD), and wheat straw with chemical fertilizer (RSD + NP) treatments, indicated augmentation in the formation of macro-aggregates (>2 mm and 0.25–2 mm) under RSD, particularly in the RSD + NP treatment. Silty clay particles transform into macro- and micro-aggregates. Fourier infrared spectroscopy highlighted the augmentation of carbon-containing functional groups in SOC, with aliphatic carbon accumulating in macro-aggregates and aromatic carbon in silt clay. Laboratory culture experiments employing different C/N ratios (RSD1 with wheat straw, RSD2 with kiwifruit branches) underscored the beneficial impact of low C/N ratio organic matter on coarse and fine macro-aggregate content, mean weight diameter, geometric mean diameter, and reduced silt clay. Low C/N ratios enhance SOC retention in large aggregates, while high ratios stabilise micro-aggregate carbon. This research underscores the severe degradation in continuous greenhouse cropping systems and emphasises RSD’s dual benefits—disease prevention and improved SOC retention. Implementing RSD requires careful consideration of organic material choices, specifically their C/N ratios, as a pivotal factor influencing SOC dynamics.

Efficient degradation of fluoroquinolone antibiotics in the landfill leachate by sludge biochar activated peracetic acid: Radical vs non-radical process

Peracetic acid (PAA) has been increasingly used as a disinfectant and oxidant in wastewater treatment. The activation of PAA was crucial for the oxidation of refractory contaminants in the wastewater. Herein, the sludge biochar (SDBC) was fabricated, and then used as the activator for PAA to degrade fluoroquinolone antibiotics (FQs). Results show that FQs underwent rapid degradation by SDBC/PAA system at neutral pH, and the first-order rate constant (kobs) of enrofloxacin (ENR, 0.0886 min−1) was higher than those of ciprofloxacin (CIP, 0.0313 min−1) and ofloxacin (OFL, 0.0327 min−1). FQs degradation conformed the first order kinetics. Scavenging experiments and EPR analysis indicated both radical and non-radical process contributed to FQs degradation, with non-radical process act as the dominant role. The abundant π electrons and carbon-containing functional groups on the surface of SDBC facilitated electron transfer, resulting in PAA activation for 1O2 generation; while the iron species on SDBC could also activate PAA to generate the organic radicals, i.e., CH3COO· and CH3COOO·. The degradation of FQs underwent the defluorination, decomposition and shedding of piperazine rings, and the toxicity of FQs was significantly diminished after treatment by SDBC/PAA. SDBC had excellent activity and reusability in PAA activation, and SDBC/PAA process could resist the interference by the complicated water matrices with wide pH adaptability. Hence, the non-radical dominated degradation of FQs by SDBC/PAA maintained high efficiency in the real landfill leachate. This work provides a promising strategy to eliminate antibiotics and its biological activity in the complicated water matrices.

Effect of Water Vapor on Pore Structure, Surface Functional Groups, and Combustion Performance of Pyrolytic Semicoke.

The coal tends to be affected by the water vapor from quenching coke process in the pyrolysis process during the coal carbonization process and in turn causes the variation of physicochemical properties of semicoke. The preparation of semicoke based on different pyrolysis temperatures and water vapor content was carried out in order to investigate the influence of water vaper on physicochemical properties of the pyrolytic semicoke, combined with specific surface area analysis and thermal analysis to study the pore structure and combustion properties of semicoke. The morphology of the semicoke and the alteration rule of carbon-containing functional groups were analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy. The result indicates that adding an appropriate amount of water vapor (40%) instead of excess (60%) in the pyrolysis process (800 °C) is beneficial to the increase of the proportion of fixed carbon and the removal of volatile and ash. The specific surface area and the combustion performance of the semicoke is significantly improved when the appropriate amount of water vapor was added. The water vapor content has a slight effect on surface functional groups when the temperature ranges from 500 to 700 °C, whereas the higher water vapor content inhibits the improvement of physicochemical properties of the semicoke when the pyrolysis temperature is higher (800 °C). Therefore, the entry of excess water vapor (60%) into the high-temperature pyrolysis section should be avoided in the process of quenching coke or it would have an adverse impact on the performance of semicoke.

Spectroscopic investigations and density functional theory calculations reveal differences in retention mechanisms of lead and copper on chemically-modified phytolith-rich biochars

A better understanding of different retention mechanisms of potentially toxic elements (PTEs) by biochars during the remediation of contaminated sites is critically needed. In this study, different spectroscopic techniques including synchrotron-based micro-X-ray fluorescence (μ-XRF), X-ray absorption fine structure (XAFS), and near-edge XAFS spectroscopy (NEXAFS), were used to investigate the spatial distributions and retention mechanisms of lead (Pb) and copper (Cu) on phytolith-rich coconut-fiber biochar (CFB), and ammonia, nitric acid and hydrogen peroxide modified CFB (MCFB) (i.e., ACFB, NCFB and HCFB). The μ-XRF analyses indicated that sorption sites on ACFB and NCFB were more efficient compared to those on CFB and HCFB to bind Pb/Cu. XAFS analyses revealed that the percentage of Pb species as Pb(C2H3O2)2 increased from 22.2% (Pb-loaded CFBs) to 47.4% and 41.9% on Pb-loaded NCFBs and HCFBs, while the percentage of Cu(OH)2 and Cu(C2H3O2)2 increased from 5.8% to 32.8% (Cu-loaded CFBs) to 41.5% and 43.4% (Cu-loaded NCFBs), and 27.1% and 35.1% (Cu-loaded HCFBs), respectively. Due to their similar atomic structures of Pb/Cu, Pb(C2H3O2)2/Pb-loaded montmorillonite and Cu(C2H3O2)2/Cu(OH)2 were identified as the predominant Pb/Cu species observed in Pb- and Cu-loaded MCFBs. The NEXAFS analyses of carbon confirmed that increasing amounts of carboxylic groups were formed on HCFB and NCFB by oxidizing carbon-containing functional groups, which could provide additional active binding sites for Pb/Cu retention. Results from the X-ray photoelectron spectroscopy analyses of nitrogen showed that azido-groups of ACFB played major roles in Pb/Cu retention, while amide-groups and pyridine-groups of NCFB primarily participated in Pb/Cu retention. Overall, density functional theory calculations suggested that silicate and the synergistic effect of hydroxyl and carboxylic-groups on MCFBs were highly efficient in Pb retention, while azido-groups and/or carboxylic-groups played major roles in Cu retention. These results provide novel insights into the PTE retention mechanisms of MCFBs.

Study of effect and mechanism of flame retardation-bursting liability reduction based on chelating water injection wetting agent in coal seam

As coal mines continue to deepen high-intensity mining, the two disasters of coal seam rock burst and spontaneous combustion obviously have a trend of compound occurrence. How to achieve the integrated prevention and control of the two disasters is an important guarantee to realize coal mine safety. As a result, it is very important to select a coal seam water injection additive that can not only reduce the bursting liability, but also prolong the spontaneous combustion period of coal. In this paper, the chelating wetting agent was chosen to soak the coal, and the mass changed and carbon-containing functional groups during the coal oxidation process were studied by thermogravimetric and X-ray photoelectron spectroscopy, and tested the strength of coal by uniaxial compression experiment, and the scanning electron microscopy and low-temperature N2 adsorption were used to analyze the pore structure of coal. The experiment results show that the mass of the raw coal, the mass of the coal soaked in FeSO4 solution, and the mass of the coal soaked in the chelating wetting agent were reduced by 30.01%, 34.62% and 19.00%, respectively. The amount of the carbon–carbon bond and carbon–hydrogen bond decrease and the amount of carbon–oxygen bond increase in the chelating wetting agent soaking coal were less than in the water soaking coal and FeSO4 solution soaking coal. After soaking in the chelating wetting agent, the mechanical properties of the coal were changed, and the uniaxial compressive strength was reduced by 52.55%. The fractal dimension of the coal surface increased from 1.8448 to 1.8575, the average pore diameter in the coal was increased, the specific surface area was reduced, and the number of mesopores also increased. The above results can provide an important theoretical basis for the integrated prevention and control of rock burst-spontaneous combustion compound disaster.

Characterization of activated biomass carbon from tea leaf for supercapacitor applications

In this study, a facile synthesis of chemical and thermal activation of biomass tea-waste materials was explored. A tea-waste biosource carbon was explored by chemical vapor deposition (CVD) method at 700 °C. The KOH-treated carbon (AC-KH) and H3PO4-treated carbon (AC-HP) were systematically studied for morphological characteristics and showed good morphological structures and a few transparent focused layered nanosheets. The elemental analysis done by scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed the presence of activated carbon. Fourier transform infrared spectroscopy (FT-IR) showed carbon-containing functional groups. The electrochemical analysis showed cyclic voltammetry (CV) curves for electric double layer capacitance (EDLC) with 3 M KOH electrolyte. The Nyquist plot obtained using electrochemical impedance spectroscopy (EIS) showed charge transfer resistance value (Rct) of 6.08 Ω. The electrochemical galvanostatic charge-discharge (GCD) study was conducted to obtain the specific capacitance (Scp) values of AC-KH, which were found to be 131.95 F/g at 0.5 A/g and also AC-HP active material was observed 55.76 F/g at 1 A/g. The AC-KH showed superior electrochemical performance when compared to AC-HP material. Hence, AC-KH is a promising active material for high-energy supercapacitor applications.

Photo-transformation of microplastics and its toxicity to Caco-2 cells

In recent years, microplastics (MPs) pollution, as a global environmental problem, has been widely concerned by countries all over the world. However, the research on the impact of MPs on human health is still limited. In this study, we studied the photo-transformation behavior of polystyrene microplastics (PS-MPs) under ultraviolet light and its toxicity to Caco-2 cells. Our results showed that the surface of PS-MPs was roughened by light, and cracks and pits appeared. UV–vis spectra showed that the opening of phenyl ring and the formation of carbonyl group might exist in this process. Based on FTIR and 2D-COS analysis, we observed the formation of carbonyl group and hydroxyl group, and preliminarily determined that the order of photo-transformation of PS-MPs was 698 (CH) > 752 (CH) > 1030 (CO) > 3645 (OH/OOH) > 1740 (CO). XPS showed that the photo-transformation of PS-MPs was a process in which carbon-containing functional groups were gradually partially transformed into oxygen-containing functional groups. Finally, the toxicity results showed that with the increase of PS-MPs concentration and the extension of light irradiation time, the survival rate of Caco-2 cells gradually decreased and the integrity of cell membrane was destroyed. The increased cytotoxicity can be explained at least in part by the fact that the toxicity of oxygen-containing functional groups is greater than that of carbon-containing functional groups, but how these functional groups affect the cytotoxicity of cells still needs sustained research in the future. This study can provide new insights for understanding the environmental behavior and ecological effects of PS-MPs in the environment.

Successive Free-Radical C(sp 2 )–C(sp 2 ) Coupling Reactions to Form Graphene

Successive Free-Radical C(sp ² )–C(sp ² ) Coupling Reactions to Form Graphene

Efficient performance of magnesium oxide loaded biochar for the significant removal of Pb2+ and Cd2+ from aqueous solution

Lead (Pb) and cadmium (Cd) are considered as a typical heavy metals in aqueous solution, which may pose adverse health effects on human beings. For the removal of these two pollutants, magnesium oxide (MgO) was successfully immobilized onto eucalyptus biochar (BC) matrix via simple and cost-effective pyrolysis process of MgCl2-pretreated eucalyptus biomass under high temperature (500 °C). Synthesized MgO nanoparticles-biochar composites (MBC) exhibited superior removal performance for target pollutants, and achieve 99.9% removal efficiency for Pb(II) and Cd(II) at optimum conditions (0.02 g, pH in range of 4–7, and reaction time 120, 240 min). Furthermore, the maximum theoretical adsorbing amount of MBC was 829.11 mg/g for Pb(II) and 515.17 mg/g for Cd(II). Pseudo-second-order model and Langmuir models were well-determined for isotherm and adsorption kinetics. FTIR, XRD, and XPS analysis revealed that precipitation and ion exchange was of great importance for the removal of contaminants. Besides, cation-π interaction and complexation from the carbon-containing functional groups should not be neglected. Considering the advantage of low-cost, facile preparation, and brilliant adsorption capacity, it is anticipated that MBC has a promising prospect for the broad application in Pb(II)/Cd(II)-containing wastewater treatment.

Highly stable bifunctional catalyst for Zn-Air batteries: The effect of a nitrated carbon support on Co3O4 activity

The use of Co3O4 as electrocatalyst in Zn-air batteries has been extensively studied. However, electrical rechargeability has only been achieved by combining metal oxides with precious metals or using a second electrode/electrolyte to promote the oxygen evolution reaction. In this work, we report efficient catalytic activity of Co3O4 for both, the oxygen reduction and oxygen evolution reaction by fusing Co3O4 particles to a nitrated carbon support. The functionalized carbon matrix improves not only the carbon wettability, but also provides acidic sites and carbon-containing functional groups. This synergistic configuration enhances the reaction kinetics especially for the oxygen evolution reaction. The electrochemical characterization demonstrated lower overpotential and higher stability over 160 cycles for the Co3O4 catalyst attached to the nitrated carbon matrix compared to the pristine carbon matrix. Electrochemical impedance spectroscopy demonstrated 21 times lower degradation for the functionalized air-cathode at 2 mA cm−2, 12.4 times lower degradation at 5 mA cm−2, and 1.15 times lower degradation at 10 mA cm−2. Although further work is required, the low-cost process and the electrochemical performance of this catalyst represent considerable progress towards the development of rechargeable and flexible Zn-air batteries.

Exploring how fire spread mode shapes the composition of pyrogenic carbon from burning forest litter fuels in a combustion wind tunnel

In this study, solid state 13C nuclear magnetic resonance (NMR) spectroscopy was used to explore the carbon-containing functional groups present in pyrogenic carbon (PyC) produced during different fire spread modes to forest litter fuels from a dry sclerophyll eucalypt forest burnt in a combustion wind tunnel. A replicated experimental study was performed using three different fire spread modes: heading fires (i.e. fires which spread with the wind), flanking fires (i.e. fires which spread perpendicular to the wind) and backing fires (i.e. fires which spread against the wind). In addition to 13C NMR measurements of PyC, detailed fire behaviour measurements were recorded during experiments. Experiments showed that heading fires produced significantly more aryl carbon in ash samples than flanking fires. All other experimental comparisons for burnt fuel samples involving different fire spread modes were statistically insignificant. Principal component analysis (PCA) was used to explore the relationship between 13C NMR functional groups and fire behaviour observations. Results from PCA indicate that maximising the residence time of high temperature combustion and the combustion factor (i.e. the fraction of pre-fire biomass consumed by fire) could be a method for increasing the amount of aryl carbon in PyC. Maximising the amount of aryl carbon could be beneficial for the overall PyC balance from fire, since more recalcitrant carbon (e.g. carbon with a higher aryl carbon content) that is not emitted to the atmosphere has been shown to have longer residence times in environmental media such as soils or sediments.

Synthesis of iron oxides impregnated green adsorbent from sugarcane bagasse: Characterization and evaluation of adsorption efficiency

This present research aims to synthesize and investigate the adsorption potential of sugarcane bagasse (SCB) impregnated with iron oxide (Fe3O4) for dye removal. The surface morphology and functional groups of the newly developed adsorbent (ISCB) were studied using Scanning Electron Microscopy/Energy-dispersive X-ray spectroscopy (SEM/EDX), Fourier transforms infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD) analysis. The effects of the operating parameters, including initial dye concentration, adsorbent dosage, contact time and initial pH of the dye solution on the adsorption efficiency were investigated to identify an optimal condition. The characterization of SEM-EDX and FTIR analyses shows that ISCB has a porous structure and carbon-containing functional groups. The adsorption result revealed that ISCB removed 93.7% of dye, 88.8% of color and had a dye adsorption capacity of 7.2 mg/g within 6 h of contact time using 0.7 g/L of ISCB at pH 8.4. The result obtained fitted well for Langmuir isotherms, and adsorption process followed the pseudo-second-order kinetic model. In conclusion, this study proved that ISCB has the potential to be used as an effective and low-cost adsorbent to remove dyes from wastewater.

Carbon consumption of activated coke in the thermal regeneration process for flue gas desulfurization and denitrification

In the process of flue gas purification with activated coke, sulfuric acid and sulfate are deposited on the activated coke surface; therefore, thermal regeneration is needed to recover the activated coke activity, which leads to carbon consumption. In this work, various regeneration parameters, including temperature, time and atmosphere, were investigated to optimize carbon consumption. The experimental results showed that the desulfurization capacity of the activated coke was clearly improved after thermal regeneration, while the denitrification capacity demonstrated no obvious or regular changes. Based on dozens of groups of regeneration experiments, it was found that the chemical carbon consumption per mol SO2 recovery ranged from 0.5 to 2.0 mol, which was higher than the theoretical value of 0.5 mol. The proportion of CO2 in chemical carbon consumption ranged from 60%–80% with an average value of 70%, and the rest was CO. According to the results from temperature-programmed desorption (TPD), CO and CO2 consumption was mainly derived from the decomposition of carboxyl and anhydride groups, with a small contribution from the reduction reaction of sulfuric acid with carbon. CO and CO2 consumption occupied only 10%–18% of the total carbon-containing functional groups, so the reaction activity was retained after thermal regeneration. The carbon consumption in an NH3/N2 atmosphere was smaller than that in a N2 atmosphere, which was about half of that in a H2O/N2 atmosphere due to the inhibition of carboxyl group decomposition, based on the results from TPD and in situ diffuse reflectance infrared Fourier transform (In situ DRIFT). Analysis of the thermal regeneration process in four iron and steel factories revealed that the chemical carbon consumption of activated coke accounted for approximately 20%–40% of the total carbon consumption, which was smaller than the contribution from physical carbon abrasion.

Effects of exhaust gas recirculation on the functional groups and oxidation characteristics of diesel particulate matter

The effects of EGR on the carbon-containing functional groups in PM were determined by X-ray absorption near-edge spectroscopy. A TG analyzer was used to determine the effects of EGR on the components and oxidative activity of PM. The results show that the use of EGR in the diesel engine had a minor influence on the types of carbon-containing functional groups in the PM; however, it did affect their relative contents. As the EGR rate increased, the aromatic and graphitized carbon contents of the PM gradually decreased, and the contents of the oxygen-containing and aliphatic CH functional groups increased, which strongly promoted the oxidative activity of the PM. The percentage of soot in the PM decreased with the use of EGR, while the percentages of water and volatile organic matter increased. In addition, the volatile emission temperature TSOF1 gradually decreased, and the trends in the initial volatile combustion temperature TSOF2, the soot ignition temperature Ti, and the burnout temperature Th were consistent with that in the volatile emission temperature. Both the combustion and burnout characteristic indices gradually increased as the EGR rate grows. Instead, the activation energy decreased dramatically, and the energy required for PM to react decreased with the increase of EGR rate.

Promoting Effect of ZSM-5 Catalyst on Carbonization via Hydrothermal Conversion of Sewage Sludge

An in-depth study on the transformation and distribution of carbons via hydrothermal conversion (HTC) of sewage sludge was conducted to evaluate the catalytic impact of Zeolite Socony Mobil-5 (ZSM-5). All the experiments were carried out between 180 and 300 °C with ZSM-5 catalyst during the HTC. Chars were analyzed for their carbon content distribution, carbonization degree, carbon-containing functional groups, and Raman chemical structural properties. The results revealed that ZSM-5 catalyst could concentrate carbon-containing matter in char and have distinct catalytic effects of ZSM-5 on carbonization degree. The catalyst with an Si/Al ratio of 300 is appropriate for char production at lower reaction temperatures, whereas the char with lower Si/Al ratio catalyst has better performance under higher reaction temperatures. ZSM-5 has a positive effect on the decomposition of C–(C,H) and promotes formation of C–(O,N) structure. Moreover, it can increase the decomposition of functional groups C═N and enhance ...

Mineral additive enhanced carbon retention and stabilization in sewage sludge-derived biochar

Abstract Biochar is getting increasing attention due to good performance in carbon retention and strong stability, and has been proposed as a promising material for long-term carbon sequestration. In this study, sewage sludge was used as feedstock, and Ca(OH)2 was added to improve carbon stability in biochar through pyrolysis at temperature range of 300–700 °C. A systematical analysis was conducted for the sludge-derived biochar with and without Ca(OH)2 addition, with respect to physiochemical properties, molecular structure, and chemical stability. Results indicated an obvious increase of DOC content and carbon retention in biochar when the Ca(OH)2 was added in the sludge feed. The CaCO3 formation and an increase in carbon-containing functional groups were evidenced from X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra, respectively. Furthermore, the amount of carbon loss decreased over 3 times when H2O2 was added to the biochar as chemical oxidant, showing an obvious increase in carbon stability with mineral additive. Moreover, the Ca(OH)2 addition also improved the surface area and alkalinity of the biochar, which may enhance the potential application of biochar products. Therefore, from effective increase in carbon retention and biochar stability, a novel idea can be provided for further production of sewage sludge-derived biochar with high carbon sequestration capacity and stability, and will help to further promote the utilization of pyrolysis as a promising strategy for the management of bio-waste.

Synthesis of P-Stereogenic Phosphinates via an Axis-to-Center Chirality Transfer by the Reaction of Phosphonates Having a Binaphthyloxy Group with Grignard Reagents

The reactions of phosphonates having a binaphthyloxy group with Grignard reagents gave the corresponding P-stereogenic phosphinates in good to high yields with high diastereoselectivity. In this reaction, an axis-to-center chirality transfer from a binaphthyl group to the resulting phosphorus atom took place stereospecifically. Both diastereomers with opposite configurations could be obtained by changing the combination of carbon-containing functional groups on the phosphorus atom and the Grignard reagents.

Superior adsorption capacity of g-C3N4 for heavy metal ions from aqueous solutions

In this work, graphitic-C3N4 (g-C3N4) was synthesized by a simple and environmentally friendly salt melt method, and characterized by using field-emission scanning and transmission electron microscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and N2 adsorption–desorption analysis. The as-prepared g-C3N4 was used as an adsorbent to remove heavy metal ions from aqueous solutions. The adsorption kinetics of Pb(II) and Cu(II) followed the pseudo-second-order model. The g-C3N4 exhibited much higher adsorption capacity toward heavy metal ions (1.36mmol/g for Pb(II), 2.09mmol/g for Cu(II), 1.00mmol/g for Cd(II) and 0.64mmol/g for Ni(II)) than other adsorbents. The adsorption of Pb(II) and Cu(II) on g-C3N4 was slightly affected by ionic strength at pH<5.0 and increased with the increase of ionic strength at pH>5.0. The inner-sphere surface complexation mechanism was suitable to explain the interaction between heavy metal ions and the nitrogen- and carbon-containing functional groups of the g-C3N4. The experimental results reveal that g-C3N4 is a potential adsorbent for the removal of heavy metal ions from large volumes of aqueous solutions.

Oxygen/Carbon Ratio Effects on Surface-Modified Carbon Nanotubes

Carbon nanotubes (CNTs) were functionalized using a simple method of heat treatment under oxygen atmosphere followed by an immersion in a tin nitrate aqueous solution. And well-dispersed SnOx nanodots were decorated on the surface of CNTs. X-ray photoelectron spectroscopy (XPS) analysis showed that the O/C ratio increases with oxygen-treated time. The distribution of carbon-containing functional groups on the CNTs surface, i.e., C−C, C−O, C=O, O−C=O, and π−π* shake up bonds can be identified and deconvoluted by a symmetrical Gauss function. The contact angle of H2O and CNTs is dependent on O/C ration. The relationships between the fraction of carbon-containing functional groups and various oxygen treatment times are also discussed.

Functionality number. A new focus on an advanced organic chemistry course

A relatively simple method is proposed whereby the reactivity of carbon-containing functional groups is analyzed systematically with emphasis on carbon-carbon bond-forming reactions.