High-temperature Pyrolysis Research Articles

Development and Application of an Atomic Absorption Spectrometry-Based Method to Quantify Magnesium in Leaves of Dioscorea polystachya.

The Chinese yam (Dioscorea polystachya, DP) is known for the nutritional value of its tuber. Nevertheless, DP also has promising pharmacological properties. Compared with the tuber, the leaves of DP are still very little studied. However, it may be possible to draw conclusions about the plant quality based on the coloration of the leaves. Magnesium, as a component of chlorophyll, seems to play a role. Therefore, the aim of this research work was to develop an atomic absorption spectrometry-based method for the analysis of magnesium (285.2125 nm) in leaf extracts of DP following the graphite furnace sub-technique. The optimization of the pyrolysis and atomization temperatures resulted in 1500 °C and 1800 °C, respectively. The general presence of flavonoids in the extracts was detected and could explain the high pyrolysis temperature due to the potential complexation of magnesium. The elaborated method had linearity in a range of 1-10 µg L-1 (R2 = 0.9975). The limits of detection and quantification amounted to 0.23 µg L-1 and 2.00 µg L-1, respectively. The characteristic mass was 0.027 pg, and the recovery was 96.7-102.0%. Finally, the method was applied to extracts prepared from differently colored leaves of DP. Similar magnesium contents were obtained for extracts made of dried and fresh leaves. It is often assumed that the yellowing of the leaves is associated with reduced magnesium content. However, the results indicated that yellow leaves are not due to lower magnesium levels. This stimulates the future analysis of DP leaves considering other essential minerals such as molybdenum or manganese.

Iron-Phthalocyanine Based Oxygen Reduction Reaction Electrocatalyst: Structure-Performance Relationship Evolution during Pyrolysis

Fuel cells efficiently convert hydrogen into green electricity however the key bottleneck in their deployment lies at the cathode where oxygen reduction reaction (ORR) exhibits sluggish kinetics and requires high loading of precious metals.In this view, Iron-Nitrogen-Carbons (Fe-Nx-Cs) are promising electrocatalysts to replace expensive and scarce noble metals currently used for the ORR. Fe-Nx-Cs are typically synthesized through pyrolysis using iron, nitrogen and/or carbon precursors of diverse nature. However, in general, pyrolysis is a process poorly understood despite recently a couple of manuscripts with in-situ investigations that have been presented [1-2]. The pyrolysis process defines the structural and chemical evolution of the electrocatalyst that ultimately governs its overall electroactivity. Therefore, in this study, the influence of pyrolysis conditions i.e. temperature (200-1000 °C) and atmosphere (Ar or Ar/H2) on the morphological and superficial development of electrocatalyst was elucidated that initially consisted of Iron (II) Phthalocyanine (FePc) mixed with Ketjen Black 600. The morphological and chemical features were then correlated with the electrochemical performance in alkaline and acidic media through a structure-to-property relationship. In-depth analysis showed that pyrolysis conditions significantly affect the nature and proportion of active Fe-based and nitrogen-based moieties that collaboratively determine the pathway and kinetics of the ORR in acid and alkaline media. X-ray diffraction (XRD) showed that reducing atmosphere (Ar/H2) inhibits the crystallographic growth of Fe-containing nanoparticles. In parallel, the neutral atmosphere (Ar) enhanced the aggregation of Fe into oxides as diffraction peaks corresponded to Fe3O4 after a pyrolysis temperature of 600°C. High-resolution-transmission electron microscopy (HR-TEM) showed the formation of nanoparticles and oxides at temperatures above 600°C. X-ray photoelectron spectroscopy (XPS) revealed multitudinous nitrogen-based moieties with varying proportions in the Fe-Nx-C electrocatalysts developed under different pyrolysis conditions. Interestingly, the samples pyrolyzed in Ar/H2 showed an increasing trend of Fe-Nx with respect to a pyrolysis temperature whereas, in Ar-pyrolysed samples, Fe-Nx started plummeting after 600°C. On the other hand, graphitic nitrogen increased prominently after 700°C in both pyrolytic conditions. Using a rotating ring disc electrode (RRDE), the dependence of performance parameters on the chemical and structural features that evolved during the pyrolysis was clarified. Particularly, in acidic media (0.5 M H2SO4), Fe-Nx-C synthesized at 600 ºC under both Ar and Ar/H2 conditions demonstrated higher electrocatalytic activity, with half-wave potentials (E1/2) of ≈ 0.70-0.72 V (vs RHE) while maintaining the direct tetra-electronic ORR (low peroxide production). A similar trend was witnessed in an alkaline media (0.1 M KOH) but with relatively higher performance than in acid media. The highest onset potentials and E1/2 observed in alkaline media were obtained by the Fe-Nx-Cs pyrolyzed at 600°C and 700 ºC in both atmospheres i.e. Ar (E1/2 ≈ 0. 89 V vs RHE) and Ar/H2 (E1/2 ≈ 0. 87 V vs RHE). A prompt reduction in the performance was highlighted at higher pyrolysis temperatures where an increase in peroxide yield might be related to the formation of iron oxide nanoparticles. This work presents a novel insight into the evolution of Fe-Nx-C electrocatalysts during pyrolysis with optimum performance.

Biochar and soil properties affect remediation of Zn contamination by biochar: A global meta-analysis

Zinc (Zn) is one of the most common heavy metals that pollute soils and can threaten both environmental and human health. Biochar is a potential solution for remediating soil Zn contamination. This meta-analysis investigates the effect of biochar application on the remediation of Zn-contaminated soils and the factors affecting the remediation efficiency. We found that biochar application in Zn-contaminated soils reduced Zn bioavailability by up to 77.2% in urban soils, 55.1% in acidic soils, and 50.8% in coarse textured soils. Moreover, the remediation efficiency depends on the biochar production condition, with crop straw and sewage sludge feedstocks, high pyrolysis temperature (450–550 °C), low heating rate (<10 °C min−1), and short residence time (<180 min) producing high performing biochars. Biochar affects soil Zn bioavailability by changing soil pH and organic carbon, as well as through its high surface area, ash content, and O-containing surface functional groups. Our findings highlight the role of biochar as a promising and environmentally friendly material for remediating Zn contamination in acidic and/or coarse textured soils. We conclude that soil properties must be considered when selecting biochars for remediating soil Zn contamination.

Dual-atomic-sites anchored on nanosized hollow polyhedron to boost oxygen reduction reaction in acidic electrolyte

Fe and Co dual atomic sites anchored on a hollow carbon nanocage (Fe/Co–N–C) have shown notable advantages in improving the activity and stability toward the oxygen reduction reaction (ORR) in the acidic media. However, it is yet challenging to design such nanostructured Fe/Co–N–C electrocatalysts in a simple manner. In this research, hollow polyhedral carbon nanocages modified by Fe, Co-dual metal atoms are designed from ZIF-8 which involves cage-inclusion of mixed metal salts and conversion to mixed metal hydroxides before high-temperature pyrolysis. The optimized Fe/Co–N–C demonstrated one of the best acidic ORR performances, exhibiting a half-wave potential (E1/2) of 0.81 V (vs. RHE) in 0.5 M H2SO4, and a slight decay of 13 mV in E1/2 after 10,000 cycles. Compared to Fe–N–C counterpart, the improved ORR performance of Fe/Co–N–C is attributed to the synergism between Fe-Nx and Co-Nx active sites, which are attested by various characterizations and control experiments.

Enhancing U(VI) removal by using biomass-derived hierarchical porous carbon/α-MnO2 nano fiber composites as high hybrid capacitance electrodes for capacitive deionization

The radioactive pollution caused by uranium containing wastewater generated during the nuclear fuel cycle seriously threatens human health and environmental safety. The electrosorption (or capacitive deionization, CDI) separation of U(VI) from wastewater has the advantages of high efficiency, low energy consumption, convenient operation, and no secondary pollution, making it a promising new separation technology. By combining double layer capacitive materials with pseudo capacitive materials, the specific capacitance and ion storage capacity of the composites can be significantly improved, thereby improving the electrosorption performance. This work used natural biomass as raw material to prepare hierarchical porous biocarbon through high-temperature pyrolysis and chemical activation, and then it was incorporated with hydrothermally synthesized α-MnO2 nanofibers to obtain novel composites (BC/α-MnO2) with high hybrid capacitance for U(VI) removal in CDI. The electrochemical characteristics of the composites and their electrosorption performances for U (VI) were respectively investigated in a three electrode system and a CDI device. The results suggested that BC/α-MnO2 exhibited an ideal capacitive behavior, and theoretical calculations indicated the synergistic effect of capacitive and diffusion control processes on ion storage. Among different BC/α-MnO2 electrodes, BC/α-MnO2-2 had the highest specific capacitance (130.48 F/g) and also the highest adsorption capacity for U (VI) (280.20 mg/g at 0.9 V and pH 4.0). The isotherms and kinetics of U (VI) electrosorption were consistent with the Langmuir and PFO models, respectively. The electrosorption mechanism was mainly related to the contribution of pseudocapacitance and EDL adsorption. Overall, BC/α-MnO2-2 exhibited ideal electrochemical properties and excellent electrsorption performance for U (VI) (high electrosorption capacity, fast kinetic rate, and good cycling stability), facile fabrication and environmentally friendly, and thus it has promising application in CDI treatment of radioactive wastewater.

Application of persulfate-assisted graphitic carbon, derived through pyrolysis of waste biomass, driven by visible light, for the removal of tetracycline from water: Mechanisms and performance influencing parameters

Sulfate radical based advanced oxidation process by using carbon-based materials has attracted widespread attention for removal of emerging contaminants in water. This paper reports the study on the efficacy of visible light activated persulfate (PS) – graphitic carbon (GC) system for the removal of tetracycline (TC) from water . Here GCs from residual agricultural biomass were synthesized via a facile and chemical-free pyrolysis route, and their characteristics were analyzed under varying thermal conditions, viz. temperature (550–950 °C) and heating rate (2.5–10 °C min−1). The GCs at high pyrolysis temperatures (> 700 °C) revealed graphitic and condensed aromatic carbon networks with enhanced textural properties, facilitating electron-mediated reactions through interconnected morphology. The methodology is derived from the research that shows certain pyrolysis derived carbon products are known to have transient photocurrent response, indicating semiconductor properties. Here, the visible light-driven GC/PS (950 °C, 5 °C min−1) system resulted in high TC removal efficiency of 91.23% within 180 min compared to other PS/GCs prepred under different conditions. The mass spectroscopy data shows that the GC/PS system successfully degraded TC into simpler products and achieved the highest mineralization efficiency of about 65.43 ± 3.62%. The radical scavenging experiments revealed that 1O2 and •OH were the dominant reactive oxygen species suppressing degradation of TC by 13% and 9%, respectively. It can be surmised that both radical and non-radical pathways facilitate TC degradation via dehydration, demethylation and oxidation of aromatic rings- due to both catalytic and physico-chemical properties of GC/PS .

Influence mechanism of K on cellulose pyrolysis by stepwise isothermal method in-situ DRIFTS method

The influence mechanism of alkali metal potassium (K) on cellulose pyrolysis is a vague and fundamental key topic in the field of biomass thermal conversion. In this study, the pyrolysis of cellulose and K-impregnated cellulose was compared by in-situ DRIFTS (Diffused Reflectance Infrared Fourier Transform Spectroscopy) and TG (Thermal Gravimetric)–MS (Mass Spectrum) experiment, and quantum chemical calculations were used to verify the peak position and pyrolysis mechanism of infrared (IR) spectroscopy. Stepwise isothermal in-situ DRIFTS was designed to study the reaction path at high temperatures. It was found that in the early stage of pyrolysis, K accelerated the activation of cellulose by attacking the hydrogen bond (H-bond) in the crystal structure of cellulose, increased the dehydration rate between molecules, and promoted the decomposition of cellulose. Simultaneously, it weakened the epoxy–ether bond, inhibited the formation of dehydrated sugar, and promoted the formation of furan. Subsequently, K combined with carbonyl groups to form C–O–K structures, which improved the thermal stability of certain oxygen-containing functional groups such as carbonyls/aldehydes, so that these structures were retained until higher temperature. K promoted the conversion of dehydrated sugars to straight-chain ketones/aldehydes, which led to an increase in carbon conversion. During the coke generation stage, K promoted the formation of disordered carbon and residues, thereby inhibiting coke aromatization. The isothermal in-situ DRIFTS method proposed in this study was demonstrated to better inhibit the high temperature drift of IR spectrum during pyrolysis. It clarified the conversion between functional groups at high temperatures, which is expected to promote the development of other high-temperature pyrolysis mechanism.

Isoreticular Metal-Organic Frameworks Confined Mononuclear Ru-Hydrides Enable Highly Efficient Shape-Selective Hydrogenolysis of Polyolefins.

Upcycling nonbiodegradable plastics such as polyolefins is paramount due to their ever-increasing demand and landfills after usage. Catalytic hydrogenolysis is highly appealing to convert polyolefins into targeted value-added products under mild reaction conditions compared with other methods, such as high-temperature incineration and pyrolysis. We have developed three isoreticular zirconium UiO-metal-organic frameworks (UiO-MOFs) node-supported ruthenium dihydrides (UiO-RuH2), which are efficient heterogeneous catalysts for hydrogenolysis of polyethylene at 200 °C, affording liquid hydrocarbons with a narrow distribution and excellent selectivity via shape-selective catalysis. UiO-66-RuH2 catalyzed hydrogenolysis of single-use low-density polyethylene (LDPE) produced a C12 centered narrow bell-shaped distribution of C8-C16 alkanes in >80% yield and 90% selectivity in the liquid phase. By tuning the pore sizes of the isoreticular UiO-RuH2 MOF catalysts, the distribution of the products could be systematically altered, affording different fuel-grade liquid hydrocarbons from LDPE in high yields. Our spectroscopic and theoretical studies and control experiments reveal that UiO-RuH2 catalysts enable highly efficient upcycling of plastic wastes under mild conditions owing to their unique combination of coordinatively unsaturated single-site Ru-active sites, uniform and tunable pores, well-defined porous structure, and superior stability. The kinetics and theoretical calculations also identify the C-C bond scission involving β-alkyl transfer as the turnover-limiting step.

Application of Palladium Single Atoms in C−C Coupling Reactions of Pharmaceutical Synthesis

Designing highly active and structurally well-defined catalysts while reducing the amount of catalyst has become a key issue in heterogeneous catalytic reactions. In this study, palladium single-atom catalysts were prepared for efficient catalysis in the Suzuki cross-coupling reaction of iodobenzene and phenylboronic acid, which was prepared by one-step high-temperature pyrolysis. The palladium single-atom catalysts have high activity as well as stability in Suzuki cross-coupling reactions and have great potential in catalyzing organic reactions.

Synergistic enhancement of chemisorption and catalytic conversion in lithium-sulfur batteries via Co3Fe7/Co5.47N separator mediator

Lithium-sulfur batteries (LSBs) show considerable potential in next-generation high performance batteries, but the heavy shuttle effect and sluggish redox kinetics of polysulfide hinder their further applications. In this paper, to address these shortcomings of LSBs, Co3Fe7/Co5.47N heterostructure were prepared and constructed from their Fe-Co Prussian blue analogue precursors under the condition of high temperature pyrolysis. The obtained Co3Fe7/Co5.47N display excellent immobilization-diffusion-conversion performance for polysulfides by synergistic effect in successfully hindering the shuttle effect of polysulfides. When the Co3Fe7/Co5.47N heterostructure were applied to modify the commercial polypropylene (PP) separator, the batteries displayed fantastic rate capacity and cycling stability. Specifically, the Co3Fe7/Co5.47N-PP batteries exhibit an extremely satisfactory initial specific capacity of 1430 m Ah/g at 0.5C, wonderful rate capacity of around 780 m Ah/g at 3C and superior per cycle decaying rate of 0.08 % for 500 cycles at 0.5C. When the current density reaches to 2C, the batteries still exhibit 501 m Ah/g after 900 cycles with 0.015 % per cycle decay rate. Besides, even in the high loading of sulfur (3.0 mg cm−2) at 0.5C, the superior cycling stability (0.075 % per cycle decay rate after 200 cycles) and high specific capacity (741 mAh/g after 200 cycles) can still be performed. Thus, this work provides a facile method for high-powered and long-life Li-S batteries with eminent entrapping-conversion processes of polysulfides.

HKUST-1 derived one-dimensional Cu/N-doped carbon nanofibers for simultaneous detection of acetaminophen and sulfanilamide

The design of novel signal amplification elements was key to improving the sensing and analysis performance of electrochemical sensors. In this work, porous one-dimensional copper nitrogen-doped carbon nanofibers (Cu-NCNFs) were successfully prepared via the coupled process of electrospinning technology and high-temperature pyrolysis. This coupling of multiple processes and the introduction of heteroatoms pyrolyzed the HKUST-1 particles to generate three-dimensional Cu-doped carbon octahedra and mosaic them inside the one-dimensional carbon nitride channels, obtaining small-sized Cu particles while introducing a large number of N species, and constructing a three-dimensional MOFs-derived metal-carbon hybrid one-dimensional multistage carbon nitride structure. The resulting Cu-NCNFs sensor could simultaneously determine acetaminophen and sulfanilamide and exhibit superior electroanalytical performance, reproducibility, stability, and selectivity. This strategy provides a new approach to preparing novel signal amplification elements for the efficient monitoring of micropollutants.

Pyrolysis or hydrothermal carbonisation for anaerobic-digested sewage sludge? A comparison of pyrochar and hydrochar structure and stability

Thermochemical conversion of sewage sludge was proven as a useful method for waste management. Moderate temperatures in the absence of oxygen (pyrolysis) and hydrothermal carbonisation (HTC) performed in the presence of water, under autogenous pressures, were selected to treat the same sample of anaerobic-digested sewage sludge (SS). Two hydrochars were prepared by HTC in one high-pressure reactor using SS at 80% humidity content and heating it at 180 and 240 °C for 4 h, leading to H180-4 and H240-4, respectively. Two pyrochars were prepared from a pre-oven-dried SS at 105 °C for 48 h, followed by slow pyrolysis at 300 °C for 1 h, and 400 °C for 1 h leading to P300-1 and P400-1, respectively. HTC and slow pyrolysis significantly increased thermal stability of chars with higher temperatures, only reducing organic matter content (from 68.4 to 46.7–59.2%). Based on the characterisation results, the treatments could be a suitable choice to pre-treat sludge as soil amendment. Higher temperatures of pyrolysis would be attractive to store stable carbon in soil and construction materials, whilst lower temperatures of pyrolysis and HTC would produce a material that could be used as a source of organic matter providing a pool of labile carbon and fixed carbon. Thermochemical conversions generated mesopores (10–50 nm, >40%) and slightly increased surface area from 2 m2/g (SS) to 5–17 m2/g (pyrochars) and to 20 m2/g (hydrochars). Hence, HTC showed the greatest potential to produce a material with higher adsorption capacity (100 cm3/g for H180-4) but all chars should be subjected to an activation process to be able to compete with other kinds of feedstocks. The reduction of the H:C and O:C from the original SS after the treatments indicated a greater carbonisation degree, but a general reduction of the high heating value (HHV) from 17.94 MJ kg−1 in SS to (14.93 MJ kg−1). The torrefied char and hydrochars could be an attractive option to reduce energy of the process and drying stage in the case of HTC.

Plasticization resistant gas separation membranes derived from polyimides exhibiting polyethylene-oxide moieties

Despite exhibiting excellent thermal/chemical stability, mechanical robustness, and easy processability, which makes them attractive candidates for gas separation applications, aromatic polyimides are susceptible to plasticization. This study proposes an effective approach to suppress CO2-induced plasticization in a high fractional free volume (FFV) polyimide (PI*) derived from 4,4’-(hexafluoroisopropylidene)diphthalic anhydride and 2,4,6-trimethylphenyldiamine. PI* was first modified by incorporating 3,5-diaminobenzoic acid (DABA) and polyethylene oxide segments (PEO) into the polymer backbone, with the goal of partially removing PEO through high temperature (450 °C) pyrolysis, thereby increasing the membrane FFV and, simultaneously, providing enhanced plasticization resistance via DABA cross-linking. To mitigate the effects of themomechanical history, the membranes were aged prior to the thermal treatment process. However, the great enhancement in plasticization resistance was not accompanied by a parallel improvement in the separation performance relative to PI*. To address this shortcoming, a microporous organic polymer (POP) was blended with the polyimides to fabricate mechanically-robust mixed matrix membranes (MMMs). Remarkably, MMM plasticization was suppressed even without the aid of thermal crosslinking for PEO-containing PI*, which was rationalized by molecular simulation invoking the formation of hydrogen bonds between the lactam groups of the POP and PEO moieties.

Development of high-strength lightweight concrete by utilizing food waste digestate based biochar aggregate

The application of carbon-negative biochar in cement composites can effectively reduce carbon emissions of construction materials. In this study, low-carbon composites were tailored with high volume of food waste digestate (FWD) biochar aggregate. The biochar was customized at different temperatures with the goal of enhancing the properties of cement-based composites. Backscattered electron microscopy (BSEM) images show that FWD biochar with a grey circle shape exhibited strong bonding with the cement matrix. Nano-indentation results indicate that the two statuses of FWD biochar showed visco-elastic and elastic-plastic modes of deformation, respectively. The FWD biochar aggregate prepared at higher pyrolysis temperatures (i.e., 650 °C and 750 °C) has higher elastic modulus (up to 11.4 GPa), which can be applied to make biochar blocks with higher strength and lower density compared to the biochar pyrolyzed at 550 °C. As a result, FWD 750BC blocks could reach 28-d compressive strength of 57.8 MPa and density of 1.77 g cm−3, which fulfilled the requirements of high-strength lightweight aggregate concrete. Hence, this study established a foundation to utilize FWD biochar as an aggregate in high-strength biochar construction materials.

Effective aerobic oxidative denitrogenation of model fuel with metal-free porous carbon derived from phytic acid-loaded polyaniline

Aerobic oxidative denitrogenation (ODN) of a model fuel was first done with metal-free P and O co-doped carbon catalysts. The catalysts, phytic acid (PA)-loaded polyaniline-derived carbons (PPDCs), were firstly prepared by high-temperature pyrolysis of polyaniline with phytic acid (as P/O sources). One material, PPDC-2 showed a conversion of 95 % and 86 % for indole (IND) and quinoline (500 ppm each), respectively, at 100 °C, with O2 as an oxidant. A very small activation energy of 26.6 kJ mol−1 was observed in the IND oxidation. Radical trapping experiments and electron spin resonance spectroscopy analyses supported the formation of superoxide anion radicals (O2−) from the fed O2, which was responsible for the IND oxidation. A plausible reaction mechanism was proposed by analyzing the experimental results and DFT calculations on charge separations on carbons. Defect sites also could play an important role in the activation of O2 since PPDC-2 showed higher defect sites compared to the non-doped carbon. PPDC-2 was also found to be recyclable for the ODN, by simple acetone soaking, without a considerable loss in performance.

Polyaniline as a Nitrogen Source and Lignosulfonate as a Sulphur Source for the Preparation of the Porous Carbon Adsorption of Dyes and Heavy Metal Ions.

Using agricultural and forestry wastes as raw materials, adsorbent materials were prepared for dye adsorption in wastewater, which can minimize the environmental load and fully realize sustainability by treating waste with waste. Taking lignosulfonate as a raw material, due to its molecular structure having more reactive groups, it is easy to form composite materials via a chemical oxidation reaction with an aniline monomer. After that, using a sodium lignosulfonate/polyaniline composite as the precursor, the activated high-temperature pyrolysis process is used to prepare porous carbon materials with controllable morphology, structure, oxygen, sulfur, and nitrogen content, which opens up a new way for the preparation of functional carbon materials. When the prepared O-N-S co-doped activated carbon materials (SNC) were used as adsorbents, the adsorption study of cationic dye methylene blue was carried out, and the removal rate of SNC could reach up to 99.53% in a methylene blue solution with an initial concentration of 100 mg/L, which was much higher than that of undoped lignocellulosic carbon materials, and the kinetic model conformed to the pseudo-second-order kinetic model. The adsorption equilibrium amount of NC (lignosulfonate-free) and SNC reached 478.30 mg/g and 509.00 mg/g, respectively, at an initial concentration of 500 mg/L, which was consistent with the Langmuir adsorption isothermal model, and the adsorption of methylene blue on the surface of the carbon material was a monomolecular layer. The adsorption of methylene blue dye on the carbon-based adsorbent was confirmed to be a spontaneous and feasible adsorption process by thermodynamic parameters. Finally, the adsorption of SNC on methylene blue, rhodamine B, Congo red, and methyl orange dyes were compared, and it was found that the material adsorbed cationic dyes better. Furthermore, we also studied the adsorption of SNC on different kinds of heavy metal ions and found that its adsorption selectivity is better for Cr3+ and Pb2+ ions.

Porous pie-like nitrogen-doped biochar as a metal-free peroxymonosulfate activator for sulfamethoxazole degradation: Performance, DFT calculation and mechanism

Design and development of low-cost, high-efficient, metal-free persulfate heterogeneous catalysts was a hot research topic. Herein, porous pie-like nitrogen-doped biochar (NBC) was prepared by one step high temperature pyrolysis of rape straw, urea and ZnCl2 mixture, and applied for peroxymonosulfate (PMS) activation toward sulfamethoxazole (SMX) degradation. Among these as-prepared catalysts, the NBC2.0 sample presented the best catalytic activity, with the 99.8 % SMX degradation efficiency in 5 mins and the 81.7 % total organic carbon (TOC) removal rate in 30 mins. Additionally, it could realize an excellent SMX degradation in the wide pH range of 3.0 to 9.0, and possessed the high degradation efficiency in presence of various organic pollutants or in real water environments, indicating its good pH adaptability, universality and practicality. Mechanistic investigations disclosed that the NBC2.0/PMS/SMX system involved both radical and non-radical degradation pathways, with singlet oxygen (1O2) and the direct electron transfer mechanism being the main contributors. The main active reaction sites of NBC were graphitic N, pyridinic N and C = O group, as corroborated by density functional theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) measurement. The possible SMX breakdown routes were determined by intermediate identification. This work provides a promising metal-free persulfate catalyst for environment remediation.

Enhancement of the Mechanical Performance of SiCf/Phenolic Composites after High-temperature Pyrolysis Using ZrC/B4C Particles

Enhancement of the Mechanical Performance of SiCf/Phenolic Composites after High-temperature Pyrolysis Using ZrC/B4C Particles

MOFs self-templated hollow Co/NC@PANI composites for high-efficiency electromagnetic absorption

Considering the diverse structures and superior properties of metal-organic frameworks (MOFs), we successfully synthesized Co/NC@PANI composites through high-temperature pyrolysis and in-situ chemical oxidation using zeolitic imidazolate framework compounds (ZIFs) as precursors. The inclusion of polyaniline in the composites improved conductive loss and interfacial polarization, while the porous structure of Co/NC and uniformly dispersed cobalt nanoparticles can contribute to electromagnetic wave multiple reflection and magnetic loss. By synergistically dissipating electromagnetic waves through various loss mechanisms, we were able to control electromagnetic parameters and optimize performance, resulting in the development of Co/NC@PANI composites with exceptional electromagnetic properties. The minimum reflection loss (RLmin) reaches − 46.28 dB at 5.76 GHz, with a matching thickness of 5 mm. And the effective absorption bandwidth (EAB, RL<− 10 dB) reaches 3.52 GHz at a thickness of 2.5 mm. This work provides an efficient enlightenment for constructing microwave-absorbing material with high performance.

Ice-phobic properties of MoS2-loaded rice straw biogas residue biochar-based photothermal and anti-corrosion coating with low oxygen to carbon ratio

Icing of wind turbine blades will seriously hinder the development of the wind power industry, and the use of biomass resources to solve the icing problem is conducive to promoting the synergistic development of biomass and wind energy. In this study, ice-phobic coatings with photothermal and anti-corrosion properties were prepared by surface modification pyrolysis and hydrothermal reaction with rice straw biogas residue as raw material. The erosion of KOH and the surface modification of MoS2 produced a rough structure of the material, and the high-temperature pyrolysis and hydrothermal reaction promoted the dehydrogenation and decarboxylation reactions, which reduced the number of oxygen-containing functional groups and decreased the surface energy of the material. The ice-phobic coating has superhydrophobic properties with a contact angle of 158.32°. Due to the small surface area in contact with water, the coating was able to significantly reduce the icing adhesion strength to 53.23 kPa. The icing wind tunnel test results showed that the icing area and mass were reduced by 10.54% and 30.08%, respectively, when the wind speed was 10 m s−1 and the temperature was − 10 °C. Photothermal performance tests showed that the MoS2-loaded material had light absorption properties, and the coating could rapidly warm up to 58.3 ℃ under xenon lamp irradiation with photothermal cycle stability. The loading of MoS2 acts as a physical barrier, reducing the contact of corrosive media with the substrate, thus improving the anti-corrosion of the coating. This study has practical application value and significance for the development of the anti-icing field under complex environmental conditions.Graphical