Search

In this paper, pristine and nitrogen doped ordered porous carbon materials were fabricated by using maltose and amino-maltose synthesized by hydrothermal reaction as precursors via template strategy. The fabricated pristine ordered porous carbon (OPC) and nitrogen doped ordered porous carbon (NOPC) exhibit excellent textural properties and good capacitance performance, which specific surface area ( S) reach 1107 and 726 m g for the pristine OPC and NOPC materials while the specific capacitance reach up to 139 and 183 F g under a current density of 0.5 A g, respectively. The capacitance retention rate for the pristine OPC and NOPC reaches ca. 81 and 92% as the current density increased from 0.5 to 20 A g, and no apparent capacitance decrease was observed after 5000 cycles. Although a sharp decrease of specific surface area was observed after N doping, the specific capacitance of NOPC was improved about 31% than that of the pristine OPC, the enhanced wettability and surface availability after N doping were found to be responsible for the enhanced capacitance performance of NOPC. [ABSTRACT FROM AUTHOR]

ABSTRACT Secondary doping method was introduced into fabricating polypyrrole/oganic modified attapulgite conductive composites. The preparation conditions, such as amount of hexadecylpyridinium chloride (CPC, modifying agent), organic modified attapulgite (OATP), and HCl (secondary dopant) have been optimized to get the composites with the highest conductivity. When mCPC/ mATP, mOATP/ mPy, and nHCl/ nSA (SA is sulfamic acid) reaches 0.03, 0.6, and 0.5, respectively, the PPy/OATP composites possess the highest conductivity of 87.59 S cm−1 as well as the highest thermal degradation temperature of 249.29°C. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, UV-Visible diffuse reflectance study, and X-ray photoelectron Spectroscopy results showed that PPy chains form the core-shell structure and may combine with OATP via π-π stacking interaction. Thermogravimetric analysis showed that the thermal stability of PPy/OATP-SH composites was enhanced and these could be attributed to the retardation effect of OATP as barriers for the degradation of PPy. This method may open a new door for PPy-based composites with special structures, higher performance, and thus broader application ranges. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41407. [ABSTRACT FROM AUTHOR]

To discuss the source of sulfolane (SL) in decreasing the interface resistance of Li/mesophase carbon microbeads cell with lithium bis(oxalate)borate (LiBOB)-based electrolyte, the morphology and the composition of the solid electrolyte interphase (SEI) layer on the surface of carbonaceous anode material have been investigated. Compared with the cell with 0.7 mol l−1 LiBOB-ethylene carbonate/ethyl methyl carbonate (EMC) (1 : 1, v/v) electrolyte, the cell with 0.7 mol l−1 LiBOB-SL/EMC (1 : 1, v/v) electrolyte shows better film-forming characteristics in SEM (SEI) spectra. According to the results obtained from Fourier transform infrared spectroscopy, XPS, and density functional theory calculations, SL is reduced to Li2SO3 and LiO2S(CH2)8SO2Li through electrochemical processes, which happens prior to the reduction of either ethylene carbonate or EMC. It is believed that the root of impedance reduction benefits from the rich existence of sulfurous compounds in SEI layer, which are better conductors of Li+ ions than analogical carbonates. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Phenol–formaldehyde resin can be used to improve oil recovery; its key lies in its aggregation behavior and blocking strength. However, the traditional phenol–formaldehyde resin used in the petroleum field is all prepared by phenol and formaldehyde. In order to get rid of the dependence on fossil resources and make full use of renewable biomass resources, we used the abandoned walnut shells of the unique agricultural and forestry crops in Gansu province, which contains lignin partially replaced phenol to synthesize the new sulfonated lignin-based phenol–formaldehyde resin (SLPFR). The results showed that the optimum conditions for microwave polymers were polystyrene substitution rate of 20 wt%, decomposition temperature of 160 ℃, decommissioning time of 20 min, and sodium hydroxide concentration of 0.3 mol/L. Infrared spectroscopes and scanning telescopes have shown that after disintegration, there was an increased concentration of phosphorus, which had more active spots and was more suitable for replacing phenylphenol-synthetic formaldehyde resins. LC–MS indicated the molecular mass of SLPFR and the possible structure of molecules, indicating the successful synthesis of SLPFR. In this work, the aggregation behavior and dispersion stability of SLPFR were investigated from the composition of formation water. The effects of metal cations (Na+, Mg2+, Ca2+) on the dispersion stability of SLPFR in formation water were determined by turbidimetry, and the effects of metal cations on the particle size and zeta potential of the SLPFR system were measured by dynamic light scattering method and electrophoretic light scattering method. The stability of the aggregate structure of the SLPFR system was calculated by combining the fractal dimension. In this paper, the surfactant + SLPFR system and partially hydrolyzed polyacrylamide (HPAM) + SLPFR system were designed for the specific conditions of oil reservoirs, and the effects of metal cations on the aggregation behavior and dispersion stability of these two systems were studied. Based on the above comprehensive analysis, aggregation models were constructed to describe the aggregation behavior and dispersion stability of the HPAM + surfactant + SLPFR system. This makes it possible to predict in real time the migration and plugging of SLPFR aggregates in formation water. [ABSTRACT FROM AUTHOR]

Lightweight and high‐strength polymer–metal hybrid structures are favored for reducing material and energy consumption. In this study, carbon fiber‐reinforced polyamide 6 (CFPA) composite materials were prepared through melt blending, and 30 wt% CFPA exhibited the highest shear strength and lowest shrinkage rate among other carbon fiber contents. With pretreatments of anodizing and etching treatment, injection molded direct joining was employed to create polyamide 6 (PA)/CFPA–Aluminum alloy (Al) composites. The impacts of the injection temperature and speed on the bonding strength of the PA/CFPA–Al composite materials were investigated. The characterization results confirmed that carbon fiber doping reduces the coefficient of linear thermal expansion (CLTE) and enhances crystallization ability of PA. The higher injection temperatures and lower injection speed significantly increase the crystallinity of PA and the infiltration of the molten polymer into the nanoporous anodic aluminum oxide films. When the injection temperature was 270°C and the speed was 6 mm/s, the bonding strength of the PA–Al hybrid structure reached a maximum of 36.6 MPa. When the injection temperature was 300°C, the bonding strength of the CFPA–Al hybrid structure reached a maximum of 40.8 MPa. Adhesive parts with high shear bonding strength are critical to satisfying engineering requirements and have significant potential, particularly in polymer–metal composite structures. The polymer‐metal hybrid structure can meet the high interfacial bonding strength required in most engineering applications. Highlights: Injection temperature and speed in IMDJ affect PA crystallinity.Carbon fiber doping reduces the CLTE of PA and increases the shear strength.High temperatures and low injection speeds are beneficial to adhesives.The bonding strength of PA–Al reached a maximum of 36.6 MPa.The bonding strength of CFPA–Al reached a maximum of 40.8 MPa. [ABSTRACT FROM AUTHOR]

In recent years, magnetic metal nanoparticles (NPs)/carbon nanofibers (CNFs) composites have become very promising electromagnetic waves (EMWs) absorbers. However, how to achieve controllable growth of magnetic metals in CNFs is still an urgent problem to be solved. Herein, we reported a pore-confined strategy for constructing the porous Co/CoO/CNFs. By introducing different amounts of acetone (0.20 g, 0.30 g and 0.40 g) into the aqueous phase spinning solution to construct the porous structure, we achieved uniform distribution of Co/CoO NPs and ultimately obtained the porous Co/CoO/CNFs microwave absorbers (MAs) with excellent microwave absorption performance. Thanks to the excellent impedance matching and enhanced polarization loss, the porous Co/CoO/CNFs obtained the minimum reflection loss (RL) of −52.2 dB with a thickness of 3.0 mm, and the effective bandwidth (EBW) was 3.02 GHz when the acetone addition in the spinning solution was 0.30 g. Therefore, the pore-confined strategy proposed herein is conducive to the design of the MAs with excellent performance and low infilling rates based on CNFs. Furthermore, the porous structure of CNFs also improves the lightweight performance of the MAs. [ABSTRACT FROM AUTHOR]

Pipeline is now a commonly-used transportation mode for hazardous liquid, whereas followed by frequent pipeline leakage accidents. Research on the leakage post-assessment of hazard liquid pipeline has received increasing attention, but the in-situ data are hard to be accurately captured, resulting in a series of uncertainties affecting the accuracy and practicality of the risk assessment. This paper puts forward a novel method, which is able to accurately achieve leakage detection, cause analysis and leakage volume forecast by avoiding deviation of in-situ data, model parameters and the uncertainties caused by method, thereby quickly assessing the impact on the surrounding environment. The Markov Chain Monte Carlo (MCMC) algorithm is employed for repeatedly sampling leakage position and coefficient, furthermore, the transient hydrothermal and the leakage risk assessment model are established for determining the leakage volume and the risk grade. The influence of real-time measurement data and the deviation of the method are taken into consideration through the frequency distribution statistics of numerous sampling data. Based on two real examples, it is verified that the risk assessment method has practical value for the in-situ analysis and emergency treatment. [ABSTRACT FROM AUTHOR]

MG Imprinted polymer was synthesized by free radical cross-linking polymerization (RAFT) rising 2-acrylamy-2-methylpropanesulfonic acid as functional monomer (AMPS), Malachite green (MG) as template molecule and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent. The adsorbent was applied to study the adsorption of cationic dyes in aqueous solution. The effects of temperature, concentration and pH on the adsorption process were investigated. Through experimental investigation, it was found that the adsorption process was more in line with the quasi-second-order kinetic model and consistent with Langmuir adsorption. When the adsorption time was 3 h, the solution temperature was 25 °C, the pH was 7, and the dosage of adsorbent was 5 mg, the adsorption capacity of Malachite green by MIP could reach 1 808.91 mg/g. [ABSTRACT FROM AUTHOR]

Due to their physicochemical properties, the three-dimensional Metal-organic frameworks (MOFs) derived composites show great potential as electromagnetic wave (EMW) absorbers. However, poor impedance matching limits their actual EMW absorption performance. Composite materials that combine magnetic and dielectric losses offer a potential solution to enhance impedance match and significantly improve microwave absorption. In this work, a novel N,S-GS/Co/C composite was fabricated via a solvothermal method and a subsequent pyrolysis process to introducing nitrogen and sulfur co-doped graphene (N,S-GS) into Co-MOF. By co-doping nitrogen and sulfur, abundant defects and disordered sites were introduced on graphene, which stimulate interfacial polarization and dipole polarization. The minimum reflection loss (RL) of the sample obtained by pyrolysis at 600 °C is −68.8 dB at 9.7 GHz. Simultaneously, the thickness is 2.51 mm, and the effective absorption bandwidth (EAB) can reach 3.04 GHz. Its excellent EMW absorption performance is mainly attributed to interfacial polarization, multiple reflections, dipole polarization, magnetic resonance and eddy current loss. Accordingly, the N,S-GS/Co/C composite is convinced to be a competent candidate among EMW absorbers with high absorption intensity. [ABSTRACT FROM AUTHOR]

Pyrolysis gasoline is applied to extract aromatics and to be gasoline blending stock, and its stabilization by catalytic hydrogenation under mild temperature is an important reaction in petrochemical field. Thereinto, styrene hydrogenation was considered as an example for the assessment of the catalysis performance for pyrolysis gasoline hydrogenation. In this work, the adsorption and diffusion of reactants (styrene and H) and the activation energy of styrene hydrogenation on Pd(111), Pd(100), and Pd(110) surfaces are discussed by density functional theory calculations. The adsorption energy of reactants (styrene and H) decreases in the order of Pd(110) > Pd(111) > Pd(100). The activation barriers with feasible intermediate products are investigated and the reaction activity based on the activation barriers follows the order of Pd(111) > Pd(100) > Pd(110). In addition, the diffusion barrier for styrene or H is smaller than the reaction barrier of styrene hydrogenation, indicating the true rate limiting step is the process of hydrogenation rather than the diffusion. Our results provide theoretical guide for the prepared catalyst with feasible surfaces by careful selection of preparation techniques in experiments. [ABSTRACT FROM AUTHOR]

Phenol-formaldehyde resins combined with polymers have a wide range of industrial applications as plugging agents for profile control and enhanced oil recovery. Due to the structural resemblance between lignin and phenol, there are possibilities for environmentally friendly phenol-formaldehyde resin manufacturing. Sulfonated lignin–based phenol-formaldehyde resin was synthesized by partially replacing phenol with lignin, which improved the utilization rate of lignin and achieved the purpose of environmental preservation and resource conservation. Partially hydrolyzed polyacrylamide is the most widely used polymer in chemical methods for enhanced oil recovery. However, the stability of reservoirs with high salt and high temperatures is weak under these conditions. To solve the problem of low oil recovery in high-salt reservoir environments, polymer flooding is adopted, which utilizes high-molecular-weight polymers to raise the viscosity of injected fluids, thereby improving sweep efficiency and altering mobility ratio between oil and injected fluid. We focus on the stability study of different molecular weights partially hydrolyzed polyacrylamide combined with sulfonated lignin – based phenol-formaldehyde resins in metal ions and surfactants. The zeta potential and hydrodynamic diameter of the partially hydrolyzed polyacrylamide – sulfonated lignin – based phenol-formaldehyde resin system in Ca2+ were measured by dynamic light scattering and static light scattering, and the dispersion stability was analyzed. The interfacial energy – modified DLVO theory was introduced to evaluate the stability of its colloidal solution, which made it possible to predict the aggregation behavior of sulfonated lignin – based phenol-formaldehyde resin and the co-migration process of metal cations in real time. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the influence of polyepoxysuccinic acid sodium (PESA), a green antiscalant, on the nucleation, crystallization and precipitation of magnesium phosphate. Design/methodology/approach: The conductivity method was used to investigate the maximum relative supersaturation of magnesium phosphate across various PESA dosages. Subsequently, a magnesium phosphate scale was prepared using the static scale inhibition method (GB/T16632-1996) and then analyzed via scanning electron microscopy. Findings: The findings showed that PESA extends the induction period of magnesium phosphate crystallization, reduces crystal growth rate and elevates the solution's relative supersaturation. Notably, PESA exerts a low dosage effect on inhibition of the magnesium phosphate scale, with the optimal dosage identified at 10 mL. Scanning electron microscopy revealed that PESA dispenses a dispersing effect on the magnesium phosphate scale, generating numerous concave, convex and deeper pores on the scale particles' surface, and thereby significantly enhancing the surface area, especially when using an antiscalant with variable dosages. Originality/value: This study sheds new light on the impact of PESA, a green antiscalant, on the crystallization and precipitation of magnesium phosphate, thus paving the way for the development of enhanced and eco-friendly scale inhibition strategies in future applications. [ABSTRACT FROM AUTHOR]

Enhanced oil recovery research focuses on the phenol–formaldehyde resin (PFR) solution (EOR). We studied PFR's morphology and aggregation kinetics at various pH levels. A hydrated layer formed on the surface of PFR as a result of hydrogen bonding between the hydroxyl and phenolic hydroxyl groups and water molecules. We quantitatively quantified the impact of pH on the morphology and aggregation kinetics of PFR by incorporating the hydrated force into the DLVO (Derjaguin Landau Verwey Overbeek) theory. We were able to predict the situation of aggregates plugging into the reservoir by altering the size of PFR aggregates in a capillary. [ABSTRACT FROM AUTHOR]

The stability of phenol–formaldehyde resin (nHAP) in the oil displacement process influences its flooding and profile control capabilities. There aren't many studies that compare how various surfactants affect PFR stability. The surfactants CTAB, Tween 60, and SDS were selected as representative ones. To look at the changes in stability, spectral turbidity and dynamic light scattering experiments were employed. It was found that the cationic surfactant CTAB can connect with the surface of PFR, just as metal cations, lowering electrostatic repulsion and facilitating the aggregation of PFR composite molecules. Anionic and nonionic surfactants both have some degree of system stability stabilizing properties. When Tween 60 and SDS adsorbed on the surface of the PFR molecule formed a hydrogen bond network with the hydroxymethyl or phenolic hydroxyl group, for example by hydrogen bond interaction, the PFR molecule's dispersion stability was increased. The Tween 60 and PFR composite systems have bigger particle sizes in addition to being more stable. Additionally, the energy barrier of the Tween 60/PFR composite system is determined using the modified DLVO theory for Lewis acid–base hydration, and it is discovered to be consistent with the experimental findings. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. Understanding the co-migration of PFR and surface activity during oil displacement depends heavily on the data. [ABSTRACT FROM AUTHOR]

MnO 2 /carbon nanowires composites (CNWMn) have been prepared through a simple hydrothermal method using carbon nanowires (CNW) as the both reducing agents and scaffolds for MnO 2 growth. The crystalline phase of CNWMn is closely related to the hydrothermal reaction time, which has a profound impact on the electrochemical performance of CNWMn composites. Typically, the CNMWn2 (reaction time is 2 h) exhibits a highest specific capacitance of 465 F g −1 at the current density of 1 A g −1 in three-electrode systems. In addition, a two-electrode asymmetric system has also been fabricated using CNWMn2 and porous carbon nanowires (PCNW) as positive and negative electrode, respectively. The asymmetric system presents a maximum energy density of 39.2 Wh kg −1 at the current density of 0.5 A g −1 , which is much higher than that of traditional sense supercapacitors. Moreover, the asymmetric system exhibits excellent rate capability (high energy density of 24.2 Wh kg −1 at the current density of 10 A g −1 ) and high cycle stability with only 7% loss of its initial capacitance after 2000 cycles. [ABSTRACT FROM AUTHOR]

We employ a direct carbonization method for preparation of nitrogen-doped carbon nanowires using polypyrrole nanowires as the carbon precursor. Microstructural characterization indicates that the specific surface area and nitrogen content of carbon nanowires depend strongly on the carbonization temperature. As the carbonization temperature increases from 650 °C to 950 °C (the molar ratio of pyrrole and hexadecyl trimethyl ammonium bromide is 3.4), the specific surface area of nitrogen doped carbon nanowires increases from 306.9 to 580.2 m 2 g − 1 ; while, the nitrogen content decreases from 6.62 to 1.55 at.%. The carbonization temperature of nitrogen doped carbon nanowires is 750 °C, which strikes a balanced specific surface area (405.6 m 2 g − 1 ) and nitrogen content (5.59 at.%), exhibiting excellent capacitance performance. It delivers a large specific capacitance of 207 F g − 1 at 1 A g − 1 in three electrode systems. It also shows good cycle stability (the capacitance retention of 98.5% over 5000 cycles) and high energy density (13.2 Wh kg − 1 at the current density of 0.33 A g − 1 and the voltage window of 0–1.5 V) in symmetric two-electrode systems. These features warrant a potential useful material for supercapacitors. [ABSTRACT FROM AUTHOR]

Nitrogen-doped porous carbon nanowires were prepared by KOH activation of nitrogen doped carbon nanowires derived from direct carbonization of polypyrrole nanowires. The porous structure and nitrogen content were closely related to the mass ratio of KOH and carbon nanowires. The resultant nanowires demonstrated the highest specific surface area (1642 m 2 g −1 ) and capacitance (291 F g −1 at the current density of 1 A g −1 in three-electrode systems), when the mass ratio of KOH and nitrogen doped carbon nanowires reached 2. It also exhibited the excellent high rate performance and good cycle stability (94.8% capacitance retention after 5000 cycles) in three-electrode systems. High energy density (21.9 Wh kg −1 at a current density of 0.4 A g −1 in 0-1.6 V) and good cycle stability (the capacitance retention of 98.1% over 5000 cycles) were shown in symmetric two-electrode systems. These excellent electrochemical performances could be attributed to the high surface area, unique micro/meso/macroporous structure, and optimized nitrogen content. [ABSTRACT FROM AUTHOR]

Phenol-formaldehyde resin (PFR) has been synthesized in a reaction catalyzed with NaOH. The molecular structures of PFR were investigated using Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography-mass spectrometry (HPLC-MS). In this study, the size of PFR aggregates were measured by a dynamic light scattering technique (DLS) in order to elucidate the dispersion performance of PFR dispersed in water. The coagulation behavior of the PFR aggregates with various pH values, valences and concentrations of H+ were investigated using DLS. The highest coagulation rate (ddt) at different pH values followed the order of: acidic > alkaline, which can be explained by the effects of electrostatic repulsion at protonation states of phenolic –OH groups. The coagulation phenomenon appeared at pH values less than 7. The fractal dimension d f ≈ 2.1 could be determined for reaction-linked colloid aggregation (RLCA) when pH < 7. These results indicated that PFR had a coagulation behavior which could be exploited in enhanced oil recovery (EOR) processes. [ABSTRACT FROM AUTHOR]