Formation Of Porous Structure Research Articles

Investigation on Effects and Properties of Concrete Structure after Exposed to Fire

Abstract: The integrity and strength of the materials used in reinforced concrete structures are highly influenced by their exposure environment. Exposing the building materials to high temperature changes their performance. The change in the performance is a result of the change in the material properties. When subjecting a building material to fire, the occurring damage depends on the severity of the fire in terms ofthe fire temperature and time of exposure. This study investigates the effects of fireexposure on the set of RC beams. Through controlled experiments, varyingtemperatures from 3000C to 7000C areapplied to RC beams, analyzing changes in compressive strength, spalling, andmicrostructure by using rebound hammer,UPV meter and applying two-point loading in UTM. Results indicate a significantreduction in compressive strength with increasing fire temperature, attributed to thermal degradation of cement paste and aggregate. Additionally, changes inmicrostructure, such as pore structure alterations and formation of cracks, are observed. Also, few of RC beams were strengthened using GFRP sheets as a U- shaped wrapping to entire beam and U- shaped wrapping at certain intervals. The strengthened specimens are again tested in UTM for two-point loading, the results of the tests showed the feasibility of rehabilitating RC beams exposed to fire using GFRP plates.U-shaped wrapping to entire beam showed the good performance

Role of solvent composition and sintering time on the porosity of α‐alumina monoliths produced by freeze casting

AbstractThe present study reports the investigation of the influence of naphthalene–camphor binary solvent and the densification process on the pore structure formation of α‐alumina monoliths using the freeze‐casting technique with a freezing temperature control mechanism. Freeze‐casting technique allowed a controlled production of monoliths with high porosity (65%–70%) and distinct pore morphologies based on the adjustment of solvent composition (hypoeutectic, eutectic, and hypereutectic) and sintering time. In general, the longer the sintering time, the greater the average pore diameter (8–10 µm), the larger the grain size (∼319–596 nm), the higher the material density (∼1450–1650 kg/m3), the lower the open porosity (∼60%–49%), the higher the closed porosity (5%–18%), and the greater the compressive strength of the monoliths (hypoeutectic: 23.56 MPa; eutectic: 4.81 MPa; hypereutectic: 23.49 MPa). The study also reveals that the solvent composition directly influenced the alignment of the pore structure, as the pores of the final monolith resemble frozen solvent crystals. Hydraulic tortuosity varied from 1.30 to 1.53 for selected samples. Finally, solvent composition and sintering time proved to be important parameters that should be considered in the manufacturing process of porous ceramic structures via freeze casting.

Synthesis of activated carbon from waste polyester fabric activated by ZnCl2 and its adsorption for organic dyes

In order to achieve the resource utilization of waste polyester (WPT), the WPT based activated carbon (WPT-AC) was prepared by ZnCl2 activation high-temperature pyrolysis method. The phase morphology, characteristic groups, pore structure of specific surface area and microstructure were characterized by TGA, XRD, FTIR, BET and SEM. The optimum preparation process of WPT-AC was determined by L9(34) orthogonal experiment, and the adsorption performance of WPT-AC for methylene blue (MB) was evaluated. WPT-AC showed a high specific surface area of 1037.62 m2/g, with rich pore structure, which provided the possibility for efficient adsorption. The pretreatment of ZnCl2 plays a key role in the formation of WPT-AC pore structure, and the abundant pore structure is conducive to improving the adsorption of pollutants. WPT-AC showed excellent performance in the field of organic dye adsorption, and the highest removal rate of MB reached 97.34%. The adsorption was mainly related to electrostatic attraction, hydrogen bonding and π–π conjugation. The analysis of adsorption kinetics and thermodynamics is conducive to a better understanding of the adsorption process.

Behaviour of sewage sludge based lightweight aggregate in geopolymer concrete

The global challenge of sewage sludge disposal has encouraged innovative solutions aimed at reducing environmental impact while simultaneously addressing the growing demand for sustainable construction materials. This study aimed to develop treated raw sewage sludge-based lightweight aggregates with strength comparable to commercially available aggregates. Two methods, namely cold bonding and sintering, were employed for the formation of aggregates. The sintering method produced well-formed and hard aggregates, while the cold bonded aggregates exhibited weakness and disintegrated under the slightest pressure. The optimal mix for quality aggregates was found to be 10%–20% sewage sludge, 70%–80% fly ash, and 10% lime using the sintering method. In the sintering method, an increase in sewage sludge content resulted in the reduction of bulk density and specific gravity by 13% and 4% respectively due to the high organic content in sewage sludge, volatile gas release, and porous structure formation. When 10% to 20% sewage sludge content was added, water absorption of the aggregates also increased by approximately 2%. Physical properties such as individual pellet strength. aggregate crushing value reduced by 18%, 20% respectively and the aggregate impact value increased by about 9%. These aggregates were then used to produce lightweight geopolymer concrete, which exceeded the design strength by 7% for the aggregate containing 20% sewage sludge and demonstrated excellent physical properties. The use of waste-based aggregates offers advantages including savings in cost, sustainability, resource conservation, waste reduction, and reduced environmental impact, making them a valuable alternative to natural crushed stone aggregates in specific applications.

Catalytic pyrolysis of wood dust for monophenol over macroalgal biochar-based catalyst: Effects of activation agents and atmospheres during catalyst synthesis on its performance

After introducing heteroatoms into the carbon material skeleton, the performance of carbocatalyst during catalytic pyrolysis of biomass for monophenol production is significantly improved. Algae, as a carbon source with intrinsic nitrogen content, is well-identified as a suitable raw material for preparing heteroatom-doped carbocatalyst. The present study aimed to investigate the effects of different alkaline activation agents (KOH/NaOH) and gas atmospheres (N2/CO2) during the carbonization-activation synthesis process of macroalgal biochar-based catalysts (MBBCs) on their properties and performances. Characterizations of carbocatalysts were carried out via BET and XPS analyses to investigate the porous structures and surface functional groups. Results showed that CO2, as a weakly oxidizing atmosphere, can promote the formation of porous structure of MBBCs. However, the promotion is not as strong as that of chemical activation agents (KOH/NaOH). Furthermore, KOH can promote the formation of porous structure more strongly than NaOH, but NaOH can substantially enhance the formation of surface oxygen‑nitrogen groups compared to KOH. All the MBBCs exhibited the increment of monophenols in the bio-oil obtained from catalytic pyrolysis of wood dust, especially phenol, o-cresol, and p-cresol. Amongst, the biochar-based catalyst activated with NaOH in CO2 atmosphere was the most effective one in promoting monophenols content (up to 59.46 %). Compared with the control group (without catalyst), the phenol content was increased from 5.03 % to 19.40 %. Moreover, it is found that the catalytic performance was positively correlated with the CO species percentage on the surface of MBBCs. The macroalgal biochar-based catalyst has an excellent catalytic performance, which is of great significance for achieving the complete utilization of algae and thereby improving the quality of catalytic pyrolysis products.

N, O-codoped porous carbon fiber cloth synthesized by molecular dispersed CaCl2·6H2O in situ activation for high performance supercapacitors

In this study, a nitrogen/oxygen co-doped carbon fiber cloth with a hierarchical porous structure was synthesized by one-step carbonization and in situ activation method and acted as binder-free electrode materials for supercapacitors. Cotton fiber cloth served as the carbon precursor, while molecular dispersed CaCl2·6H2O and urea functioned as activator and N dopant, respectively. The influence of molar concentration of CaCl2·6H2O and urea on the microstructure and capacitive performance of the resulting products were investigated. CaCl2·6H2O has an expansion effect on pores, resulting in reduction of micropores. Hence, the specific surface area of the resulting porous carbon increased first and then decreased with the increase of CaCl2·6H2O concentration. In addition, the erosion of NH3 and CO2 (produced by the decomposition of urea) at high temperature on the surface of the samples promoted the formation of porous structure. Urea plays the dual role of doping and activation agent. The morphology and structure analysis shown that the activated samples exhibited hierarchical pore structure, large specific surface area, and high heteroatom content. The optimal sample NAC-20 exhibited good capacitive performance, including high specific capacitance of 260.9 F g−1 at 0.1 A g−1 and good rate performance. Moreover, the symmetric supercapacitor exhibited a maximum energy density and power density of 16.2 Wh kg−1 and 19.0 kW kg−1, respectively, in 6 M KOH electrolyte. In this work, a green, low-cost molten salt activation method was proposed to synthesis biomass derived porous carbon materials for energy storage devices.

Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

Study on mechanism of supercritical water gasification of hemicellulose for hydrogen-rich syngas based on experiments and reaction molecular dynamics simulations

Hydrogen-rich syngas from supercritical water gasification (SCWG) of renewable biomass is a promising technology. However, the mechanistic studies related to experiments and simulations on hemicellulose, an important component of biomass, are still limited. Therefore, in this study, the SCWG mechanism of hemicellulose was investigated using a batch reactor and via ReaxFF molecular dynamics simulations. The results indicated that the long chains of xylan broke to short chains during the heating process, which was accompanied by the occurrence of ring-opening reactions. SCWG occurred more completely with increasing temperature or decreasing concentration, when hydrogen was more selective and methane was produced mainly by gas reforming reactions. At 600 °C and 5 g/100 g water, the total gas yield of xylan SCWG was 38.65 mmol g−1, and the hydrogen yield could reach 14.48 mmol g−1. The liquid products mainly included furfural and phenol. The solid products consisted of a high C content, which could reach more than 90 % at 500 °C, and were dominated by polycyclic aromatic hydrocarbons, and at 600 °C by benzene and naphthalene. Xylan formed carbon balls on the surface of the solid products, while hemicellulose exhibited the formation of a dense porous structure.

Fenton Reaction Doubled Biomass Carbon Activation Efficiency for High‐Performance Supercapacitors

AbstractThe huge consumption of alkali during biomass‐derived porous carbon production leads to pollution and high carbon‐emission. This study employs the concept of Fenton chemistry to achieve hierarchical porous biomass carbon materials with a remarkably high specific surface area of 3440 m2 g−1 with double activation efficiency compared to traditional activation process. The optimized carbon electrode demonstrates exceptional specific capacitance of 425.2 F g−1at a current density of 0.1 A g−1 and great rate performance (286.1 F g−1 at 100 A g−1) in 6 m KOH electrolyte. The enabled supercapacitor demonstrates remarkable cycling stability, retaining up to 99.74% of its initial capacitance after undergoing 20 000 charge–discharge cycles. In addition, the electrolyte ion distribution in different pore structures is simulated using Molecular Dynamics, which confirms that the structure is conducive to the rapid diffusion of ions, thus matching the excellent electrochemical properties. The assembled symmetric supercapacitors achieve a maximum energy density of 42.1 Wh kg−1 (12.1 Wh kg−1 based on cell stack mass) in TEABF4/AN electrolyte. This work presents an effective technique for the formation of porous structures from biomass precursors. The novel methodology can be applied to many other similar systems for energy storage and beyond.

Coupling control of organic and inorganic rock components on porosity and pore structure of lacustrine shale with medium maturity: A case study of the Qingshankou Formation in the southern Songliao Basin

Shale components affect organic–inorganic diagenesis, control the formation and evolution of pore structure, and lead to heterogeneity of shale reservoirs. Therefore, revealing the coupling control of shale components on the porosity and pore structure is crucial for selecting the dominant lithofacies. In this study, the lacustrine shale with medium maturity in the first member of the Qingshankou Formation (Qing1 Member) in the Changling Sag, southern Songliao Basin, China, was analyzed. Using pressurized sealed original shale samples and 2-D nuclear magnetic resonance (2D-NMR) analysis, the effective porosity of shale was accurately determined. The pore structure was characterized via experiments such as low-temperature nitrogen adsorption, NMR, and scanning electron microscope (SEM) analyses. In addition, the joint influences of the shale rock components, sedimentary structure, and maturity on the porosity and pore structure were investigated. Finally, the favorable reservoirs in the lacustrine shale with medium maturity and their formation conditions were identified. Studies have shown that for lacustrine shale with medium maturity: (1) a moderate total organic carbon (TOC) content (between 1% and 2.5%) is a key factor for improving the effective porosity and the proportions of mesopores (100–1000 nm) and small-pores (30–100 nm). This is related to the generation of organic acids and the cracking of organic matter into pores. An excessive TOC content can lead to increased plasticity of the rock and filling of the pores by bitumen. (2) The porosity and pore structure are controlled by the organic matter and inorganic minerals as well as sedimentary structure. Organic matter has dual impacts on the porosity improvement related to clay minerals, promotion of clay conversion and filling of clay-related pores, and the ratio of the clay content to the TOC (Vsh/TOC) can reflect the degree of influence of organic matter, the greater the Vsh/TOC ratio is, the greater the effective porosity and proportion of micropores are. (3) Organic matter and felsic minerals jointly effect the improvement of the effective porosity and larger pores (>30 nm), which is related to their good compression resistance, organic pore retention, and dissolution-enhanced porosity effect. The product of the TOC and felsic mineral content (Vsi*TOC) can reflect the degree of their coupled effect. For moderate TOC contents, a higher felsic mineral content, and moderate shell laminae (Vca>10%) are conducive to the development of the effective porosity and larger pores. (4) The organic medium-rich argillaceous laminated felsic shale and organic-medium argillaceous laminated clayey shale have a higher effective porosity and higher proportion of larger pores, making them the dominant lithofacies for shale oil sweet spots.

Nanoscale mechanisms of carboxyl carbon preservation during Fe(II)-induced ferrihydrite transformation

The persistence of organic carbon (OC) in natural environments is widely attributed to OC associations with minerals such as iron (Fe) minerals. Carboxyl, a critical structure of OC, can form strong complexes with Fe minerals, but it is still largely unknown about the effects of carboxyl groups on the transformation of Fe oxides and the stabilization mechanisms of OC on Fe oxides at nanoscales. In this study, four carboxylic acids with varying numbers of carboxyl groups (2, 3, 4, and 27 carboxyls) and molecular weight (ranging from 100 to 2000 Da) were added during the coprecipitation of Fe oxides and OC. This approach was taken to systematically elucidate the nanoscale distribution and sequestration mechanisms of carboxyl-containing OC on Fe oxides over different aging periods. Results suggested that ferrihydrite transformed quickly into lepidocrocite, goethite, and magnetite with the presence of Fe(II). The transformation rate of lepidocrocite to goethite slowed with increasing carboxyl number in OC molecules for the low molecular weight carboxylic acids (100–300 Da), but the high molecular weight carboxylic acid (∼2000 Da) promoted ferrihydrite transformation into goethite. Meanwhile, the particle sizes of produced magnetite decreased with increasing carboxyl number in OC molecules. During the mineral transformation, the release of OC from Fe oxides to aqueous solution decreased with increasing numbers of carboxyl groups. Spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) coupled with electron-energy-loss spectroscopy (EELS) suggested that carboxyl-rich OC promoted the formation of abundant defective or porous structures in goethite, resulting in OC accumulation in the bulk areas of goethite, which provided an effective way to sequester OC. The aggregation of high molecular weight OC containing more carboxyl groups with magnetite nanoparticles also played an important role in the preservation of OC. Furthermore, Fourier-transform infrared spectroscopy (FTIR) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) indicated that OC may form bidentate binding with Fe oxides and the binding strength of Fe(III) and OC may change with varying numbers of carboxyl groups. Results in this study provided a comprehensive understanding of the dynamic interactions between OC with different numbers of carboxyl groups and Fe oxides, and shed insights into the nanoscale mechanisms of OC stabilization during Fe oxide transformation process.

Synthesis and characterization of bentonite-based lightweight ceramic aggregates using coal combustion residue and kerosene bloating agent

Coal combustion residue (CCR) is an industrial by-product that has been widely adopted in civil engineering applications. However, a significant portion of CCR is still left unused around the world. This study investigates the feasibility of incorporating CCR into ceramic aggregates to enhance their engineering properties. Through a combination of kerosene as a bloating agent and CCR addition, the study demonstrates significant improvements in ceramic aggregate properties. Particle strength ranged from 0.33 to 8.53 MPa, with density variations between 0.39 and 0.95 g/cm³. Additionally, the additives also promoted the crystallization process, as shown by the increase in crystallinity from 40.67% to 61.87%. This was confirmed by the X-ray diffraction analysis, which revealed the changes in the mineral composition and crystallinity due to the additives. Furthermore, the micro and macro pores of bentonite profoundly influence the bloating process of aggregate, contributing to the formation of a well-distributed porous structure in ceramic pellets. The resulting ceramic aggregate exhibited favorable strength-to-density ratios suitable for both structural and non-structural concrete applications. This research highlights the potential of CCR utilization in ceramic aggregates, offering sustainable solutions for the construction industry while mitigating waste disposal concerns.

Preparation and performance of aluminosilicate fibrous porous ceramics-supported catalyst for NOx removal

In this study, we report a new aluminosilicate fibrous porous ceramics-supported catalyst for the removal of [Formula: see text]. The influence of raw materials and sintering process on the structure and properties of aluminosilicate fibrous porous ceramics was studied. The composition and the structure of the catalysts were characterized by XRF, XRD, SEM-EDS, and XPS analysis, and the experiments of denitrification were performed to determine the influence of the porous structure and the calcination process on the denitrification efficiency. The results indicated that the glass fibers facilitate the formation of a uniform porous network structure within aluminosilicate fibrous porous ceramics, and that the optimal sintering temperature is 1000∘C. Under the condition, the loaded catalysts were highly dispersed on the surface of aluminosilicate fibrous porous ceramics, which possessed high porosity and large average pore sizes. The aluminosilicate fibrous porous ceramics-supported catalyst exhibited excellent denitrification efficiency and catalytic stability, which is expected to be used for the treatment of [Formula: see text] in flue gas.

Oxygen Vacancy‐Rich Defects Porous Cu2MgO3/Mg0.78Cu0.22O Composite with Sinter‐Resistant and Highly Reactive for Long‐Duration High‐Temperature Thermochemical Energy Storage

AbstractHigh‐temperature thermochemical energy storage based on metal oxides is the key technology to reducing the levelized costs of electricity of the next‐generation concentrated solar power plants. CuO/Cu2O has wide availability and high energy density, but severe sintering leads to low reactivity. In this study, an innovative approach to modulate the oxygen vacancy content to change the surface properties and crystal structure to enhance the sintering resistance and redox reversibility is proposed. The re‐oxidation degree is increased from 46% to 99%, and the energy release rate is increased by 3.5 times. It remains 99.9% reduction and 97.1% oxidation activity after 3000 cycles, which is very valuable for engineering applications. Cu2MgO3 and Mg0.78Cu0.22O are prone to form oxygen vacancies, which promotes the formation of porous structures. Mg0.78Cu0.22O helps Cu2MgO3/CuO/Cu2O deliver more O through the surface. Mg0.78Cu0.22O is firmly and uniformly dispersed on the CuO/Cu2O surface after long cycling. They have a large binding energy, more charge transfer and enhanced bond energy at the interface. The mechanism of composite in increasing the sintering temperature and long‐term reaction stability is revealed from experimental and theoretical calculations, which provides a new idea for the rational design of thermochemical energy storage materials.

Novel process for facile preparation of mesoporous silica-based materials with controllable pore structure from coal fly ash

Extraction of silica from fly ash to produce mesoporous silica materials is one of the most important utilization approaches. Mesoporous silica could not be synthesized on a large-scale by conventional sol-gel method. In this paper, facile preparation of mesoporous silica with controllable pore structure from fly ash by the template-free process via two steps of mineral phase transformation and selective acid etching was proposed. The influence of crystalline structure and acid etching degree on structure of as-synthesized mesoporous silica materials was revealed, as well as mechanism of crystalline structure transformation and pore structure formation. The results show that mullite and quartz could be transformed into acid-soluble kaliophilite when fly ash reacted with K2CO3 at temperature of 800–1100 °C. The hexagonal kaliophilite would be transformed into orthorhombic KAlSiO4–O1 phase when the temperature is controlled at 1100 °C. Mesoporous silica with specific surface area of 475.93 m2/g and 642.57 m2/g could be synthesized from activated fly ash with kaliophilite and KAlSiO4–O1 phase crystalline structure. By controlling the degree of acid etching, mesoporous silica materials with different pore structures can be obtained. This paper provides a cost-effective and large-scale process for the preparation of mesoporous silica materials with controllable pore structure from solid waste fly ash.

Bioinspired, surfactant-free, dual-layer asymmetric structures based on polysaccharides, gelatin, and tannic acid for potential applications in biomedicine

The formation of dual-layer asymmetric porous structures in surfactant-based systems is significantly influenced by emulsions. Surfactants self-assemble to alter the conformational arrangement of polysaccharides, while gravity disrupts the initial uniformity of the established equilibrium droplet concentration gradient in the emulsion, thus achieving delamination. Specifically, high-speed rotation and non-instantaneous freezing allow the gelatin solution to form two different states of foam layers. The integrated dual-layer asymmetric porous structure, composed of polysaccharides and tannic acid, is constructed with gelatin as a skeleton and surfactant. This innovative approach eliminates the need to consider the toxicity of chemically synthesized surfactants and expands the concept of gelatin utilization. This intriguing structure exhibits a variety of desirable characteristics within 30 days (e.g., tailorable performance, ultrarapid antioxidant activity, efficient antibacterial activity, low differential blood clotting index, and good hemocompatibility and cytocompatibility), suggesting its potential as a valuable reference for applying hierarchical porous structures, thereby offering more formulation flexibility for biomaterials with adjustable properties.

Effect of the hydrotalcite formation on the fracture behavior and corrosion resistance of HA‐bonded alumina‐spinel castables

AbstractHydratable alumina‐bonded castable is a promising non‐cement bonded refractory for ladle lining. An in situ formation of layered double hydroxides (Mg–Al hydrotalcite, M–A–H) using reactive MgO powders is proposed as a means of enhancing the castables during curing, drying, and after the high‐temperature treatment. The formation of hydrotalcite, spinel transformation, pore structure, mechanical properties, fracture behavior, and slag corrosion resistance have been systematically investigated. The results indicate that the hydrotalcite formation is governed by the hydration reactivity of MgO, which promotes the formation of Mg(OH)2 as an intermediate hydrate, and the ultimate growth of hydrotalcite. The residual MgO and newly formed hydrotalcite are eventually transformed into micron size and submicron size spinel, respectively. This structural evolution contributes to an optimized pore structure and microstructure, enhancing the castables. The ultimate pore structure and enhanced interfaces between aggregate and matrix facilitate the improvement of toughness and slag corrosion/penetration resistance.

Construction of porous flower-like Ru-doped CoNiFe layered double hydroxide for supercapacitors and oxygen evolution reaction catalysts

In recent years, ternary layered double hydroxide (LDH) has become a research hotspot for electrode materials and oxygen evolution reaction (OER) catalyst due to the enhanced synergistic effect between individual elements. However, the application of LDH is greatly limited by its low electrical conductivity and the disadvantage that nanosheets tend to accumulate and mask the active sites. Herein, a novel Ru-doped CoNiFe − LDH was prepared via a facile hydrothermal method. According to the density functional theory (DFT) calculations, the doping of Ru element could improve electron state density and band gaps of LDH and consequently boosted the electrochemical reaction kinetics as well as electrical conductivity. Furthermore, introduction of Ru atom induced the formation of porous flower-like structures in nanosheets. Compared to CoNiFe − LDH (28.9 m2/g), Ru-doped CoNiFe − LDH performed larger specific surface area of 53.1 m2/g, resulting in more electrochemically active sites. In these case, Ru-doped CoNiFe − LDH demonstrated better energy storage performance of 176.0 mAh/g at 1 A/g compared to original CoNiFe − LDH (78.9 mAh/g at 1 A/g). Besides, the assembled Ru-doped CoNiFe − LDH//activated carbon (AC) device delivered a maximum energy density of 36.4 W h kg−1 at the power density of 740.3 W kg−1 and an outstanding cycle life (78.7 % after 10,000 cycles). Meanwhile, Ru-doped CoNiFe − LDH exhibited lower overpotential (339 mV at 50 mA cm−2) and Tafel slope (93.2 mV dec−1). Therefore, this work provided novel and valuable insights into the rational doping of Ru elements for the controlled synthesis of supercapacitor electrode materials and OER catalysts.

The Formation Process and Mechanism of the 3D Porous Network on the Sulfonated PEEK Surface.

A three-dimensional (3D) porous network can be prepared on the PEEK surface by sulfonation with enhanced osseointegration and antibacterial properties. However, few studies have been conducted on the formation mechanism of a 3D porous network. In this work, the surface and cross-sectional morphologies, chemical compositions, functional groups, surface wettability, and crystalline states of sulfonated PEEK were investigated at different sulfonation times and coagulant concentrations. The results show that the number of nodular structures and broken fibers on the sulfonated PEEK surface as well as the size of macrovoids in the cross sections increase with increasing sulfonation times when water is used as a coagulant. In contrast, dilute sulfuric acid as a coagulant can inhibit the formation of surface porous structures and macrovoids in the cross sections. Moreover, all of the sulfonated PEEK samples have the same chemical compositions but exhibit better hydrophilicity as the number of microsized pores decreases. It is proposed that non-solvent-induced phase separation (NIPS) occurs during the sulfonation process, and the formation mechanism of surface and cross-sectional morphologies is discussed. Furthermore, it is assumed that the air is trapped in the microsized pores, leaving the surface of the 3D porous network in the Cassie-wetting state. All of these preliminary results throw light on the nature of the sulfonation process and may guide further modification of the structures of sulfonated PEEK.

Phytic acid pre-modulated and Fe/N co-doped biochar derived from ramie fiber to active persulfate for efficient degradation of tetracycline via radical and non-radical pathways

Biochar-driven advanced oxidation processes (AOPs) have been widely applied in water decontamination from recalcitrant organic pollutants, yet its performance is restricted due to the complex functional groups of precursors and the obstacles of regulating the active sites. Herein, we prepared a phytic acid (PA) pre-modulated and Fe/N co-doped biochar derived from ramie fiber (Fe/N-PABC) to activate peroxydisulfate (PDS) for tetracycline hydrochloride (TCH) removal. The pre-treatment by PA facilitates the formation of pore structure and provide abundant loading sites for subsequent iron and nitrogen (Fe, N) doping. The main forms of Fe, N present in Fe/N-PABC are Fe0, Fe (II), pyridine N, and graphite N, respectively. In the presence of Fe/N-PABC, 80 % of TCH were degraded by PDS in 20 min at pH 5.0, whereas only 16.3 % of TCH was removed by single PDS. The oxidation of TCH was affected in the presence of Cl-, NO3–, SO42-, H2PO4- and HCO3–. Meanwhile, the performance was also validated in authentic waters in terms of degradation efficiency of TCH. The synergistic effects of radical and 1O2 dominated non-radical pathways were confirmed with the introduction of Fe, N in the system. Electrochemical oxidation experiments and density functional theory (DFT) calculations unveiled the electron transfer pathway and the key role of Fe/N-PABC/PDS* as an intermediate oxide. The possible degradation pathways were proposed based on the identification of degradation products. This study sheds light on the innovative concepts for modulating functional biochar and offering fundamental mechanisms of antibiotic degradation in wastewater treatment.