To address the problem of low toughness and brittleness in carbonated magnesium slag, acrylamide (AM) was introduced as an additive in this study. The effects of molding pressure, liquid-to-solid ratio, and carbonation time on the properties of magnesium slag were systematically investigated. The structural evolution of the material during carbonation was characterized and analyzed by XRD, FT-IR, SEM-EDS, LF-NMR, and AC impedance spectroscopy. The results showed that the flexural and compressive strengths of magnesium slag were significantly improved with increasing molding pressure and carbonation time. The porosity was gradually reduced. The optimization of the liquid-to-solid ratio also played a critical role in ensuring sufficient carbonation reaction and strength development. Under the conditions of 5 wt% acrylamide dosage, 4 MPa molding pressure, 0.15 liquid-to-solid ratio, and 24 h carbonation time, the flexural strength of magnesium slag reached 26.84 MPa. The compressive strength reached 76.21 MPa. The CO2 absorption was 20.16%. The total porosity was reduced to 7.23%. The comprehensive performance was optimal. The study demonstrated that the introduction of acrylamide effectively improved the density and toughness of carbonated magnesium slag. The synergistic optimization of strength enhancement and carbon sequestration efficiency was achieved. These findings provide a new technical approach and theoretical support for the development and application of high-performance carbon sequestration building materials.
Currently, animal models of chronic compression disorders primarily focus on acute compression and lack the capability for real-time electrophysiological signal monitoring. To address this issue, sodium alginate (SA), acrylamide (AM) and chitosan hydrochloride (CSCl) were used as raw materials to prepare polyacrylamide (PAM)/SA/CSCl composite hydrogels via photo-crosslinking. Subsequent immersion in solutions with different ions (Mn+) at varying concentrations (x) yielded conductive PAM/SA/CSCl/Mn+(x) composite hydrogels with a multi-crosslinked double-network structure, whose properties were systematically characterized. Results show that the PAM/SA/CSCl/Mg2+ (1 mol/L) hydrogel exhibits an equilibrium swelling time of 106±2 h, equilibrium swelling ratio of (360±30)%, and electrical conductivity of 158.5 μS/cm. This hydrogel is an ideal material for chronic compression models.
Three polymers, namely polyacrylamide (PAM), styrene-butadiene emulsion (SBR), and sodium carboxymethyl cellulose (CMC-Na), were selected to prepare polymer dual-liquid grout. Through basic performance and water loss tests, the effect of polymer incorporation compressive strength, water dispersion resistance and water loss performance of mortar was investigated, and the mechanism of polymer action was analyzed using CT and SEM. The results show that the incorporation of polymers has a thickening and retarding effect, which reduces the early strength of the slurry but improves its water dispersion resistance. Under different grouting pressure conditions, the water retention effect of the slurry mixed with polymer PAM is better. The film-forming and adsorption effects of the polymer can improve the interface morphology and optimize the pore size distribution, which can significantly improve the microstructure of the slurry.
This study employed a four-factor, four-level orthogonal design to systematically investigate the effects of water—binder ratio, sand—binder ratio, ultrafine mineral admixture, and silica fume content on the workability, mechanical properties, and durability of manufactured sand—solid waste cementitious system ultra-high-performance concrete (UHPC). Flowability, compressive strength, and rapid chloride permeability tests, combined with range and variance analyses, were conducted to identify the dominant influencing factors. Results indicate that water—binder and sand—binder ratios have significant impacts on flowability, while ultrafine mineral admixture and silica fume play decisive roles in enhancing strength and durability. The optimized mix proportion was determined as: water—binder ratio 0.16, sand—binder ratio 1.0, 30% ultrafine mineral admixture, and 10% silica fume. Under this condition, UHPC exhibited a flowability of 247 mm and a 28-day compressive strength of 174.1 MPa, markedly superior to other combinations, while rapid chloride permeability results confirmed extremely low charge passed, reflecting excellent impermeability. SEM observations revealed that C—S—H gels and secondary C—A—S—H gels interwove to form a dense microstructure, thereby enhancing macroscopic performance. This study demonstrates that orthogonal design provides an efficient method to optimize UHPC mix design based on manufactured sand and solid waste binders, offering a scientific basis for its practical engineering application.
Against the backdrop of rapid advancements in 5G communications, high-frequency electronic devices, and aerospace technology, the increased power density of electronic equipment has led to significant thermal accumulation and electromagnetic interference. These issues severely impact signal transmission and pose risks to human health, thereby severely constraining further development. Consequently, the development of composite materials that combine high-efficiency electromagnetic wave absorption with thermal management capabilities has become a research hotspot. This paper reviews the implementation pathways for electromagnetic wave absorbing materials and thermally conductive, insulating, and phase change heat storage materials, focusing on their mechanisms and based on their structure and composition. It systematically examines various types of fillers, high-thermal-conductivity fillers, and thermal insulation structures within electromagnetic wave absorbers. The paper introduces research progress on integrating electromagnetic wave absorbers with thermal management materials across different applications, analyzes current challenges such as filler dispersion, performance balancing, and large-scale cost-effectiveness, and outlines future prospects for functional integration and intelligent adaptation.
Due to its unique interfacial hydration characteristics and eco-friendly advantages, superhydrophilic antifouling coating has become a research hotspot in the fields of materials science and surface engineering in recent years. This paper systematically reviews the formation mechanisms, preparation methods and application prospects of superhydrophilic antifouling coatings. First, the formation mechanism of superhydrophilic surfaces is discussed. Then, the main preparation strategies currently in use are summarized. Finally, the key challenges faced in practical applications are analyzed, and the crucial roles of green synthesis, AI-driven material screening, and multiscale theoretical modeling in future research are explored. This work provides theoretical guidance and technological insights for the engineering applications of protective coatings on marine equipment, biomedical devices, and optical components.
Silicon carbide whiskers have shown promising application prospects in aerospace, composite materials and other fields due to their excellent high strength, high temperature resistance and outstanding chemical stability. Currently, there are many reports on the preparation methods of silicon carbide whiskers, and different preparation methods have their own characteristics in terms of reaction mechanism, process conditions, product quality and economic cost. The lastest research progress in the preparation of silicon carbide whiskers by chemical vapor deposition, thermal evaporation, sol-gel, carbothermal reduction and microwave heating methods in recent years were reviewed in this paper. And the process parameters, advantages, disadvantages, and application scenarios of various preparation methods were compared. On this basis, the existing problems in the current preparation methods of silicon carbide whiskers were proposed, and the future research directions are prospected, in order to provide some useful references for the basic research and large-scale synthesis of silicon carbide whiskers.
Photocatalytic technology allows for the sustainable conversion of solar energy into chemical energy and has been widely used in environmental pollution cleanup and energy generation. However, single-component photocatalysts face limitations such as narrow light absorption, high recombination of photogenerated carriers, and limited redox abilities, resulting in low overall efficiency that cannot meet practical needs. Therefore, building heterojunctions by combining two or more photocatalytic materials has become a key strategy for enhancing performance. Currently, hetero-junction photocatalysts are extensively studied in various areas, including photocatalytic hydrogen production, ammonia synthesis, hydrogen peroxide creation, carbon dioxide reduction, and pollutant degradation. To further advance heterojunction materials in photocatalysis, a systematic review of these catalysts is essential. This review discusses the background of photocatalytic technology, compares and summarizes the structures and mechanisms of Type-Ⅰ, Type-Ⅱ, Type-Ⅲ, Z-scheme, S-scheme, and double S-scheme heterojunctions, and highlights the main challenges and future trends for heterojunction photocatalytic materials.
Quasi-spherical nitrogen-containing heterocyclic ligands are key building blocks for the construction of dielectric functional materials due to their low rotational barriers and high symmetry structures. Their functionalized modifications can adjust the molecular anisotropy and precisely optimize the material properties: tunable response and ordered-disordered phase transition in dielectric materials; induction of non-centrosymmetric structure through halogen bonding and other strategies to significantly enhance the piezoelectric coefficient; and development of multiaxial high-temperature ferroelectrics by using cation dynamics in combination with chiral design. Current research still needs to break through the limitation of molecular ferroelectric species to promote the application of flexible electronics and sensing technology.
Film thickness uniformity is a critical quality control metric in high-tech fields, including electronic devices, optical coatings, and biomedical materials. It directly impacts the product consistency, performance stability, and system reliability. Hence, how to precisely measure the film thickness, assess the thickness uniformity, optimize the process parameters and improve the uniformity at wafer scale have become core research focuses and hotspots. This review begins by briefly describe the influence of thickness uniformity on film performance. Subsequently, it systematically reviews the statistical sampling methods, high-precision film thickness measurement techniques, and quantitative assessment schemes for thickness uniformity. Following this, the strategies for improve the film uniformity are summarized and discussed by combining theoretical models and experimental progress. Finally, it analyzes the main challenges currently faced in the field of uniform film fabrication and provides an outlook on future trends.
In recent years, the nonmetallic photocatalyst graphite phase carbon nitride (g-C3N4) has attracted more and more attention because of its low price, non-toxicity, physical and chemical stability. However, its photocatalytic efficiency is unsatisfactory under visible light due to the high electron-vacancy recombination rate, low surface active sites and low visible light response. At present, there are many strategies to improve its photocatalytic activity, such as element doping, morphology control, heterojunction construction and precious metal deposition, and heterojunction has been proved to be one of the important and feasible means. In this paper, the research progress of heterojunction of g-C3N4 photocatalyst and its application in the fields of pollutant degradation, hydrogen production CO2 reduction and nitrogen fixation are reviewed.
This study focuses on the effects of phosphoric acid doping on the structure and electrochemical properties of PAN/CMC-based carbon nanofibers. Polyacrylonitrile (PAN) nanofibers doped with varying contents of carboxymethyl cellulose (CMC) were prepared via electrospinning, and 5% CMC was identified as the optimal ratio. Subsequently, different proportions of phosphoric acid (0%, 20%, 40%, 60%) were added to the spinning solution for doping. After electrospinning, pre-oxidation, and carbonization, phosphorus-doped carbon nanofibers (PCNFs) were obtained. The materials were characterized using SEM, XPS, XRD, and Raman spectroscopy, and the results confirmed successful phosphorus doping. Electrochemical tests revealed that phosphorus doping significantly influenced the electrode performance. Among the samples, PCNFs60 exhibited the highest specific capacitance of 89 F/g at a current density of 0.1 A/g, outperforming the undoped sample (CNFs). However, intermediate doping levels (20% and 40%) showed lower capacitive performance compared to the undoped sample. This study elucidates the trade-off mechanism between “pseudocapacitance enhancement” and “conductivity loss” during phosphorus doping, providing important insights for the design of high-performance electrode materials.
In this study, we synthesized three copper-alkynyl photocatalysts, phenylacetylene copper (PACU), 2-ethynylnaphthalene copper (NACU) and 9-ethynylphenanthrene copper (FACU)-by coordinating organic alkyne monomers with varying aromatic ring numbers, phenylacetylene, 2-ethynylnaphthalene and 9-ethynylphenanthrene. The structures, compositions, and properties of these catalysts were thoroughly characterized, and their performance and mechanisms in photocatalytic CO2 reduction reactions were systematically investigated. The results show that as the conjugation length of the monomer increases, the Cu+ valence state and the Cu—C≡ coordination structure remain unchanged. However, the steric hindrance effect is significantly enhanced, leading to a decrease in molecular packing order and crystallinity. Photoelectrochemical tests indicate that the extended conjugation improves charge separation and reduces exciton binding energy, thereby enhancing photocatalytic activity. Among the three catalysts, NACU, based on 2-ethynylnaphthalene, exhibited the best CO2 reduction performance, with a CO generation rate of 35.27 μmol/g, which is twice that of PACU under identical conditions. This study demonstrates that, while maintaining a stable coordination structure, it is crucial to optimize the conjugation size to balance steric hindrance and charge transport, offering valuable insights for the rational design of efficient copper-alkynyl photocatalysts.
Thermal conductivity is a critical property affecting the durability and energy efficiency of desert sand concrete (DSC). To reveal its heat transfer mechanism and establish an accurate prediction model, experimental research and theoretical analysis were used in this paper. Thermal conductivity and porosity test of DSC were conducted to investigate the influence of desert sand replacement ratio (DSRR) on the thermal properties. DSC was considered as a four-phase composite comprising of desert sand mortar, coarse aggregate, interface transition zone (ITZ) and pores. A porosity adjustment factor was introduced, and prediction model for the thermal conductivity of DSC was developed based on Maxwell’s effective medium theory. The effects of coarse aggregate volume fraction, rock type and porosity on thermal conductivity were analyzed. The results indicate that as the DSRR increases, the thermal conductivity of DSC first increases and then decreases, reaching a maximum with the replacement ratio of 40%. The porosity first decreases and then increases, attaining a minimum at the replacement ratio of 40%. The predication results from the model are in good agreement with the experimental results. The thermal conductivity of DSC increases with the enhancement of coarse aggregate content and positively correlates with the thermal conductivity of rock, while negatively correlates with porosity. These findings provide theoretical support for the heat transfer mechanism of DSC.
In the clinical treatment of bone defects, orthopedic implant materials play a crucial role. Compared with metallic materials, carbon fiber reinforced polyetheretherketone (CF/PEEK) composites have advantages such as adjustable mechanical properties and X-ray permeability, and are gradually becoming the optimal choice for orthopedic implant materials. However, CF/PEEK implant materials still face clinical application challenges, typically characterized by insufficient biological activity. This study aims to address this issue by introducing a functional coating on the surface of short carbon fiber reinforced polyetheretherketone (SCF/PEEK) composites. Based on the injection molding preparation of SCF/PEEK substrates, a zirconium/silver (Zr/Ag) modified dual-ion functional coating was constructed using the plasma immersion ion implantation (PIII) method to further improve the biological activity of the substrate. Firstly, the mechanical properties of SCF/PEEK substrates with different short fiber contents were tested. Then, the surface characteristics of the modified composites were analyzed using scanning electron microscopy, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry, and contact angle measurement. Finally, the cell compatibility, osteogenic differentiation, and antibacterial properties of the modified SCF/PEEK were evaluated through in vitro cell experiments including cell morphology observation, cell proliferation, and alkaline phosphatase (ALP) activity, as well as antibacterial experiments. The results showed that the SCF/PEEK composite with 40 wt% SCF presented the highest tensile modulus (17 GPa) and flexural modulus (24 GPa). In addition, the zirconium/silver modified SCF/PEEK composites not only exhibited good hydrophilicity and continuous ion release process, but also achieved excellent cell compatibility and antibacterial activity. This functional composite system provides new ideas for the long-term use of orthopedic implant materials and the healing of bone injuries.
In view of the environmental problems caused by the massive accumulation of lithium tailings and the demand for high value utilization of solid wastes in the context of the rapid development of lithium industry, this study takes Yichun lithium tailings as the main raw material, designs the basic formula based on the CaO-SiO2-Al2O3 ternary phase diagram, and uses one-step sintering method to prepare foam microcrystalline glass. The effects of SiC foaming agent dosage, sintering temperature, and insulation time on material properties through DSC, SEM, and other methods were studied. The results showed that under the conditions of SiC content of 0.26 wt%, sintering temperature of 1 050 ℃, and insulation time of 20 min, the material formed a uniform closed cell structure of 700 μm, achieving a synergistic breakthrough of porosity of 79.3%, bulk density of 0.856 g/cm3, compressive strength of 17.3 MPa, thermal conductivity of 0.316 W/(m·K), and water absorption rate of 3.80%. This provides a new path for the resource utilization of lithium tailings, and its excellent performance also supports the development of environmentally friendly building materials.
With the increasing focus on energy conservation, lightweight thermal insulators have become essential in various fields. Fly ash (FA) is a promising material for filler in polymer matrix composites(PMCs) owing to its composition, availability and low cost. Due to its low density, good thermal insulation, and good machinability, hollow glass microspheres (HGM) is widely used in various fields such as heat insulation materials. In this study, a series of FA/PVA/HGM (PF-HGM) composite aerogels with ordered structures, increased compressive strength, and excellent thermal insulation properties were prepared via the unidirectional ice-templating method. After introducing HGM into the FA/PVA aerogel, the thermal conductivity of the composite aerogel reached a minimum of 0.033 W/(m·K) when the HGM content reached 16%. Thermogravimetric analysis (TGA) revealed that the residual carbon content of the composite aerogel, with the addition of FA and HGM, significantly increased from 2.7% for pure PVA to 58%. The surface temperatures of the PF-HGM composite aerogels placed on a hot stage under different heating durations were recorded using a thermal imaging camera, and the results showed a notable decrease in the surface temperature of the aerogel as the HGM addition amount increased. This study successfully developed a novel composite aerogel with ultra-low thermal conductivity, significantly enhanced mechanical properties, and excellent thermal stability, demonstrating broad application prospects in the field of building insulation materials.
In order to realize the environmental friendliness and long-term effectiveness of marine antifouling coating, carboxymethyl chitosan was modified by polydimethylsiloxane (PDMS) and nano copper oxide (CuO). The modified carboxymethyl chitosan/PVA hydrogel composite coating was prepared with polyvinyl alcohol (PVA) as the substrate, and its mechanical, swelling and antifouling properties were systematically evaluated. FT-IR, XPS, and XRD analysis confirmed that CuO successfully reacts with carboxymethyl chitosan to form NOMS-CuO complex. The SEM image shows that the nano CuO particles are uniformly dispersed in the polymer matrix, indicating their good compatibility. After adding NOMS CuO into PVA hydrogel to make the coating, the performance test shows that with the increase of the content of nano particles, the swelling rate of the coating gradually decreases, and the mechanical properties are significantly enhanced. In terms of anti fouling performance, both anti algae and antibacterial properties show an increasing and then decreasing trend with the increase of NOMS-CuO content. The coating with a 4 wt% addition shows the best performance, with inhibition diameters of 15 mm and 14 mm against Escherichia coli and Staphylococcus aureus, respectively, demonstrating excellent anti fouling effect.
Steel slag is a commercial solid waste material mainly derived from the steel iron-making and metallurgy processes, which hardly pollutes the environmental atmosphere and could not be reused with high valorization level. In this paper, the attempts are being developed for the preparation of porous zeolite materials with low-calcium content and the insights on its potential exploring of the hydrogen storage application. The steel slag was successfully converted into X type zeolites with rich microporous structures by a hydrothermal synthesis route combining with both acid-leaching pretreatment and alkali-melting activation. In this study, the factors including acid-leaching condition, aluminum source selection, alkali melting reagents and the adding amounts, aging times, hydrothermal crystallization condition as well as the ion-exchanging condition that will influence on the zeolite synthesis and the hydrogen storage capacity were investigated in detail. The representative NaX zeolites along with the FAU zeolite cages were successfully obtained with the optimized synthetic parameters as molar ratios of n(Si)/n(Al)=1.25 and n(Na)/n(Si)=5.0. The synthetic zeolites behaves as the hydrogen storage capacity of ca.1.6wt% at room temperature 298 K and the pressure of 4.5 MPa. Therefore, the synthetic porous zeolite functional materials transformed from steel slag exhibits great high valued potentials in the solid state hydrogen energy storage applications.
Constructing a comprehensive power battery recycling industry system faces a key challenge, the efficient purification of recycled lithium iron phosphate (LiFePO4, LFP) powder and the regeneration of its crystal structure. This study utilized the off-specification LiFePO4 (OSL) generated during LFP production as the primary raw material. The OSL was mixed with appropriate amounts of Li2CO3, FeC2O4·2H2O, and C12H22O11, followed by ball milling, drying, and solid-state sintering for regeneration. The repaired LFP’s crystal structure and its impact on electrochemical performance were investigated by using laser particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical tests. Results indicated that the performance of the regenerated LFP powder had a significant improvement with the tap density increasing by 9.7% in the optimal sintering regime of 700 ℃ for 9 h. Under this process, the peak intensity ratios of the repaired LFP on crystal planes such as (101) and (020) increased significantly. The cross-sectional area of the (010) crystal orientation expanded, which was 4.3×10-4 nm2 higher than that of OSL. These changes enabled the effective restoration of the Li+ diffusion channel. The reconstruction of the LFP crystal structure and the formation of a uniformly distributed carbon coating were the main reasons for the recovery of the electrochemical performance of OSL. The regenerated LFP exhibited excellent charge/discharge performance with an initial discharge specific capacity of 149.2 mA·h/g at 0.2 C and high capacity retention with a capacity of 109.5 mA·h/g after 300 cycles at 1 C. This work is of great significance for improving the economic benefits of LFP production enterprises and regenerating of off-specification LiFePO4 at the terminal of the industrial chain.
To improve the flame retardancy of wood-plastic composites (WPC) and broaden their functionality, wood flour (WF)/high-density polyethylene (HDPE) was used as the matrix, with aluminum diethyl phosphinate (ADP) and melamine phosphate (MPP) serving as flame retardants. WPC flame-retardant composites were prepared through melt blending, and their flame retardant properties and mechanisms were investigated using methods such as limiting oxygen index, vertical combustion, thermogravimetric analysis, and cone calorimetry. The results indicated that the combination of ADP and MPP enhanced the flame retardancy of the wood-plastic composites, showing a synergistic effect. The samples with a mass fraction of 25% of ADP/MPP achieved a limiting oxygen index (LOI) value higher than that of WPC. Among them, the WPC-A3 sample (with an ADP:MPP mass ratio of 3∶1) had an LOI value of 31.3%, reached V-0 level in UL-94, and showed a 30.6% reduction in peak weight loss rate, a residual char yield of 17.18% at 800 ℃, an 81.6% decrease in maximum heat release rate, and a 51.3% reduction in total heat released. The tensile strength was 9.47 MPa, and the elongation at break reached 6.5%.
This study investigated the effects of different hot rolling reduction rates (5%, 10%, 25%,40%) on the Lüders band formation behavior and mechanical properties of Fe-0.2C-8.5Mn-1.5Al lightweight medium manganese steel during the tensile process under critical annealing conditions. The results indicate that with the increase of warm rolling reduction rate, the strain of Lüders band gradually decreases until it is eliminated at a reduction rate of 40%. The microstructure analysis shows that with the increase of the reduction rate, the ferrite decreases, and the austenite content increases. The grains gradually change from equiaxial structure to strip shape along the rolling direction. The grain refinement trend is obvious, and the austenite stability is enhanced. Increasing the reduction rate promotes the formation of preferred grain orientation and significantly increases the dislocation density in ferrite. Under low pressure, the sample exhibits strong TRIP effect and good plasticity matching, but the Lüders band is obvious. Under high pressure, the strain in the Lüders band significantly decreases or even disappears due to the enhanced stability of austenite and increased dislocation density, but the strength plastic product slightly decreases. By regulating the hot rolling reduction rate, the formation of Lüders bands in medium manganese steel can be effectively suppressed, providing theoretical basis and process reference for optimizing its formability.
To address the challenges of large emissions and low utilization rates of industrial solid wastes such as water purifying material waste (WP) and red mud (RM), this study explores the potential of incorporating WP and RM as supplementary cementitious materials into the magnesium phosphate cement (MPC) system, building upon MPC’s capability as a repair material. The effects of WP and RM on MPC’s mechanical strength and bonding performance of MPC were comparatively investigated. The results indicate that the incorporation of WP or RM refines the pore structure of the MPC matrix, reduces pore size distribution, and enhances matrix density and strength. Adding 5.0 wt% WP increases the 28 d compressive strength to (57.5±1.2)MPa (a 14.2% increase over the control), while 40.0 wt% RM achieves (64.1±2.0)MPa (a 27.4% increase). Furthermore, compared to the control group, the addition of 5.0 wt% WP enhances bonding performance with ordinary Portland cement mortar, yielding a 7 d bond strength of (2.7±0.1)MPa (a 17.8% increase), along with enhanced elastic modulus and hardness in the interfacial transition zone, whereas 40.0 wt% RM weakens interfacial bonding strength. The study provides a new approach for the application of WP and RM as mineral admixtures in repair materials.
To improve the performance of ceramic membranes, the coating conditions for TiO2/ZrO2 composite sol on fly ash-based substrates were studied and optimized. The TiO2/ZrO2 composite sol was prepared using the sol-gel method, and the coating was performed using the dip-coating method. Factors such as the molar ratio of raw materials and hydrolysis time were investigated for their effects on the synthesis of the composite sol. Factors such as the number of coatings and dipping time were studied for their impact on the coating effect of the substrate. The coating effect was evaluated through pure water flux, flexural strength, and microstructure. The results showed that the optimal raw material ratio for preparing the TiO2/ZrO2 composite sol was 2∶1, with an optimal hydrolysis temperature of 40 ℃ and a hydrolysis time of 1 h. The performance values of the TiO2/ZrO2 sol were viscosity 1.61 of mPa·s and solid content of 7.83%. When the coating process was repeated 3 times and the immersion time was 20 s, the ceramic membrane performed well, with a pure water flux of 8925.73 L/(m2·h·MPa) and a flexural strength of 29.37 MPa.
Iron oxide is commonly used as the active component of catalysts. Highly crystalline pure-phase porous α-Fe2O3 particles were prepared by direct thermal decomposition of Fe(NO3)3·9H2O through a solid-state one-step method of ball milling and mixing with the assistance of citric acid. The thermal decomposition process was discussed. The results show that after the addition of citric acid, the temperature at which all the crystalline water in Fe(NO3)3·9H2O was removed was 18 ℃ lower than that of the single component Fe(NO3)3·9H2O, and the initial temperature for the decomposition of Fe(NO3)3 was 6 ℃ lower. The interaction between citric acid and Fe(NO3)3·9H2O, as well as the formation of new chemical bonds at high temperatures, increased the decomposition temperature of Fe(NO3)3 by 36 ℃. The apparent activation energies of precursor decomposition were estimated by KAS and FWO methods, which were 109.8 kJ/mol and 111.9 kJ/mol, respectively. α-Fe2O3 particles with different worm-like pore structures were prepared by changing the dosages of citric acid and Fe(NO3)3·9H2O. This solid-phase method is an effective way to controllably prepare porous α-Fe2O3 with high yield and high crystallinity.
Epoxy resin (EP) emulsion was mixed with Portland cement to prepare epoxy resin foam concrete with hydrogen peroxide as foaming agent and triethanolamine as curing agent. The influence of EP content on the microstructure and macro performance of foam concrete was systematically studied by means of XRD, SEM and FT-IR. The results showed that the pore morphology of foam concrete was improved after EP doping, and the pore structure showed a more regular spherical shape. The micropore ratio of EP3% sample increased to 55.8%, and the coarse pore ratio decreased to 0.3%. The mechanical properties of the EP3% sample at 28 d of age are the best, with a maximum compressive strength of 1.62 MPa and a flexural strength of 0.55 MPa. After 700 ℃ high temperature heat treatment, the mass loss rate, water absorption rate and thermal conductivity of epoxy resin foam concrete increased. After 500 ℃ high-temperature treatment, the thermal conductivity of EP3% sample increased to 0.2364 W/(m·K), the mass loss rate was 11.5%, and the water absorption rate was the lowest value of 53.9%. Comprehensive analysis showed that the EP3% sample had excellent thermal stability and thermal insulation properties, and had broad prospects for engineering applications in high-temperature and high humidity areas.
Due to the insufficient adsorption performance and poor selectivity of the original biochar, coupled with regeneration difficulties and secondary contamination risks during adsorption processes, green modification technologies and waste valorization approaches have been employed to achieve “waste-treats-waste” remediation. This study selected walnut shells as the raw material to prepare shell-based biochar through carbonization and activation methods. A FeCl3 metal salt solution was used to modify the shell-based biochar via impregnation-roasting. The prepared materials were characterized using SEM, BET, FTIR, XRD, and Raman. The adsorption rate of RhB was used as the evaluation index, and the optimal modification conditions were determined through single-factor and orthogonal experiments. Response surface methodology revealed that the best preparation conditions for Fe-BC material were a roasting temperature of 588.07 ℃, an impregnation concentration of 4.03%, and an impregnation time of 16.11 h. Under these conditions, the adsorption rate of RhB could reach 97.12%. This study provides an efficient and low-cost adsorption material for the resource utilization of agricultural waste and the treatment of dye wastewater, demonstrating potential practical application value.
This study compared the effects of serine (Ser), a bio-based polyol amine chain extender containing a carboxyl group, and ethylamine (MEA), a petrochemical chain extender without a carboxyl group, on the mechanical and thermal properties of polyurethanes. The results demonstrated that the presence of a carboxyl group is crucial for enhancing polyurethane performance. Polyurethanes synthesized with the carboxyl-containing Ser (Ser-PU) exhibited markedly different mechanical properties to those synthesized with the non-carboxyl-containing MEA (MEA-PU). The former demonstrated tensile strength, elongation at break and toughness values of 22.7±0.38 MPa, 1064.11±38.21% and 118.47±7.95 MJ/m3, respectively, representing improvements of 3.64, 1.72 and 3.73-fold over the latter. Ser-PU exhibited a strain recovery rate of 100% at 94.24%, maintaining 83.42% recovery after 800 stretching cycles. This demonstrates that the presence of carboxyl groups substantially enhances the mechanical properties of polyurethanes via hydrogen bonding. The thermal properties of Ser-PU are comparable to those of MEA-PU. This indicates that replacing petrochemical-based alcoholamine chain extenders with bio-based alternatives can facilitate the transition from petrochemical to bio-based polyurethanes, which would promote green development in the polyurethane industry.