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Scanning and transmission electron microscopy, powder X-ray diffraction and thermogravimetric analyses were used to study the dynamics of the sorption processes of ligand-free iron nanoparticles produced by highly efficient physical synthesis, namely, the molecular beam method. The structure, chemical and phase composition of Fe-NaCl condensates with different iron contents, crystallite dimensions (nanoparticles) and nanoparticle surface areas depending on the condensation temperature, which characterize the sorption capacity, primarily for moisture and oxygen, were studied. Finally, the gravimetric analysis method was used to investigate the kinetics of the relative change in the weight of porous Fe–NaCl condensates with different iron contents, depending on the condensation temperature. With increasing synthesis temperature, the nanoparticle size increases, and the specific surface area decreases. Therefore, by changing the size of the nanoparticles at the same volume, we can regulate the ratio of the nanoparticle surface to the nanoparticle volume, i.e., change the properties of the reaction surface and, in this way, the contribution of the excess surface energy to the total free energy of the system. The mass fraction of physically adsorbed and bound oxygen (moisture) correlates with the size (area, surface) of the nanoparticles. [ABSTRACT FROM AUTHOR]

To enhance the understanding of the effect of C3A-gypsum hydration on the time-dependent flowability of cement paste, calcium carbonate powder was introduced to prepare a simplified model system representing cement paste, referred to as CaCO3-C3A-gypsum. Effect of C3A content, gypsum content, and types of sulfates on the C3A-gypsum hydration and then the time-dependent flowability of paste was investigated. The results shown that for CaCO3-C3A-gypsum paste, it was the substantial increase in specific surface area that caused by the precipitation of ettringite during the C3A-gypsum hydration, resulted in the loss of flow spread. As hemihydrate gypsum was introduced, the dissolution of hemihydrate gypsum and the precipitation of dihydrate gypsum was important for temporal evolution of flowability. This study has scientific guiding significance for predicting or exploring the internal essence of the temporal evolution of early flowability of cement paste or concrete. [ABSTRACT FROM AUTHOR]

Introduction: In ruminants, a symbiotic rumen microbiota is responsible for supporting the digestion of dietary fiber and contributes to health traits closely associated with meat and milk quality. A holistic view of the physicochemical profiles of mixed rumen microbiota (MRM) is not well-illustrated. Methods: The experiment was performed with a 3 × 4 factorial arrangement of the specific surface area (SSA: 3.37, 3.73, and 4.44 m2/g) of NDF extracted from rice straw and the surface tension (ST: 54, 46, 43, and 36 dyn/cm) of a fermented medium in a fermentation time series of 6, 12, 24, 48 h with three experimental units. Here, we used three rumen-fistulated adult Liuyang black goats as the rumen liquid donors for this experiment. Results: It was found that increasing SSA decreased the average acetate/propionate ratio (A/P, p < 0.05) and increased the molarity of propionate (p < 0.05). Increasing ST decreased total volatile fatty acid (tVFA) concentration (p < 0.01). Greater SSA increased (p < 0.01) MRM hydrophobicity, whereas increasing ST increased MRM cell membrane permeability (p < 0.01). The neutral detergent fiber digestibility (NDFD, r = 0.937) and tVFA (r = 0.809) were positively correlated with the membrane permeability of MRM. Discussion: The surface tension of the artificial medium and substrate-specific surface area had a significant influence on MRM's fermentation profiles, hydrophobicity, and permeability. The results suggest that physical environmental properties are key in regulating rumen fermentation function and homeostasis in the gastrointestinal tract ecosystem. [ABSTRACT FROM AUTHOR]

This study presents the preparation, characterization, and application of a reduced graphene oxide-Zinc Oxide-Elwendia persica seed (rGO-ZnO-EPs) hybrid composite for supercapacitor electrode material. The rGO-ZnO-EPs composite was synthesized using a straightforward chemical route, followed by extensive characterization to elucidate its structural and electrochemical properties. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed the successful incorporation of ZnO nanospheres and EPs into the rGO matrix, forming a highly porous and well-integrated composite structure. Electrochemical performance assessments revealed that the rGO-ZnO-EPs composite exhibits a high specific capacitance of 535 F/g at a current density of 1 A/g, significantly surpassing traditional electrode materials. Notably, the composite demonstrated exceptional cyclic stability, retaining 90% of its initial capacitance after 3000 charge-discharge cycles, indicative of its robust long-term stability. Further analysis using electrochemical impedance spectroscopy (EIS) indicated low electrical resistance, which facilitates enhanced ion diffusion and surface charge transfer processes. This low resistance, combined with the high surface area and abundant active sites provided by the porous structure of ZnO nanospheres, contributes to the superior electrochemical performance of the rGO-ZnO-EPs composite. These findings emphasize the potential of the rGO-ZnO-EPs hybrid composite for advanced energy storage applications, particularly in supercapacitors, where high capacitance, excellent cyclic stability, and efficient charge transfer are critical. This study not only demonstrates the viability of incorporating natural resources such as Elwendia persica seeds into advanced materials but also paves the way for future research into eco-friendly and high-performance energy storage solutions. [ABSTRACT FROM AUTHOR]

The physicochemical and adsorption properties of granular sorbents based on natural bentonite and modified sorbents based on it have been studied. It was found that modification of natural bentonite with iron (III) polyhydroxocations (mod. 1_Fe_5 GA) and aluminum (III) (mod. 1_Al_5 GA) by the "co-precipitation" method leads to a change in their chemical composition, structure, and sorption properties. It is shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores measuring 1.5–8.0 nm, with a specific surface area of 55–65 m2/g. Modification of bentonite with iron (III) and aluminum compounds by the "co-precipitation" method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions and nickel cations by 5-10 times compared with natural bentonite. The obtained sorption isotherms were classified as Langmuir type isotherms. Kinetic analysis showed that at the initial stage the sorption process is controlled by an external diffusion factor, i.e. refers to the diffusion of sorbent from solution into a liquid film on the surface of the sorbent. Then the sorption process begins to proceed in a mixed diffusion mode, when it limits both the external diffusion factor and the internal diffusion factor (the diffusion of the sorbent to the active centers through the system of pores and capillaries). To determine the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions and nickel(II) cations with the studied granular sorbents, kinetic curves were processed using the equations of chemical kinetics (pseudo-second-order model). As a result, it was found that the adsorption of the studied anions by modified sorbents based on natural bentonite is best described by a pseudo-second-order kinetic model. It is shown that the use of natural bentonite for the development of technology for the production of granular sorbents based on it has an undeniable advantage, firstly, in terms of its chemical and structural properties, it is easily and effectively modified, and secondly, having astringent properties, granules are easily made on its basis, which turn into ceramics during high-temperature firing. The result is a granular sorbent with high physical and mechanical properties. Since bentonite is an environmentally friendly product, the technology of recycling spent sorbents is also greatly simplified. [ABSTRACT FROM AUTHOR]

Brochantite was precipitated using stoichiometric amounts of CuSO4 and NaOH and characterized by scanning electron microscopy, specific surface area, thermogravimetric analysis, and zeta potential. Brochantite can be converted into paratacamite, basic copper bromide, and copper phthalate by shaking the powder with solutions containing excess corresponding anions. By contrast, attempts to convert brochantite into basic iodide, acetate, nitrate, or rhodanide in a similar way failed, that is, the powder after shaking with solutions containing excess corresponding anions still showed the powder X-ray diffraction pattern of brochantite. Successful ion exchange resulted in a decrease in the specific surface area by a factor of 10, but the specific surface area was unchanged when attempts to exchange the anion failed. Interestingly enough, paratacamite can also be converted into brochantite by shaking with solution containing excess sulfate. Brochantite and paratacamite obtained by precipitation and the salts obtained by ion exchange showed a negative zeta potential at pH > 9. [ABSTRACT FROM AUTHOR]

Influence of the specific surface area and filler concentration on the coefficient of linear thermal expansion (CLTE) of sintered composites based on high lead fused glass and lead titanate was investigated in order to obtain solder materials offering unusually low CLTE values. The microstructure of compositions was investigated by optical microscopy methods in combination with birefringence testing with a localization of about 1 μm. In samples containing up to 55% PbTiO3 powder having a specific surface area of less than 560 cm2/g, near-zero and even negative values have been achieved. [ABSTRACT FROM AUTHOR]

The tunnel-type MnO2 structure is regarded as one of the most promising cathode materials for aqueous zinc-ion batteries due to its high theoretical specific capacity and excellent rate capability. In this study, α-MnO2 nanorods (MnO2-r) and nanotubes (MnO2-t) were synthesized by reacting KMnO4 with different reducing agents, namely Cr(NO3)3 and hydrochloric acid. Their molecular formulas were determined using various techniques as K0.8Mn8O16·1.44H2O and K0.8Mn8O16·0.80 H2O, respectively. By taking advantage of the charge screening effect induced by the higher crystal water content including enhanced Zn2+ diffusion kinetics, the zinc-ion storage capacity of MnO2-r is significantly improved. This results in a consistently increasing specific capacity of 372 mAh·g−1 on the 50th cycle at 0.1 A·g−1, excellent cycle stability over 1600 cycles at 1.0 A·g−1 and superior rate performance. Moreover, a two-stage process involving the insertion/extraction of H+ and Zn2+ accompanied by precipitation/dissolution of ZnSO4 [Zn (OH)2]3·3H2O (ZHS) on the electrode surface was tentatively proposed as the mechanism for Zn2+ storage in two electrode materials. [ABSTRACT FROM AUTHOR]

This study investigates the mechanisms behind fluidity loss in superplasticized limestone calcined clay cement (LC3), a sustainable alternative to ordinary Portland cement (OPC). Despite its environmental benefits, in presence of superplasticizers, LC3 experiences significant challenges in maintaining workability, an issue of which this paper examines the root cause. It focuses on the role that initial reactions play in creating additional surface area and the consequence thereof on the performance of polycarboxylate ether superplasticizers (PCE) in LC3. Experimental results reveal that while PCEs initially disperse the cement particles, fluidity decreases rapidly over time, primarily due to the continuous generation of those new surfaces that exceed the adsorption capacity of PCEs. The study also examines the potential intercalation of PCE side chains into calcined clays and shows that even in the worst‐case scenario with montmorillonite clays, intercalation is not a significant contributor to slump loss when the clays are calcined. These findings suggest that alternative strategies, such as slowing down the initial reactivity of the calcined clays, for example by combining PCEs with other additives like diphosphonates, may be necessary to improve flow retention in superplasticized LC3 systems. [ABSTRACT FROM AUTHOR]

The properties of soil matrix have an impact on the fluorescence intensity of polycyclic aromatic hydrocarbons (PAHs), which restricts the application of fluorescence spectral technology in detecting PAHs in soil. The present study explored the mechanism of the influence of soil matrix properties on the fluorescence intensity of PAHs from the perspective of specific surface area (SSA). A three-factor three-level experimental design was adopted for investigating the relationship between soil matrix properties, PAH fluorescence intensity, and soil SSA. The typical benzo[ghi]perylene pollutant in soil as the research object, 27 soil samples with different sand content, moisture content, humic acid content, and given benzo[ghi]perylene concentration (2 mg/g) were prepared. On the basis of obtaining the fluorescence spectra and SSA data of soil samples, statistical analyses of fluorescence intensity and SSA were investigated in relation to the soil matrix properties. The statistical results showed that the soil matrix properties had a significant influence (P < 0.05) on the fluorescence intensity and SSA. Furthermore, combined with the technology of fluorescence microscopy imaging, the influence mechanism of soil matrix properties on fluorescence intensity was revealed. The soil matrix properties affected the soil SSA, resulting in a change of benzo[ghi]perylene concentration in the soil surface at the probe window, thereby affecting the fluorescence intensity. [ABSTRACT FROM AUTHOR]

This study investigates the effect of rare earth oxide CeO 2 on the physical properties of ceramsite and its efficiency in treating ammonia-nitrogen wastewater. Ceramsite was prepared from solid waste with 10 % coal gangue added as a pore-forming agent. Ceramsite sample I with CeO 2 and sample II without CeO 2 were prepared using pure reagents. The process parameters for both samples were optimized using an orthogonal test. Additionally, the effects of CeO 2 on ceramsite performance and the treatment of ammonia-nitrogen wastewater were studied, and the adsorption mechanism of CeO 2 on ammonia-nitrogen wastewater was clarified. The process parameters for preparing ceramsite sample Ⅰ were: preheating for 30 min at 600 °C, followed by roasting for 20 min at 1090 °C. The parameters for preparing ceramsite sample Ⅱ were: preheating for 30 min at 600 °C, followed by roasting time for 15 min at 1090 °C. The presence of CeO 2 increased the porosity of the ceramsite by 0.89 % and the specific surface area by 0.66 m2/g. Under neutral environmental conditions of water samples, CeO 2 increased the removal rate of ammonia nitrogen by 1.85 %. Ceramsite has a high porosity and specific surface area, indicating that it has abundant internal pores, a large contact area with ammonia-nitrogen, a strong ability to remove ammonia nitrogen, and resistance to erosion and water flow shear, which are conducive to the treatment of ammonia-nitrogen wastewater. [ABSTRACT FROM AUTHOR]

The thermal decomposition of complex oxide phases, such as perovskite, in the La2O3-Lu2O3-Yb2O3 systemwith a specific surface area of 37 m2/g, synthesised by the heterogeneous precipitation method under non-isothermal conditions of linear heating at a rate of 5 deg/min, was studied to reveal the features of structure changes in intermediate products. Thermogravimetric and adsorption-structural analyses, infrared spectroscopy, powder diffraction and electron microscopy revealed that the decomposition of precursors occurs in two main stages. Up to 700 °C, the initial coordination spheres are destroyed in a sequential manner, resulting in the powders remaining amorphous in phase composition. However, with a gradual increase in the order of the atoms, the change in the pore structure is non-monotonic, with an inflection point observed at 450 and 675 °C. At 675 °C, the system undergoes a collapse, accompanied with decrease in both the pore volume (V∑) and the specific surface area (SBET), which attain the lowest values of 0.0415 cm3/g and 16.5 m2/g, respectively. The second stage of decomposition of the precursor in the temperature range of 750-825 °C is associated with the formation and accumulation of the crystalline phase of perovskite in the form of a nanodispersed mesoporous powder with a specific surface area of 18 m2/g and the average mesopore diameter of 17 nm corresponding to a particle size of 40 nm when using the calculated X-ray density of 8.26 g/cm3. [ABSTRACT FROM AUTHOR]

In this study, the surface property parameters of non-swelling variable charge minerals, kaolinite and goethite, were determined using the ion-selective electrode method. The effects of experimental conditions, such as pH, ion concentration ratio, and liquid addition method, on the measurement results were clarified to provide a reference for accurately assessing the surface properties of variable charge materials. The research employed ion adsorption equilibrium experiments under varying pH levels, ion concentration ratios, and liquid addition methods. A combined surface property analysis was conducted using K+ and Ca2+ as indicator ions to characterize surface parameters. The results were compared with the specific surface area obtained via the BET method to verify accuracy, thereby identifying optimal measurement conditions. The study led to the following five conclusions. (1) pH significantly affected the adsorption amount and ratio of indicator cations, thereby influencing the accuracy of surface property parameters. (2) The addition method and concentration ratio of electrolytes influenced the measurement accuracy by affecting the adsorption state and equilibrium time of the two indicator cations. (3) For kaolinite, the optimal initial pH ranged from 7.5 to 8.5 in the KOH + Ca(OH)2 system and from 8.0 to 8.5 in the KOH + CaCl2 system, while the equilibrium pH was 7.5 to 8.0 in both systems. The optimal ion concentration ratios were cK:cCa = 2:1 and 9:1, respectively. (4) For goethite, the optimal initial and equilibrium pH values were 8.5 to 9.0 and 7.5 to 8.0, respectively, in both KOH + Ca(OH)2 and KOH + CaCl2 systems. The optimal ion concentration ratios were 4:1 and 20:1, respectively. (5) Through comparison, the optimal initial pH for measuring the two variable charge minerals was determined to be 8.5 ± 0.1, with the optimal equilibrium pH at 7.5 ± 0.1. However, the concentration ratios varied significantly, suggesting the need for systematic research by adjusting a series of ion concentration ratios based on the initial pH. [ABSTRACT FROM AUTHOR]