ISIJ INTERNATIONAL
·
2017
·Vol. 57
·期 1
·62-67
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IF 1.11
Zijian Su,Yuanbo Zhang,Yingming Chen,Guanghui Li,Tao Jiang
A considerable amount of works were focused on the formation mechanism of calcium ferrite phases during the iron ore sintering process, especially under various O2 content atmospheres at temperatures higher than 1100°C. But little attention has been paid on reactions between CaO and iron oxides in CO–CO2 atmospheres at lower temperatures. In this study, the solid state reaction mechanisms between CaO and Fe3O4 under CO–CO2 atmospheres at 800°C–1100°C were revealed by using XRD, VSM, etc. The results indicated that Ca2Fe2O5 was easily formed under 5–50 vol% CO/(CO+CO2) atmosphere above 850°C via the reaction of 6CaO + 2Fe3O4 +CO2 = 3Ca2Fe2O5 + CO and the reaction would be promoted with increasing the roasting temperature. In the CO–CO2 atmosphere, Fe3O4 is easily oxidized to Fe2O3 in the presence of CaO because CO2 components act as oxidative medium for the oxidation of Fe2+ to Fe3+.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2025
·
IF 2.8
Tao Liu
The current preparation of biomass-based hydrophobic absorbents still relies excessively on the use of fluorinated hydrophobic substances, which poses a risk of environmental pollution. This study aims to develop a sustainable and nonfluorinated method for fabricating biomass-based hydrophobic absorbents with enhanced recyclability and multifunctional surface properties. The chemical vapor deposition method based on nonfluorinated methyltrichlorosilane is used for the in situ growth of polysiloxane nanofilaments on the surface of Tong Cao (TC), resulting in the development of a TC-based hydrophobic absorbent. Upon organosilane modification, modified TC shows good hydrophobicity with a water contact angle of 93° and can be used to remove organic solvents from water. The absorption capacity of modified TC for different organic solvents is from 3.1 to 6.5 g/g. The percentage of retained absorption capacity of modified TC still remains at 98% after 10 consecutive uses, demonstrating a good recyclability. Modified TC also holds high organic solvents retention capacity as well as good self-cleaning and anti-fouling ability. These results indicate that modified TC with hydrophobicity and recyclability has potential for practical oily wastewater treatment.
研究领域:
材料科学
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环境工程
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生物质利用
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表面化学
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可持续技术
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Journal of Rock Mechanics and Geotechnical Engineering
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2025
·
IF 10.2
Guanghe Li,Jiankang Feng,Dong Wang,Jingjing Zou,Yanrong Dong,Laigui Wang,Kun Fang,Chunbin Guo
Mudstone found in open-pit coal mines is prone to softening, expansion, and disintegration when exposed to water, leading to deterioration of its mechanical properties and causing slope instability. To address this issue, this study introduced a novel slope stabilization method that integrates coal-based solid waste (fly ash) with microbially induced carbonate precipitation. The effects of fly ash (FA) and CaO (FC) and Bacillus subtilis (BS) contents on the cohesion ( c ), internal friction angle ( φ ), unconfined compressive strength ( q u ), elastic modulus ( E ), Poisson’s ratio ( μ ), disintegration resistance, and microstructural characteristics of mudstone were evaluated through unconfined compressive strength tests, direct shear tests, disintegration test, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results showed that under optimal curing conditions, the growth rates of c , φ , q u , E , and μ of the treated mudstone sample improved by +251.46%, +53.86%, +134.1%, +66.3%, and −65.61%, respectively, compared with those of plain mudstone samples. Moreover, its resistance to disintegration upon contact with water could be extended from 72 h to 10 d. The curing mechanism primarily involved the activation of FA into calcium silicate hydrate (C-S-H), calcium aluminate hydrate (C-A-H), Calcium Aluminum Silicate Hydrate (C-A-S-H), and microbially induced calcite (CaCO 3 ) precipitates. Under the action of an appropriate amount of curing agent, FC can provide an alkaline environment and nucleation sites for BS, making the calcium carbonate distribution more uniform. BS accelerates the catalysis of FC to form gelation products. Meanwhile, due to the continuous consumption of Ca 2+ and OH - , the equilibrium of the CaO dissolution shifts toward generating more Ca(OH) 2 , achieving a “three-way promotion” effect. On the contrary, these factors will inhibit each other due to the different rates of reaction output. The findings offer a viable solution for slope stability in open-pit coal mines and hold significance for safe mining, environmental protection, and sustainable use of coal-based solid waste.
研究领域:
岩土工程
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采矿工程
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环境科学
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生物地球化学
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固废资源化利用
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CALPHAD-COMPUTER COUPLING OF PHASE DIAGRAMS AND THERMOCHEMISTRY
·
2026
·
IF 2.2
Zhilong Sun,Jiyu Qiu,Chengjun Liu,Jie Qi,Bo Zhang
This study investigates the phase stability and isobaric heat capacities of some compounds in the CaO-Nb 2 O 5 -TiO 2 slag system derived from the Bayan Obo ore deposit. Four compounds in the CaO-Nb 2 O 5 system and three compounds in the Nb 2 O 5 -TiO 2 system were synthesized by solid-state sintering, viz CaNb 2 O 6 , Ca 2 Nb 2 O 7 , Ca 3 Nb 2 O 8 , Ca 4 Nb 2 O 9 , Nb 2 TiO 7 , Nb 10 Ti 4 O 29 and Nb 24 TiO 62' . In addition, we also tried to synthesize the potential ternary compounds C 8 N 7 T 6 , C 6 NT 3 , C 3 NT 3 , and “X” reported in literature. The phase synthesis results were characterized using a combined approach of SEM-EDS, XRD, and Rietveld refinement; then the isobaric heat capacities of the successfully synthesized compounds were determined over the temperature range from 373 K to temperatures below their melting points, from which the corresponding temperature-dependent polynomial expressions were established. Meanwhile, the standard molar enthalpies of formation and standard entropies of the synthesized compounds at 298 K were calculated using the two-parameter model. The current results can provide necessary experimental data for thermodynamic assessment and database development of the CaO-Nb 2 O 5 -TiO 2 system.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2026
·
IF 6.7
Zewei Liu,Fuhang Huo,Liping Zhang,Yong Liu,Xianglong Li,Lei Zhang,Huarui Zhang,Zixian Pang,Linhua Jiang,Bin Li
A composite material synthesized from HCl-treated red mud and γ-Al 2 O 3 (Al 1 HRM 2 ), was developed to enhance CF 4 decomposition in our previous study. However, its catalytic performance requires improvement, as it suffers from poor stability. In this study, the low-cost and anti-HF-corrosive CaO was utilized to further boost the material's CF 4 decomposition efficiency and stability. Specifically, decomposition efficiency and stability increased by 30% and 2.25 times than that of Al 1 HRM 2 , respectively. At the microscopic level, it was observed that after CaO uniformly distributed across the catalyst surface, it enhanced the Al-O (Al-O-Al) stretching vibration, increased the number of oxygen vacancies, and simultaneously prevented the phase transition from γ to α. Additionally, CaO intensifies the characteristic peaks of strong L-acid sites, enhancing their CF 4 adsorption capacity and strength. Specifically, Al Ⅲ sites facilitate C-F bond cleavage to form AlF 3 , which undergoes fluorine-oxygen exchange with CaO to produce CaF 2 . This process effectively inhibits F + occupation of γ-Al 2 O 3 active sites, thereby promoting CF 4 decomposition. This study utilizes RM as a high-performance material for CF 4 pollution control, achieving the goal of treating waste with waste across the aluminum industry supply chain. It provides a new technological foundation for purifying difficult-to-treat Perfluorocarbons greenhouse gases.
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Journal of Materials Research and Technology-JMR&T
·
2024
·
IF 6.2
Ruijing Sun,Jinhu Wu,Hui Wang,Wei Zhang,Chao Liu,Shaopeng Gu,Weihong Xing,Liang Yu
The reaction behavior between the carbon and mold fluxes during the heating process is vital for a successful continuous casting process and the high billet quality. A detailed investigation combined with thermogravimetry-mass spectrometry (TG-MS), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM) techniques was carried out to systematically investigate the transformation mechanistic of the macro physicochemical properties, melting behavior, viscosity, crystallization, and heat transfer performance caused by the reaction behavior. The results showed that the mold flux underwent carbonate decomposition (973–1223 K), solid reaction (1273–1573 K), and melting process (1473–1673 K) during the continuous casting process. The carbon-bearing mold flux exhibited an endothermic peak at approximately 1673 K, corresponding to a weight loss ratio of approximately 14.5% on the TG curve, confirming that carbon could react with the middle mineral phases Ca 2 SiO 4 , Ca 2 Al 2 SiO 7, and Na 6 Ca 3 Si 6 O 18 to form SiC, increasing the breaking temperature by approximately 293 K. SEM and TEM results indicated that the melting behavior was restrained by the carbon itself and the newly formed components. Besides, the addition of carbon increased the degree of polymerization of molten slag, the thickness of slag film and the proportion of small crystals in slag film, further leading to an increase in crystallization and heat transfer performances. The reaction mechanism between carbon and slag and the subsequent effects on melting point, viscosity, crystallization ratio and heat flux density were clearly understood, which is meaningful for the carbon blending process of the mold flux.
研究领域:
材料科学
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冶金工程
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JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2022
·Vol. 169
·期 5
·052504
·
IF 4.386
Kun Zhao,Kejia Liu
The formation of CaTiO3 during the electro-reduction of TiO2 pellets in CaCl2-based molten salts is unavoidable. So in present paper, the electro-deoxidation of porous CaTiO3 pellets was investigated. Cyclic voltammetry and constant potential electrolysis experiments were conducted to gain insight into the electro-deoxidation mechanism. From the results, two new reduction pathways of the porous CaTiO3 pellets were determined. The main factor influencing the reduction pathways is the porosity. When the porosity is low, CaTiO3 is directly reduced into TiO. With the porosity increases, some CaTiO3 will firstly be reduced into CaTi2O4 and then the CaTi2O4 is further reduced into TiO. The effect of the potential applied on the cathode on the possible reduction limit of the sample was discussed. The results indicated that the more negative the potential is, the faster the deoxidation rate is and the lower the deoxidation limit is. Only when the applied potential is more negative than −1.6 V vs Ag+/Ag, low-oxygen titanium (the oxygen content is lower than 1%) can be obtained in our experimental conditions. In addition, the microstructural kinetics of phase transformations during reduction of the CaTiO3 pellets were also discussed.
研究领域:
材料科学
·
电化学
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CERAMICS INTERNATIONAL
·
2026
·
IF 5.6
Jingxuan Luo,Rong Li,Wenhao Li,Shuhui Zhou,Zhiyuan Xu,Bangbang Liu,Chen Chen,Naijing Bu,Xiaodong Mao,Shaowei Zhang,Qiang Zhen
Hydration resistance is a critical performance indicator for MgO-CaO refractories in industrial applications. In this study, a novel anti-hydration strategy was developed through the construction of a composite organic–inorganic coating on MgO-CaO aggregates using a facile impregnation approach. The coating comprises a ZrCl 4 -derived sol, docosanoic acid (DCA, C 22 H 44 O 2 ), and nano-ZrO 2 particles. The modified aggregates exhibited super-hydrophobicity properties, with a water contact angle of 150.47°, which effectively inhibited moisture penetration. Upon heat treatment, the ZrCl 4 -derived sol decomposed and further reacted with CaO to form a dense CaZrO 3 layer, providing long-term hydration resistance. Hydration tests demonstrated exceptional stability, with a weight gain of only 0.025 % after 10 days of exposure to humid environments (at 25 °C and 85 % relative humidity). This work offers a scalable approach to enhance the durability of MgO-CaO refractories by integrating short-term hydrophobicity and long-term ceramic passivation.
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PROGRESS IN REACTION KINETICS AND MECHANISM
·
2026
·Vol. 51
·期 1
·
IF 4.8
Songsong Zhang,Daokuan Liang,Xiaofeng Li,Yaohui Fan,Heyi Huang,Xiao He,Lin Wang,Zhaoying Li,Yong Dong
As a major type of agricultural waste, bagasse is rich in volatile matter and low in ash, making it an ideal raw material for thermochemical conversion to hydrogen-rich gas. In this study, an ex-situ microwave-assisted catalytic pyrolysis technique was used. CaO and Na2CO3 and their mixed catalysts in different ratios were selected for the experiments at 550 °C. The aim is to optimize both the hydrogen yield and concentration of the components to produce high-quality fuel. Thermogravimetric analysis (TG/DTG) revealed the influence of the catalysts: Na2CO3 significantly promotes low-temperature deoxygenation, and CaO can effectively adsorb CO2. Molecular dynamics simulations showed that elevated temperatures promote carbon chain breakage, but too high a temperature (2,500 K) may lead to a carbonization cascade reaction, which inhibits bond breakage. The gas-phase products indicate that the mixed catalyst is most effective at a ratio of CaO : Na2CO3 of 1:3, achieving the highest H2 yield (maximum 17.26%) along with significant hydrocarbon generation inhibition (24.90%), and CO content reduction (23.45%). Catalyst characterization confirmed the presence of CaCO3 in the mixed catalysts after pyrolysis. The CaO : Na2CO3 = 1:3 catalyst was found to have a unique fibrous structure and a microporous network. Raman spectroscopy reveals the ordering of the carbon structure and differences in functional groups under the action of different catalysts. This study provides a theoretical basis for further optimizing the pyrolysis process of bagasse, and helps improve the conversion efficiency of biomass energy.
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RENEWABLE ENERGY
·
2023
·
IF 8.7
Azhar Abbas Khosa,Xinyue Han,C.Y. Zhao
CaCO 3 /CaO thermochemical energy storage (TCES) system has been widely studied on laboratory scale for its potential in concentrated solar power (CSP) plants. However, there is still need for the large-scale experiments based on which a detailed analysis can be obtained to improve this system for real-time applications. In this study, we developed a packed bed reactor capable of operating at high temperature and pressure providing the carbonation and decarbonation reactions of CaCO 3 /CaO reaction pair. The heat storage process is studied with the aspect of different decarbonation temperatures and different sample sizes (amount of sample in grams) placed in the reactor. Furthermore, we compared the heat storage performance of pure and composite samples. The heat release process is performed by varying the concentration of CO 2 and the sample size of the loaded material. The results showed that the heat storage rate and efficiency improve by increasing the temperature of the decarbonation, implying that this reaction must be carried out above 925 °C for better performance. The heat is released smoothly and at a good rate when the concentration of CO 2 is high in the reactor. Also, carbonation reaction (heat release process) depicts that CaCO 3 /CaO TCES system has a great potential to be used as a heat pump and is capable of upgrading the temperature of the released heat from lower to higher value.
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Colloid and Interface Science Communications
·
2023
·
IF 4.5
Lihuan Wang,Feng Gan,Jinpeng Mo,Jing Zhao,Xi Yu,Hui Yu
Rare earth-doped bioactive ceramics are promising biomaterials due to their unique optical properties, biocompatibility, antioxidants, and antibacterial activity. In this study, a series of SiO 2 -CaO-Er 2 O 3 nanofiber mats were fabricated by sol-gel electrospinning. The morphology, flexibility, physicochemical and biological properties of the nanofibers were investigated. The flexibility of the nanofiber mats containing 5 and 10 wt% of Er 2 O 3 was better than that of samples without or with >10 wt% Er 2 O 3 . The chemical property assay indicated that addition of Er can lead to changes in the degree of crystallinity and the degree of silica network polymerization, which further affect the flexibility. Photoluminescent spectra showed that the Er-doped nanofibers exist green and near infrared emissions. The in vitro bio experiments demonstrated that Er-doped nanofibers present excellent biocompatibility, and the mineralization experiment demonstrated that Er-doped nanofibers present favorable mineralization activity. Therefore, these SiO 2 -CaO-Er 2 O 3 flexible nanofibers may be promising candidates for biomedical applications.
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CONSTRUCTION AND BUILDING MATERIALS
·
2023
·
IF 7.4
Yanchen Oinam,Suhawn Ju,Myoungsu Shin,Sukhoon Pyo
This study aimed to investigate the influence of natural cellulose fibers (NCFs) on improving the hydration characteristics of cementless ultra-high performance concrete (UHPC) using CaO-activated ground granulated blast furnace slag (GGBFS). The NCFs were added in a saturated condition as an internal-curing agent so as to supply additional water to the UHPC matrix and subsequently increase the reactivity of unhydrated phases. To evaluate the hydration characteristics, saturated NCFs were added at 0 to 1.5 wt% of the GGBFS plus CaO. TGA and FTIR analyses showed that, as the amount of NCFs increased, the formation of hydration products was improved as evidenced by an increase in heat of hydration, indicating that more reactions of unhydrated phases occurred. Similarly, morphologies of the samples revealed the formation of hydration products on and near the surfaces of the NCFs due to the additional water exerted during the process of internal curing. Moreover, the compressive and tensile strengths were not compromised by the incorporation of weak and flexible NCFs, but rather a slight improvement was observed with a certain content of NCFs.
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