Crystals
·
2021
·Vol. 11
·期 3
·278
·
IF 2.589
Liangqun Yang,Hongli Suo,Lin Ma,Min Liu,Wanli Zhao,Jianhua Liu,Lei Wang,Zili Zhang,Qiuliang Wang
In this study, boron powder with different particle sizes was purified by both chemical and heat treatment methods. The reduction in the particle size can improve the chemical purification with no effort on the heat treatment. The superconducting properties of the powder drastically changed even with only a partial elimination of oxygen. On the one hand, less oxygen content resulted in highTcandJcvalues under the low magnetic field, and most importantly, a significant improvement in the superconducting connectivity (Afvalue). On the other hand, the degradation ofJcunder a high field and a change in the pinning mechanism were also found, along with decreasing oxygen. This result indicated that oxygen, probably MgO, might act as the pinning center and as an obstacle for the supercurrent in MgB2at the same time. This work paves the way for obtaining pure oxygen-free MgB2and understanding the real effect of oxygen in MgB2.Keywords:boron powder;purification;particle size;MgB2;superconducting connectivity
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
ULTRASONICS SONOCHEMISTRY
·
2024
·
IF 8.7
Haoran Xu,Guang Fu,Duclenh Phan,Liuxin Xiang,Thiquynhxuan Le,Libo Zhang
Ultrasound enhanced evaporating crystallization has been proposed to solve the problems of low crystallization yield and uneven particle size in the evaporating crystallization process of ammonium sulfate solution at atmospheric pressure. The effects of key operating parameters, including the ultrasound power, stirring speed, pH value, and ultrasound time, on the yield of ammonium sulfate product and the duration of solid–liquid transformation time are studied. The results show that the ultrasound crystallization can increase the ammonium sulfate yield by 52.9 %, reduce the solid–liquid transformation time of ammonium sulfate by 10 %, and obtain ammonium sulfate products with higher crystallinity and more uniform particle size. Ultrasound promotes the crystallization of ammonium sulfate by enhancing the transfer of heat in the solution and reducing the supersolubility of the ammonium sulfate solution from 937.5 g/L to 833.33 g/L. This study provides experimental justification for the use of ultrasound in atmospheric evaporative crystallization.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Environmental Sciences
·
2019
·
IF 3.556
Hongyan Sun,Ruyuan Jiao,Hui Xu,Guangyu An,Dongsheng Wang
In order to evaluate the influence of particle size and particle concentration on the coagulation process, two kinds of particle suspensions, nanoparticles and microparticles , were employed to investigate the effect of particle size on coagulation mechanisms with varying coagulation parameters. Results showed that it is easier for nanoparticles to cause self-aggregation because of Brownian motion, while interception and sedimentation are the mainly physical processes affecting particle transport for microparticles, so they are more stable and disperse more easily. The particle size distribution and particle concentration had distinct influence on the coagulation mechanisms. Under neutral conditions, as the amount of coagulant increased, the coagulation mechanism for nanoparticles changed from charge neutralization to sweep flocculation and the nanoparticles became destabilized, re-stabilized and again destabilized. For microparticles, although the coagulation mechanism was the same as that of nanoparticles, the increased rate of aluminum hydroxide precipitation exceeded the adsorption of incipiently formed soluble alum species, resulting in the disappearance of the re-stabilization zone. Under acidic conditions, Brownian motion dominates for nanoparticles at low particle concentrations, while sweep flocculation is predominant at high particle concentrations. As for microparticles, charge neutralization and sweep flocculation are the mechanisms for low and high particle concentrations respectively. Under alkaline condition, although the mechanisms for both nano- and microparticles are the same, the morphology of flocs and the kinetics of floc formation are different. At low particle concentrations, nanoparticles have larger growth rate and final size of flocs, while at high particle concentrations, nanoparticles have higher fractal dimension and recovery factors.
研究领域:
环境科学
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化学工程
·
胶体与表面化学
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产品关联
DOI
PubMed
高影响因子
Polymers
·
2016
·Vol. 8
·期 2
·55
·
IF 2.944
Baijun Liu,Yajun Wang,Mingyao Zhang,Huixuan Zhang
Particle coagulation is a facile approach to produce large-scale polymer latex particles. This approach has been widely used in academic and industrial research owing to its higher polymerization rate and one-step polymerization process. Our work was motivated to control the extent (or time) of particle coagulation. Depending on reaction parameters, particle coagulation is also able to produce narrowly dispersed latex particles. In this study, a series of experiments were performed to investigate the role of the initiator system in determining particle coagulation and particle size distribution. Under the optimal initiation conditions, such as cationic initiator systems or higher reaction temperature, the time of particle coagulation would be advanced to particle nucleation period, leading to the narrowly dispersed polymer latex particles. By using a combination of the Smoluchowski equation and the electrostatic stability theory, the relationship between the particle size distribution and particle coagulation was established: the earlier the particle coagulation, the narrower the particle size distribution, while the larger the extent of particle coagulation, the larger the average particle size. Combined with the results of previous studies, a systematic method controlling the particle size distribution in the presence of particle coagulation was developed.Keywords:emulsion polymerization;particle size distribution;coagulation;initiator
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2023
·
IF 3.9
Guangyuan Chen,Meng Zhang,Tong Zhou,Zhongxiang Ding,Haiying Tang,Yuanhui Ji,Changsong Wang
Struvite (MgNH 4 PO 4 ·6 H 2 O，MAP), a type of high-quality, slow-release fertilizer, is the main component of urinary stones in animals and humans and causes scale formation in industrial pipes. Therefore, MAP dissolution is an important research topic. Herein, MAP dissolution experiments are performed and a thermodynamic model is developed to evaluate the influences of pH, temperature ( T ), and particle size ( P s ) on surface reaction resistance ( 1/k s ) and diffusion resistance ( 1/k d ). The results show that MAP solubility decreases with an increase in pH and the effects of pH change are more obvious than those of T or P s . The total resistance ( 1/k T ) of MAP dissolution increases with pH increase, P s growth, or T reduction. The comparison of 1/k s and 1/k d reveals surface reaction as the MAP dissolution control step and indicates a linear relation among 1/k s , 1/k d , and the natural logarithm of P s at pH 7.0.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2022
·
IF 5.64
Chengyang Zhou,Lingyun Liu,Jun Chen,Fanfei Min,Fangqin Lu
The influences of particle size on the flotation separation of kaolinite and quartz was explored by flotation tests of full-size and various sizes, zeta potential analysis. The flotation separation effects of kaolinite and quartz mixed minerals under different conditions were analyzed by calculating the characteristic parameters such as K, R ∞ , Km, SI and SE. Results show that in the sodium oleate scenario, kaolinite has better floatability under neutral conditions, while quartz has better floatability at pH 12. Ca 2+ has little effect on the floatability of kaolinite but it does inhibit the floatability of quartz under acid and weak alkali conditions. As well it can improve the floatability of quartz at a pH 12. In the two mineral flotation separation tests, reverse flotation had better selectivity for coarse-grained minerals. The maximum separation efficiency of the mixed ore with a particle size of 0.125–0.075 mm was 71.88%, the recovery of kaolinite in the concentrate was 84.97%, and the recovery of quartz amounted to 13.10%. It is of great significance to the research on the flotation separation of kaolinite and the high resource utilization of kaolinite.
研究领域:
矿物加工工程
·
材料科学与工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Jiguang Huang,Haiping Chen,Jihao Yang,Tian Zhou,Heng Zhang
Recycling fly ash for ceramic membrane fabrication not only reduces solid waste discharge, but also decreases the membrane cost. Now, fly ash is becoming a promising substitute material for ceramic membrane preparation. A significant difference between fly ashes from different plants is the particle size, which makes performances of fly ash membranes unpredictable. The novelty of this work is to clarify the effects of the particle size of fly ash on ceramic membranes, thereby giving practical suggestions on fly ash selection for ceramic membrane preparation. Ceramic membranes were fabricated with different sizes of fly ashes. Effects of particle size on porosity, pore size, microstructure, mechanical strength and gas permeability of the membrane were investigated. Results indicate that a broader particle size distribution of fly ash leads to a denser structure of membrane with a lower porosity. Pore size and gas permeability of membrane increase while bending strength decreases with the particle size increasing. Bending strength of a fly ash membrane is largely determined by large particles in the fly ash because the large particles lead to cracks in the membrane. This work provides experimental bases for developing high performance ceramic membranes from fly ash.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Fangming Liu,Jiawei Zhang,Pingping Liu,Duanwei He
The cold compression behavior of alumina samples, with average grain sizes of 350 nm, 7.9 μm, and 18.2 μm, has been investigated under non-hydrostatic conditions by using a diamond anvil cell. After treatment with various pressures, the in situ axial X-ray diffraction patterns , transparency variations, and microstructures after decompression of the samples were also analyzed. The results showed that the submicron grains became easily translucent. The larger the grain size, the higher the pressure needed to compress the sample to transparency. On the other hand, for a similar grain size, the various geometrical shapes of the grains did not affect the pressure dependency on transparency. The elastoplastic characteristics of the alumina grains of different sizes under cold compression were found to be consistent with the transparency variation. As a conclusion, alumina particles under cold compression were found to be applicable in the pressure-assisted preparation of alumina transparent ceramics.
研究领域:
材料科学
·
高压物理
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Ruolin Li,Yang Ren,Chengyang Cao,Chao He,Hongyun Hu,Xian Li,Hong Yao
Recently, waste tires gain a growing recognition of the potential as value-added fuel via pyrolysis. In the present study, molten salt was proposed to be used for the waste tires pyrolysis, aims to enhance heat transfer efficiency, and then reduce energy input for the mechanical shredding of waste tires into small particles before pyrolysis. In detail, the conversion and products formation behavior of two waste tires (of different particle sizes) were compared by a constructed molten salt thermal treatment system. Results show that H 2 and CH 4 contents of the pyrolysis gas increased substantially, and smaller tire particles produced more H 2 and CH 4 (up to 500%), while CO 2 content dropped to zero. Also, the contents of benzene increased remarkably with molten salt added (growth rate is between 1100% and 1800%) for electro-mobile tires, while caprolactam was disappeared. Specifically, benzene yield increases and then decreases with increasing particle size. In addition, molten salts were also effective in removing sulfur and ash from pyrolytic char, with more than 60% of the sulfur fraction being removed. These findings could provide theoretical support for the development of low-cost thermal treatment technology for waste tires.
研究领域:
能源与环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2025
·Vol. 30
·期 3
·502
·
IF 4.6
Tian Lan,Xiaofan Ding,Qi Chen,Songtao Xiao,Taihong Yan,Tianchi Li,Weifang Zheng
Iodine is one of the key elements that must be removed from the off-gas systems of nuclear fuel reprocessing. This study systematically investigates the iodine vapor adsorption performance of the metal–organic framework (MOF) material HKUST-1(1-(2-methyl-4-(2-oxopyrrolidin-1-yl)phenyl)-3-morpholino-5,6-dihydropyridin-2(1H)-one), with particle sizes of 100 nm and 20 μm. HKUST-1 samples with varying particle sizes were synthesized via a hydrothermal method. The experimental results show that the 20 μm HKUST-1 exhibits superior crystallinity, a more intact pore structure, and a higher iodine adsorption capacity, reaching 700 mg/g, which is significantly greater than the 300 mg/g capacity of the 100 nm HKUST-1. Kinetic analysis reveals that the adsorption process follows the pseudo-second-order model, with physical adsorption as the predominant mechanism, where iodine molecules are accommodated within the pores. FTIR and XRD further confirm the structural stability of the HKUST-1 framework after iodine adsorption. However, desorption experiments show that iodine molecules are easily volatilized into the air, with a 20% weight loss observed within 10 h and a color change from black to green. The results provide experimental evidence for optimizing the application of HKUST-1 materials in iodine capture and suggest that material modification could enhance the long-term stability of iodine fixation.
研究领域:
材料科学
·
核工程
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials
·
2020
·Vol. 13
·期 24
·5768
·
IF 3.057
Zhuo Wang,Zhu Chen,Jie Zheng,Shufeng Zuo
In this study, three kinds of CeO2were synthesized, and supported PdOx(x = 0,1) catalysts were prepared for benzene catalytic combustion. The samples were characterized by XRD, N2adsorption/desorption, HRTEM, XPS and H2-TPR. The results show that three kinds of CeO2with different structures can be formed by different preparation methods. This is mainly reflected in the differences in pore structure, particle size and crystal plane. CeO2-DC obtained from directly calcined Ce(NO3)3·6H2O had the largest pore volume and pore diameter and smallest particle size. CeO2-DC was mainly exposed to the (200) plane. Combined with the results of the ability test, it could be concluded that when Pd2+and Pd0exist at the same time, the activity increases with an increase in the proportion of Pd2+. Meanwhile, the structure of CeO2affects the formation of oxygen vacancies, thereby affecting the adsorption and degradation of benzene. This article reveals that the particle size, crystal planes, oxygen vacancies and proportion of Pd2+have a great impact on the catalytic combustion of benzene and allow a more comprehensive understanding of the structure–activity relationship, which can guide us to design high-efficiency catalysts targeted to obtain suitable CeO2-based catalysts for the catalytic combustion of benzene.Keywords:cerium oxide;benzene;catalytic combustion;particle size;crystal surface
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2023
·
IF 3.6
Meng-Chao Li,Lu Wang,Zheng-Liang Xue
The influences of different parameters, such as reaction temperature, yttrium (Y) content, and H 2 concentration, on the particle size and morphological structure of Mo powder prepared via the H 2 reduction of MoO 2 , were investigated in the work. TG, XRD , FE-SEM, laser particle size analysis , model fitting, and orthogonal design experiment methods were adopted to analyze the reaction kinetic and reduction mechanism. The results showed that the optimum conditions for preparing ultrafine Mo powder were recognized as 1073 K, 1 mass% Y content, and a H 2 concentration of 0.000576 mol·cm −2 ·min −1 , which enabled the as-prepared Mo powder with a particle size as small as 107 nm. A new interfacial chemical reaction model with the consideration of reaction temperature, H 2 concentration, and sample thickness, was proposed to analyze the reaction kinetic. It was found that the curves predicted by the model agreed well with the experimental data, with the apparent activation energy extracted to be 94.686 kJ/mol. The effect of different individual parameter on the reaction rate and the possible reduction mechanism were also elucidated.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）