CRYSTAL GROWTH & DESIGN
·
2018
·
IF 3.972
Shijie Xu,Yifu Chen,Junbo Gong,Jingkang Wang
In this contribution, by employing the Poisson distribution combined with the regular solution theory in the classical nucleation theory (CNT) framework, we construct a new model to uncover the relationship between induction time (tind) and supercooling (ΔT) and saturation temperature (T0) at different specific probabilities. By choosing the urea aqueous solution as a benchmark system, we show that the value of ln(1/tind) follows a reasonable linear relationship with (T0/ΔT)2/(T0 – ΔT), except the probability value tends to be 0 or 1. Furthermore, we also shed new light on the role of chemical potential difference and nucleation temperature in determining the nucleation rate; namely, although the chemical potential difference is the driving force for the crystallization process, it does not always favor the nucleation process. We demonstrated that when the chemical potential difference increases as the nucleation temperature decreases (ΔT gradually increases), in this case, the kinetic factor overwhelms the thermodynamic factor thus leading to a faster nucleation rate by employing the CNT theory. However, when the chemical potential difference decreases as the nucleation temperature increases, we found that increasing the nucleation temperature favors the nucleation process both in kinetic and thermodynamic aspects.
研究领域:
物理化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2024
·
IF 5.2
Ying Xu,Dong Wang,Xin Wang,Jian Dong
The rapid growth of natural gas clathrate hydrate has been a significant safety hazard in off-shore natural gas drilling and gas transport. Alleviation of hydrate formation can be achieved by applying low-dosage hydrate inhibitors of polymers during operation. In order to combine the advantages of high adsorption potential and environmental friendliness, we study the kinetics of hydrate inhibition of amphiphilic highly branched poly(l-lysine) (PLL) by NMR relaxometry. The introduction of n-butyl and cyclohexyl groups in PLLs was found to be significantly effective in prolonging the induction times of sII clathrate hydrates. Key physical–chemical factors involved in the mechanism previously proposed by molecular dynamics simulations can be clarified by NMR relaxometry. Induction times for the formation of hydrate are associated with the interfacial water amount but are not related to the hydrogen bonding strength or dynamics of the free water component. The amphiphilic PLLs in the interface interact with the hydrate surfaces through their hydration shell. Analysis of the molecular motion and freezing kinetics of water in the fluid before and during hydrate formation reveals that the polymers can reduce the rates of hydrate growth from the free water by a factor of 5 to 10. A further significant decrease in the growth rates from small hydrate particles by a factor of 10 to 2600 was observed in the presence of the amphiphilic PLLs with n-butyl and cyclohexyl groups. The distinct crystal growth kinetics in the heterogeneous interface are influenced by the terminal alkyl groups of the polymers, with changing growth geometry or crystal shapes and consistent with the interfacial Gibbs–Thomson effect. A high Avrami index value of the isothermal crystal growth and nonfreezable water amount favors a long induction time. The PLL inhibitors adsorb to the hydrate surface and act via an interfacial mechanism.
研究领域:
化学工程
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Lubricants
·
2023
·Vol. 11
·期 6
·260
·
IF 3.5
Yong Li,Weidong Zhou,Wanan Xue,Yongwang Huang,Qiang Zhang,Jingbin Han
In this work, MgAl-layered double hydroxides (LDH) were synthesized by co-precipitation method using a colloid mill and characterized by XRD and SEM. It was found that the environmentally friendly LDHs had greater performance than the traditional antioxidant. By adding LDHs into large electric shovel grease (GRK-A) in open-pit coal mine, the service lifetime of grease was extended by 20%. With the increase in LDH addition, the grease sample attains greater activation energy, and the thermal oxidation and decomposition resistance become stronger. Comparing the energy storage modulus and flow transition index at different temperatures, adding the right amount of LDHs needs close attention for the system oxidation resistance and viscoelasticity. For the electric shovel grease, the best oxidation resistance and rheological properties can be achieved by adding 2% of LDHs. The rheological viscosity–temperature curves show that the grease samples with different ratios of solid LDHs have better low-temperature properties than the mine grease. This work outlines a simple method for creating an environmentally sustainable lubricant additive with the use of LDH. LDH serves as a novel inorganic antioxidant additive that is optimal for open gear lubrication and sliding friction.Keywords:layered double hydroxides;grease;antioxidant;oxidative induction time
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2018
·
IF 4.513
Hui-Bo Qin,Yi-Le Du,Yu Zhang,Xiao-Qin Wang,Zhen-Feng Sun,Chang-Yu Sun,Guang-Jin Chen,Lan-Ying Yang,Zhi Li
The toxicity of hydrate inhibitors used in the field has attracted more attention. A natural material, i.e. , whey protein, was assessed to act as kinetic hydrate inhibitors (KHIs) in a sapphire cell and an autoclave equipped with particle video microscope (PVM) and focused beam reflectance measurement (FBRM) probes. The pressure dropping method was utilized to estimate the hydrate induction time, and the results demonstrate that the hydrate inhibition performance of whey protein is superior to that of the commercial KHI, polyvinylpyrrolidone. The induction time for the pure water system was found to increase linearly with the increase in the dosage of whey protein until it reached approximately 2.5 wt%. As it is usually inevasible to apply KHIs under conditions of high water contents , the feasibility of whey protein as a KHI in the (oil + water) system with and without an emulsifier of Tween 20 was evaluated. A small amount of oil was found to have no obvious influence on the induction time for the system with whey protein under the circumstances without the addition of emulsifier. When Tween 20 was added, the induction time obviously increased under the same operating conditions, which could be attributed to the emulsifier–protein interactions in aqueous solutions. The oil drops decrease and are distributed more evenly with the increasing dosage of Tween 20 under the PVM and FBRM probes measurement. Additionally, the particles decrease during the hydrate formation process. This work presents a natural KHI and gives the inhibition discipline in a high-water-content system.
研究领域:
化学工程
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2013
·
IF 2.77
Xiaofeng Wang,Weiyi Xing,Gang Tang,Ningning Hong,Weizhao Hu,Jing Zhan,Lei Song,Wei Yang,Yuan Hu
A novel sulfur-bearing secondary antioxidant with a high molecular weight of 2252 (OS-POSS), successfully synthesized via photoinitiated thiol-ene click reaction, was compared with two commercial sulfur-bearing secondary antioxidants on the stabilization of polypropylene (PP). The results of their oxidation induction time (OIT) via differential scanning calorimeter measurement (DSC) showed that the higher the molecular weight of secondary antioxidant is, the longer the OIT value, whether such sulfur-bearing antioxidant is used singly or in combination with primary antioxidant. The study of their long-term accelerated thermal aging in the air oven at 150 °C displayed that the molecular structure of sulfur-bearing secondary antioxidant, besides molecular weight, is another highly important factor determining the antioxidant efficiency, i.e., physical loss of antioxidants with the relatively low molecular weight may determine antioxidant efficiency, whereas thioether groups having neighboring ester carbonyl moieties may decompose more hydroperoxides with quicker rate.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
Particuology
·
2023
·
IF 3.5
Yujie Song,Rongfei Ren,Min Su,Zhihan Liang,Qi Hao
Surfactants were used to assist crystallization of lysozyme. Three types of surfactants with different structures (sodium dodecyl sulfate, cetyltrimethyl ammonium bromide, or betaine hydrochloride (BH)) were used. The study indicated that three surfactants were all capable of shortening the crystallization induction time of lysozyme, with BH inducing the shortest crystallization induction time (t=1 min) and the largest crystal size (37 μm). The molecular interactions among each of the three surfactants abovementioned and lysozyme was also investigated by simulations. It was found that hydrogen bonding dominantly acted between the carboxyl structure of the surfactant BH and the lysozyme, which produced the most favorable conformation for the self-assembly of lysozyme (promote lysozyme orderly aggregation and shorten the crystallization induction time). On this basis, the mechanism of surfactant-promoted lysozyme crystallization was proposed.
研究领域:
生物化学
·
结构生物学
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产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2025
·
IF 5.2
Yongliang Xu,Yuanwei Huang,Lanyun Wang,Kun Zhang,Yao Li,Haidong Chen
The kinetic formation of CH 4 hydrates formation was investigated in the presence of [P 2444 ][PF 6 ], [P 4444 ][PF 6 ], [P 6444 ][PF 6 ], [P 4444 ]Br, [P 6444 ]Br and [P 12444 ]Br with concentrations of 0.25 wt%, 6.25 wt%, 10 wt% under the pressure of 4.0 and 5.0 MPa. The results show that [P 2444 ][PF 6 ], [P 4444 ][PF 6 ] and [P 6444 ][PF 6 ] increase the nucleation temperatures and shorten the induction time, where [P 4444 ][PF 6 ] improves the gas consumption and consumption rates of CH 4 hydrates. At the same time, [P 4444 ]Br, [P 6444 ]Br, and [P 12444 ]Br are unfavorable for increasing the nucleation temperature and shortening the induction time. This implies that [PF 6 ] − anion is more favorable for rapid nucleation than the Br − anion. However, in the presence of [P 4444 ]Br, [P 6444 ]Br and [P 12444 ]Br, the gas consumption was clearly enhanced, following an order of [P 12444 ]Br > [P 6444 ]Br > [P 4444 ]Br, indicating the superiority of long alkyl chains. The dissociation behaviors of CH 4 hydrates were also measured and the pre-dissociation time, dissociation temperature, and fast dissociation time were analyzed. It is found that [P 4444 ][PF 6 ] significantly enhanced the thermal stability of CH 4 hydrate due to a longer pre-dissociation time and a higher dissociation temperature. In contrast, ionic liquids with Br − anion exhibited the opposite effect. Despite having a greater ability to reabsorb CH 4 gas during the self-protection, [P 6444 ]Br and [P 12444 ]Br exhibit faster hydrate dissociation with larger gas-releasing amount compared to the symmetric [P 4444 ]Br and [P 4444 ][PF 6 ]. In general, [P 4444 ][PF 6 ] offers more advantages from the standpoint of safety regarding the storage and transportation of CH 4 hydrate.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION SCIENCE AND TECHNOLOGY
·
2019
·
IF 1.354
Airong Li,Dan Luo,Lele Jiang,Jie Wang,Yi Zhou
A series of experiments on CO2 hydrate formation were carried out in the presence of titanium dioxide (TiO2), silicon dioxide (SiO2), multi-walled carbon nanotubes (MWNTs) nanoparticles. The effects of these nanoparticles on induction time, final gas consumption, and gas storage capacity have been investigated at the temperature of 274.15 K and the initial pressure of 5.0 MPa.g. The induction time of CO2 hydrate formation was remarkably shortened to 12.5 min in the presence of 0.005 wt% MWNTs nanoparticles. The high thermal conductivity and heat capacity of MWNTs nanoparticles presented better heat transfer, and large surface area provided more suitable sites for heterogeneous nucleation of CO2 hydrate.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Lanyun Wang,Yongliang Xu,Kun Zhang,Yan Wang
Three kinds of porous metal foam , alumnium foam(AF), ion foam(IF) and copper foam(CF), were immersed into the aqueous phase, expecting to increase the equilibrium temperature, accelerate the CH 4 hydrates nucleation, reduce the induction time and enhance gas consumption. CF was verified to be an optimal porous medium for CH 4 hydrates due to its equilibrium temperature of 279.26 K with an induction time of 66 min around 5.0 MPa, and the accelerated gas consuming rate, showing an excellent thermodynamic-kinetic dual promotion ability. In order to enhance CH 4 consumption, 0.3 wt% leucine was added as a kinetic promoter, increasing the CH 4 consumption to be around 0.15 mol per mole of water, nearly 3–4 times more than that of pure water and those without leucine.
研究领域:
化学工程
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材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2022
·Vol. 24
·期 45
·27900-27907
·
IF 3.945
Shan Xue,Shun-Li Chen,Qunhui Yuan,Wei Gan
The catalytic reduction of aromatic nitro compounds by metallic nanoparticles in the presence of sodium borohydride (NaBH4) has been widely studied as model reactions. However, the reaction mechanisms still need further investigations. For example, the origin of the induction time that has often been observed is still controversial. Here, we demonstrated that such catalytic reduction reactions on the surface of colloidal gold nanoparticles (AuNPs) may be inspected by the second-harmonic generation (SHG) and two-photon luminescence (TPL) emission from AuNPs. It was revealed that the SHG and TPL signals from AuNPs were sensitive to the substitution of citrate by active hydride species derived from the hydrolysis of NaBH4. Based on the UV-vis spectroscopy analyses and monitoring the SHG/TPL signals, the induction time in the catalytic reaction of 4-nitrothiophenol was revealed to originate from the hindered adsorption of hydride on the gold surface. This work demonstrated that SHG and TPL can provide a new approach for detecting active hydrides on the surface of metallic nanoparticles in colloids.
研究领域:
化学
·
纳米科技
·
光学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2017
·
IF 3.671
Kai Chen,Dezhan Ye,Shaojin Gu,Yingshan Zhou
Which factors are crucial to improving lignin antioxidant ability in polymers has been debated over years. Here, the structural effect of natural antioxidant from technical Kraft lignin (KL) on the oxidation induction time (OIT) of KL/polypropylene (PP) was quantitatively investigated using correlation analysis model instead of traditional linear fitting model. The correlation coefficient and significance value of their relationship clearly demonstrated the dominating role of non-condensed Phenolic OH (Ph-OH) in improving KL/PP thermal-oxidation stability, subsequently followed by M ¯ n , aliphatic OH/total Ph-OH, condensed Ph-OH and polydispersity. OIT is positive with non-condensed and total Ph-OH, while it declines with increase of the above other factors. Remarkably, the longest OIT (∼90 min) was obtained even at extreme loading (0.5 wt%), almost ∼911% and ∼201% huge increase in contrast to that of pure PP and crude KL/PP composite, respectively. Meanwhile, the mechanical properties of KL fractions/PP blends can be maintained at the same or better level than that of pure PP, due to strong interfacial adhesion strength.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY
·
2021
·Vol. 98
·期 6
·673-682
·
IF 1.849
Changqing Miao,Yanbo Wang,Zhiying Ma,Yang Luo,Yu Miao,Pingfang Yuan,Jiao Guo,Gairong Chen,Hongbo Liu
In this study, poly( p- phenylenediamine) (PPDA) was synthesized by an enzymatic polymerization method using p- phenylenediamine as the monomer in the water phase. The PPDA structure was characterized by infrared (IR), gel permeation chromatography, and elemental analysis. The antioxidation behavior of the as-synthesized PPDA in biodegradable castor oil was investigated using a rotary oxygen bomb test and pressurized differential scanning calorimetry. A theoretical calculation was conducted to investigate its antioxidation mechanism. PPDA was found to exhibit excellent oxidation resistance in castor oil at 150 °C, which effectively prolonged the oxidation induction time of the oil. The results obtained herein suggest that as with phenolic antioxidants, PPDA with a hindered structure effectively improves the antioxidation performance of the oil by enhancing the stability of nitrogen free radicals.
研究领域:
材料科学
·
生物化学
✓ 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）