APPLIED ENERGY
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2020
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IF 8.848
J. Yan,Z.H. Pan,C.Y. Zhao
Thermochemical heat storage uses a reversible chemical reaction to store thermal energy. This thermal energy storage method has high energy density and allows long-term thermal energy storage. MgO/Mg(OH) 2 is a promising reversible reaction for thermochemical heat storage systems. The performance of this reversible reaction inside a reactor plays a key role in its practical applications. The direct type heat transfer reactor is a novel design compared with an indirect powder bed reactor. It allows the gaseous heat transfer fluid to flow through the powder in order to break the heat transfer limitation from the heat exchanger between the MgO/Mg(OH) 2 powder and the heat transfer fluid. In this study, we evaluated the performance of a direct type MgO/Mg(OH) 2 reactor under various operating conditions. Parametric analyses indicated that the heat output is limited by the reaction rate rather than the heat transfer efficiency. Results also showed the best bed thickness in order to achieve the highest temperature output. Material characterization indicated that the MgO/Mg(OH) 2 particles did not agglomerate with each other after 15 heat charging and discharging cycles.
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SURFACE & COATINGS TECHNOLOGY
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2020
·
IF 3.784
Hanaa Soliman,Junyu Qian,Shuai Tang,Peng xian,Yingqi Chen,Abdel-Salam Makhlouf,Guojiang Wan
The polymerized Hydroxyquinoline (HQ) coatings incorporated with corrosion inhibitor nano-Graphene Oxide (GO) particles were fabricated on treated magnesium AZ31 alloy. The effect of surface treatment of AZ31 using either oxidation or phosphating was much more effective than GO embedment on the corrosion resistance and self-healing functionality. Surface treatment prior to GO/HQ deposition plays a vital role in initiating more anchoring bonds between molecules to fasten any scratch healing. The anticorrosion behavior of the GO/HQ hybrid coating will be discussed in the light of SEM, XRD , XPS and FTIR analysis.
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CLAYS AND CLAY MINERALS
·
2021
·Vol. 69
·期 4
·434-442
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IF 1.609
Zhang Mingzhu,Sun Shiyong,Lv Rui,Golubev Yevgeny Aleksandrovich,Wang Ke,Dong Faqin,Kotova Olga Borisovna,Kotova Elena Leonidovna
Lipase is an industrial enzyme, the catalytic efficiency of which is restricted by various environmental factors. To improve this efficiency, immobilization technology has been utilized in the past to improve the stability of lipase in harsh conditions. Immobilization technology can be divided into physical methods and chemical methods. Some unsolved problems remain in current immobilization technology. The interaction between enzyme and immobilization support is weak and reversible during physical adsorption, resulting in poor stability of the immobilized enzyme and the contamination of substrate solution by leached enzymes. In chemical methods, enzyme-active sites might be inactivated due to the chemical reactions between enzyme molecules and support, resulting in a decrease in the enzymes’ catalytic activity (Liu et al., 2018a ). The objective of the current study was to construct a nanostructured lipase via Mg-amino-clay as a carrier and improve the catalytic activity and stability of lipase by immobilization. Lipase produced by Aspergillus oryzae was immobilized on aminopropyl functionalized magnesium phyllosilicate (a 2:1 trioctahedral talc-like silicate Mg-amino-clay) via a 1-(3-Dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride (EDC) coupling agent. The physical and chemical properties of the Mg-amino-clay and Mg-amino-clay-based nanostructured biocatalyst (Mg-clay-lipase) were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Optimal immobilization conditions were determined by taking into account the following variables: amount of initial lipase, EDC concentration, and reaction time. The results revealed that the optimum temperature, pH, and thermal stability of Mg-clay-lipase were greater than equivalent values for free lipase under optimal conditions (described below – Process for Immobilization of Lipase on Mg-amino-clay ). The Michaelis-Menten constant (K m ) values were 5.25 mM and 7.42 mM while the maximum reaction rates ( v max ) were 30.58 mM/(L·min) and 55.87 mM/(L·min) for free lipase and Mg-clay-lipase, respectively. The present study provided a new nanostructured biocatalyst and demonstrated that the enzyme activity and stability of Mg-clay-lipase were superior to those of free lipase due to the mechanism of 'interface activation'.
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CHEMOSPHERE
·
2021
·
IF 7.086
Fang Zhu,Siyi Zhou,Mengying Sun,Jianfeng Ma,Wei Zhang,Kunjie Li,Hao Cheng,Sridhar Komarneni
Mg doped Ni(OH) 2 was synthesized and investigated as an efficient material to activate persulfate (PS) for phenol degradation. The property of the Ni(OH) 2 material was enhanced by Mg doping as the removal efficiency of phenol was increased from 74.82 % in Ni(OH) 2 /PS system to 89.53 % in Mg-doped Ni(OH) 2 /PS system within 20 min. Such a high removal efficiency revealed that doping Mg into Ni(OH) 2 brings about more defects (oxygen vacancies), which facilitated the formation of more active species in the degradation process. The removal efficiencies of phenol increased with the increase of the initial pH from 3 to 11. The influences of Cl − , NO 3 − and HCO 3 − on the stability of the system were also studied and the results showed that removal rates of all systems in the presence of these different inorganic anions could reached about 90 % within 20 min. Based on the electron spin resonance (ESR) experiments, 1 O 2 , O 2 ·- , ·OH and SO 4 •− were identified as the active species in Mg-doped Ni(OH) 2 /PS system for phenol degradation and a degradation mechanism was proposed for this system. In addition, the as-prepared material retained its activation performance even after 3 repeated cycles.
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PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2021
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IF 4.527
Bin Xiao,Gang Wu,Tongde Wang,Zhengang Wei,Yanwei Sui,Baolong Shen,Jiqiu Qi,Fuxiang Wei,Qingkun Meng,Yaojian Ren,Xiaolan Xue,Junchao Zheng,Jing Mao,Kehua Dai
High entropy oxides (HEOs) have attracted the attention of researchers due to their high theoretical specific capacity and structural stability. However, the effect of elements in HEOs on material properties is unknown. In this work, HEOs (FeNiCrMnZn) 3 O 4 and (FeNiCrMnMg) 3 O 4 were successfully synthesized and used as anode materials for lithium ion batteries . The effects of Zn and Mg on the properties of HEOs were studied from the aspects of crystal structure, micro morphology, and surface valence. Results show that Zn enhances the lithium storage performance of HEOs theoretically, which is verified in the later electrochemical performance tests. (FeNiCrMnZn) 3 O 4 is better than (FeNiCrMnMg) 3 O 4 in all aspects of rate properties, cycle performance, and electrochemical impedance spectroscopy . Therefore, the introduction of electrochemically active metals, such as Zn, can improve the performance of HEOs, thereby providing ideas for the subsequent design and application of HEOs.
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Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 24
·14629-14637
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IF 10.733
Chong Lu,Yanling Ma,Fan Li,Hong Zhu,Xiaoqin Zeng,Wenjiang Ding,Tao Deng,Jianbo Wu,Jianxin Zou
A core–shell nanostructured Mg@Pt composite, consisting many of icosahedral Mg particles as the core with nano-sized Pt particles distributed homogeneously on different surfaces, was synthesized through an arc plasma method followed by the generic solid-state method. The microstructures and hydrogen sorption properties of the Mg@Pt composite were carefully investigated and compared to that of pure Mg powder. In particular, the dehydrogenation behaviors of the hydrogenated Mg@Pt composite were observed in situ via high-resolution transmission electron microscopy (HRTEM). The results revealed that the Pt on Mg particles showed a “spillover” effect to improve the hydrogen absorption kinetics in the early stage. It then transformed into H-stabilized Mg3Pt, followed by the formation of MgH2. DFT calculation and in situ TEM observations demonstrated that the H-stabilized Mg3Pt acted as a “hydrogen pump” for the dehydrogenation of MgH2 and then transformed into Pt after desorption. Through this effect, the dehydriding kinetics of the hydrogenated Mg@Pt composite was improved and the onset dehydrogenation temperature was reduced compared to that of the pure MgH2 powder.
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APPLIED SURFACE SCIENCE
·
2018
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IF 4.439
Zhiqiang Qian,Shidong Wang,Xiushen Ye,Zhong Liu,Zhijian Wu
A spraying method has been employed to prepare silica-based superhydrophobic coatings on AZ31B Mg alloy surfaces. Both nanometer and micrometer silica particles were used to construct the micrometer and nanometer scale binary structures, and 1H, 1H, 2H, 2H-Perfluorooctyltriethoxysilane (PFOTES) was used as the fluorine silane coupling agent. The coatings were characterized using the techniques of Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectra. The corrosion resistance properties of the prepared superhydrophobic surfaces were checked based on polarization curves. And their wetting properties were studied for aqueous solutions of HCl, NaOH, NaCl, MgCl 2 , NaI, CH 3 COONa, C 2 H 5 OH, C 17 H 33 COONa, and sodium dodecylbenzene sulfonate, respectively, with contact angle and sliding angle as the parameters. In contrast with the bare magnesium alloy AZ31B, after coating, the corrosion current density shows a more than three-order of magnitude smaller value, and the water contact angle increases from ∼32° to over 155°. Solution pH and coexisted NaCl, MgCl 2 , NaI, and CH 3 COONa salts have little effect on the wetting properties of the prepared superhydrophobic surfaces. On the contrary, coexisted C 2 H 5 OH, C 17 H 33 COONa, or sodium dodecylbenzene sulfonate has an obvious effect on the wetting properties. The differences in the wetting properties were explained by considering the interactions between the superhydrophobic surfaces and the surfaces of the solution droplets. In addition, the superhydrophobicity coating also exhibited good mechanical, chemical and environment stability in the abrasion test, immersion test, salt spray test, etc.
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MATERIALS LETTERS
·
2015
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IF 2.489
Zhang Leilei,Li Hejun,Li Kezhi,Liu Shoujie,Zhang Yulei,Yao Pei,Zhang Wenqi,Chen Guanzheng
A multi-layer coating composed of SiC inner-layer and Mg and F co-substituted hydroxyapatite/chitosan hybrid out-layer for carbon fibers has been synthesized using a combination method of chemical vapor deposition , electrochemical deposition and ion exchange method. The morphology, microstructure and in-vitro bioactivity of the multi-layer coating are analyzed. The results show that the SiC inner-layer exhibits a squamous shape. Mg and F co-substituted hydroxyapatite/chitosan hybrid out-layer covers the SiC inner-layer coated carbon fiber entirely and uniformly with a flat structure. The multi-layer coating could induce the precipitation of particle-shaped apatite crystals with Ca/P molar ratios of 1.34–1.51 on its surface in simulated body fluid. The multi-layer SiC/Mg and F co-substituted hydroxyapatite/chitosan coated carbon fibers should have potential application for tissue engineering.
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高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
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2014
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IF 2.063
Ran-ran Shan,Liang-guo Yan,Yan-ming Yang,Kun Yang,Shu-jun Yu,Hai-qin Yu,Bao-cun Zhu,Bin Du
The Mg–Al-CO 3 -LDH with Mg 2+ /Al 3+ molar ratio of 2 was prepared via coprecipitation method at constant pH of 9–10 and used to remove three red dyes by batch adsorption method. The results showed the Mg–Al-LDH were well crystallized and can adsorb the red dyes effectively. The optimal adsorbent dosage and contact time were 1.0 g and 60 min, respectively. Adsorbed amount hardly changed when pH < 10. The adsorption kinetics fit the pseudo-second order kinetic models well and isotherms correspond to Langmuir model strictly. All the relevant mechanisms were studied and manifested as anion exchange and also electrostatic attraction for CR.
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JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2013
·Vol. 51
·期 16
·3328-3332
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IF 3.543
Hou Chen,Gaojian Lv,Ying Liang,Jinming Sun
High performance polyacrylonitrile (PAN) was prepared with Mg powder as both reducing agent (RA) and supplemental activator (SA) by single electron transfer-living radical polymerization (RASA SET-LRP). First-order kinetics of polymerization with respect to monomer concentration, linear increase of molecular weight, and narrow polydispersity with monomer conversion, and the obtained high isotacticity PAN indicate that RASA SET-LRP in the presence of Mg powder could simultaneously control molecular weight and tacticity of PAN. compared with that obtained with ascorbic acid (VC) as RA, an obvious increase in isotacticity of PAN was observed. the block copolymer pan- b -pAN with molecular weight at 112,460, polydispersity at 1.33, and isotacticity at 0.314 was successfully prepared. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51 , 3328–3332
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ACS Omega
·
2016
·
IF 0
Zhiyi Wu,Qiangqiang Zhu,Chun Shen,Tianwei Tan
Aimed at the green synthesis of supported noble metal nanoparticles without any additional reducing agents or stabilizers at room temperature, a new strategy in which monodispersed Pd nanoparticles were successfully immobilized on Mg–Al mixed metal oxides derived from layered double hydroxides was developed, and the reduction mechanism was also proposed. It allowed the in situ immobilization of monodispersed Pd nanoparticles with a face-centered cubic structure, using only alcohols with α-hydrogen atom as the solvent and reducing agent. Control over the mean particle size and content of Pd nanoparticles was realized by adjusting the temperature, initial concentration, and type of alcohol. With the content of Pd varied from 6.4 to 42.3 mg/g, the mean particle size of Pd increased from 1.1 to 4.9 nm. The as-prepared catalyst showed high catalytic activity for oxidation of benzyl alcohol: when the Pd content was 6.4 mg/g, conversion of 60.3% and selectivity of 99.2% were obtained with a turnover frequency of 4807 h–1. Similarly, on the basis of the high stand electrode potentials, immobilized Ag (5.6 nm) and Au (4.7 nm) nanoparticles were also prepared through this methodology. Moreover, the choice of supports was extended to other powder supports that would react with the byproduced acid. Overall, this facile method opens up new opportunities for controllable synthesis of supported nanoparticle catalysts in a green way.
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PubMed
Progress in Natural Science-Materials International
·
2017
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IF 2.038
Xuezhang Xiao,Teng Qin,Yiqun Jiang,Fulei Jiang,Meng Li,Xiulin Fan,Shouquan Li,Hongwei Ge,Qidong Wang,Lixin Chen
Mg(AlH 4 ) 2 nanoparticles with a particle size less than 10 nm have been successfully synthesized by mechanochemical method using LiAlH 4 and MgCl 2 as raw materials together with LiCl buffering additive. In comparison to Mg(AlH 4 ) 2 microparticles, Mg(AlH 4 ) 2 nanoparticles exhibit a faster hydrogen desorption kinetics and lower desorption temperature. The hydrogen desorption temperatures of the first and second dehydrogenation steps are 80 and 220 °C for the Mg(AlH 4 ) 2 nanoparticles, which are about 65 and 60 °C, respectively, lower than those of Mg(AlH 4 ) 2 microparticles. The decomposition activation energy is reduced from 135 kJ/mol for Mg(AlH 4 ) 2 microparticles to 105.3 kJ/mol for Mg(AlH 4 ) 2 nanoparticles. It is proposed that the shortened diffusion distance and enhanced diffusivity of Mg(AlH 4 ) 2 /MgH 2 nanoparticles provide an energy destabilization for lowering the dehydrogenation temperature, and thus being the key factor for promoting the hydrogen desorption kinetics. More importantly, it is demonstrated that the dehydrided nano MgH 2 hydride with a particle size below 10 nm can be formed after rehydrogenation process, resulting in the good cycling hydrogen desorption performance of nano MgH 2 .
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