SOLAR ENERGY
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2022
·
IF 7.188
J. Yan,B.W. Yang,C.Y. Zhao
Thermochemical energy storage (TCES) is a promising energy storage method because of its high energy storage density and long-term storage ability. The reactor is the most critical part of the TCES system, and the fluidized bed reactor (FBR) is a novel reactor, which is not restricted by the low effective thermal conductivity of energy storage materials. However, there is little theoretical guidance about the design and operation of the FBR for a TCES system. In this study, we investigated the performance of an FBR using MgO/Mg(OH) 2 as reaction materials by establishing a numerical model followed by experimental validation. The influence of operating parameters on the bed temperature was discussed based on numerical results. According to the sensitivity analysis, the reactor inner diameter, material mass, and inlet gas velocity were the main factors affecting the bed temperature. The optimal boundary surface temperature was analyzed, which influences the proportion of TCES in the total heat storage.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Ying Zhang,Pei Sun,Zak Fang,Shili Zheng,Xiaofang Zhu
Deoxygenation is in high demand in the titanium industry. This research was carried out to experimentally determine the oxygen removal limits by the novel hydrogen-assisted Mg deoxygenation method. Spherical Ti and Ti-6Al-4V (or TC4, Ti64) powders with around 2.2 wt% oxygen were prepared for the deoxygenation research. The deoxygenation kinetics were modeled based on a non-steady-state radial diffusion. The results show that in the β phase region, the time to reach the equilibrium is slightly affected by the initial oxygen content in titanium, but is strongly influenced by the particle size. The reliance of the equilibrium duration on the diffusion coefficient is stronger when the particle size is larger. Guided by the kinetic prediction, deoxygenation experiments were carried out. Under a 1 atm pure H 2 atmosphere, the deoxygenation limits by Mg for pure Ti are 252 ppm at 700 °C, 289 ppm at 750 °C, and 554 ppm at 800 °C, and for TC4 are 296 ppm at 750 °C, 371 ppm at 800 °C, and 743 ppm at 850 °C, consistent with the thermodynamics that a lower temperature possesses a more potent driving force for deoxygenation. These data have clearly demonstrated the strong deoxygenation capability of the hydrogen-assisted Mg deoxygenation method.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Yuanyuan Yang,Xiaofei Tan,Eydhah Almatrafi,Shujing Ye,Biao Song,Qiang Chen,Hailan Yang,Qianmin Fu,Yuanyuan Deng,Zhuotong Zeng,Guangming Zeng
Polluted stormwater (PSW) treatment is becoming increasingly important because of the existence of multiple pollutants from non-point pollution sources. Alfalfa biochar loaded with Mg/Fe layered double hydroxide (AF-LDH) was successfully synthesized to remove trace metal(loid)s from stormwater. The adsorption kinetics and isotherms of metal(loid)s in a mono-component system and the reusability of the composite materials was investigated in this study. The result showed that the maximum removal efficiency for Pb(II), Cu(II), Zn(II), Cd(II), As(V), and Cr(VI) were 98.98 %, 98.11 %, 97.88 %, 97.71 %, 98.81 %, and 50.89 %, respectively, when added calcined AF-LDH (AF-LDO) composite material to the multi-component solution. The AF-LDH and AF-LDO could efficiently remove trace pollutants (10‐100 μg/L) from multi-component solution, especially for AF-LDO, which could completely remove the tested six trace metal(loid)s. Furthermore, Fourier transform infrared spectra and X-ray diffraction characterizations supported the Mg/Fe layered double hydroxide reconstruction. The main mechanisms of Pb(II), Cu(II), Zn(II), and Cd(II) (cationic metals) removal were ion exchange and surface precipitation, whereas As(V) and Cr(VI) (anionic metals) were mainly dislodged through the formation of surface complexation, electrostatic attraction, and interlayer anion exchange, concerning the –OH and –COOH of AF-LDH. Importantly, the results of the column experiment demonstrated that AF-LDO was superior to AF-LDH for anionic metal removal from stormwater. In this study, we synthesized AF-LDH and AF-LDO for trace metal(loid) removal and proposed a new and practical approach for stormwater purification.
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Journal of Cleaner Production
·
2021
·
IF 9.297
Weiye Wang,Qingliang Zhao,Jing Ding,Kun Wang,Junqiu Jiang
Bio-electro-Fenton powered by microbial fuel cell (MFC-powered BEF) can in-situ generate and utilize hydrogen peroxide to degrade refractory pollutants. Most of the previous works loaded transition metal on the cathode to participate in the Fenton reaction showed limited electrical or degradation performance. The coupling of alkaline-earth metal (Mg 0 and MgO) and transition metal on cathode could improve the electrochemical and catalytic properties of MFC-powered BEF system, which had not been reported so far. In this research, a novel cathode of Fe–Mn–Mg/carbon fiber (Fe–Mn–Mg/CF) was developed with good polymerization effect of Mg to Fe and Mn, and outstanding production of reactive oxide species (•OH and •O 2 − ), which further improved the overall electricity generation efficiency and enhanced the degradation of pollutants. Accordingly, the maximum power density generated in MFC-powered BEF system with Fe–Mn–Mg/CF cathode was 2.07 times higher than that of the frequently used Fe–Mn/CF. Owing to the superiority of surface holes and MgO in H + adsorption and electron transfer , the integration of Fe, Mn with Mg promoted the in-situ generation of H 2 O 2 and active radicals, resulting in the highest catalytic performance of degrading refractory pollutants . Initial pH, external resistance, initial concentration of contaminant and cycle use frequency of cathode were also evaluated on the degradation efficiency of the BEF system. Furthermore, reaction and degradation mechanisms were proposed from H 2 O 2 production and free radical characterization. Overall, this study provided a novel cathode preparation approach for the MFC-powered BEF system, which vastly promoted its electrochemical and catalytic properties.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Yanqiu Li,Yuejun Ouyang,Rui Fang,Xiao Jiang,Zhi-Hui Xie,Liang Wu,Jilan Long,Chuan-Jian Zhong
To obtain high corrosion protection and break the bottleneck arising from galvanic corrosion between Ni layer and Mg alloy substrate, we report herein a triple-layer composite coating approach, consisting of Ni (ENP) underlayer, NiAl-layered double hydroxide (LDH) middle layer, and silane (PFDTMS) toplayer, i.e., ENP/LDH/PFDTMS. This nanocomposite coating was prepared on the Mg alloy surface by a combination of simple electroless plating, hydrothermal-assisted in situ growth, and condensation reaction. The surface morphology, structure, and chemical composition of the resulting composite coating are characterized using several techniques, including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The corrosion protection performance of the composite coating in a saline solution is evaluated by electrochemical impedance spectroscopy (EIS), Tafel curve, and immersion measurements. The results indicated that the ENP/LDH/PFDTMS composite coating possesses a much higher corrosion resistance than the single Ni coating and the LDH-grown Ni (ENP/LDH) coating. In contrast to the severe galvanic corrosion the Mg alloy with single Ni coating observed in two days of exposure, the substrate with either ENP/LDH/PFDTMS coating or ENP/LDH coating is shown to exbibit no galvanic corrosion phenomenon even after 30 days of exposure. Moreover, the result from tests including contact angle measurement of the ENP/DLH/PFDTMS coating demonstrates the superhydrophobic function to several typical liquids in daily life and the good self-cleaning capability after contamination by graphite powder. These findings provide a fresh insight into the design of advanced coatings for inhibiting galvanic corrosion between Ni layer and Mg alloy.
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Journal of Energy Chemistry
·
2021
·
IF 9.676
Zhiguo Zhu,Xiongjie Gao,Xiuming Wang,Mengdie Yin,Qingyao Wang,Wanzhong Ren,Bo Wang,Hongying Lü,Weiping Liao
The selective aerobic oxidation of biomass-derived 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid (FDCA, a potential renewable substitution of fossil-based terephthalic acid to produce polyethylene 2,5-furandicarboxylate plastic) is an appealing transformation for constructing eco-friendly and sustainable chemical processes. Au supported catalysts have showed encouraging performances for this well-received conversion, whose catalytic behavior was greatly affected by the adopted support derived from the existence of metal-support interactions. Herein, a series of Mg-Beta zeolites were hydrothermally synthesized via developed structural reconstruction, which were employed as basic supports for Au catalysts to construct bifunctional catalysts. The relationship between structure (Au particle size, basicity within zeolites and Au δ+ contents) and FDCA yield was concretely established. The conclusion was made that the utilization of Mg-Beta zeolites with strong basicity as the support could not only improve the FDCA yield but also decrease the amount of additional base. Furthermore, the possible reaction mechanism was also proposed via tracking time-dependent variations of corresponding organics and controlled experiment. This work provides some guidance for rationally designing multifunctional catalysts in the view of integrating metal catalysts with metallosilicate zeolites, which was beneficial to the catalytic upgrading of organic compounds with multiple functional groups.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Xiaomeng Zhang,Yang Zong,Longqian Xu,Yunfeng Mao,Deli Wu
Abiotic humification can be facilitated by iron-containing minerals or oxides, but most studies have focused on well-crystallized and stable iron phases, the catalytic effect of which is generally unremarkable. In the present study, we report an enhanced abiotic integrated polyphenol-Maillard humification reaction catalysed by Mg/Fe-layered double hydroxide (Mg/Fe-LDH) with high surface reactivity. The results demonstrated that Mg/Fe-LDH could effectively promote the humification reaction at a lower dosage compared with Fe 2 O 3 . As an iron-chelating ligand, catechol rapidly induced iron dissolution from Mg/Fe-LDH through the formation of an Fe(III)-catechol complex, which strengthened the catalytic effect of Fe(III). The photochemical behaviour of Fe(III)-catechol complex and its impact on the Fe(III)-catalysed humification process were investigated. Under light irradiation, environmentally persistent free radicals (EPFRs) originated from the Fe(III)-catechol complex were formed and stabilized in the presence of Mg/Fe-LDH particles, which inhibited the oxidation of catechol and the humification process. Hence, the formation of humic substances (HS) catalysed by Mg/Fe-LDH was more efficient under darkness. Iron redox cycling and generation of reactive oxygen species (ROS), HO• and O 2 •- , were also involved. According to transformation products (TPs) analysis, ortho -aminophenol was proposed to be a key product in the humification reaction. Self-coupling of catechol radical and ortho -aminophenol radical, ring cleavage were likely to occur in the Fe(III)-catalysed humification process. Higher relative abundance of CHO products was observed in the presence of Mg/Fe-LDH by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), suggesting that iron is effective on promoting C–C bonds formation. The above results provide more comprehensive insights into Fe(III)-catalysed humification and a guidance to improve the efficiency of HS formation and carbon sequestration in organic wastes utilization.
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Journal of Magnesium and Alloys
·
2021
·
IF 10.088
Baojing Feng,Guonan Liu,Peixu Yang,Sensen Huang,Dongqing Qi,Peng Chen,Chengduo Wang,Jiang Du,Shaojun Zhang,Jinhui Liu
Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy, was investigated in 0.6 M NaCl solution and 0.6 M Na 2 SO 4 solution by scanning electron microscopy (SEM) observations, scanning Kelvin probe force microscopy (SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na 2 SO 4 solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na 2 SO 4 solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.
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ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Xiaojuan Zhang,Edouard Asselin,Zhibao Li
The precipitation of CaCO3 and its kinetics for the CaCl2–CO2–Mg(OH)2–H2O system were systematically studied to develop a novel process for eliminating solid and liquid waste from the Solvay soda process. The effects of operating conditions including temperature, CaCl2 concentration, flow rate of CO2, and stirring speed on the reaction kinetics were experimentally determined. The results revealed that low temperature, high CO2 flow rate, and fast stirring speed can accelerate the reaction rate, and the mass transfer of CO2 is the controlling step. An MSMPR crystallizer was used to obtain the experimental crystal size distribution (CSD). A simplified population balance equation (PBE) was used to correlate the parameters on the basis of supersaturation. The soda solid and liquid wastes discharged from the Solvay industry were used as raw material to test the new process and validate the methodology. The precipitated CaCO3 consists of calcite or aragonite with high purity and uniform CSD. A double-effect evaporative-cooling crystallization process to recover MgCl2·6H2O and NaCl was simulated with help of Aspen plus and the electrolyte-NRTL (ELENRTL) model, suggesting economic benefits.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Mengying Sun,Yu Lei,Hao Cheng,Jianfeng Ma,Yong Qin,Yong Kong,Sridhar Komarneni
Mg doped CuO–Fe 2 O 3 composites were hydrothermally synthesized and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy . Mg doping improved the catalytic performance of CuO–Fe 2 O 3 for phenol degradation as the removal efficiency of phenol (33 mg/L) reached up to 84.36% within 45 min using 3.2% Mg doped CuO–Fe 2 O 3 when coupled with persulfate (PS) system. The results revealed that Mg doping generated more defects (oxygen vacancies), which result in the generation of more active species during the degradation process. The influence of catalysts and PS dosages were investigated to obtain the optimum conditions. The effects of pH and dissolved oxygen were also evaluated. Increase of solution pH was found to be beneficial for the removal of phenol because of reduced copper leaching at higher pH. However, decrease in dissolved oxygen concentration retarded the degradation of phenol because of the reduced production of O 2 • - . Based on the quenching experiments and ESR experiments, 1 O 2 , O 2 • - , ·OH and ·SO 4 − were confirmed as the active species in the phenol degradation process and a phenol degradation pathway was proposed. Other contaminants such as nitrobenzene (NB), P-nitrophenol (PNP) and P-Chlorophenol (4-CP) could also be removed to some extent using the present catalyst system.
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POLYMER TESTING
·
2020
·
IF 3.275
Tongyi Wu,Xuejun Lai,Hongqiang Li,Yishen Chen,Yanlin Wang,Tian Liu,Xingrong Zeng
It is of great significance and challenge to efficiently improve the tracking and erosion resistance of silicone rubber along with the growing requirements in the field of outdoor high voltage insulation. In this work, we herein proposed an effective way to address this issue by incorporating vinyltriethoxysilane (ViTES) and layered Mg–Al double hydroxide (LDH) into high temperature vulcanized silicone rubber (HTVSR). ViTES/LDH notably enhanced the tracking and erosion resistance of HTVSR. With addition of 3.33 phr ViTES and 5.00 phr LDH, the anti-tracking performance of HTVSR reached the 1A 4.5 level, and the eroded mass was merely 0.3%. The results of scanning electron microscopy and equilibrium swelling showed that ViTES substantially improved the interfacial interaction between HTVSR and LDH and the crosslinking density of HTVSR, and enhanced the dispersion of LDH sheets in the HTVSR matrix. The possible synergistic suppression mechanism of ViTES/LDH on the tracking and erosion of HTVSR was further studied and demonstrated by the plasma irradiation analysis, thermogravimetry and thermogravimetry-Fourier transform infrared spectrometry. It was indicated that under the high voltage arcing discharge, LDH facilitated the formation of a dense barrier layer consisting of bimetal mixed oxides on the HTVSR surface, exerting outstanding lamellar barrier effect. The further degradation and the generation as well as development of electrical tracking were efficiently suppressed. Our findings provided a new approach to fabricate silicone rubber with excellent tracking and erosion resistance.
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JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2019
·Vol. 19
·期 11
·7169-7177
·
IF 1.093
Qin Zhuozhuo,Liu Wenxia,Chen Huabin,Chen Jun,Li Zhenzhen
Developing full-spectrum photocatalysts that harvests solar light from ultraviolet to near-infrared light has aroused great interest in photodegradation of organic pollutants, due to the imminent energy crisis and growing pollution issues. Herein, we report an excellent full-spectrum
photocatalyst derived from calcination of an Mg/Zn/Al/Er-hydrotalcite-like compound. The photocatalyst is a stable multi-phase oxide consisting of various syntrophic Er3+-doped metal oxides with different particle sizes and morphology. Its ultraviolet (UV) photocatalytic activity
is maximized by increasing the fraction of Zn2+ and sustaining the pure hydrotalcite-like phase with an appropriate fraction of Mg2+ in preparing the Mg/Zn/Al/Er-hydrotalcite-like precursor. The visible and NIR photocatalytic activities are triggered by an indirect excitation
involving an up-conversion process. The major active species of the photocatalyst in the photodegradation of methyl orange are superoxide anions and photogenerated holes. Nevertheless, hydroxyl radicals also play a moderate role in the photodegradation process. This work finds a new way to
prepare full-spectrum photocatalysts with tunable chemical compositions via an environmentally friendly hydrotalcite-like precursor.
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