Environmental Science-Water Research & Technology
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2020
·Vol. 7
·期 3
·479-486
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IF 3.449
Zhiwei Yang,Xiaonan Tan,Daojian Tang,Jing Li,Jiahai Ma
In this study, the contrasting activities and pathways of Mn2+/Cu2+–HCO3− systems for Congo red (CR) dye degradation are presented. The Mn2+–HCO3− system (with the well-known MnIVO as the reactive species) did not degrade CR, while the Cu2+–HCO3− system (with high-valent Cu proposed as the reactive species) had a good oxidizing ability for CR. Further, HO radicals in the classic Fenton-like system made no contribution to CR degradation with both Cu and Fe ions as catalysts. The results indicate that reactive species in metal–HCO3− AOPs need prudent examination and better understanding of the underlying mechanism would benefit the development of more efficient AOPs.
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Arabian Journal of Chemistry
·
2020
·
IF 4.762
Jiayao Li,Weifeng Song,Zefeng Yu,Qiuhua Li
The quality of dairy farming wastewater in different regions is particular and different. In Southern China, the Chemical Oxygen Demand (COD Cr ) and colourity of effluent from conventional dairy farming wastewater treatment processes are similar. Catalytic ozonation is a very promising technical method. In this paper, the Mn-Fe-Ce/γ-Al 2 O 3 catalyst was prepared via the optimized preparation method of impregnation roasting using γ-Al 2 O 3 as the carrier, and this catalyst was used in the ozonation of actual dairy farming wastewater from treatment facilities. The performance of the Mn-Fe-Ce/γ-Al 2 O 3 catalyst on dairy farming wastewater was investigated using a simulated dynamic test. The effects of the reaction time, pH and catalyst dosage on COD Cr and the colourity removal ratio were investigated. The results show that the optimum treatment conditions were a reaction time of 20 min, pH 9, and catalyst dosage of 15 g/L. The COD Cr removal ratio reached 48.9% and the colourity was 95% under the optimum conditions. BOD 5 /COD Cr increased from 0.21 to 0.54 after catalytic ozonation, indicating that the biodegradability of wastewater was significantly improved. This research provides a new method and theoretical guidance for dairy farming wastewater treatment.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Zhiqun Xie,Zhiping Lyu,Jinnan Wang,Aimin Li,Philippe François-Xavier Corvini
Ultrafine-Mn 2 O 3 @N-doped porous carbon hybrids [Mn 2 O 3 @NC] derived from Mn-MOFs was constructed with 1 O 2 and O 2 −• as main Reactive oxygen species (ROS). Cation-π bonds and N-Mn complexation induced the formation of electron-rich Mn centre which provided electron for peroxymonosulfate activation to produce radicals, accompanying with generation of 1 O 2 via chain reaction. Notably, the porous structure of N-doped carbon shell could not only facilitate free radical recombination for generation of 1 O 2 but also provide adsorption sites for organics. On the other hand, as electron-poor centre, N-doped carbon shell could improve the electrons transfer from organic intermediate radicals to electron-rich Mn centre via π -π reaction, C-O-Mn and C-N-Mn bonds, which promote the redox of Mn to avoid peroxymonosulfate invalid decomposition. Being attributed to synergistic effects of dual-reaction centres and strong oxidation ability of 1 O 2 , Mn 2 O 3 @NC achieved high mineralization of BPA at low-dose peroxymonosulfate (0.033 g/L).
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DYES AND PIGMENTS
·
2019
·
IF 4.018
Xiuquan Xu,Songmei Wang,Tongjie Hu,Xiaofeng Yu,Jiapeng Wang,Chao Jia
Co-doping has been proven to significantly enhance the photocatalytic performance of g-C 3 N 4 . Herein, Mn and O co-doped g-C 3 N 4 (Mn/O-CN) composites were constructed for the first time by a simple one-pot calcining route. The systematic characterization results of XRD , FT-IR, TEM-EDS, XPS and DRS revealed that the Mn and O elements were co-doped into the CN framework successfully as Mn 3+ / 4+ and n-π* conjugate forms, respectively. The as-prepared Mn/O-CN-2 achieved the highest visible-light-driven degradation rate constant of 0.0290 and 0.0267 min −1 for degradation of Malachite green (MG) and Amido black 10B (AB 10B), which were about 5.09 and 5.45 folds higher than that of pristine CN, respectively. The improved photocatalytic degradation property of Mn/O-CN were mainly benefited from the extended visible light utilization, the enlarged specific surface area, and the accelerated separation and transfer of photo-induced charge carriers, which were all induced by the synergistic effects of Mn and O co-doped. Finally, the active species capturing experiments proved that the superoxide radicals (·O 2 − ) and holes (h + ) acted as the predominant roles in the photocatalytic degradation process .
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SOLAR ENERGY
·
2019
·
IF 4.674
Zhen Li,Libo Yu
Mn-Cd x Zn 1-x Se@ZnO multi-shelled (including single-shelled, double-shelled, and triple-shelled) hollow microspheres (HMS) were successfully synthesized for application in quantum dots sensitized solar cell (QDSSC). The influence of shell numbers on photovoltaic performance of QDSSC were investigated. The results showed that larger surface area, repeated light reflection and reinforced light scattering can be achieved with triple-shelled HMS, which can improve light harvesting efficiency. Furthermore, midgap state created by Mn-doping in Cd x Zn 1-x Se will facilitate electrons injection and collection from excited Cd x Zn 1-x Se quantum dots (QDs) to ZnO. The multi-shelled effects and Mn-doping finally improve the short-circuit current (J sc ) of Mn-Cd x Zn 1-x Se@ZnO tripled-shelled HMS solar cell to 20.21 mA cm −2 , leading to the power conversion efficiency significantly enhanced to 3.39%.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
·
IF 4.175
Yuefeng Liu,Jun Zhao,Yan Zhang,Huafang Zhang,Zhenlong Zhang,Huiping Gao,Yanli Mao
Upconversion nanoparticles (UCNPs) doped with lanthanide ions have potential applications in biomedical, solar cells and displays. However, the intensity of the upconversion luminescence (UCL) is limited by the surface effects of nanomaterials , lattice defects, etc. Here, a novel α-NaErF 4 hollow nanocube is fabricated by using divalent manganese ions (Mn 2+ ) to substitute trivalent erbium ions (Er 3+ ) in the NaErF 4 matrix. The hollow-shell structure can weaken the luminescence quenching and surface quenching effects, reduce the energy loss of higher energy levels in nanoparticles , and improve the light capture ability of nanoparticles. So the UCL of α-NaErF 4 hollow nanocubes is greatly improved, which is 14, 790 and 1071 times higher than that of the β-NaErF 4 under 808, 980 and 1530 nm laser excitation, respectively, and the emission in the red region is enhanced respectively by 69, 2049 and 2902 times. In particular, the hollow nanocubes emit intense single-band red emission under the three different wavelengths, respectively. Moreover, the magnetization of α-NaErF 4 hollow nanocubes is 2.16 emu g −1 at room temperature, which is larger than that of gadolinium-based materials. Hollow-shell structure, excellent paramagnetism and single-band red upconversion emission excited by various wavelengths will create NaErF 4 :40Mn UCNPs a good application prospect in the biomedical field.
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Haitao Li,Qiang Gao,Guanshuai Wang,Bo Han,Kaisheng Xia,Chenghang Zhou
Developing high-performance heterogeneous Fenton-like catalyst and understanding its intrinsic catalytic properties are of fundamental and practical significance. In this work, a mesoporous Mn(II)-doped CeO 2 (MCO) with monodisperse spherical morphology and large surface area (141.8 m 2 g −1 ) was fabricated through a simple hydrothermal–calcination process, and further utilized as the heterogeneous catalyst for oxidative degradation of organic pollutants in the presence of H 2 O 2 . The density functional theory (DFT) simulations were carried out to study the H 2 O 2 decomposition process on the MCO surface. It was revealed that the Mn(II) doping in the CeO 2 could significantly promote the complex of the surface Ce sites and H 2 O 2 molecules. More importantly, the manganese dopants could serve as electron reservoirs, capable of reversibly donating and accepting electrons, which facilitated the electron transfer between Ce and H 2 O 2 . Owing to the electron reservoir properties of manganese, this MCO showed significantly enhanced catalytic efficiency in comparison to pure CeO 2 . Moreover, the catalytic activity of MCO almost kept unchanged after reuse several times, demonstrating its long-circulating characteristics. This study provides new and important insights into the electron transfer pathway involved in the heterogeneous Fenton-like process.
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ENERGY & FUELS
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2020
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IF 3.421
Jun Chen,Yi Chen,Dzmitry Hrynsphan,Yu Mei,Hua Pan,Jiali Wu,Jianmeng Chen,Jiachao Yao
FeII(EDTA) solution has been considered an efficient option in wet flue gas denitrification, whereas the generated FeII(EDTA)–NO restricts its wide application, suggesting that FeII(EDTA)–NO reduction is the key to this process. This work investigated the performance, kinetics, and mechanism of FeII(EDTA)–NO reduction by Mn powder coupled with manganese ion (Mn2+) recovery. We initially studied the performance of FeII(EDTA)–NO reduction with respect to the major influencing factors (i.e., the particle size of Mn powder, initial FeII(EDTA)–NO concentration, Mn powder concentration, stirring speed, and temperature). Shrinking core model and Arrhenius law were applied to illustrate the kinetics and mechanism between FeII(EDTA)–NO solution and Mn powder, suggesting that the solid–liquid reaction was fitted on chemical reaction control, and the activation energy was calculated as 43.0 kJ mol–1. The effects of main operating parameters, such as precipitant concentration, pH value, and temperature, were studied on Mn2+ recovery. Results indicated that the pseudo-second-order model could precisely describe the kinetics of Mn2+ recovery. Finally, according to Arrhenius and Eyring–Polanyi equations, the reaction activation energy, enthalpy of activation, and entropy of activation for Mn2+ recovery were calculated as 17.25 kJ mol–1, 14.55 kJ mol–1, and 252.07 J (k mol)−1, respectively.
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Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 28
·13668-13675
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IF 9.931
Hongtao Guan,Pan Cai,Xiaomeng Zhang,Yanlin Zhang,Gang Chen,Chengjun Dong
We demonstrate the design and fabrication of novel Cu2O@Mn(OH)2 core–shell hierarchical structures using octahedral Cu2O as a template. The Cu2O backbone supports the growth of an ultrathin Mn(OH)2 nanoflake shell, leading to a relatively large surface area (65.8 m2 g−1) for sufficient utilization of active materials. Cyclic voltammetry (CV) and galvanostatic charge–discharge measurements (GCD), as well as cycling stability and electrochemical impedance spectroscopy (EIS) were performed to examine the electrochemical performances of the Cu2O@Mn(OH)2 core–shell structure. Applied as a supercapacitor electrode, the Cu2O@Mn(OH)2 composite delivers a high specific capacitance of 540.9 F g−1 at 1 A g−1 and an energy density of 6.4–18.2 Wh kg−1. After conducting 3000 cycles at 5.0 A g−1, the capacitance retention of 71.5% was achieved. The unique core–shell structure of the Cu2O@Mn(OH)2 composite favours the effective transport of electrolytes and shortens the ion diffusion path. In addition, the synergetic effects from both Cu2O and Mn(OH)2 significantly enhance the electrochemical performances. Our findings suggest that this Cu2O@Mn(OH)2 core–shell is very promising for next generation high-performance supercapacitors.
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RSC Advances
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2015
·Vol. 5
·期 28
·21504-21510
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IF 3.84
Xiaojuan Zhao,Fengxia Li,Qingyan Zhang,Zengbo Li,Yehong Zhou,Jun Yang,Chuan Dong,Junping Wang,Shaomin Shuang
Mn-doped ZnS quantum dots capped with 3-mercaptopropionic acid (MPA) were synthesized by a facile method in aqueous solution as a ratiometric fluorescent (I590 nm/I458 nm) probe for curcumin. Curcumin caused defect-related fluorescence quenching of the probe at 458 nm, whereas the orange transition emission of the probe at 590 nm changed only negligibly with variations in curcumin concentration. The MPA-assembled Mn-doped ZnS quantum dots were used for the simple, sensitive and non-toxic determination of curcumin. Under the optimized conditions, the response to curcumin was linear in the range 0.16–16.9 μM with a detection limit of 37 nM. The method was successfully applied to the determination of trace amounts of curcumin in urine samples with recoveries of 97.73–109.73%.
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Analytical Methods
·
2013
·Vol. 5
·期 21
·5929-5937
·
IF 1.855
Rui Ban,Jingjing Li,Juntao Cao,Penghui Zhang,Jianrong Zhang,Jun-jie Zhu
High-quality glutathione (GSH) capped ZnS : Mn/ZnS core/shell doped quantum dots (d-dots) with pure dopant emission band and excellent stability have been synthesized directly in aqueous media. The influences of experimental variables on the luminescent properties of the ZnS : Mn/ZnS nanocrystals have been investigated. The quantum yield of the dopant Mn photoluminescence in the as-prepared ZnS : Mn/ZnS core/shell d-dots can be up to 27.4%. The value is the highest reported to date for ZnS : Mn d-dots via the direct aqueous synthetic method. Their optical features and structure have been characterized by UV-Visible spectroscopy, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) in detail. Additionally, the stability study against UV irradiation indicated that the obtained d-dots possess excellent photostability. Furthermore, the MTT assay demonstrated that the ZnS : Mn QDs do not exhibit any cytotoxicity toward HeLa cells up to a concentration of 600 μg mL−1. Using the Con A-mannose recognition system as a model, Con A functionalized ZnS : Mn/ZnS nanocrystals were prepared and successfully used for targeted mannosyl groups expression on the HeLa cells surface. Our investigation clearly shows that the GSH capped ZnS : Mn QDs are promising candidates as biological fluorescent labels.
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TALANTA
·
2013
·
IF 3.498
Wei Bian,Jing Ma,Wenrong Guo,Dongtao Lu,Meng Fan,Yanli Wei,Yingfu Li,Shaomin Shuang,Martin M.F. Choi
N -Acetyl-L-cysteine (NAC) and L-cysteine (Cys) capped Mn doped ZnS quantum dots (NAC-Mn/ZnS QDs and Cys-Mn/ZnS QDs) are firstly prepared by hydrothermal methods . These QDs display strong phosphorescence emission peaks at 583 and 580 nm upon excitation at 315 and 306 nm, respectively. Since their room-temperature phosphorescence is efficiently quenched by L-ascorbic acid (AA), they have been employed as phosphorescence probes for detecting AA. The linear working ranges are 2.5–37.5 and 2.5–47.5 µM and the limits of detection are 0.72 and 1.38 µM for NAC-Mn/ZnS QDs and Cys-Mn/ZnS QDs, respectively. The possible quenching mechanisms have been discussed in detail. The QDs probes are highly selective to AA over other common ions, amino acids , glucose and bovine serum album. Finally, they have been applied successfully for detection of AA in human urine samples with satisfactory results. The recoveries are 98–104%. Our work provides a simple and convenient phosphorescence method to determine AA in real samples.
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