ENVIRONMENTAL RESEARCH
·
2021
·
IF 6.498
Yanan Cai,Jing He
The release of Mn(II) occurs in the degradation of organic matters by manganese ore (MnO 2 ), resulting in a reduced efficiency. During the degradation of ciprofloxacin (CIP), in a biofilter, this paper put forward a novel method that similar to the geo-cycle of Mn (MnCS) on the Earth to regenerate MnO 2 . The freshly prepared MnO 2 was suitable for the use in the MnCS. It indicated that the mutual conversion between Mn(II), Mn(III), and Mn(IV) in the MnCS, which was driven by CIP and manganese oxidizing bacteria (MnOB), could maintain the activity of MnO 2 . The MnCS showed feasibility in the coexistence of ammonia or humic acid , and provided a kinetic degradation. The physicochemical features of MnO 2 before and after bio-regeneration were characterized by TEM , XRD, BET, and XPS. It was found that the morphological structure of MnO 2 became loose and the maximum peak of pore size distribution became smaller, but the increase of surface area, the change of Mn(III/IV) content, and the decrease of crystallinity favored the bio-regeneration process. Moreover, as a mediator in the MnCS, the group of MnOB was dramatically inhibited by CIP, and the bacterial community had changed significantly. The typical MnOB shared low abundance in the biofilter, while the rarely reported genera (e.g. Sphingomonas ) that related to the formation of Mn deposits appeared to be involved in the MnCS.
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PubMed
高影响因子
Nanomaterials
·
2020
·Vol. 10
·期 9
·1745
·
IF 4.324
Ze Sun,Liuting Zhang,Nianhua Yan,Jiaguang Zheng,Ting Bian,Zongming Yang,Shichuan Su
Magnesium hydride (MgH2) has been considered as a potential material for storing hydrogen, but its practical application is still hindered by the kinetic and thermodynamic obstacles. Herein, Mn-based catalysts (MnCl2and Mn) are adopted and doped into MgH2to improve its hydrogen storage performance. The onset dehydrogenation temperatures of MnCl2and submicron-Mn-doped MgH2are reduced to 225 °C and 183 °C, while the un-doped MgH2starts to release hydrogen at 315 °C. Further study reveals that 10 wt% of Mn is the better doping amount and the MgH2+ 10 wt% submicron-Mn composite can quickly release 6.6 wt% hydrogen in 8 min at 300 °C. For hydrogenation, the completely dehydrogenated composite starts to absorb hydrogen even at room temperature and almost 3.0 wt% H2can be rehydrogenated in 30 min under 3 MPa hydrogen at 100 °C. Additionally, the activation energy of hydrogenation reaction for the modified MgH2composite significantly decreases to 17.3 ± 0.4 kJ/mol, which is much lower than that of the primitive MgH2. Furthermore, the submicron-Mn-doped sample presents favorable cycling stability in 20 cycles, providing a good reference for designing and constructing efficient solid-state hydrogen storage systems for future application.Keywords:hydrogen storage;MgH2;Mn-based catalysts;catalytic effect;reversibility
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高影响因子
Energy Technology
·
2020
·Vol. 8
·期 5
·2000008
·
IF 3.404
Chengrui Wang,Lei Zhang,Yuhai Dou,Luke Hencz,Lixue Jiang,Mohammad Al-Mamun,Porun Liu,Shanqing Zhang,Dan Wang,Huijun Zhao
Further commercial application of low-cost NiO-based anodes is hindered by their large volume expansion after full lithiation and relatively poor theoretical capacity. To improve these issues, transition metal (Fe, Co, or Mn)-modified triple-shelled NiO microspheres (TS-NiO) are successfully synthesized by using a hard template double-adsorption method. Among them, the Fe-modified TS-NiO (TS-NFO) exhibits an extraordinary lithium storage ability with high reversible capacity and outstanding cycling stability (2061.1 mAh g −1 after 800 cycles at 0.5 A g −1 ), which is the highest performing nickel oxide-based anode reported to date. The outstanding electrochemical performance of TS-NFO can be ascribed to its unique triple-shelled structure. The inner core of TS-NFO is composed of NiO and is encapsulated by two outer shells which are composed of a mixture of α-Fe 2 O 3 and NiFe 2 O 4 , resulting in a unique hollow triple-shelled structure (NiO@α-Fe 2 O 3 /NiFe 2 O 4 ). The void space between the triple shells leaves room for their volume changes during lithiation/delithiation, which improves the cycling stability. In addition, the introduced α-Fe 2 O 3 /NiFe 2 O 4 outer shells increase the energy density and reversible capacity due to a synergistically interactive effect.
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高影响因子
MATERIALS TECHNOLOGY
·
2020
·
IF 1.738
Huan Yang,Renxin Xu,Yaohui Zhao,Jian Cai
Mg0.2Mn0.8NdxFe2-xO4 (x = 0.000, 0.025, 0.050, 0.075 and 0.010) nano crystalline is synthesized via hydrothermal technique. Single cubic spinel phase is confirmed by XRD and the formation of Mg0.2Mn0.8NdxFe2-xO4 is verified by EDS. The average size of the nanoferrites is examined by TEM image. Nd3+ substituted Mg-Mn nanoferrites exhibit the low saturation magnetization (Ms) and high coercivity (Hc). The ferrite composites present that the resistivity and the magnetic loss are less than 2.8×107 Ω·cm and 0.75 in the range of 2-18 GHz, respectively. The optimized Mg0.2Mn0.8NdxFe2-xO4 (x=0.050) showed the minimum reflection loss of -39.80 dB at 1.4 GHz and effective absorption bandwidth (lower than -10 dB) of 7.58 GHz with a thickness of only 3 mm. The high coercivity, resistivity and excellent wave absorption performance indicate that the addition of Nd3+ contributes to the synthesis of the excellent soft magnetic materials and wave absorbing materials.
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高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2020
·
IF 3.408
Tengyan Wu,Guokang Shen,Feng Ding,Duxin Li,Hongbin Zhong
In this study, the La doped Mn–Zn nanoferrites were synthesized through hydrothermal method , and then were used to activate persulfate for degrading azo dye the Direct Blue 15 (DB15). The structure and morphology of the as-prepared sample were characterized by X-ray Diffraction (XRD), Fourier Transformed Infrared Spectrometer (FTIR), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectrometer (EDS). The results indicated that the La doped Mn–Zn ferrite was successfully synthesized in this study. Four absorption bands were observed in FTIR spectra and assigned to the corresponding site bonds. Mn 0.6 Zn 0.4 La x Fe 2- x O 4 was chosen as catalysts to activate persulfate (PS/Mn 0.6 Zn 0.4 La x Fe 2- x O 4 ) to decolorize the DB15. It was found that the DB15 was degraded effectively by PS/Mn 0.6 Zn 0.4 La x Fe 2- x O 4 systems. Furthermore, the influences of synthesized conditions (such as the temperature, holding time and doping content of La) of Mn 0.6 Zn 0.4 La x Fe 2- x O 4 on the DB15 decolorization were analyzed. The results indicated that the doping of La can significantly improve the DB15 degradation, 100% degradation of DB15 can be obtained by PS/Mn 0.6 Zn 0.4 La 0.09 Fe 1.91 O 4 within 15 min. The enhancement of synthesized holding time of Mn 0.6 Zn 0.4 La x Fe 2- x O 4 at 160 °C can also increase the DB15 decolorization, and the degradation rate of the DB15 reached almost 100% within 25 min when using Mn 0.6 Zn 0.4 La 0.05 Fe 1.95 O 4 synthesized at 160 °C for 13 h as catalyst.
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高影响因子
MATERIALS RESEARCH BULLETIN
·
2019
·
IF 3.355
Lijun Zhu,Hao Cheng,Jianfeng Ma,Yong Kong,Yong Qin,Sridhar Komarneni
Decolorization of methyl orange (MO) by MnO 2 was investigated with and without small molecules of organic acids such as formic acid. It was found that the decolorization could be significantly improved by MnO 2 with the assistance of organic acids. The effect of various conditions was investigated on MO decolorization by using different crystal types of MnO 2 and changing the types of organic acids. One of the optimum treatment conditions was δ-MnO 2 /formic acid system, which led to the removal efficiency of 90.6% at 30 min. The pseudo-second-order kinetic rate constant of δ-MnO 2 /formic acid was 0.1626. A reasonable decolorization mechanism involving Mn(III) species was proposed and the mechanism was validated by simple detection of ionic species such as, Mn(II) and Mn(III) during the reaction. The δ-MnO 2 /formic acid process designed here may lead to a new advanced oxidation technology based on the in-situ generation of active Mn(III) species and their ability for oxidation.
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高影响因子
Materials Research Express
·
2019
·Vol. 6
·期 12
·125017
·
IF 1.449
Hanyu Yao,Honglie Shen,Quntao Tang
In this paper, Mn doped NaYF4:Er,Yb phosphors were successfully synthesized by a simple solvothermal method. According to the results of x-ray diffraction, scanning electron microscopy and photoluminescence measurement, Mn doping had a remarkable effect on the crystal phase, size, and especially upconversion (UC) properties of these phosphors. Under 980 nanometer (nm) laser excitation, the UC luminescence intensity could be enhanced by increasing Mn concentration. Temperature-dependence measurement of the samples from 300–30 K showed two green emission bands (2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of the Er3+ ion), which meant that the UC phosphors were suitable for temperature sensor by using the fluorescence intensity ratio (FIR) method. The FIR value decreased with temperature, and the experimental data were well fitted with a theoretical function. The higher maximum value of sensitivity (0.0057 K−1) for 20% Mn sample in contrast to that of 0% Mn one (0.0036 K−1) indicated that Mn doped sample had a higher sensitivity for temperature sensing. The results demonstrated that Mn doping would be a good way for optimizing the sensitivity of fluorescence-based temperature sensor.
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高影响因子
Water
·
2019
·Vol. 11
·期 11
·2302
·
IF 2.524
Dingyun Yan,Zhe Sun,Jiajie Wang,Lili Wang,Ruijun Pan,Qiang Wu,Xiaowei Liu
Mn(III) oxidation technology has attracted increasing interest in recent years because of its fast decontamination kinetics and second-pollution-free characteristic. Whether it can be used as a pre-oxidation step to enhance conventional coagulation process remains to be evaluated. Herein, an Fe-coagulation/sedimentation process combined with Mn(III) pre-oxidation (Mn(III)+C/S), hypochlorite pre-oxidation (Cl2+C/S), and permanganate pre-oxidation (PM+C/S) was applied to treat simulated micro-polluted raw water. The removal performance of routine water quality indices (turbidity, dissolved organic carbon, total nitrogen, nitrate-nitrogen, ammonia-nitrogen, Pb(II), and Cr(VI)) and the emerging pollutants (acesulfame, carbamazepine, bisphenol S, and nano-ZnO) created by these three processes were researched. The mechanism of how Mn(III) pre-oxidation influences C/S was explored by identifying the transformation products of Mn(III), measuring the timely variation of flocs’ zeta potential and size, and scanning flocs’ micromorphology. Compared to Cl2+C/S and PM+C/S, Mn(III)+C/S exhibited its superiority in removing dissolved organic carbon (72.9%), total nitrogen (31.74%), and emerging pollutants (21.78%–93.49%). The enhanced removal of these contaminants by Mn(III)+C/S found its explanation in the strong oxidation power of Mn(III) and the multiple roles of in-situ formed MnO2(e.g., flocculation core, adsorption co-precipitant, and densification agent). The acute toxicity tests confirmed that water treated by Mn(III)+C/S did not show a significant change in the associated toxicity. The findings of the present study indicate that Mn(III) oxidation technology shows great potential as an alternative to pre-oxidation technology of waterworks.Keywords:pre-oxidation;enhanced coagulation;Mn(III);emerging pollutants;micro-polluted raw water
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高影响因子
Journal of Physical Chemistry C
·
2023
·
IF 3.7
Zhaolun Yang,Xi Yuan,Yusheng Song,Mingyan Chen,Ke Xing,Sheng Cao,Jinju Zheng,Jialong Zhao
Mn-doped CsPbBr3 perovskite nanoplatelets (NPLs) with multicolor emission have very promising applications in light-emitting devices. However, the effects of NPL thickness on the Mn2+ luminescence properties remain to be investigated. Herein, a series of Mn-doped CsPbBr3 NPLs and nanocubes with different Mn/Pb molar ratios were synthesized by a supersaturated crystallization method at room temperature. The incorporation of Mn2+ ions into CsPbBr3 perovskites is attributed to the formation of the L2[Pb1–xMnx]Br4 intermediate structure in the precursor. The excitonic peak is tuned from 437 to 488 nm and the morphology evolves from NPLs to nanocubes with an increasing Mn2+ ion doping concentration due to the excess Br– from MnBr2. The photoluminescence quantum yields (PL QYs) of NPLs/nanocubes were greatly enhanced, achieving the maximum PL QYs of 88.7% at the Mn/Pb molar ratio of 3/1. The PL lifetime of Mn2+ emission is tuned from 0.19 to 0.44 ms due to the passivation of defect states and morphology transformation. Temperature-dependent steady-state and time-resolved PL spectra revealed that deep defect states in the NPLs/nanocubes were significantly reduced as the thickness increased. The Mn-doped CsPbBr3 NPLs/nanocubes show great potential for application in white light-emitting diodes.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yong Suo,Quanwu Guo,Yutong Liao,Jianhong Luo
Inspired by the mechanical reciprocating movement, a novel active microchannel device (RCSM) utilizing segmented flow and cavity squeezing technique was designed for the enhanced extraction and separation of Mn (II). The experiment evaluated the separation efficiency of Mn (II) under different conditions from two aspects: static and movement states of the reciprocating plate, and the results showed that residence time was the main factor effecting the extraction efficiency. At the same time, the movement of reciprocating plate produced a cyclic flow between oil and aqueous phases, which effectively enhanced the mixing and internal mixing of the two phases, reduced the effective mass transfer distance, and increased the effective contact area. The thermodynamics calculations indicated that the additional enthalpy was generated by the movement of reciprocating plate. And the kinetics calculations indicated that inertial forces and interfacial tensions significantly acted in the formation, fragmentation, agglomeration, and mixing of oil ∼ aqueous phases droplets in the microchannel, ultimately leading to different results in the interface and fluid flow form of the oil ∼ aqueous phases. At both high and low flow rates, regular slug flows were observed at the outlet of the RCSM, and the fusion between adjacent slugs played a positive role in improving the efficiency of extraction. In addition, the total volume mass transfer coefficient (K L a) was calculated in this experiment to further reveal the mass transfer enhancement mechanism of RCSM. Compared with static experiments, dynamic experiments demonstrated stronger mass and heat transfer performance.
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高影响因子
NANO
·
2019
·
IF 1.293
Renxin Xu,Huan Yang,Huajun Sun,Jing Zhou,Zhijun Yue,Xinhua Gao
Mg 0 . 2 Mn 0 . 8 Y x Fe 2 − x O 4 ( x = 0 . 0 0 0 , 0.025, 0.050 and 0.075) nanocrystalline is synthesized via hydrothermal technique. Single cubic spinel phase is confirmed by XRD and the formation of Mg 0 . 2 Mn 0 . 8 Y x Fe 2 − x O 4 is verified by EDS. The average size of the nanoferrites is around 80 nm, which is examined by TEM image. Y 3 + substituted Mg-Mn nanoferrites exhibit low saturation magnetization ( M s ) and coercivity ( H c ) . Especially, the nanoferrites with x = 0 . 0 7 5 show the lowest M s and H c of 46.96 emu/g and 12.04 Oe, respectively. The ferrite composites present that the resistivity and the magnetic loss are less than 4 . 5 × 1 0 7 Ω ⋅ cm and 0.7 in the range of 2–18 GHz, respectively. The low coercivity and high resistivity indicate that the addition of Y 3 + contributes to the synthesis of the excellent soft magnetic materials.
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高影响因子
Journal of Earth Science
·
2019
·Vol. 30
·期 4
·861-869
·
IF 1.784
Zhang Caixiang,Liao Xiaoping,Lü You,Nan Chao
The ligand-stabilized soluble Mn(III) recognized as active intermediate can potentially mediate the attenuation of contaminants. In this study, the abiotic degradation behaviors of methyl parathion in the ligand stabilized Mn(III)-sulfite system were investigated. The results showed that the yield of soluble Mn(III) produced from the redox reaction of MnO 2 and oxalic acid was dependent linearly on the dosage of MnO 2 and caused the decomposition of methyl parathion up to 50.1% in Mn(III)-sulfite system after 30 minutes. The fitted pseudo-first-order reaction constants of methyl parathion degradation increased with the increasing of the amount of produced Mn(III) but was not effected linearly by the addition of sulfite. Other ligands, including pyrophosphate and oxalic acid, acted as effective complexing agents to stabilize soluble Mn(III), and exhibited competitive effect on methyl parathion degradation with sulfite. The formation of Mn(III)-sulfite complexes is the critical step in the system to produce abundant reactive oxygen species identified as SO 3 • - to facilitate methyl parathion degradation. The hydrolysis and oxidation of methyl parathion were acknowledged as two primary transformation mechanisms in Mn(III)-sulfite system. These findings indicate that naturally ligands-stabilized soluble Mn(III) can be generated and could oxidatively decompose organophosphate pesticides such as methyl parathion.
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高影响因子
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