SCIENCE OF THE TOTAL ENVIRONMENT
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2018
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IF 4.61
Jun Zhai,Quanfeng Wang,Qing Li,Bo Shang,Md. Hasibur Rahaman,Jialiang Liang,Jiucui Ji,Wenbo Liu
Carbamazepine (CBZ), a widely used antiepileptic drug, is refractory to biological wastewater treatment . Rapid removal of CBZ is possible using synthetic manganese oxide (δ-MnO 2 ) but the removal mechanisms require further investigation. In this study, CBZ degradation by δ-MnO 2 was carried out at different pH to further explore the degradation mechanisms. Results show that CBZ degradation by δ-MnO 2 was highly pH dependent, and rapid degradation occurred when pH <2.8. Based on the density functional theory calculations, increasing [H + ] not only increased the reactivity of δ-MnO 2 , but also enhanced the secondary reactions of the intermediates. During the degradation process, protonation of CBZ degradation intermediates, instead of CBZ, played an important role. The overall kinetics of CBZ degradation was then described by the retarded first-order model. The initial rate (r init ) in the model between pH 2.0 and 6.2 was determined to be r init = (2.41 ± 0.51) × 10 −3 [CBZ] 1.21 [MnO 2 ] 1.07 [H + ] 1.41 . This is the first report revealing that protonation of intermediates from CBZ degradation can improve the CBZ oxidation by δ-MnO2. The pathways of CBZ degradation by δ-MnO 2 were also proposed. The results of this study provide a new insight into the processing mechanism.
研究领域:
环境科学
·
药物化学
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DOI
PubMed
高影响因子
CATALYSIS LETTERS
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2023
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IF 2.8
Gao Youxin,Zhou Aojia,Min Jie,Yu Chengbing
A simple redox method was used to synthesize δ-MnO 2 and introduce the first main group metal elements between the layers of δ-MnO 2 . Through testing, we found that δ-MnO 2 doped with Rb + demonstrated the best catalytic performance for formaldehyde removal. Under the condition of 36 °C and the initial formaldehyde concentration of 200 ppm, a 200 mg of Rb-MnO 2 could achieve the percentage of removal of formaldehyde 97.48%. We found that doping elements with low electronegativity and large ion radius could weaken the Mn–O bond, which is conducive to the formation of reactive oxygen species and improve the performance of catalytic oxidation. Graphical Abstract
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
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2016
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IF 7.145
Zhibin Geng,Yanxiang Wang,Jinghai Liu,Guangshe Li,Liping Li,Keke Huang,Long Yuan,Shouhua Feng
Pure phase manganese oxides have been widely studied as water oxidation catalysts, but further improvement of their activities is much challenging. Herein, we report an effective method to improve the water oxidation activity by fabricating a nanocomposite of Mn3O4 and δ-MnO2 with an active interface. The nanocomposite was achieved by a partial reduction approach which induced an in situ growth of Mn3O4 nanoparticles from the surface of δ-MnO2 nanosheets. The optimum composition was determined to be 38% Mn3O4 and 62% δ-MnO2 as confirmed by X-ray photoelectron spectra (XPS) and X-ray absorption spectra (XAS). The δ-MnO2–Mn3O4 nanocomposite is a highly active water oxidation catalyst with a turnover frequency (TOF) of 0.93 s–1, which is much higher than the individual components of δ-MnO2 and Mn3O4. We consider that the enhanced water oxidation activity could be explained by the active interface between two components. At the phase interface, weak Mn–O bonds are introduced by lattice disorder in the transition of hausmannite phase to birnessite phase, which provides active sites for water oxidation catalysis. Our study illustrates a new view to improve water oxidation activity of manganese oxides.
研究领域:
材料科学
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化学
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DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
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2018
·Vol. 42
·期 9
·6770-6777
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IF 3.201
Kai Luo,Shi-Xi Zhao,Yi-Feng Wang,Shu-Jin Zhao,Xi-Hui Zhang
Petal-like δ-MnO2 microspheres were successfully synthesized by a very simple hydrothermal method with potassium permanganate (KMnO4) as the only raw material. By adjusting the initial concentration of KMnO4 solution and the time of the hydrothermal reaction, the morphology and crystallinity of δ-MnO2 can be controlled. The synthesized δ-MnO2 microspheres were characterized by XRD, SEM, TEM, TG/DSC, BET, ICP-AES and XPS. The catalytic ozonation performance of δ-MnO2 prepared by a hydrothermal reaction at 160 °C for 24 h using 0.1 mol L−1 KMnO4 solution was tested. Its catalytic activity is excellent. The degradation efficiencies of bisphenol A and ibuprofen using 0.1 g L−1 δ-MnO2 as the catalyst were 68.2% and 68.5% in 20 min reaction time. The results were much better than those of individual ozone treatment and with commercial MnO2 as the catalyst. The formation of hydroxyl radicals was not the main reason for the rapid degradation of organic compounds in the catalytic reaction with δ-MnO2 as the catalyst. The strong interaction among the catalyst surface, ozone and organic molecules was the important reason for catalysis based on the related experimental results.
研究领域:
环境科学
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材料化学
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产品关联
DOI
高影响因子
ENVIRONMENTAL POLLUTION
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2024
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IF 7.6
Ruihan Xiong,Caixiang Zhang,Hanxiang Xiong,Shuxin Huang,Jiasen Li
Glyphosate as an effective broad-spectrum herbicide is frequently detected in various water and soil resources. Given the ubiquity of β-MnO 2 and δ-MnO 2 colloids in groundwater and soil, the abiotic removal of glyphosate by MnO 2 colloids was investigated. β-MnO 2 colloids exhibited superior glyphosate removal efficiency, up to 37%, compared to 21% for δ-MnO 2 colloids at a pH of 4.0. Glyphosate removal involved simultaneous adsorption and oxidation process , identified by HRTEM , NH 3 -TPD, XPS , LC-MS, FTIR analyses and the occurrence of aminomethylphosphonic acid (AMPA) and Mn 2+ . Moreover, adsorption dominated the removal of glyphosate by two MnO 2 colloids. The solution pH had a substantial effect on glyphosate removal. Co-existing ions in the solution, such as carbonate (CO 3 2− ), phosphate (Na 2 HPO 4 , NaH 2 PO 4 ) and humic acid (HA), were also found to impede glyphosate removal. Phosphate, in particular, exhibited a strong competitive effect for adsorption sites on both MnO 2 colloids. Of them, the removal of glyphosate by β-MnO 2 colloids was more prone to occur due to its higher specific surface area , abundant oxygen vacancies , and moderate acid sites. However, δ-MnO 2 colloids presented a stronger oxidation capacity than that of β-MnO 2 colloids due to the quicker generation rate of Mn 2+ . Finally, AMPA was the same products by two MnO 2 colloids in the oxidation process, revealing the degradation pathway based on the cleavage of C–N bond. Therefore, by comparing kinetics and mechanisms of glyphosate removal by β- and δ-MnO 2 colloids, this study improves us better understanding for the behavior of glyphosate in the environment.
研究领域:
环境科学
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化学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2024
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IF 5.8
Xinying Ding,Yuanbin Wen,Chen Qing,Yaru Wei,Pengcheng Wang,Jingyi Liu,Zhanhong Peng,Yihui Song,Houyang Chen,Qian Rong
δ-MnO 2 was proposed as a promising cathode material for aqueous Zn-ion batteries. Nonetheless, its potential application has been impeded by its unstable crystal structure and sluggish reaction kinetics with Zn ions. Herein, we utilized Cr to modify δ-MnO 2 by a simple hydrothermal method to develop cathode materials for aqueous Zn-ion batteries with better stability and electron transport properties. The introduction of Cr enhanced the specific capacity and cycling stability of δ-MnO 2 , in particular, the 3% Cr doped δ-MnO 2 electrode exhibited a large specific capacity of 229.2 mAh·g −1 at 0.1 A·g −1 and an excellent capacitance retention of 86.0% after performing 300 cycles. The density functional theory (DFT) calculations indicate that the introduction of Cr decreases the band gap of MnO 2 and enhances electron migration in the electrode material. Meanwhile, the introduction of Cr substantially improved the Zn ion adsorption and enhanced the binding energy of δ-MnO 2 , indicating that the addition of Cr promoted the interaction between the Cr doping δ-MnO 2 (Cr-MnO 2 ) electrode materials with Zn ions, while making the structure of the electrode materials more stable. As a result, this suppresses the Jahn-Teller distortion and reduces the solvation and phase transition of Mn.
研究领域:
材料科学
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电化学
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产品关联
DOI
高影响因子
Science Bulletin
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2024
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IF 18.8
Wei Lv,Zilei Shen,Junlin Liu,Xudong Li,Fang Ding,Dongyue Zhang,Licheng Miao,Xuefeng Lyu,Ruijie Li,Miaomiao Wang,Yiming Li,Jingwen Meng,Chao Xu
In this study, we successfully synthesized a δ-MnO 2 cathode with O vacancies, encapsulated by C derived from pyromellitic acid, using a facile hydrothermal method followed by annealing in an Ar atmosphere. The cathode’s structural stability and charge transfer kinetics are enhanced by inhibiting the formation of the by-product Zn 4 SO 4 (OH) 6 ·4H 2 O, regulating the Mn valence state, and suppressing the Jahn–Teller effect through the synergy of C encapsulation and O vacancies. This results in remarkable electrochemical performance, including a large capacity of 421.2 mAh g −1 at 0.1 A g −1 , a high specific energy density of 595.53 Wh kg −1 , and exceptional long-cycle life stability with 90.88% over 4000 cycles at 10 A g −1 , together with superior coulombic efficiency (∼100%) in pure ZnSO 4 electrolyte. Moreover, the cathode materials demonstrate specific antitumor efficacy. In brief, this work introduces an in situ synthetic C encapsulated δ-MnO 2 with O vacancies expected to be applied in both large-scale energy storage and biomedicine.
研究领域:
材料科学
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生物医学工程
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产品关联
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
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2021
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IF 5.909
Binliang Wang,Junli Zheng,Yingying Li,Adel Zaidi,Yiwei Hu,Baowei Hu
Exploitation of algal biochar is a profitable opportunity for the utilization of filamentous green algae due to its sustainable growth and ease of harvest. In this study, Rhizoclonium -derived biochar (CB) and δ-MnO 2 -modified biochar (MnO 2 /CB) were fabricated for uranium (U(VI)) removal. The results showed that the δ-MnO 2 modification increased the BET surface area and decreased the isoelectric point. The maximum sorption amount of U(VI) by the MnO 2 /CB reached up to 100.2 mg/g (pH = 6.0, 289 K, and 0.01 M NaCl), which was two times higher than that of the CB. After five consecutive sorption/desorption cycles, the affinity of the MnO 2 /CB for U(VI) maintained in 94.8%. According to the analysis of X-ray photoelectron spectroscopy, it confirmed that the U(VI) sorption was mainly ascribed to the surface complexation between U(VI) and oxygen-containing functional groups on the surface of the MnO 2 /CB. Therefore, this investigation not only encourages the development of algal biochar derived from the filamentous green algae but also provides a novel adsorbent for U(VI) removal from aqueous solutions.
研究领域:
环境科学
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材料科学
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产品关联
DOI
高影响因子
Journal of Materials Chemistry A
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2016
·Vol. 4
·期 5
·1970-1979
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IF 8.262
Juntao Liu,Xiao Ge,Xinxin Ye,Guozhong Wang,Haimin Zhang,Hongjian Zhou,Yunxia Zhang,Huijun Zhao
Novel three-dimensional (3D) graphene/δ-MnO2 aerogels were fabricated via self-assembly and reduction of graphene oxide, followed by in situ solution-phase deposition of ultrathin δ-MnO2 nanosheets. The resultant graphene/δ-MnO2 architectures showed an interconnected 3D network microstructure, in which a large number of ultrathin birnessite MnO2 nanosheets were homogenously deposited on the graphene framework. Due to their unique structural characteristics, the resulting 3D aerogels exhibited a fast adsorption kinetic rate and superior adsorption capacity toward heavy metal ions. The saturated adsorption capacities of graphene/δ-MnO2 aerogels were as large as 643.62 mg g−1 for Pb2+, 250.31 mg g−1 for Cd2+ and 228.46 mg g−1 for Cu2+ calculated by the Langmuir isotherm model, exceeding largely the corresponding pristine 3D graphene and δ-MnO2 nanosheets. It was noted that the heavy metal ions could not only adsorb on the surface of graphene/δ-MnO2, but also intercalate into the interlayer gaps of birnessite MnO2, which reveals the synergistic effect of the static electrical attraction, surface complexation and ion exchange between heavy metal ions and pre-intercalated K+, supported by the expansion of the basic crystal structure of layered MnO2 after adsorption. Furthermore, it is interesting that the regenerated aerogels after the initial HCl and subsequent KOH treatment still maintain their original shape and can be repeatedly used for more than eight cycles without obvious degradation of performance, which achieved the sustainability of the absorbents. More importantly, the hybrid aerogels can be easily separated and do not generate secondary contaminants. High removal efficiency, fast adsorption kinetics, excellent regeneration and reusability, and ease of separation operation make these hybrid aerogels ideal candidates for heavy metal ion decontamination in practical application.
研究领域:
材料科学
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环境科学
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DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Xu Wu,Heqin Guo,Litao Jia,Yong Xiao,Bo Hou,Yongxiang Gao,Debao Li
δ-MnO 2 exhibits excellent activity for furfural oxidation to furoic acid under base-free conditions. However, its poor C H bond breaking capacity leads to lower conversion efficiency per unit mass catalyst than noble metal. Thus, a series of Ru-modified δ-MnO 2 (Ru x /δ-MnO 2 ) have been made to enhance its C H bond breaking ability. The result showed that the furfural conversion was greatly enhanced on Ru x /δ-MnO 2 due to the enhanced capability for breaking the C H bond. Especially for Ru0.25/δ-MnO 2 , whose conversion rate per unit mass was 18 times higher than δ-MnO 2 . The characterization results showed that the Ru species mainly existed as single atoms or clusters on Ru0.25/δ-MnO 2 and Ru0.5/δ-MnO 2 , while started to aggregate to RuO 2 nanoparticles on Ru1/δ-MnO 2 and Ru2/δ-MnO 2 . With the increase of Ru particles, the Ru's average oxidation state (AOS) decreased from +6 on Ru0.25/δ-MnO 2 to +4.74 on Ru2/δ-MnO 2. The Ru's TOF (intrinsic activity per Ru) was positively linearly related to the Ru's AOS. The electron-deficient Ru in Ru0.25/δ-MnO 2 can strongly adsorb the H atom of the C H of geminal diol intermediate and accelerate the breakage of its C H bond. As a result, Ru in the Ru0.25/δ-MnO 2 exhibited the highest TOF, which can even reach 29.85 mmol FF /mmol Ru /h.
研究领域:
化学工程
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材料科学
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Peiyan Liu,Meiri Wang,Jing Li,Hongtao Cui,Tao Zeng,Shubin Yang,Huan Wang,Yuanyuan Liu
Rechargeable aqueous Zn//MnO 2 batteries are the promising alternatives to lithium-ion batteries owing to their high safety, high energy density, low cost, and environmental friendliness. However, the unstable MnO 2 cathode causes poor practical energy density and serious capacity fading. To overcome this issue, herein, a unique 2D nanosheets self-supported 3D δ -MnO 2 microflower hierarchical architecture is rationally designed and synthesized by taking advantage of its microwave-absorbing characteristics. The 2D nanosheets with high surface area could expose numerous active sites for ions/electrons transfer. Also, the 3D assembled structure acting as building blocks would ensure structural stability for long-life cycles. Benefiting from these synergistic merits, the δ -MnO 2 microflowers deliver a high capacity of 287.6 mA h g −1 at 0.5 C, an excellent rate capability of 202.7 mA h g −1 at 5 C, and a superior cycling retention of 76.5% over 1000 cycles at 10 C. Furthermore, a storage mechanism of H + /Zn 2+ co-insertion accompanied by the deposition of zinc sulfate hydroxide hydrate is clarified by the aid of ex-situ XRD and SEM technologies. This work provides a new pathway for developing high capacity and long lifespan ZIBs.
研究领域:
材料科学
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电化学
·
能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2016
·Vol. 82
·期 1
·85-91
·
IF 1.473
Wang Li,Ma Wenle,Li Yanhong,Cui Hongtao
Abstract By a microwave-assisted hydrothermal method, nanoflower-like δ-MnO 2 was prepared for application in supercapacitors as electrode material. The characterization results indicated that the obtained architecture had the characteristics of electrode materials with high electrochemical performance. The flower architecture provided the channel surrounded by the nanosheets-like petals for the fast transfer of electrolyte ions. The thin thickness of nanosheets minimized the diffusion distance of electrolyte ions beneath the surface of material particles. The two advantages of the material guaranteed the high performance of material. It presented specific capacitance of 328 F g −1 at 5 mV s −1 in 1 M Na 2 SO 4 aqueous solution within a wide potential window of −0.5~1.0 V. During cycle stability test, the capacitance of material still remained 89% of its initial value after 5000 charge–discharge cycles. These results demonstrated that the nanoflower-like δ-MnO 2 could be applied as high performance electrode material. Graphical Abstract MnO 2 with different crystallographic forms and architectures was prepared by normal hydrothermal and microwave-assisted hydrothermal methods, respectively. The α-MnO 2 prepared by normal hydrothermal method presented architecture of nanobundles and the δ-MnO 2 prepared by microwave-assisted hydrothermal method exhibited architecture of nanoflower. The results of electrochemical measurements indicated that δ-MnO 2 had the higher performance than α-MnO 2 due to its unique nanoflower architecture.
研究领域:
材料科学
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电化学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）