SEPARATION AND PURIFICATION TECHNOLOGY
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2020
·
IF 5.774
Weike Zhao,Bo Zhou
In recent years, multi-walled carbon nanotubes (CNTs), which are emerging nanocatalysts, have received much attention in advanced oxidation processes. CNTs were introduced into H 2 O 2 /Fe(III) Fenton-like process to enhance the degradation of bisphenol A (BPA) in this study. The results of the study suggests that CNTs could effectively promote electron transfer from H 2 O 2 to Fe(III) and directly reduce Fe(III) to Fe(II) to accelerate Fe(III)/Fe(II) cycles, in which carbonyl groups and structural defects of CNTs were identified as the major active sites via SEM, Raman, XRD, FTIR and XPS analyses. It was revealed that hydroxyl radical (·OH) majorly contributed to the degradation of BPA, and the generation efficiency of ·OH was significantly increased by 3.2 times with the addition of CNTs. Also, nine intermediate products were identified, and the possible degradation pathways of BPA were proposed through the density functional theory (DFT) calculations and HPLC-MS/MS analysis. The ecotoxicity evaluation of BPA demonstrates that the oxidative degradation of BPA in CNTs/H 2 O 2 /Fe(III) system could effectively reduce its environmental risk. The critical experimental parameters including the dosage of Fe(III), H 2 O 2 , CNTs, initial pH and various anions (Cl − , HCO 3 – , SO 4 2− ) were investigated, and the reusability experiments indicate that CNTs maintained high stability and reusability during the reaction.
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Metals
·
2020
·Vol. 10
·期 12
·1574
·
IF 2.117
Ruochen Shen,Chaohui Pu,Xiaoou Xu,Youpeng Xu,Zhilin Li,Zhu Wu
The research aims to study the effect of adding mischmetal (Mm) to the TiFe0.86Mn0.07Co0.07alloy on its hydrogen storage performance and cyclic stability. The results show that TiFe0.86Mn0.07Co0.07+ x% Mm (x = 0,4,6,8) alloys can be easily activated. The hydrogen absorption capacity of TiFe0.86Mn0.07Co0.07+ 4% Mm reaches 1.76 wt% (mass fraction) at 298 K. With the increase of Mm addition, the hydrogen storage capacity decreases slightly. Furthermore, after 40 absorption and desorption cycles in hydrogen containing 250 ppm O2, the alloy still has 36% of its initial hydrogen storage capacity, and the alloy can recover 93% of its hydrogen storage capacity through heat treatment.Keywords:TiFe hydrogen storage alloys;life test;impure hydrogen gas;cyclic stability
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Catalysts
·
2020
·Vol. 10
·期 12
·1379
·
IF 3.52
He Liu,Shiguang Fan,Xu Gong,Jian Wang,Aijun Guo,Kun Chen,Zongxian Wang
Partial hydrogenation of anthracene under CO-H2O, N2-H2O, and H2-H2O over Fe-based catalysts was studied at 400 °C and 10 MPa. Results show that the Fe-based catalysts display obvious catalytic activity for anthracene hydrogenation under CO-H2O instead of hydrogenation under N2-H2O and H2-H2O. The activity follows in the order of Fe(NO3)3·9H2O > Fe naphthenate > FeSO4·7H2O. Even though the amount of molecular hydrogen remains higher than that of in situ hydrogen, the anthracene conversion with in situ hydrogen is remarkably higher. It demonstrates that the in situ hydrogen is more active than molecular hydrogen for PAH hydrogenation. To further reveal the exact fate of these Fe-based catalysts, the decomposed products under CO-H2O, N2-H2O and H2-H2O were characterized by TG, XRD, and TEM. Results indicate that the Fe3O4species play a key role in hydrogenation of anthracene under CO and H2O. Higher catalytic activity for Fe(NO3)3·9H2O is due to its complete decomposition at 350 °C to acquire higher concentration of active Fe3O4species. The possible form of in situ hydrogen during this process is also discussed. Given that heavy oil contains abundant polyaromatics, these results are meaningful for enhancing hydrogen shuttling to heavy oil by producing natural hydrogen donors and, thus, benefiting the high-efficient upgrading.Keywords:PAH hydrogenation;in situ hydrogen;water gas shift reaction;natural hydrogen donors
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SEPARATION SCIENCE AND TECHNOLOGY
·
2021
·
IF 2.475
Xuekai Zhang,Kanggen Zhou,Qingyuan Lei,Yan Xing,Changhong Peng,Wei Chen
A new approach was developed using NaH2PO4 as the stripping agent for Fe stripping from Fe-loaded Aliquat 336 during rare-earth elements recovery from red mud leachate. Owing to the strong coordination between Fe3+ and H2PO4‒, Fe mainly exists as FeH2PO42+ at [H2PO4‒] higher than 0.5 M, which can be readily stripped. The results showed a maximum Fe stripping efficiency of 95.5% under optimal condition. Moreover, the extraction capacity of the extractant after stripping was comparable to that of fresh extractant, and decreased only by 2% after 6 cycles, indicating the robustness of this approach for Fe stripping and extractant regeneration.
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JOURNAL OF HAZARDOUS MATERIALS
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2020
·
IF 9.038
Guangda Yu,Fenglian Fu,Chujia Ye,Bing Tang
The mobility of Cr(VI) in the environment is affected by the transformation of ferrihydrite (Fh) and ferrihydrite-humic acid co-precipitates (Fh-HA). However, the impacts of Fe(II)-induced transformation of Fh and Fh-HA on the mobility, speciation and partitioning of associated Cr(VI) remain unclear. In this study, the behaviors of adsorbed Cr(VI) during Fh and Fh-HA aging at 70 °C for 9 days (pH 0 = 3.0 and 7.0) in the absence and presence of Fe(II) were studied. Results revealed that the main speciation of Cr(VI) after transformation was non-desorbable Cr and its formation involved the following pathways. Firstly, Fe(II) (0.2 and 2.0 mM) induced the transformation of Fh-HA to hematite and goethite, promoting the structural incorporation of adsorbed Cr into hematite and goethite via complexation. Secondly, under neutral condition (pH 0 = 7.0), the low concentration of Fe(II) (0.2 mM) could not reduce completely Cr(VI) to Cr(III) and thus residual Cr(VI) was incorporated into the Cr(III)-Fe(III) co-precipitates. Thirdly, coprecipitated humic acid not only reduced Cr(VI) to Cr(III) via polysaccharide, but also formed complexes with incorporated Cr through carboxylic groups to sequester Cr. Our results demonstrate that Fe(II)-induced transformation of Fh-HA exerts major influences on associated Cr(VI) speciation and partitioning.
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高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2020
·
IF 16.683
Kai Zhao,Zisheng Zhang,Yalan Feng,Shuanglong Lin,Hong Li,Xin Gao
The development of efficient strategies to promote spatial charge separation is a promising way for the improvement of photocatalytic performance. Herein, a novel surface oxygen vacancy (OVs) modified Bi 2 MoO 6 /MIL-88B(Fe) heterostructure (BMO/M88) was exemplified by a facile two steps solvothermal method to demonstrate synergistic promotion of bulk & interface charge separation. Due to the existence of OVs and the construction of heterostructure, the Bi 2 MoO 6 /MIL-88B(Fe) composites exhibited significant enhancement of visible-light responsive range and possessed more efficient bulk & interface charge separation. This novel Bi 2 MoO 6 /MIL-88B(Fe) composites exhibited high visible light photocatalytic performance toward dye pollutant rhodamine B (RhB) and model colorless pollutant bisphenol A (BPA) photodegradation , and the possible Type II heterojunction mechanism of photocatalysis process was investigated. This work not only provides a novel pathway for design of MOFs-based heterojunction with surface OVs defect modification but also offers a strategy for significantly enhanced bulk & interface charge carriers separation.
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PROPELLANTS EXPLOSIVES PYROTECHNICS
·
2020
·Vol. 45
·期 3
·368-373
·
IF 1.544
Naimeng Song,Li Yang,Pingan Liu
In this study, the ultrasonic spray drying technology was applied to prepare composite microspheres of catalyst (Ta−Fe, Ph−Fe) and AP. The surface morphology of the two composite microspheres was characterized by scanning electron microscopy (SEM). Their particle size distribution characteristics were tested by a nano laser particle size analyzer. The results showed that the spray drying technology can uniformly compound the AP and the catalyst into spherical particles. The thermal decomposition process of Ta(Ph)-Fe/AP composite microspheres were tested by differential scanning calorimetry (DSC). The DSC data demonstrated that Ta(Ph)-Fe/AP composite microsphere had a very good catalytic effect and significantly promoted the thermal decomposition process of AP. In addition, the catalytic mechanism was discussed by calculating the change in activation energy. Compared with the raw AP, the activation energies of the Ta−Fe/AP and Ph−Fe/AP composite microspheres were reduced by 18.5 kJ/mol and 28.1 kJ/mol, respectively.
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Nanoscale Research Letters
·
2020
·Vol. 15
·期 1
·1-14
·
IF 3.578
Guo Chaozhong,Li Yanrong,Li Zhaoxu,Liu Yao,Si Yujun,Luo Zhongli
Designing appropriate methods to effectively enhance nitrogen-doping efficiency and active-site density is essential to boost the oxygen reduction reaction (ORR) activity of non-platinum Fe/N/C-type electrocatalysts. Here, we propose a facile and effective strategy to design a mesopore-structured Fe/N/C catalyst for the ORR with ultrahigh BET surface area and outstanding conductivity via nanochannels of molecular sieve-confined pyrolysis of Fe 2+ ions coordinated with 2,4,6-tri(2-pyridyl)-1,3,5-triazine complexes as a novel precursor with the stable coordination effect. Combining the nanochannel-confined effect with the stable coordination effect can synergistically improve the thermal stability and stabilize the nitrogen-enriched active sites, and help to control the loss of active N atoms during pyrolysis process and to further obtain a high active-site density for enhancing the ORR activity. The as-prepared Fe/N/C electrocatalyst has exhibited excellent catalytic activity with an onset potential of ~ 0.841 V (versus RHE) closely approaching the Pt/C catalyst and high long-term stability in alkaline electrolyte. Besides, low-hydrogen peroxide yield (< 6.5%) and high electron transfer number (3.88–3.94) can be found on this catalyst, indicating that it is a valuable substitute for traditional Pt/C catalysts. This work paves a new way to design high-performance Fe/N/C electrocatalysts and deepens the understanding of active site and ORR catalysis mechanism.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2020
·
IF 7.489
Jiuli Chang,Liming Chen,Shiqi Zang,Yifan Wang,Dapeng Wu,Fang Xu,Kai Jiang,Zhiyong Gao
A facile and efficient oxygen evolution reaction (OER) catalytic system was constructed based on interconnected Ni(OH) 2 nanosheets arrays electrode and Fe(III) containing alkali electrolyte. The partial deposition of Fe(III) onto Ni(OH) 2 with heterostructure obviously enhanced the OER current density and reduced the overpotential, and the Fe(III) cations in electrolyte also furnished positive contribution to the catalytic reaction, the synergy between Ni(OH) 2 electrode and Fe(III) cations in electrolyte therefore substantially improved the OER catalytic efficiency with low overpotential (285 mV at current density of 50 mA cm −2 ) and obviously enhanced current density (391 mA cm −2 at 1.8 V). The current work expands our understanding on the effect of Fe(III) cations in electrolyte to OER efficiency of Ni based catalyst, and opens up a cost-effective and practical avenue to enhance the OER catalytic efficiency by introducing metal cations in alkali electrolyte.
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MATERIALS & DESIGN
·
2020
·
IF 6.289
Yiqun Zhang,Yaqiang Dong,Bang Zhou,Qiang Chi,Liang Chang,Mengji Gong,Jianjun Huang,Yan Pan,Aina He,Jiawei Li,Xinmin Wang
In this work, dense and pinhole-free poly-para-xylylene (PPX) with high thermal stability, high insulating property and high lubricity has been designed as coating layer for Fe-based amorphous powder. Three ultra-thin PPX layers have been successfully deposited on the surface of FeSiBPNbCr amorphous powder via chemical vapor deposition (CVD) polymerization. The micromorphology and chemical structure of the PPX layer on the powder surface, as well as the conversion mechanisms, has been investigated systematically. Several methods have been used to estimate the amount and thickness of PPX layers. The corresponding amorphous powder cores (AMPCs) were also prepared. With the increasing thickness of the PPX layer, the saturation magnetization ( M s ) of the powder decreased slightly but the magnetic flux density ( B s ) of the AMPCs kept at a similar level thanked to the enhanced green density. In addition, the DC bias performance was improved and core loss ( P cv ) was reduced. Compare with other coating materials like epoxy and silicon resin, the PPX layer provided better insulation and higher lubricity for the AMPCs, thus reduced the P cv and improved the DC bias performance. The AMPCs coated by PPX-3 exhibited excellent comprehensive soft magnetic properties, which were promising for high-power and high-frequency applications.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2020
·
IF 6.551
Xiong Jia,Yujie He,Philippe F.-X. Corvini,Rong Ji
Humic substances are reactive during redox alteration. However, the role of this reactivity in the transformation of organic compounds and in carbon cycling in the environment is still unclear. Here, we used 14 C-radioactive tracer to study abiotic transformation and humification of catechol, a representative of naturally occurring monomeric phenols and phenolic pollutants, in suspensions of humic acids (HAs) at original and H 2 /Pd-reduced redox states with flux of air (HA org -Air and HA red -Air, respectively) or N 2 (HA org -N 2 and HA red -N 2 , respectively) for 20 min in absence and presence of Cu(II) and Fe(II). Both HA org and HA red can transform catechol in the absence of O 2 to 19% and 25% of the initially applied amount, respectively. The transformation of catechol strongly increased when air was introduced, amounting to 75% in HA red -Air treatment and 43% in HA org -Air treatment, owing to the generation of reactive oxygen species . Considerable amounts of catecholic carbons were incorporated into HAs (26% for HA red -Air and 19% for HA org -Air), constituting humification of catechol. The presence of Cu(II) strongly inhibited the overall transformation and humification of catechol, although it significantly increased humification at the start of incubation. The presence of Fe(II) overall enhanced both the transformation and humification. The results provide first insights into the impacts of redox alteration of humic substances together with the presence of metal ions with variable valences on the fate of phenolic compounds in the environment. This study points out that redox alteration-induced abiotic transformation may be one important process for dissipation of phenolic pollutants and humification of phenolic carbons in environments rich in HAs and subject to redox fluctuation.
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 5
·2102-2110
·
IF 3.288
Shuangyan Meng,Wei Zeng,Mingming Wang,Litong Niu,Shaoping Hu,Bitao Su,Yaoxia Yang,Zhiwang Yang,Qunji Xue
Polydopamine/MIL-53(Fe) (PDA/MIL-53(Fe)) nanocomposite photocatalysts were synthesized with PDA (PDA = polydopamine) and MIL-53(Fe) using a nature-mimicking method. The structures, morphologies, optical properties and thermal stabilities of all the synthesized materials were characterized using a series of methods. In particular, the separation efficiency of photogenerated charge significantly increased after the incorporation of PDA into MIL-53(Fe), which resulted in an elevated photocatalytic activity of PDA/MIL-53(Fe) compared with the control groups. The PDA/MIL-53(Fe) nanocomposite could accelerate the conversion of primary or secondary alcohols into the corresponding aldehydes or ketones with a high specificity by direct hole-involving oxidation under visible-light irradiation and room temperature. The catalysts could be cycled at least three times without a significant decrease in the catalytic activity and this result showed the excellent recyclability and stability of the catalysts.
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