Designing 3D-MoS2 Sponge as Excellent Cocatalysts in Advanced Oxidation Processes for Pollutant Control

3D-MoS₂ can adsorb organic molecules and provide multidimensional electron transport pathways, implying a potential application for environment remediation. Here, we study the degradation of aromatic organics in advanced oxidation processes (AOPs) by a 3D-MoS₂ sponge loaded with MoS₂ nanospheres and graphene oxide (GO). Exposed Mo⁴⁺ active sites on 3D-MoS₂ can significantly improve the concentration and stability of Fe²⁺ in AOPs and keep the Fe³⁺/Fe²⁺ in a stable dynamic cycle, thus effectively promoting the activation of H₂O₂/peroxymonosulfate (PMS). The degradation rate of organic pollutants in the 3D-MoS₂ system is about 50 times higher than without cocatalyst. After a 140 L pilot-scale experiment, it still maintains high efficiency and stable AOPs activity. After 16 days of continuous reaction, the 3D-MoS₂ achieves a degradation rate of 120 mg L⁻¹ antibiotic wastewater up to 97.87 %. The operating cost of treating a ton of wastewater is only US$ 0.33, suggesting huge industrial applications.     

Designing 3D‐MoS2 Sponge as Excellent Cocatalysts in Advanced Oxidation Processes for Pollutant Control

3D‐MoS₂ can adsorb organic molecules and provide multidimensional electron transport pathways, implying a potential application for environment remediation. Here, we study the degradation of aromatic organics in advanced oxidation processes (AOPs) by a 3D‐MoS₂ sponge loaded with MoS₂ nanospheres and graphene oxide (GO). Exposed Mo⁴⁺ active sites on 3D‐MoS₂ can significantly improve the concentration and stability of Fe²⁺ in AOPs and keep the Fe³⁺/Fe²⁺ in a stable dynamic cycle, thus effectively promoting the activation of H₂O₂/peroxymonosulfate (PMS). The degradation rate of organic pollutants in the 3D‐MoS₂ system is about 50 times higher than without cocatalyst. After a 140 L pilot‐scale experiment, it still maintains high efficiency and stable AOPs activity. After 16 days of continuous reaction, the 3D‐MoS₂ achieves a degradation rate of 120 mg L^?1 antibiotic wastewater up to 97.87 %. The operating cost of treating a ton of wastewater is only US$ 0.33, suggesting huge industrial applications.     

Y2SiO5:Ce3+荧光体的基质多面体替换及其对发光性能的调控研究

荧光材料基质的结构调制对于调控发光材料的发光性能,探索固体结构-性能关系具有重要的研究意义。本文以Y2SiO5基质为模型,分别利用Si/Al和Si/P取代,以[AlO4]和[PO4]四面体替换[SiO4]四面体,设计合成了一系列组成为Y1.95Si1-xAlxO5-xFx∶0.05Ce3+(x=0.05,x=0.1,x=0.2,x=0.4,x=1)和Y1.95-yCaySi1-yPyO5∶0.05Ce3+(y=0,y=0.02,y=0.04,y=0.06,y=0.08,y=0.2)的荧光材料。结合X射线衍射、荧光光谱、荧光寿命等测试手段对其进行了表征分析。结果表明,在x≤0.2,y≤0.04时得到的产物能够保持Y2SiO5的结构特征,在一定的基质组成替换范围内,设计合成的样品Y1.95Si1-xAlxO5-xFx∶0.05Ce3+、Y1.95-yCaySi1-yPyO5∶0.05Ce3+能提高发光强度,发射光谱呈现蓝移现象。荧光寿命测试表明这两个系列的化合物中Ce3+所处的基质环境变化较小,Ce3+发光也未产生较大的变化。     

"Small amount for multiple times" of H2O2 feeding way in MoS2-Fex heterogeneous fenton for enhancing sulfadiazine degradation

In recent years, MoS₂catalyzed/cocatalyzed Fenton/Fenton-like systems have attracted wide attention in the field of pollution control, but there are few studies on the effect of H₂O₂ feeding way on the whole Fenton process. Here, we report a new type of composite catalyst（MoS₂-Fex） prepared in a simple way with highly dispersed iron to provide more active sites. MoS₂-Fexwas proved to possess selectivity for singlet oxygen（1O2） in effectively...     

纳米CexFe1-xO2固溶体的模板法制备及其乙醇水蒸气重整催化性能

以超高比表面炭材料为模板,硝酸盐为氧化物前体,通过改进的模板路线制备了具有较高比表面积的纳米CexFe1-xO2固溶体.采用X射线衍射、拉曼光谱、物理吸附和透射电镜对制备的样品进行了表征.结果表明,α-Fe2O3,CexFe1-xO2固溶体和CeO2的粒子尺寸为5~15nm,CeO2中部分Ce4 离子被Fe3 离子取代,从而形成了CexFe1-xO2固溶体.乙醇水蒸气重整反应结果显示,CexFe1-xO2固溶体比相应的α-Fe2O3和CeO2具有更高的催化活性和对氢气的选择性.     

The Photo-Fenton Oxidation — A cheap and efficient wastewater treatment method

Advanced Oxidation Processes (AOPs) for wastewater treatment are gaining more importance since biological treatment plants are often not sufficient for highly contaminated or toxic wastewaters. In order to find out the most efficient and cheap AOP, investigations were concentrated on methods that can use sunlight. The systems TiO₂/UV, Fe²⁺/H₂O₂/UV (Photo-Fenton reaction), Fe²⁺/O₂/UV and Fe²⁺/O₃/UV were compared. Since the Photo-Fenton system was the most effective, pilot plant experiments with industrial wastewaters and sunlight experiments were carried out. Finally a rough cost estimate shows that Photo-Fenton treatment with sunlight is far cheaper than other available AOPs, namely ozonization.     

Y2O3 and MgO co-doped ceria based electrolytes

Electrolytes of Ce_1-x-y Y _x Mg _y O_2-0.5x-y were prepared with citrate method and were characterized by inductively coupled plasma-atomic emission spectrometry, energy dispersive spectrometry, powder X-ray diffraction, and impedance spectroscopy. The effect of composition on the structure, conductivity, and stability of the electrolytes were investigated. When 0≤x≤ about 0.2 and 0≤y≤ about 0.05, the electrolytes were all single phase materials of ceria-based solid solution. However, when y> about 0.05, the electrolytes became two-phase materials, Y³⁺ and Mg²⁺ co-doped ceria-based solid solution and free MgO. The sample with nominal composition of Ce_0.815Y_0.065Mg_0.12O_2-d showed ionic conductivity at 973 K close to or even a little higher than that of similarly prepared Ce_0.9Gd_0.1O_1.95, but had lower cost of raw materials and a little better stability in reducing atmosphere. The existing of free MgO improved the stability of the electrolytes in reducing atmosphere, but too much free MgO reduced the conductivity.     

The carbon nanotubes-based materials and their applications for organic pollutant removal:A critical review

The carbon nanotubes(CNTs) as the emerging materials for organic pollutant removal have gradually become a burgeoning research field.Herein,a mini-review of CNTs-based materials curre ntly studies for organic pollutant elimination is presented.This review summarizes the preparation methods of CNTsbased materials.CNTs-based materials can be used as adsorbents to remove organic pollutants in wastewater.The adsorption mechanisms mainly include surface diffusio n,pore diffusion and adsorption reaction.Most importantly,an in-depth overview of CNTs-based materials currently available in advanced oxidation processes(AOPs) applications for wastewater treatment is proposed.CNTs-based materials can catalyze different oxidants(e.g.,hydrogen peroxide(H_2 O_2),persulfates(PMS/PDS),ozone(O_3) and ferrate/permanganate(Fe(Ⅵ)/Mn(Ⅶ)) to generate more reactive oxygen species(ROS) for organic pollutant elimination.Moreover,the possible reaction mechanisms of removing organic pollutants by CNTs-based materials are summarized systematically and discussed in detail.Finally,application potential and future research directions of CNTs-based materials in the environmental remediation field are proposed.     

Electrochemical performance of spindle-like Fe2Co-MOF and derived magnetic yolk-shell CoFe2O4 microspheres for supercapacitor applications

Nanostructured cobalt ferrite (CoFe₂O₄) has been synthesized by a two-step process, a facile ultrasonic-assisted solvothermal technique for Fe₂Co-MOF preparation and subsequent calcination. X-ray diffraction (XRD) patterns confirm the formation of MIL-88A(Fe) structure of Fe₂Co-MOF and the cubic spinel structure of CoFe₂O₄. Field emission scanning electron microscope (FESEM) images reveal that calcination process converts the spindle-like morphology of Fe₂Co-MOF to yolk-shell CoFe₂O₄ microspheres. From Brunauer–Emmett–Teller (BET) analysis, the specific surface areas of 36.0 and 29.2 m² g^?1 are measured for Fe₂Co-MOF and CoFe₂O₄, respectively. Vibrating sample magnetometer (VSM) analysis of CoFe₂O₄ displays high coercivity of 2500 Oe due to surface anisotropy. Conversion of Fe₂Co-MOF to CoFe₂O₄ reduces the optical band gap from 1.92 to 1.77 eV. Electrochemical performance of Fe₂Co-MOF and CoFe₂O₄ deposited on Ni foams (NFs) is examined by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) tests. Specific capacitances of 489.9 and 192.6 F g^?1 have been achieved from GCD curves at a current density of 1 A g^?1 for Fe₂Co-MOF/NF and CoFe₂O₄/NF electrodes, respectively. Fe₂Co-MOF/NF electrode exhibits more cyclic stability than CoFe₂O₄/NF electrode after 3000 cycles.

     

Magnetically separable CoFe2O4/CoxFey/activated carbon composites for Cd(II) removal from wastewater

CoFe₂O₄ and Co_x Fe_y were anchored into activated carbon (AC) to synthesize CoFe₂O₄/Co_x Fe_y /AC composites using the sol–gel method for Cd(II) adsorption from wastewater. The results indicated that CoFe₂O₄ and Co_x Fe_y nanoparticles existed in the pores of AC. The magnetic properties of CoFe₂O₄/Co_x Fe_y /AC indicated it could be separated and retrieved easily using an external magnet after Cd(II) adsorption. The effects of solution pH, temperature and initial Cd(II) concentration on the Cd(II) adsorption of AC and CoFe₂O₄/Co_x Fe_y /AC were investigated. The standard free energy, enthalpy change and entropy change were evaluated. The kinetic parameters of Langmuir and Freundlich isothermal equation were analyzed, and the Freundlich kinetic model was feasible for describing the Cd(II) adsorption process of CoFe₂O₄/Co_x Fe_y /AC composites.     

Control over the self-assembly of polymers and layered molybdenum oxide: from the micrometer scale to the molecular scale

We report adjustment on the self-assembly between polymer of polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) and inorganic molybdenum oxide layers from the micrometer scale to the nanometer scale. Our method is to break the strong interactions between the organic polymers by introducing suitable bridging agents and adjust the reaction speeds of the two competitive reactions in the reaction system. We use I₂ to complex with PVA and break the strong hydrogen interactions between the PVA chains, resulting in a PVA-I₂/(Mo_xO_y)_∞ⁿ⁻ complex, in which the organic and inorganic species self-assemble homogenously on the molecular scale. We also adjust the thickness of the inorganic (Mo_xO_y)_∞ⁿ⁻ layers in the hybrid of PVP/(Mo_xO_y)_∞ⁿ⁻ by controlling the reaction speeds of the two competitive reactions: hydrolysis of Mo₇O₂₄ ⁶⁻ into (Mo_xO_y)_∞ⁿ⁻ and packing into thick inorganic layers on the one hand, and hybridization of (Mo_xO_y)_∞ⁿ⁻ and PVP into layered hybrid on the other hand. Experimental results proved that when the hydrolysis is overwhelming, the inorganic molybdenum oxide chains pack into heavy layers and self-assemble with PVP polymers on the micrometer scale, and when the hybrid reaction dominates, the organic polymer and molybdenum oxide hybridize on the molecular scale. These findings open new routes to disperse organic polymer and inorganic species homogenously and fabricate novel organic/inorganic hybrid nanomaterials in situ.     

Ferromagnetic and dielectric properties of lead free KNbO3-CoFe2O4 composites

Multiferroic (1-x)KNbO₃-(x)CoFe₂O₄ (x = 0.0, 0.25, 0.5, 0.75 and 1.0 mol) composites were prepared by solid state reaction method. X-ray diffraction results showed that the prepared (1-x)KNbO₃-(x)CoFe₂O₄ composites belong to orthorhombic system for x = 0.0 (perovskite KNbO₃), cubic system for x = 1.0 (spinel CoFe₂O₄) and mixed phase of KNbO₃ and CoFe₂O₄ for x = 0.25, 0.5 and 0.75. Nb-O and Fe-O stretching vibrational modes were observed in the Fourier transform and Raman spectral analyses, respectively. The HR-SEM analysis showed that the morphology of KNbO₃ and CoFe₂O₄ composites was significantly modified by CoFe₂O₄ content. Energy dispersive X-ray spectroscopy results confirmed the presence of K, Nb, Fe, Co and O in (1-x)KNbO₃-(x)CoFe₂O₄ composites. The ionic state of Nb, Co, Fe and O was examined by X-ray photoelectron spectroscopy analysis. The high value of coercivity (H_c = ∼981Oe) for x = 0.5 and the enhanced dielectric constant for x = 0.5 and 0.75 were observed.     

Sustainable activation of peroxymonosulfate by the Mo(IV) in MoS2 for the remediation of aromatic organic pollutants

Although MoS₂ has been proved to be a very ideal cocatalyst in advanced oxidation process (AOPs), the activation process of peroxymonosulfate (PMS) is still inseparable from metal ions which inevitably brings the risk of secondary pollution and it is not conducive to large-scale industrial application. In this study, the commercial MoS₂, as a durable and efficient catalyst, was used for directly activating PMS to degrade aromatic organic pollutant. The commercial MoS₂/PMS catalytic system demonstrated excellent removal efficiency of phenol and the total organic carbon (TOC) residual rate reach to 25%. The degradation rate was significantly reduced if the used MoS₂ was directly carried out the next cycle experiment without any post-treatment. Interestingly, the commercial MoS₂ after post-treated with H₂O₂ can exhibit good stability and recyclability for cyclic degradation of phenol. Furthermore, the mechanism for the activation of PMS had been investigated by density functional theory (DFT) calculation. The renewable Mo⁴⁺ exposed on the surface of MoS₂ was deduced as the primary active site, which realized the direct activation of PMS and avoided secondary pollution. Taking into account the reaction cost and efficient activity, the development of commercial MoS₂ catalytic system is expected to be applied in industrial wastewater.     

Ni_xCu_(1-x)Fe_2O_4的H_2/CO_2氧化还原反应性能

完全还原的NixCu1-xFe2O4(x=0.25,0.5,0.75)可用来分解CO2。采用共沉淀法制备了NixCu1-xFe2O4(x=0.25,0.5,0.75)系列铁酸盐的纳米微粒,利用H2-TG数据分析NixCu1-xFe2O4(x=0.25,0.5,0.75)中Cu2+的还原反应动力学数据,得出表观活化能Ea并不是单纯随着Ni2+或Cu2+含量的变化而变化,当x=0.25时反应活化能具有最大值。通过CO2-TG比较不同样品经H2完全还原后分解CO2的活性,得出Ni0.5Cu0.5Fe2O4具有最低的起始反应温度和最大的分解活性,并采用XRDRietveld拟合方法对Ni0.5Cu0.5Fe2O4的完全还原产物和分解CO2产物进行物相分析。     

Selective Production of CO from Organic Pollutants by Coupling Piezocatalysis and Advanced Oxidation Processes

To date, the chemical conversion of organic pollutants into value-added chemical feedstocks rather than CO₂ remains a major challenge. Herein, we successfully developed a coupled piezocatalytic and advanced oxidation processes (AOPs) system for achieving the conversion of various organic pollutants to CO. The CO product stems from the specific process in which organics are first oxidized to carbonate through peroxymonosulfate (PMS)-based AOPs, and then the as-obtained carbonate is converted into CO by piezoelectric reduction under ultrasonic (US) vibration by using a Co₃S₄/MoS₂ catalyst. Experiments and DFT calculations show that the introduction of Co₃S₄ not only effectively promotes the transfer and utilization of piezoelectric electrons but also realizes highly selective conversion from carbonate to CO. The Co₃S₄/MoS₂/PMS system has achieved selective generation of CO in actual complex wastewater treatment for the first time, indicating its potential practical applicability.     

Effect of Fe2O3 Content on the Local Structure and Crystallization Mechanism of Calcium Gallate Glasses

⁵⁷Fe Mössbauer and FT-IR of 60CaO·(40-x)Ga₂O₃·xFe₂O₃ glasses revealed that Fe(III)O₄ tetrahedra occupy substitutional sites of Ga(III)O₄ tetrahedra. The activation energy for crystallizaation (E _a) obtained from DTA study decreases distinctly from 8.9 to 4.8 eV with an increase in the Fe₂O₃ content. In the case of 40CaO·(60-x)Ga₂O₃·xFe₂O₃ glasses, a week doublet due to Fe(II)O₄ tetrahedra or Fe(III)O₆ octahedra was observed in addition to Fe(III)O₄ tetrahedra. The E _avalue decreases gradually from 7.1 to 5.6 eV with an increasing Fe₂O₃ content. These results indicate that a large amount of Fe₂O₃ in the network structure is favorable for the crystallization of calcium gallate glass, since it reduces the chemical bond strength.     

AxMn1-xFe2O4铁氧体(A=Zn,Ni)中阳离子的占位有序化行为研究

基于尖晶石晶体结构信息,本文采用热力学三亚晶格模型,将材料热力学计算和第一性原理计算相结合,研究了Zn_xMn_(1-x) Fe_2O_4和Ni_xMn_(1-x)Fe_2O_4立方相中的Zn~(2+)、Ni~(2+)、Mn~(2+)以及Fe~(3+)在8a和16d亚晶格上的占位有序化行为。结果表明:在锰铁氧体中,室温下Mn~(2+)完全占据在8a亚晶格上,Fe~(3+)完全占据在16d亚晶格上,属于正尖晶石结构;随着热处理温度升高,在1 273 K达到热处理平衡时的占位构型为(Fe~(3+)0.09Mn~(2+)0.91)[Fe~(3+)1.91Mn~(2+)0.09]O_4,在热处理温度升至1 473 K时,达到热处理平衡时的占位构型为(Fe~(3+)0.11Mn~(2+)0.89)[Fe~(3+)1.89Mn~(2+)0.11]O_4,均与实验结果符合较好。在锌铁氧体中,室温下Zn~(2+)完全占据在8a亚晶格上,Fe~(3+)完全占据在16d亚晶格上,属于正尖晶石结构;在热处理温度较高时,Zn~(2+)和Fe~(3+)发生部分置换,符合实验结果。在镍铁氧体中,半数的Fe~(3+)在室温下占据在8a亚晶格上,Ni~(2+)与剩下另一半的Fe~(3+)共同占据在16d亚晶格上,仅在热处理温度较高的时候发生微弱变化,亦与已有的实验结果吻合。在此基础上,本文进一步通过热力学模型研究了立方相尖晶石结构的Zn_xMn_(1-x)Fe_2O_4、Ni_xMn_(1-x)Fe_2O_4复合体系中阳离子占位行为与热处理温度对占位的影响规律。     

空气中合成固溶体荧光粉Ba_2(Zn,Mg)Si_2O_7∶Eu~(2+),Eu~(3+),Ce~(3+)及其发光特性

采用高温固相法在空气中合成了Ba1.97-yZn1-xMgxSi2O7∶0.03Eu,y Ce3+系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba1.97-yZn1-xMgxSi2O7∶0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu2+离子的4f 65d1-4f 7跃迁,590~725 nm红光区窄带谱源于Eu3+的5D0-7FJ(J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu3+在Ba1.97-yZn1-xMgxSi2O7基质中被还原成了Eu2+;当x=0.1时,荧光粉Ba1.97Zn0.9Mg0.1Si2O7∶0.03Eu的绿色发光最强,表明Eu3+被还原成Eu2+离子的程度最大。当共掺入Ce3+离子后,形成Ba1.97-yZn0.9Mg0.1Si2O7∶0.03Eu,y Ce3+荧光粉体系,其发光随着Ce3+离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba1.96Zn0.9Mg0.1Si2O7∶0.03Eu,0.01Ce3+的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba2Zn0.9Mg0.1Si2O7基质中的能量传递与发光机理。     

Solid state reaction synthesis of filled skutterudite compounds (Ce or Y)yFexCo4-xSb12 and the effect of filling atoms Ce or Y on lattice thermal conductivity

The synthesis of filled skutterudite compounds (Ce or Y)yFexCo₄-xSb12, through a solid state reaction using chloride of Ce or Y, high purity powder of Co, Fe, and Sb as starting materials, was investigated. (Ce or Y)yFexCo₄-xSb12 (x = 0 1.0,y = 0 0.15) compounds were obtained at 850 1 123 K. The results of Rietveld analysis demonstrate that (Ce or Y)yFexCo₄-xSb12 synthesized by a solid state reaction possesses a filled skutterudite structure. The filling fraction of Ce or Y obtained by Rietveld analysis agrees well with the composition obtained by chemical analysis. The lattice constant of CeyFexCo₄-xSb12 increases with increasing substitution of Fe at Co sites, and with an increasing Ce filling fraction in the Sb-dodecahedron voids. The lattice thermal conductivity of (Ce or Y)yFexCo₄-xSb12 decreases significantly with an increasing Ce or Y filling fraction in the voids and with substitution of Fe at Co sites.     

Study on catalytic mechanisms of Fe3O4-rGOx in three typical advanced oxidation processes for tetracycline hydrochloride degradation

This study explored the catalytic mechanism and performance impacted by the materials ratio of Fe₃O₄-GO_x composites in three typical advanced oxidation processes (AOPs) of O₃, peroxodisulfate (PDS) and photo-Fenton processes for tetracycline hydrochloride (TCH) degradation. The ratio of GO in the Fe₃O₄-GO_x composites exhibited different trends of degradation capacity in each AOPs based on different mechanisms. Fe₃O₄-rGO_20wt% exhibited the optimum catalytic performance which enhanced the ozone decomposition efficiency from 33.48% (ozone alone) to 51.83% with the major reactive oxygen species (ROS) of O₂^??. In PDS and photo-Fenton processes, Fe₃O₄-rGO_5wt% had the highest catalytic performance in PDS and H₂O₂ decomposition for SO₄^??, and ^?OH generation, respectively. Compared with using PDS alone, PDS decomposition rate and TCH degradation rate could be increased by 5.97 and 1.73 times under Fe₃O₄-rGO_5wt% catalysis. In the photo-Fenton system, Fe₃O₄-rGO_5wt% with the best catalyst performance in H₂O₂ decomposition, and TCH degradation rate increased by 2.02 times compared with blank group. Meantime, the catalytic mechanisms in those systems of that the ROS produced by conversion between Fe²⁺/Fe³⁺ were also analyzed.