共查询到20条相似文献,搜索用时 15 毫秒
1.
Salt‐Induced Fabrication of Superhydrophilic and Underwater Superoleophobic PAA‐g‐PVDF Membranes for Effective Separation of Oil‐in‐Water Emulsions 下载免费PDF全文
Wenbin Zhang Yuzhang Zhu Xia Liu Dr. Dong Wang Prof. Jingye Li Prof. Lei Jiang Prof. Jian Jin 《Angewandte Chemie (International ed. in English)》2014,53(3):856-860
Conventional polymer membranes suffer from low flux and serious fouling when used for treating emulsified oil/water mixtures. Reported herein is the fabrication of a novel superhydrophilic and underwater superoleophobic poly(acrylic acid)‐grafted PVDF filtration membrane using a salt‐induced phase‐inversion approach. A hierarchical micro/nanoscale structure is constructed on the membrane surface and endows it with a superhydrophilic/underwater superoleophobic property. The membrane separates both surfactant‐free and surfactant‐stabilized oil‐in‐water emulsions under either a small applied pressure (<0.3 bar) or gravity, with high separation efficiency and high flux, which is one to two orders of magnitude higher than those of commercial filtration membranes having a similar permeation property. The membrane exhibits an excellent antifouling property and is easily recycled for long‐term use. The outstanding performance of the membrane and the efficient, energy and cost‐effective preparation process highlight its potential for practical applications. 相似文献
2.
Dr. Savio J. A. Moniz Dr. Stephen A. Shevlin Dr. Xiaoqiang An Prof. Zheng‐Xiao Guo Dr. Junwang Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15571-15579
Photocatalysis provides a cost effective method for both renewable energy synthesis and environmental purification. Photocatalytic activity is dominated by the material design strategy and synthesis methods. Here, for the first time, we report very mild and effective photo‐deposition procedures for the synthesis of novel Fe2O3–TiO2 nanocomposites. Their photocatalytic activities have been found to be dramatically enhanced for both contaminant decomposition and photoelectrochemical water splitting. When used to decompose a model contaminant herbicide, 2,4‐dichlorophenoxyacetic acid (2,4‐D), monitored by both UV/Vis and total organic carbon (TOC) analysis, 10 % Fe–TiO2–H2O displayed a remarkable enhancement of more than 200 % in the kinetics of complete mineralisation in comparison to the commercial material P25 TiO2 photocatalyst. Furthermore, the photocurrent is nearly double that of P25. The mechanism for this improvement in activity was determined using density functional theory (DFT) and photoluminescence. These approaches ultimately reveal that the photoelectron transfer is from TiO2 to Fe2O3. This favours O2 reduction which is the rate‐determining step in photocatalytic environmental purification. This in situ charge separation also allows for facile migration of holes from the valence band of TiO2 to the surface for the expected oxidation reactions, leading to higher photocurrent and better photocatalytic activity. 相似文献
3.
Dr. Zhihua Qiao Dr. Song Zhao Prof. Dr. Jixiao Wang Prof. Dr. Shichang Wang Prof. Dr. Zhi Wang Prof. Dr. Michael D. Guiver 《Angewandte Chemie (International ed. in English)》2016,55(32):9321-9325
Highly permeable montmorillonite layers bonded and aligned with the chain stretching orientation of polyvinylamineacid are immobilized onto a porous polysulfone substrate to fabricate aligned montmorillonite/polysulfone mixed‐matrix membranes for CO2 separation. High‐speed gas‐transport channels are formed by the aligned interlayer gaps of the modified montmorillonite, through which CO2 transport primarily occurs. High CO2 permeance of about 800 GPU is achieved combined with a high mixed‐gas selectivity for CO2 that is stable over a period of 600 h and independent of the water content in the feed. 相似文献
4.
《化学:亚洲杂志》2017,12(3):314-323
Self‐standing TiO2 nanotube layers in the form of membranes are fabricated by self‐organizing anodization of Ti metal and a potential shock technique. The membranes are then decorated by sputtering different Pt amounts i) only at the top, ii) only at the bottom or iii) at both top and bottom of the tube layers. The Pt‐decorated membranes are transferred either in tube top‐up or in tube top‐down configuration onto FTO slides and are investigated, after crystallization, as photocatalysts for H2 generation using either front or back‐side light irradiation. Double‐side Pt‐decoration of the tube membranes leads to higher H2 generation rates (independently of tube and light‐irradiation configuration) compared to membranes decorated at only one side with similar overall Pt amounts. The results suggest that this effect cannot be only ascribed to the overall amount of Pt co‐catalyst as such but also to its distribution at both tube extremities. This leads to optimized light absorption and electron diffusion/transfer dynamics: the central part of the membranes acts as light‐harvesting zone and electrons therein generated can diffuse towards the Pt/TiO2 active zones (tube extremities) where they can react with the environment and generate H2. 相似文献
5.
Junyi Liu Xianda Hou Dr. Ho Bum Park Dr. Haiqing Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):15980-15990
This Concept examines strategies to design advanced polymers with high CO2 permeability and high CO2/N2 selectivity, which are the key to the success of membrane technology for CO2 capture from fossil fuel‐fired power plants. Specifically, polymers with enhanced CO2 solubility and thus CO2/N2 selectivity are designed by incorporating CO2‐philic groups in polymers such as poly(ethylene oxide)‐containing polymers and poly(ionic liquids); polymers with enhanced CO2 diffusivity and thus CO2 permeability are designed with contorted rigid polymer chains to obtain high free volume, such as polymers with intrinsic microporosity and thermally rearranged polymers. The underlying rationales for materials design are discussed and polymers with promising CO2/N2 separation properties for CO2 capture from flue gas are highlighted. 相似文献
6.
Wenyuan Fang Prof. Libin Liu Ting Li Zhao Dang Dr. Congde Qiao Dr. Jinku Xu Yanyan Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):878-883
Membranes with special functionalities, such as self‐cleaning, especially those for oil/water separation, have attracted much attention due to their wide applications. However, they are difficult to recycle and reuse after being damaged. Herein, we put forward a new N‐substituted polyurethane membrane concept with self‐healing ability to address this challenge. The membrane obtained by electrospinning has a self‐cleaning surface with an excellent self‐healing ability. Importantly, by tuning the membrane composition, the membrane exhibits different wettability for effective separation of oil/water mixtures and water‐in‐oil emulsions, whilst still displaying a self‐healing ability and durability against damage. To the best of our knowledge, this is the first report to demonstrate a self‐healing membrane for oil/water separation, which provides the fundamental research for the development of advanced oil/water separation materials. 相似文献
7.
Composite photocatalyst films have been fabricated by depositing BiVO4 upon TiO2 via a sequential ionic layer adsorption reaction (SILAR) method. The photocatalytic materials were investigated by XRD, TEM, UV/Vis diffuse reflectance, inductively coupled plasma optical emission spectrometry (ICP‐OES), XPS, photoluminescence and Mott–Schottky analyses. SILAR processing was found to deposit monoclinic‐scheelite BiVO4 nanoparticles onto the surface, giving successive improvements in the films′ visible light harvesting. Electrochemical and valence band XPS studies revealed that the prepared heterojunctions have a type II band structure, with the BiVO4 conduction band and valence band lying cathodically shifted from those of TiO2. The photocatalytic activity of the films was measured by the decolourisation of the dye rhodamine 6G using λ>400 nm visible light. It was found that five SILAR cycles was optimal, with a pseudo‐first‐order rate constant of 0.004 min?1. As a reference material, the same SILAR modification has been made to an inactive wide‐band‐gap ZrO2 film, where the mismatch of conduction and valence band energies disallows charge separation. The photocatalytic activity of the BiVO4–ZrO2 system was found to be significantly reduced, highlighting the importance of charge separation across the interface. The mechanism of action of the photocatalysts has also been investigated, in particular the effect of self‐sensitisation by the model organic dye and the ability of the dye to inject electrons into the photocatalyst′s conduction band. 相似文献
8.
Efficient Noble‐Metal‐Free γ‐Fe2O3@NiO Core–Shell Nanostructured Photocatalysts for Water Oxidation 下载免费PDF全文
Flowerlike noble‐metal‐free γ‐Fe2O3@NiO core–shell hierarchical nanostructures have been fabricated and examined as a catalyst in the photocatalytic oxidation of water with [Ru(bpy)3](ClO4)2 as a photosensitizer and Na2S2O8 as a sacrificial electron acceptor. An apparent TOF of 0.29 μmols?1 m?2 and oxygen yield of 51 % were obtained with γ‐Fe2O3@NiO. The γ‐Fe2O3@NiO core–shell hierarchical nanostructures could be easily separated from the reaction solution whilst maintaining excellent water‐oxidation activity in the fourth and fifth runs. The surface conditions of γ‐Fe2O3@NiO also remained unchanged after the photocatalytic reaction, as confirmed by X‐ray photoelectron spectroscopy (XPS). 相似文献
9.
合成了一系列磷酸和二元羧酸酯化交联改性的聚乙烯醇(PVA)膜,研究了它们用于水-乙醇混合液的渗透气化分离规律。磷酸改性的PVA膜具有较大的通量,当料液浓度为50%时,通量可达1200g/m~2·hr.,分离系数α_(H_2O/EtOH)=10。丙二酸改性PVA膜在料液浓度为50%时,通量可达800g/m~2·hr.,且α_(H_2O/EtOH)=18。并作了这两种膜的通量和分离系数随料液浓度的变化曲线。草酸交联的PVA膜具有较高的分离系数,但通量很小。求出了水、乙醇及总的表现渗透活化能。 相似文献
10.
A membrane consisting of TiO2 nanofibers was successfully fabricated through a simple solvothermal water/n‐hexane interface reaction of tetra‐n‐butyl titanate with NaOH followed by post treatments of acid washing and calcination. Tetra‐n‐butyl titanate reacts with NaOH at the interface to form high‐quality nanofibers with lateral dimensions below 200 nm and longitudinal dimensions of several tens of micrometers. The membrane is formed by the interpenetration and overlapping of the flexible nanofibers and distributed by holes with sizes ranging from several tens of nanometers to several hundreds of nanometers. Because of the porous structure, this nanofiber membrane exhibited a high efficiency in the photodecomposition of dyes in water. 相似文献
11.
Biomimetic Superhydrophobic/Superoleophilic Highly Fluorinated Graphene Oxide and ZIF‐8 Composites for Oil–Water Separation 下载免费PDF全文
Dr. Kolleboyina Jayaramulu Dr. Kasibhatta Kumara Ramanatha Datta Christoph Rösler Martin Petr Prof. Dr. Michal Otyepka Prof. Dr. Radek Zboril Prof. Dr. Roland A. Fischer 《Angewandte Chemie (International ed. in English)》2016,55(3):1178-1182
Superhydrophobic/superoleophilic composites HFGO@ZIF‐8 have been prepared from highly fluorinated graphene oxide (HFGO) and the nanocrystalline zeolite imidazole framework ZIF‐8. The structure‐directing and coordination‐modulating properties of HFGO allow for the selective nucleation of ZIF‐8 nanoparticles at the graphene surface oxygen functionalities. This results in localized nucleation and size‐controlled ZIF‐8 nanocrystals intercalated in between HFGO layers. The composite microstructure features fluoride groups bonded at the graphene. Self‐assembly of a unique micro‐mesoporous architecture is achieved, where the micropores originate from ZIF‐8 nanocrystals, while the functionalized mesopores arise from randomly organized HFGO layers separated by ZIF‐8 nanopillars. The hybrid material displays an exceptional high water contact angle of 162° and low oil contact angle of 0° and thus reveals very high sorption selectivity, fast kinetics, and good absorbencies for nonpolar/polar organic solvents and oils from water. Accordingly, Sponge@HFGO@ZIF‐8 composites are successfully utilized for oil–water separation. 相似文献
12.
通过静电纺丝法制备出含有Fe3O4纳米微粒的TiO2纳米纤维,再采用浸渍还原法将Au纳米微粒嵌入到TiO2纳米纤维上,制备出一种具有较强磁性和良好可见光响应能力的复合光催化材料.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外-可见固体漫反射光谱仪(UV-VisDRS)等对样品的结构和形貌进行表征,并以降解罗丹明B(RhB)为模型反应,考察了样品在可见光照射下的光催化性能.结果表明,嵌入Au纳米微粒可使复合纳米纤维在可见光下降解RhB时表现出非常好的降解速率和降解率;同时,将Fe3O4纳米微粒嵌入TiO2纳米纤维内部可以赋予材料较强的磁性,使材料便于分离和重复利用. 相似文献
13.
A Superamphiphobic Coating with an Ammonia‐Triggered Transition to Superhydrophilic and Superoleophobic for Oil–Water Separation 下载免费PDF全文
Dr. Zhiguang Xu Dr. Yan Zhao Dr. Hongxia Wang Prof. Xungai Wang Prof. Tong Lin 《Angewandte Chemie (International ed. in English)》2015,54(15):4527-4530
Superhydrophilic and superoleophobic materials are very attractive for efficient and cost‐effective oil–water separation, but also very challenging to prepare. Reported herein is a new superamphiphobic coating that turns superhydrophilic and superoleophobic upon ammonia exposure. The coating is prepared from a mixture of silica nanoparticles and heptadecafluorononanoic acid‐modified TiO2 sol by a facile dip‐coating method. Commonly used materials, including polyester fabric and polyurethane sponge, modified with this coating show unusual capabilities for controllable filtration of an oil–water mixture and selective removal of water from bulk oil. We anticipate that this novel coating may lead to the development of advanced oil–water separation techniques. 相似文献
14.
Dr. Jay C. Bullen Hany F. Heiba Dr. Andreas Kafizas Prof. Dominik J. Weiss 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(16):e202104181
Composite photocatalyst-adsorbents such as TiO2/Fe2O3 are promising materials for the one-step treatment of arsenite contaminated water. However, no previous study has investigated how coupling TiO2 with Fe2O3 influences the photocatalytic oxidation of arsenic(III). Herein, we develop new hybrid experiment/modelling approaches to study light absorption, charge carrier behaviour and changes in the rate law of the TiO2/Fe2O3 system, using UV-Vis spectroscopy, transient absorption spectroscopy (TAS), and kinetic analysis. Whilst coupling TiO2 with Fe2O3 improves total arsenic removal by adsorption, oxidation rates significantly decrease (up to a factor of 60), primarily due to the parasitic absorption of light by Fe2O3 (88 % of photons at 368 nm) and secondly due to changes in the rate law from disguised zero-order kinetics to first-order kinetics. Charge transfer across this TiO2-Fe2O3 heterojunction is not observed. Our study demonstrates the first application of a multi-adsorbate surface complexation model (SCM) towards describing As(III) oxidation kinetics which, unlike Langmuir-Hinshelwood kinetics, includes the competitive adsorption of As(V). We further highlight the importance of parasitic light absorption and catalyst fouling when designing heterogeneous photocatalysts for As(III) remediation. 相似文献
15.
采用高温固相反应法合成了Cr2O3/TiO2复合材料, 运用X射线衍射(XRD)、扫描电子显微镜(SEM)、充放电测试、循环伏安(CV)、电化学阻抗谱(EIS)等对其结构、形貌和电化学性能进行了表征. 研究结果表明: TiO2掺杂能够显著改善Cr2O3的充放电循环性能, Cr2O3/TiO2复合材料在充放电循环22周后仍有454 mAh·g-1的可逆循环容量, 容量保持率达到了73.6%, 主要归因于TiO2掺杂能够显著提高Cr2O3的电导率. Cr2O3/TiO2复合材料首次放电过程中由于电极体积膨胀导致的固体电解质相界面(SEI)膜迅速增厚和活性材料电导率的降低可能是其首次充放电过程中存在较大不可逆容量和循环容量衰减的重要原因. 相似文献
16.
制备了新型纳米B2O3/TiO2吸附材料,并采用扫描电镜(SEM)及红外光谱(IR)对其进行表征,优化了纳米B2O3/TiO2复合材料对试液中痕量银的吸附和解吸条件,建立了纳米B2O3/TiO2分离富集-原子吸收光谱测定痕量银的新方法。当pH 4.3时,在22℃下振荡20 min,Ag+能被该材料快速吸附,其静态饱和吸附容量为11.72 mg/g,吸附在纳米B2O3/TiO2上的Ag+可用0.1 mol/L HNO3-0.05 mol/L硫脲(1∶4)完全洗脱。该方法的检出限为2.01μg/L,线性范围为0.01~4.00 mg/L,相对标准偏差(RSD)为1.8%,加标回收率为95%~105%。方法应用于实际矿渣样品中痕量银的测定,结果满意。 相似文献
17.
Songtao Liu Rui Yan Muhammad Humayun Huanli Zhang Yang Qu Yingxue Jin 《Molecules (Basel, Switzerland)》2022,27(17)
It is highly desired to enhance charge separation and O2 adsorption of the pyropheophorbide-a (Ppa) to promote visible-light activity and stability. Herein, Ppa modified 001-facet-exposed TiO2 nanosheets (Ppa/001T) nanocomposites with different weight ratios were fabricated via the self-assembly approach by OH induced. Compared with the bare Ppa, the 8% amount optimized 8Ppa/001T sample displayed 41-fold enhanced activity for degradation of Ametryn (AME) under visible-light irradiation. The promoted photoactivities could be attributed to the accelerated charge carrier’s separation by coupling TiO2 as thermodynamic platform for accepting the photoelectrons with high energy from Ppa and the promoted O2 adsorption because of the residual fluoride on TiO2. As for this, a distinctive two radicals (•O2− and •OH) involved pathway of AME degradation is carried out, which is different from the radical pathway dominated by •O2− for the bare Ppa. This work is of utmost importance since it gives us detailed information regarding the charge carrier’s separation and the impact of the radical pathway that will pave a new approach toward the design of high activity visible-light driven photocatalysts. 相似文献
18.
Ken‐ichi Sawamura Dr. Teruaki Izumi Kiyotoshi Kawasaki Shintaro Daikohara Tetsu Ohsuna Prof. Mitsuko Takada Dr. Yasushi Sekine Prof. Eiichi Kikuchi Prof. Masahiko Matsukata Prof. 《化学:亚洲杂志》2009,4(7):1015-1015
Reverse‐selective membranes , through which bigger molecules selectively permeate, are attractive for developing chemical processes utilizing hydrogen because they can maintain the high partial pressure of hydrogen required for further downstream utilization. Although several of these chemical processes are operated above 473 K, membranes with outstanding reverse‐selective separation performance at these temperatures are still to be reported. M. Matsukata et al. propose a new adsorption‐based reverse‐selective membrane that utilizes a Na cation occluded in a zeolitic framework. The membrane developed in this work enables selective permeation and separation of bigger polar molecules, such as methanol and water, from hydrogen above 473 K. For more information, see their Full Paper on page 1070 ff.
19.
Amine‐Appended Hierarchical Ca‐A Zeolite for Enhancing CO2/CH4 Selectivity of Mixed‐Matrix Membranes 下载免费PDF全文
An amine‐appended hierarchical Ca‐A zeolite that can selectively capture CO2 was synthesized and incorporated into inexpensive membrane polymers, in particular polyethylene oxide and Matrimid, to design mixed‐matrix membranes with high CO2/CH4 selectivities. Binary mixture permeation testing reveals that amine‐appended mesoporous Ca‐A is highly effective in improving CO2/CH4 selectivity of polymeric membranes. In particular, the CO2/CH4 selectivity of the polyethylene oxide membrane increases from 15 to 23 by incorporating 20 wt % amine‐appended Ca‐A zeolite. Furthermore, the formation of filler/polymer interfacial defects, which is typically found in glassy polymer‐zeolite pairs, is inhibited owing to the interaction between the amine groups on the external surface of zeolites and polymer chains. Our results suggest that the amine‐appended hierarchial Ca‐A, which was utilized in membrane fabrication for the first time, is a good filler material for fabricating a CO2‐selective mixed‐matrix membrane with defect‐free morphology. 相似文献
20.
首先采用相分离的水解-溶剂热法制备了Bi2O3纳米粒子,然后利用简单的湿化学法在Bi2O3表面负载不同比例的TiO2纳米颗粒,进而得到TiO2/Bi2O3纳米复合体。通过气氛调控的表面光电压谱(SPS)等测试表明,表面负载适量的TiO2后能够提高Bi2O3光生电荷分离。可见光催化产氢和降解污染物测试结果进一步证明,表面负载适量的TiO2后可显著提高其可见光催化活性,其中Ti/Bi摩尔比为7%时具有最高的光催化活性。这主要归因于TiO2具有较为合适的导带能级位置,可以接收Bi2O3在可见光激发下所产生的高能级电子,从而抑制光生电子-空穴对复合,并且维持了高能级电子较高的还原能力。 相似文献