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1.
Nanofiltration (NF) membranes have been widely used for the treatment of electroplating, aerospace, textile, pharmaceutical, and other chemical industries. In this work, halloysite nanotubes (HNTs) were directly anchored on the surface of commercial nanofiltration (NF) membrane by dopamine modification following advantageous bio‐inspired methods. SEM and AFM images were used to characterize the HNTs decorated membrane surface in terms of surface morphology and roughness. Water contact angle (WCA) was employed in evidencing the incorporation of HNTs and dopamine in terms of hydrophilicity or hydrophobicity. Augmentation of HNTs was found to obviously enhance the hydrophilicity and surface roughness resulting in improved water permeability of membrane. More importantly, the rejection ratios of membrane also increased during the removal of heavy metal ions from wastewater. The permeability and Cu2+ rejection ratio of modified NF membrane were as high as 13.9 L·m?2·h?1·bar?1 and 74.3%, respectively. Incorporation of HNTs was also found to enhance the anti‐fouling property and stability of membrane as evident from long‐term performance tests. The relative concentration of HNTs and dopamine on membrane surface was optimized by investigating the trade‐off between water permeability and rejection ratio.  相似文献   

2.
《先进技术聚合物》2018,29(2):795-805
In this research, composite membranes were prepared by cross‐linking of poly(vinyl alcohol) (PVA) and glutaraldehyde (GA) on amidoximated ultrafiltration membrane. During this procedure, it was taken advantage of large‐area graphene oxide sheets as graphitic nets in the active layer. These membranes were used to remove an industrial textile dye (Chrysophenine GX) from wastewater. Optimum condition for membrane preparation was 1.5% wt. of PVA, 1.5% wt. of GA, and 0.3% wt. of graphene oxide sheets. Permeation results showed that electrostatic charges on membrane surface have easily converted from positive into negative ones. Contact angle was significantly decreased (63.5° to 28.8°). Final nanofiltration membrane showed lowest fouling rate during removing the industrial direct dye (flux recovery ratio: 96.60%, reversible fouling ratio: 23.82%, and irreversible fouling ratio: 3.39%). Pore size of this membrane was <8 nm, and Chrysophenine GX was eliminated by 98.5% with water permeability of 12.23 L/m2.h.bar.  相似文献   

3.
In this study, a novel dopamine modified graphene‐based photocatalytic membrane with Bi12O17Cl2 inserted was fabricated to modify the commercial cellulose acetate membrane via vacuum filtration method. Results showed the reduced graphene oxide (RGO)/poly(dopamine) (PDA)/Bi12O17Cl2‐CA photocatalytic composite membrane exhibited 98% removal efficiency for methylene blue (MB) within 100 minutes and 96% removal efficiency for 4‐CP within 160 minutes. Importantly, the photocatalytic composite membrane can simultaneously achieve dye degradation and oil‐water separation in only one device within a short time. And the as‐prepared membrane displayed great antifouling performance and recyclability after 10 cycles. Meanwhile, the membrane showed excellent stability in the agitated water bath or different pH conditions. In summary, the photocatalytic membrane investigated in this study opens new avenue for treatment of wastewater.  相似文献   

4.
A non‐covalent functionalization based on a copper tetraphenylporphyrin/chemically reduced graphene oxide (Cu‐TPP/CRGO) nanocomposite is demonstrated for selective determination of dopamine (DA) in pharmaceutical and biological samples. A homogeneous electron‐rich environment can be created on the graphene surface by Cu‐TPP due to the π–π non‐covalent stacking interaction. The synthesized Cu‐TPP/CRGO nanocomposite was characterized using scanning electron microscopy NMR, ultraviolet–visible and electrochemical impedance spectroscopies. The electrocatalytic activity of DA was evaluated using cyclic voltammetry and differential pulse voltammetry. The oxidation peak current (Ipa) of DA increased linearly with increasing concentration of DA in the range 2–200 μM. The detection limit was calculated as 0.76 μM with a high sensitivity of 2.46 μA μM?1 cm ? 2. The practicality of the proposed DA sensor was evaluated in DA hydrochloride injection, human urine and saliva, and showed satisfactory recovery results for the detection of DA. In addition, the Cu‐TPP/CRGO nanocomposite‐modified electrode showed excellent stability, repeatability and reproducibility towards the detection of DA. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
Herein, a new Cu(II) Schiff base complex was immobilized onto the magnetic graphene oxide surface through a stepwise procedure. The as-synthesized nanostructure (GO/Fe3O4/CuL) was characterized by various techniques including Fourier transform infrared (FT-IR), Raman spectroscopies, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), energy-dispersive X-ray (EDX) and inductively coupled plasma (ICP) spectroscopies, N2 adsorption–desorption analysis, vibrating sample magnetometry (VSM), and X-ray diffraction (XRD). The catalytic activity of the synthesized nanocatalyst was examined in 4-nitrophenol (4-NP), Congo red (CR), and methylene blue (MB) reduction using NaBH4 in an aqueous solution at room temperature. The reaction progress was monitored by UV–Vis spectroscopy. Also, the synthesized nanostructure was evaluated as an efficient catalyst for the synthesis of 2-amino-4H-benzopyrans via three-component reactions of 1-naphthol, malononitrile, and various aldehydes in ethanol/water at 50°C. The use of green solvents, the short reaction time, the high product yield, and easy separation from the reaction environment are the main benefits of this catalytic system. By covalent grafting of the complex on the graphene oxide surface, its catalytic performance significantly increased compared with graphene oxide; this is probably related to the chemical change of the graphene oxide surface. The results show the high chemical stability and the improved reusability of the synthesized nanocatalyst (six times) without significant loss in the catalytic activity of GO/Fe3O4/CuL nanocomposite.  相似文献   

6.
A polyoxometalate based composite material (NiPW12NP/FrGO) was synthesized successfully, in which the nanoparticle of a polyoxometalate compound (NiPW12NP) distributes on carboxylate group functionalized reduced graphene oxide (FrGO) homogenously. There exist intensive chemical bonds between NiPW12NP and FrGO, which guarantees the stability of this composite material. When employed as a cathode material, NiPW12NP/FrGO exhibits high specific capacitance, remarkable rate capability and long-term stability. When the current density is 4 A g−1, a specific capacitance as high as 437.6 F g−1 is achieved by NiPW12NP/FrGO. With NiPW12NP/FrGO serving as cathode and MnO2 acting as anode, a high performance asymmetric supercapacitor (ASC) is assembled, which possesses a high energy density of 12.96 W h·kg−1 at 0.67 kW kg−1. It also shows a good rate capability, when the current density increases from 4 to 12 A g−1, its specific capacitances decreases from 115.2 to 90.9 F g−1, with 78.9% capacitance retention. After 5000 cycles charge-discharge experiments, 94.3% of its capacitance can be maintained, which exhibits good stability. Furthermore, NiPW12NP/FrGO composite material also shows excellent tetracycline adsorption ability with capacity 288.28 mg g−1, the adsorption can be well described with Temkin model, which suggests electrostatic attraction dominates the adsorption process.  相似文献   

7.
Herein we report an easy and efficient approach to prepare lightweight porous polyimide (PI)/reduced graphene oxide (RGO) composite films. First, porous poly (amic acid) (PAA)/graphene oxide (GO) composite films were prepared via non‐solvent induced phase separation (NIPS) process. Afterwards PAA was converted into PI through thermal imidization and simultaneously GO dispersed in PAA matrix was in situ thermally reduced to RGO. The GO undergoing the same thermal treatment process as thermal imidization was characterized with thermogravimetric analysis, Raman spectra, X‐ray photoelectron spectroscopy and X‐ray diffraction to demonstrate that GO was in situ reduced during thermal imidization process. The resultant porous PI/RGO composite film (500‐µm thickness), which was prepared from pristine PAA/GO composite with 8 wt% GO, exhibited effective electrical conductivity of 0.015 S m?1 and excellent specific shielding efficiency value of 693 dB cm2 g?1. In addition, the thermal stability of the porous PI/RGO composite films was also dramatically enhanced. Compared with that of porous PI film, the 5% weight loss temperature of the composite film mentioned above was improved from 525°C to 538°C. Moreover, tensile test showed that the composite film mentioned above possessed a tensile strength of 6.97 MPa and Young's modulus of 545 MPa, respectively. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

8.
In this article, we report on the production by electrospinning of P3HT/PEO, P3HT/PEO/GO, and P3HT/PEO/rGO nanofibers in which the filler is homogeneously dispersed and parallel oriented along the fibers axis. The effect of nanofillers' presence inside nanofibers and GO reduction was studied, in order to reveal the influence of the new hierarchical structure on the electrical conductivity and mechanical properties. An in‐depth characterization of the purity and regioregularity of the starting P3HT as well as the morphology and chemical structure of GO and rGO was carried out. The morphology of the electrospun nanofibers was examined by both scanning and transmission electron microscopy. The fibrous nanocomposites are also characterized by differential scanning calorimetry to investigate their chemical structure and polymer chains arrangements. Finally, the electrical conductivity of the electrospun fibers and the elastic modulus of the single fibers are evaluated using a four‐point probe method and atomic force microscopy nanoindentation, respectively. The electrospun materials crystallinity as well as the elastic modulus increase with the addition of the nanofillers while the electrical conductivity is positively influenced by the GO reduction. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

9.
Graphene oxide (GO)–polyaniline (PANI) composite is synthesized by in situ polymerization of aniline in the presence of GO as oxidant, resulting in highly crystalline and conductive composite. Fourier transform infrared spectrum confirms aniline polymerization in the presence of GO without using conventional oxidants. Scanning electron microscopic images show the formation of PANI nanofibers attached to GO sheets. X‐ray diffraction (XRD) patterns indicate the presence of highly crystalline PANI. The sharp peaks in XRD pattern suggest GO sheets not only play an important role in the polymerization of aniline but also in inducing highly crystalline phase of PANI in the final composite. Electrical conductivity of doped GO–PANI composite is 582.73 S m?1, compared with 20.3 S m?1 for GO–PANI obtained by ammonium persulfate assisted polymerization. The higher conductivity appears to be the result of higher crystallinity and/or chemical grafting of PANI to GO, which creates common conjugated paths between GO and PANI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1545–1554  相似文献   

10.
A new selective and fast procedure based on magnetic dispersive solid‐phase extraction and zeta potential analysis is proposed for the determination of Cd (II) in some food samples. In the developed method, novel magnetic nanoparticles modified with thioglycolic acid were synthesized/characterized and also applied for quantitative determination of trace amounts of Cd (II) in food samples. The prepared nanoparticles were characterized via infrared spectroscopy, electron microscopy and adsorption–desorption experiments. These magnetic nanocomposites carrying Cd (II) could be easily separated from real samples simply by applying an external magnetic field; no filtration or centrifugation was necessary. Several parameters affecting the analytical performance, such as sample pH, amounts of nanocomposite sample, desorption solution volumes and coexisting ions, were investigated in detail. The detection limit of the method was 0.1 μg l?1 while the relative standard deviation was 1.2% for a Cd (II) concentration of 0.5 mg l?1. The proposed method was successfully applied to food sample analysis and standard reference material samples with satisfactory results, and excellent recoveries were obtained in the range 95–99% even when the matrix, such as sea water, was complex.  相似文献   

11.
In this work, we report the efficient, high stable copper(II) complexes intercalated graphene oxide (GO) used as green catalysts for copper(II) complex mediated click reaction. Copper(II) Bis(2,2′-bipyridine) [CuII (bpy)2] (C1) and Copper(II) Bis(1,10-phenanthroline) [CuII (phen)2] (C2) have synthesized for the intercalation of corresponding nanocomposites with GO, [GO@CuII (bpy)2] (GO-C1) and [GO@CuII (phen)2] (GO-C2). The noncovalent interaction of complexes supported on the surface of the GO nanosheets proves as an evident active site to facilitate the enhanced catalytic activity of copper-catalyzed alkyne azide cycloaddition (CuIIAAC) reaction for the isolation of 1,4-disubstituted-1,2,3-triazoles as click products in shorter reaction time with 80%–91% yield (five examples). The X-ray diffraction (XRD) pattern of these composites shows the enhanced interlayers d-spacing range of 1.01–1.12 nm due to the intercalation of copper(II) complexes in between the GO basal planes and characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), Raman, UV, scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The as-prepared nanocomposites were employed for the typical click reactions using the substrates of azide and acetylene. These classes of composite materials can be referred to recyclable, heterogeneous, green catalysts with high atom economy and could also be used for the isolation of click products in biomolecules.  相似文献   

12.
The discharge of colored effluents from industries is one of the significant sources of water pollution. Therefore, there is a growing demand for efficient and low-cost treatment methods. An adsorption process with reduced graphene oxide (rGO) synthesized using a novel double carbonization and oxidation method from the natural precursor of oil palm empty fruit bunch (OPEFB) as adsorbent is a promising approach for addressing the problem. In this study, OPEFB biochar was mixed with ferrocene with a ratio of 5:1 (m/m) and oxidized under nitrogen flow at a temperature of 300 °C for 20 min, which resulted in 75.8 wt% of yield. The potential of the synthesized rGO as an effective adsorbent for dye removal from water and wastewater was explored using methylene blue (MB) as a model. Several factors were investigated, including adsorbent dosage, initial concentration, contact time, and pH, to obtain the optimum adsorption condition through batch studies. The physical and chemical characteristics of the rGO in terms of functional groups, surface morphology, elemental composition, and crystallinity phase were determined through characterization. The nonlinear isotherms were appropriated using several error functions to describe the adsorption isotherm with a maximum adsorption capacity of 50.07 mg/g. The kinetic study demonstrates that MB’s adsorption fits the PFO kinetic model and agrees with Bangham’s interpretation of pore diffusion. The adsorption mechanism was found to be physisorption on the multilayer heterogeneous surface of the rGO involving π-π interaction, hydrophobic association, and electrostatic interaction. The thermodynamics study showed that the process was spontaneous and exothermic. The mass transfer mechanism study shows that the adsorption is controlled by intraparticle diffusion and involves complex pathways. The study found that the novel non- functionalized rGO could remove cationic dyes from water and wastewater.  相似文献   

13.
An efficient adsorbent (L-Glu/GO) was successfully synthesized by the reaction between L-glutamic acid (L-Glu) and graphene oxide (GO). The structure and morphology of this adsorbent were characterized by FTIR, SEM, XRD, and TGA. The SEM result indicated that the adsorbent was a nanomaterial with a size of about 50–400 nm. The adsorption experiments of various heavy ions on L-Glu/GO demonstrated that the adsorption performance of Pb(II) was better than others. Various variables affecting the adsorption of L-Glu/GO for Pb(II) were systematically explored. The experimental results indicated that the maximum adsorption capacity and equilibrium time of Pb(II) on L-Glu/GO were 513.4 mg g?1 and 40 minute, respectively. The sorption kinetics and isotherm fitted well with the pseudo-second-order model and Langmuir model, respectively. The sorption mainly was a chemical process. Thermodynamic studies revealed that the adsorption was a spontaneous and exothermic process. The adsorbent could be regenerated with HCl solution. Hence, it was suggested that the L-Glu/GO could be applied in the removal of Pb(II) from wastewaters.  相似文献   

14.
We present here the application of graphene oxide (GO) and reduced graphene oxide (GOOH) sheet as novel stationary phases for open‐tubular CEC (OTCEC) separation based on electrostatic assembly. The inner walls of a bare capillary column was first modified by ionic assembly of poly (diallyldimethylammonium chloride) (PDDA), and then negatively charged GO or GOOH was easily assembled on a positively charged interior walls of the capillary by electrostatic force. Scanning Electron Microscope images showed that GO and GOOH can still maintain sheet‐layer‐like structure when coated onto the capillary via electrostatic assembly. The chromatographic properties of the GO and GOOH coated columns were evaluated via OTCEC separations of various kinds of analytes, including three acid nitrophenol isomers, three basic nitroaniline isomers, and four neutral PAHs. Efficient separations of all the analytes were achieved with optimized buffer pH and organic additive. The reproducibility and stability of the GO or GOOH coated columns were investigated. Our results indicate the capability of application GO or GOOH sheet in OTCEC separation, which can be coated on the inner wall of fused‐silica capillary via electrostatic assembly.  相似文献   

15.
A novel optimized chelating hydrogel was synthesized via graft copolymerization of acrylamide and 2‐hydroxyethyl methacrylate (as two‐dentate chelating co‐monomer) onto salep (a multicomponent polysaccharide obtained from dried tubers of certain natural terrestrial orchids) using N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Reaction parameters (N,N′‐methylenebisacrylamide and ammonium persulfate amounts as well as acrylamide/2‐hydroxyethyl methacrylate weight ratio) affecting the water absorption of the chelating hydrogel were optimized using a systematic method to achieve a hydrogel with high swelling capacity as possible. Heavy metal ion adsorption capacity of the optimized hydrogel for metal ions [Cu (II), Pb (II), Cd (II), and Cr (III)] were investigated in aqueous media containing different concentrations of these ions (5–50 ppm). The results showed that the hydrogel have great potential for heavy metal removal from aqueous solutions. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy, and surface morphology study of the hydrogel was performed by scanning electron microscope. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

16.
This article focuses on a room temperature copper‐free Sonagashira cross‐coupling reaction in ethanol, catalysed by palladium nanoparticles homogeneously deposited on reduced graphene oxide. The catalyst showed efficient catalytic activity towards the said coupling reaction, and was well characterized using various techniques, and could be reused up to six times with almost constant yield of the desired product. The attractions of this protocol are that the reaction completes within short reaction time under ligand‐ and copper‐free conditions and it avoids harsh reaction conditions.  相似文献   

17.
In recent years, tremendous research efforts have been made towards developing metal–organic framework (MOF)‐based composites for photocatalytic applications. In this work, bipyramid‐like MIL‐125(Ti) frustum enwrapped with reduced graphene oxide (rGO) and dispersed silver nanoparticles (Ag NPs) was fabricated using an efficient one‐pot self‐assembly and photoreduction strategy. The as‐obtained materials were characterized using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, nitrogen adsorption–desorption isotherms, and X‐ray photoelectron, ultraviolet–visible diffuse reflectance and photoluminescence spectroscopies. It is found that the as‐prepared Ag/rGO/MIL‐125(Ti) ternary hybrids have large surface area, microporous structure, enhanced visible light absorption and prolonged lifetime of charge carriers. Compared with pure MIL‐125(Ti) and its binary counterparts, the ternary composite exhibits more efficient photocatalytic performance for Rhodamine B (RhB) degradation from water under visible light irradiation. The photodegradation rate of RhB on Ag/rGO/MIL‐125(Ti) is 0.0644 min?1, which is 1.62 times higher than that of the pure MIL‐125(Ti). The improved photocatalytic performance is ascribed to the indirect dye photosensitization, the Ag NP localized surface plasmon resonance, the Ti3+–Ti4+ intervalence electron transfer and the synergistic effect among MIL‐125(Ti), Ag NPs and rGO. Ag NPs serve as an efficient ‘electron reservoir’ and rGO as an electron transporter and collector. Therefore, this work provides a new pathway into the design of MOF‐based composites for application in environmental and energy fields. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

18.
A simple, effective, and robust magnetic solid‐phase extraction method was developed using magnetite/reduced graphene oxide nanoparticles as the adsorbent for the simultaneous determination of Sudan dyes (I, II, III, and IV) in foodstuffs. The magnetite/reduced graphene oxide nanoparticles were characterized by X‐ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The extraction parameters including extraction time, elution solution, and elution time and volume were investigated in detail. Such magnetite/reduced graphene oxide nanoparticles based magnetic solid‐phase extraction in combination with high‐performance liquid chromatography and variable wavelength detection gave the detection limits of 3–6 μg/kg for Sudan I–IV in chili sauce, tomato sauce, chili powder, and chili flake samples. The recoveries were 79.6–108% at three spiked levels with the intra‐ and inter‐day relative standard deviations of 1.2–8.6 and 4.5–9.6%, respectively. The feasibility was further performed by a comparison with commercial alumina‐N. This method is suitable for the routine analysis of Sudan dyes due to its sensitivity, simplicity, and low cost.  相似文献   

19.
A novel adsorbent, Fe‐Mn‐Zr metal oxide nanocomposite was synthesized and investigated for removal of methyl orange (MO) and eosin yellow (EY) dyes from binary dye solution. The magnetic nanocomposite has shown surface area of 143.01 m2/g and saturation magnetization of 15.29 emu/g. Optimization was carried out via response surface methodology (RSM) for optimizing process variables, and optimum dye removal of 99.26% and 99.55% were obtained for MO and EY dye, respectively with contact time 62 min, adsorbent dose 0.45 g/l, initial MO concentration 11.0 mg/l, and initial EY concentration 25.0 mg/l. A feed forward back propagation neural network model has shown better prediction ability than RSM model for predicting MO and EY dye removal (%). Adsorption process strictly follows Langmuir isotherm model, and enhanced adsorption capacities of 196.07 and 175.43 mg/g were observed for MO and EY dye, respectively due to synergistic effects of physicochemical properties of trimetal oxides. Surface adsorption and pore diffusions are the mechanisms involved in the adsorption as revealed from kinetic studies.  相似文献   

20.
It remains challenging to prepare wearable strain and pressure sensors with excellent mechanical properties, ultra‐high flexibility and sensitivity. Electrically conductive graphene platelets (GnPs) with high structural integrity are used in making a composite film fabricated using robust fabrication techniques. The gauge factor for the strain is up to 100 at 0%‐5% strain and 50 at 5%‐30% strain, and the sensitivity to pressure is 2.7×10‐2 kPa‐1 between 0 and 10 kPa and 1.5×10‐4 kPa‐1 between 300 and 1000 kPa. In addition, the flexible sensor demonstrates good repeatability and durability after 1000 cycles of tensile and compression tests. The flexible sensor has fast response ability and a wide operating temperature range, suggesting the excellent response to temperature. The flexible sensor is applied in monitoring several human motions as a wearable device with high accuracy. The ability to detect strain, pressure and temperature of the flexible sensor extends its applications to multifunctional wearable devices.  相似文献   

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