Showing papers by "Rong Wang published in 2011"
TL;DR: In this article, a thin film composite (TFC) polyamide forward osmosis (FO) membranes with tailored support structure were prepared via phase inversion, and the polyamide rejection layers were synthesized by interfacial polymerization.
528 citations
TL;DR: In this paper, the authors used asymmetric microporous hollow fibers made of Torlon® polyamide-imide (PAI) material as the porous substrate followed by polyelectrolyte post-treatment using polyethyleneimine (PEI), which has not been reported previously.
237 citations
TL;DR: In this paper, three different types of hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membrane (unmodified, plasma modified and chemically modified) were used in direct contact membrane distillation (DCMD).
223 citations
TL;DR: In this article, a salt accumulation model is developed in a novel osmotic membrane bioreactors (OMBRs) using a dense salt-rejecting forward osmosis membrane, which exhibits high retention of organic matter and various other contaminants.
185 citations
TL;DR: In this article, the effects of polyethylene glycol (PEG) with different molecular weights and different loadings as an additive on the fabrication of asymmetric microporous hollow fiber membranes were investigated.
167 citations
157 citations
TL;DR: In this paper, an OMBR system was continuously operated for 73 days and it was found that the high retention property of the FO membrane and salt transmission from the draw solution resulted in increasing mixed liquor salinity until a stable state was reached.
155 citations
TL;DR: In this paper, the effects of substrate structure on the formation of the selective layer in a two-step preparation were investigated, and the results revealed that the substrate surface structure is very important for fabricating a RO-like thin film.
143 citations
TL;DR: In this paper, the effect of Pluronics with different molecular architectures and contents as a pore-forming additive on the fabrication of polyethersulfone (PES) ultrafiltration (UF) hollow fibers was investigated.
138 citations
TL;DR: In this paper, a direct contact membrane distillation system (DCMD) was simulated by using Aspen Plus for the purpose of energy efficiency and economic analyses, where a cross-flow membrane module was firstly modeled and then incorporated into the flowsheet for system simulation.
132 citations
TL;DR: In this paper, a two-dimensional heat transfer model was developed by coupling the latent heat, which is generated during the direct contact membrane distillation (MD) process, into the energy conservation equation, and the overall performance predicted by the model, in terms of fluxes and temperatures, was verified by single hollow fiber experiments with feed in the shell and permeate in the lumen.
TL;DR: The C/N-TiO2 calcinated at 300 °C (T300) exhibited the highest photocatalytic activity for sulfanilamide (SNM) degradation under irradiation of visible-light-emitting diode (vis-LED) and the acute toxicity of SNM solution could be reduced over prolonged photocatalysis according to the Microtox assay.
TL;DR: In this paper, the presence of room temperature ferromagnetism in partially hydrogenated epitaxial graphene grown on 4HSiC(0001) was confirmed by superconducting quantum interference devices measurements.
Abstract: We report room temperature ferromagnetism in partially hydrogenated epitaxial graphene grown on 4HSiC(0001). The presence of ferromagnetism was confirmed by superconducting quantum interference devices measurements. Synchrotron-based near-edge x-ray absorption fine structure and high resolution electron energy loss spectroscopy measurements have been used to investigate the hydrogenation mechanism on the epitaxial graphene and the origin of room temperature ferromagnetism. The partial hydrogenation induces the formation of unpaired electrons in graphene, which together with the remnant delocalized π bonding network, can explain the observed ferromagnetism in partially hydrogenated epitaxial graphene.
TL;DR: In this article, five types of hollow fiber module configurations with structured-straight fibers, curly fibers, central-tubing for feeding, spacer-wrapped and spacerknitted fibers, have been designed and constructed for the direct contact membrane distillation (DCMD) process.
TL;DR: In this paper, double-skinned forward osmosis (FO) membranes are designed with a feed skin similar to that of a low rejection nanofiltration membrane to minimize the overall hydraulic resistant and to reduce internal concentration polarization.
TL;DR: In this paper, the outer surface of polyvinylidene-co-hexafluoropropylene (PVDF-HFP) asymmetric microporous hollow fiber membrane prepared by phase inversion process was activated by 10% of NaOH solution, and subsequently modified with the mixture solution of α,ω-triethoxysilane terminated perfluoropolyether or Fluorolink®S 10 (FS10) and tetraethoxisilane (TEOS) in order to enhance the hydrophobicity of the membrane.
TL;DR: In this paper, the effects of ammonium-based, non-sulfate fertilizers, such as urea and/or ammonium phosphate (NH4H2PO4), on methane (CH4) emissions from paddy rice fields were investigated.
TL;DR: In this paper, the energy level alignment and the Fermi level pinning mechanism at organic donor-acceptor heterojunctions interfaces were investigated by using the model organic-organic heterjunctions (OOHs) with well-defined molecular orientation of the standing copper (II) phthalocyanine (CuPc) and zinc phthalocaline (ZnPc), and they identified two distinct regions for the energy-level alignment by in situ ultraviolet photoelectron spectroscopy investigation.
TL;DR: In this paper, a hydrophobic surface modification method for Torlon ® polyamide-imide (PAI) membrane was explored, which has not been reported previously, and the modified PAI hollow fiber membranes were, subsequently, characterized by a series of standard protocols in terms of membrane morphology, chemical structure, contact angle, porosity and critical water entry pressure.
TL;DR: The measurement system provides a reliable tool for studyingDenitrification in soil because it offers insights into the dynamics and magnitude of gaseous N emissions due to denitrification under various incubation conditions.
Abstract: Here we describe a newly designed system with three stand-alone working incubation vessels for simultaneous measurements of N2, N2O, NO, and CO2 emissions from soil. Due to the use of a new micro thermal conductivity detector and the redesign of vessels and gas sampling a so-far unmatched sensitivity (0.23 μg N2–N h–1 kg–1 ds or 8.1 μg N2–N m–2 h–1) for detecting N2 gas emissions and repeatability of experiments could be achieved. We further tested different incubation methods to improve the quantification of N2 emission via denitrification following the initialization of soil anaerobiosis. The best results with regard to the establishment of a full N balance (i.e., the changes in mineral N content being offset by simultaneous emission of N gases) were obtained when the anaerobic soil incubation at 25 °C was preceded by soil gas exchange under aerobic conditions at a lower incubation temperature. The ratios of N and C gas emission changed very dynamically following the initialization of anaerobiosis. For ...
TL;DR: In this paper, the authors carried out 4-year measurements of N2O fluxes from a conventional vegetable cultivation area in the Yangtze River delta, and found that approximately 86% of the annual total emissions occurred following fertilization events.
Abstract: [1] The annual and interannual characteristics of nitrous oxide (N2O) emissions from conventional vegetable fields are poorly understood. We carried out 4 year measurements of N2O fluxes from a conventional vegetable cultivation area in the Yangtze River delta. Under fertilized conditions subject to farming practices, approximately 86% of the annual total N2O release occurred following fertilization events. The direct emission factors (EFd) of the 12 individual vegetable seasons investigated ranged from 0.06 to 14.20%, with a mean of 3.09% and a coefficient of variation (CV) of 142%. The annual EFd varied from 0.59 to 4.98%, with a mean of 2.88% and an interannual CV of 74%. The mean value is much larger than the latest default value (1.00%) of the Intergovernmental Panel on Climate Change. Occasional application of lagoon-stored manure slurry coupled with other nitrogen fertilizers, or basal nitrogen addition immediately followed by heavy rainfall, accounted for a substantial portion of the large EFds observed in warm seasons. The large CVs suggest that the emission factors obtained from short-term observations that poorly represent seasonality and/or interannual variability will inevitably yield large uncertainties in inventory estimation. The results of this study indicate that conventional vegetable fields associated with intensive nitrogen addition, as well as occasional applications of manure slurry, may substantially account for regional N2O emissions. However, this conclusion needs to be further confirmed through studies at multiple field sites. Moreover, further experimental studies are needed to test the mitigation options suggested by this study for N2O emissions from open vegetable fields.
01 Jan 2011
TL;DR: In this chapter a general introduction is given to membrane technology in terms of the historical development, current status and future prospects, and some promising novel applications of membrane technology are pointed out.
Abstract: Membrane science and technology have experienced a long historical development in laboratory study before realizing their first significant industrial application in the 1960s. With nearly 50 years of rapid advancement, today, membrane-based processes enjoy numerous industrial applications and have brought great benefits to improve human life. In this chapter a general introduction is given to membrane technology in terms of the historical development, current status and future prospects. It begins with a description of the basic terms such as membrane, membrane structures, membrane classifications and membrane configurations. Membrane processes based on the different driving forces applied, the operation modes for filtration and membrane fouling are also briefly introduced. Section 2 is an overview of the historical development of membranes and membrane processes, including reverse osmosis, ultrafiltration, nanofiltration, microfiltration, gas separation, pervaporation and membrane bioreactors. Section 3 describes major applications and commercial relevance of the above-mentioned processes. In Sect. 4, future market development trends for membrane technology are indicated and critical technical challenges for further growth of the membrane industry are addressed. In addition, some promising novel applications of membrane technology are pointed out in the final section.
TL;DR: In this article, the authors demonstrate effective non-destructive p-type doping of graphene via surface modification with molybdenum trioxide (MoO3) thin film using electrical transport measurements.
Abstract: We demonstrate effective non-destructive p-type doping of graphene via surface modification with molybdenum trioxide (MoO3) thin film using electrical transport measurements. The p-type doping via MoO3 modification of graphene leads to the downward shift of Fermi level towards the valence band. MoO3 modified graphene retains its high charge carrier mobility, facilitating the observation of quantum Hall effect. In-situ ultraviolet photoelectron spectroscopy studies also show that air exposure of MoO3 modified graphene reduces the doping efficiency.
01 Jan 2011
TL;DR: In this paper, the principles of membrane formation process for polymeric membranes are described, with a brief introduction of relevant background information such as various membranes and membrane processes, a comprehensive list of polymer materials, which are suitable for making membranes, has been given.
Abstract: This chapter mainly describes the principles of membrane formation process for polymeric membranes. With a brief introduction of relevant background information such as various membranes and membrane processes, a comprehensive list of polymer materials, which are suitable for making membranes, has been given. The most common technique used to prepare polymeric membranes – phase inversion process, including thermally induced phase separation (TIPS) and diffusion induced phase separation (DIPS), is discussed in detail. The thermodynamic behavior of the casting polymer solution, the process of membrane formation, and the fabrication of hollow fiber and flat sheet membranes are involved.
TL;DR: In this paper, the morphology development of polyvinylidene fluoride hollow fiber membrane made using various N-methyl-2-pyrrolidone (NMP) aqueous solutions as an inner coagulant was carried out.
Abstract: A systematic investigation on the morphology development of polyvinylidene fluoride hollow fiber membrane made using various N-methyl-2-pyrrolidone (NMP) aqueous solutions as an inner coagulant was carried out. The cross-sectional and inner surface morphology were analyzed with scanning electronic microscopy (SEM). It is found that with increase on NMP concentration, the morphology of the resultant membranes gradually shifted from a double-skin to a single-skin structure. When 40.0 ∼ 55.0 wt.% NMP solution was used, some unexpected macrovoids near the inner region were observed. This special morphology feature was attributed to the reduced solidification rate of the inner surface as a result of increase on NMP concentration, which sharply weakened the inner skin strength. While the existence of centralized stress formed in the phase inversion process, such as shrinkage stress from syneresis, resulted in fractured points in the nascent skin surface that finally made it difficult to maintain a uniform structure. Investigations on effects of the dope flow rate and the bore fluid velocity on the morphology of PVDF fiber membranes experimentally confirmed the suggestion. Three model membranes with double skins, single skin and single skin with macrovoids structures, respectively, were used to test their permeation performance in a CO2 membrane contactor system. The experimental results show the membranes without an inner skin present higher permeability and lower mass transfer resistance than the membrane with a double skin structure. © 2010 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2010
TL;DR: As revealed by UPS measurements, the vacuum level is almost aligned at the C(60)∕6P interface, suggesting that the interface is dominated by weak intermolecular interactions, such as van der Waals and π-π interactions.
Abstract: In situ low-temperature scanning tunneling microscopy (LT-STM) and ultraviolet photoelectron spectroscopy (UPS) experiments have been carried out to investigate the interface properties at the C60/p-sexiphenyl (6P) organic–organic heterojunction interface, including the interfacial energy level alignment and the supramolecular packing structures. As revealed by UPS measurements, the vacuum level is almost aligned at the C60/6P interface, suggesting that the interface is dominated by weak intermolecular interactions, such as van der Waals and π–π interactions. In situ LT-STM experiments also indicate the formation of a molecularly sharp C60/6P interface with hexagonally-close-packed C60 layers nucleated atop 6P layer on graphite.
TL;DR: Local capacitance spectroscopy revealed that the charge carriers in the p-type pentacene monolayer could be depleted at high bias voltages, enabling a further determination of the charge-carrier concentration in the organic semiconductor ultrathin film.
Abstract: We report the electrical characterization of a single layer of an organic semiconductor grown on a dielectric surface. The dynamic response of the charge carriers in the monolayer film of pentacene was characterized through the electrostatic interactions between an electric force microscope (EFM) probe and pentacene islands of various sizes. These islands were formed in situ by segmenting a coalesced pentacene monolayer into separated regions. The size-dependent dielectric responses of the pentacene islands suggest that mobile charges exist in the organic monolayer. Local capacitance spectroscopy revealed that the charge carriers in the p-type pentacene monolayer could be depleted at high bias voltages, enabling a further determination of the charge-carrier concentration in the organic semiconductor ultrathin film.
TL;DR: In this article, a novel amphiphilic PDMS-containing poly(ether amine) (PDMS-gPEA) synthesized through one-pot condensation polymerization of commercial di-epoxy and amine monomers was reported.
Abstract: We report here a novel amphiphilic PDMS-containing poly(ether amine) (PDMS-gPEA) synthesized through one-pot condensation polymerization of commercial di-epoxy and amine monomers. The obtained PDMS-gPEA could be dispersed directly in aqueous solution to form stable uniform-sized nanoparticles with a diameter of about 16 nm, whose aggregation is responsive to temperature, pH and ionic strength with tunable cloud point (CP). The whole process for the responsive aggregation of PDMS-gPEA nanoparticles was revealed by transmission electron microscope (TEM) and dynamic light scattering (DLS), and was intensively studied by UV-vis spectra. The responsive nanoparticles of PDMS-gPEA possessed the unique selective encapsulation of water-soluble dye, which provides potential applications in smart separations.
TL;DR: In this paper, a multistimuli responsive microgels based on coumarin-containing hyperbranched poly(ether amine) (PEA-EC) was reported.
Abstract: We report novel multistimuli responsive microgels based on coumarin-containing hyperbranched poly(ether amine) (hPEA-EC) hPEA-EC could be dispersed directly in aqueous solution as polymer particles, whose cores were crosslinked through the photodimerization of coumarin moieties to form microgels with size of about 150 nm in diameter The obtained microgels (hPEA-diEC) exhibited good stability in aqueous solution and possessed sharp response to temperature, pH and ionic strength with tunable cloud point (CP) Simultaneously, hPEA-diEC microgels decorated with platinum nanoparticles (Pt@hPEA-diEC) were investigated as microreactors for reduction of aromatic nitro compounds Pt@hPEA-diEC exhibited interesting catalytic activities for the reduction of nitrophenol, which is obviously faster at lower temperature Compared with the reduction of 4-nitrophenol (Nip), Pt@hPEA-diEC is more efficient in catalytic activity for reduction of the hydrophobic 4-nitro-3-(trifluoromethyl)phenol (CF3Nip), which is probably ascribed to the encapsulation of CF3Nip in hPEA-diEC microgels These characteristics give hPEA-diEC microgels potential as intelligent materials for the controlled reduction of nitro compounds in water
TL;DR: In this paper, the organic donor-acceptor nanostructure formation processes of C60 and α-sexithiophene (6T) on graphite are monitored by in situ low-temperature scanning tunneling microscopy and synchrotron-based photoelectron spectroscopy experiments.
Abstract: The organic donor-acceptor nanostructure formation processes of C60 and α-sexithiophene (6T) on graphite are monitored by in situ low-temperature scanning tunneling microscopy and synchrotron-based photoelectron spectroscopy experiments. It is found that the intermolecular interaction between C60 and 6T plays a key role in the formation of organic nanostructures on graphite. Room temperature deposition of C60 on the 6T monolayer on the weakly interacting graphite substrate results in the coexistence of three energetically stable structural motifs with a well-defined supramolecular arrangement, including C60 zigzag filament, C60 hexagon and C60−pair filament, and hence the formation of C60:6T molecular glass on graphite. Our results show that only the thermally stable C60 zigzag filaments can develop into a long-range ordered two-dimensional C60 zigzag chain array by annealing the system at 350 K.