Showing papers by "Rong Wang published in 2013"
TL;DR: In this paper, a review of different types of membranes available for use including their working principles, current status and development which form the primary determinants of separation performance and efficiency is presented.
537 citations
TL;DR: In this article, the polyvinylidene fluoride (PVDF) nanofiber membranes for membrane distillation were optimized to examine their effects on pore size distribution and inorganic additives were added into the dope to improve the electro-spinability of diluted polymer dopes.
384 citations
TL;DR: In this article, two types of super-hydrophobic PVDF nanofiber membranes, integrally modified and surface-modified PVDF membranes, have been successfully fabricated by electro-spinning followed by surface modification, which includes dopamine surface activation, silver nanoparticle deposition and hydrophobic treatment.
298 citations
TL;DR: An overview of the properties of aquaporins, their preparation and characterization and the challenges in exploiting the remarkable properties are discussed, and various attempts to construct aquaporin in membranes for desalination are presented.
293 citations
TL;DR: In this paper, a thin-film selective layer of the composite hollow fiber was formed through interfacial polymerization on the inner surface of a polyethersulfone (PES) ultrafiltration (UF) membrane substrate with branched polyethyleneimine (PEI) and trymesoyl chloride (TMC) employed as the monomers in aqueous and organic phases, respectively.
250 citations
TL;DR: In this paper, a novel approach was explored to obtain a highly hydrophilic membrane surface via plasma induced grafting of polyethylene glycol (PEG) and subsequent TiO2 particles deposition onto the membrane surface The mechanism of oil affinity onto a membrane surface was quantitatively investigated by the extended Derjaguin-Landau-Verwey-Overbeek theory.
213 citations
TL;DR: In this paper, the feasibility of using electrospun polyvinylidene fluoride (PVDF) nanofibers as substrates to make high-performance forward osmosis (FO) membrane was explored.
199 citations
TL;DR: In this article, the authors developed a novel hollow fiber membrane by balancing these competing factors based on their prior experience in thin-film composite (TFC) membranes, which can achieve a power density of 20.9 W/m2 at a pressure of 15 bar, using synthetic seawater brine (1.0 M NaCl) as the draw solution and synthetic river water (1 mM NaCl), respectively.
148 citations
TL;DR: Results clearly indicate the potential of semi-IPN hydrogels as semi-solid draw agents in the FO process, in which quasi-continuous desalination could be achieved by cyclic heating and cooling within a moderate temperature change.
132 citations
TL;DR: In this article, gas bubbles were incorporated into direct contact membrane distillation (DCMD) and examined its effect on the MD performance especially at elevated salt concentrations in the feed steam, and it was shown that a higher flux enhancement could be achieved in a bubbling system with either a higher feed operating temperature, lower feed and permeate flow velocities, inclined module orientation, shorter fiber length or lower packing density.
127 citations
TL;DR: In this article, a functionalized multi-walled carbon nanotube (MWCNT) immobilized polyethyleneimine-poly(amide-imide) (PEI-PAI) hollow fiber membrane was designed and fabricated using an easily scalable method.
TL;DR: In this article, the authors provide a summary of prior studies on the mass transfer models related to both the shell-side and tube-side fluid dynamics, and two types of technique to enhance hollow fiber membrane module performance are discussed.
Abstract: Membrane-based separation processes have found numerous applications in various industries over the past decades. However, higher energy consumption, lower productivity, and shorter membrane lifespan due to polarization and membrane fouling continue to present severe technical challenges to membrane-based separation. Improved membrane module design and novel hydrodynamics offer strategies to address these challenges. This review focuses on hollow fiber membrane modules which are well suited to membrane contactor separation processes. Attempts to improve membrane module design should begin with a better understanding of the mass transfer in the hollow fiber module; therefore, this review provides a summary of prior studies on the mass transfer models related to both the shell-side and tube-side fluid dynamics. Based on the mass transfer analysis, two types of technique to enhance hollow fiber membrane module performance are discussed: (1) passive enhancement techniques that involve the design and ...
TL;DR: In this paper, a new strategy was proposed to increase water flux in a forward osmosis (FO) process using reduced graphene oxide (rGO)-composite hydrogels as draw agents as well as increasing the rate of the subsequent regain of pure water from the hydrogel particles.
Abstract: We report here a new strategy to dramatically increase water flux in a forward osmosis (FO) process using reduced graphene oxide (rGO)-composite hydrogels as draw agents as well as increasing the rate of the subsequent regain of pure water from the hydrogel particles. The composite hydrogels were prepared by incorporating 0.3 wt%–3 wt% rGO into two different hydrogels: poly(sodium acrylate) (PSA) and poly(sodium acrylate)-poly(N-isopropylacrylamide) (PSA-NIPAM). The amount of incorporated rGO sheets had a significant effect on the swelling pressure of the composite hydrogels and the composite hydrogels with contained small amounts of rGO sheets (0.3–1.2 wt%) showed significantly enhanced swelling ratios while those with more rGO (e.g., 3 wt%) exhibited decreased swelling ratios. Consequently, significant enhancements in water flux in the FO process were achieved for composite hydrogels with small amounts of rGO. When compared with the pure hydrogels, the composite hydrogels PSA-1.2 wt% rGO and PSA-NIPAM-1.2 wt% rGO showed increased water fluxes of some 310% and 227%, respectively, when 2000 ppm of a NaCl aqueous solution was used as the feed. When deionized water was used, even higher water fluxes were attained, i.e., 8.2 L m−2 h−1 for PSA-1.2 wt% rGO and 6.8 L m−2 h−1 for PSA-NIPAM-1.2 wt% rGO. The swelling process of the particles was investigated using optical microscopy where it was found that the addition of small amounts of rGO greatly increased the softness of the composite hydrogels and improved the inter-particle and particle-membrane contact, leading to dramatically improved water fluxes. In addition, the light-absorbing property of rGO produced much better outcomes in terms of dewatering of the composite hydrogels in the second stage of the FO process, in which the pure water from the hydrogels is harvested, with dewatering stimulated by heating induced from absorbed solar energy. The water recovery rate for composites with 1.2 wt% rGO was found to be twice as fast as that for pure hydrogels.
TL;DR: Low molecular weight dual responsive polymers, after purging with CO2, become polyelectrolytes with high osmolality, which can be used as draw solutes for seawater desalination.
TL;DR: In this paper, the effect of wheat straw incorporation and no-tillage on nitrous oxide (N2O) and methane (CH4) fluxes from a rice-wheat system in southeast China, using year-round field measurements.
TL;DR: In this paper, the incorporation of the fluorinated silica (fSiO 2 ) inorganic layer on the polyetherimide (PEI) organic substrate was examined and confirmed by ATR-FTIR, TGA and SEM.
TL;DR: In this article, the effects of amphiphilic pluronic block copolymer as an additive on PVDF membrane formation has been studied and a membrane formation mechanism involving pluronic has been proposed.
TL;DR: This study systematically investigated the effect of proteoliposome composition (lipid type, protein-to-lipid ratio (PLR), and the addition of cholesterol) on water permeability and NaCl retention, and design criteria for aquaporin-based biomimetic membranes are proposed in the context of desalination.
Abstract: Aquaporins are a large family of water transport proteins in cell membranes. Their high water permeability and solute rejection make them potential building blocks for high-performance biomimetic membranes for desalination. In the current study, proteoliposomes were prepared using AquaporinZ from Escherichia coli cells, and their separation properties were characterized by stopped-flow measurements. The current study systematically investigated the effect of proteoliposome composition (lipid type, protein-to-lipid ratio (PLR), and the addition of cholesterol) on water permeability and NaCl retention. Among the various lipids investigated, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-based proteoliposomes were found to have excellent osmotic water permeability and NaCl reflection coefficient values. Increasing the PLR of DOPC proteoliposomes up to 1:200 increased their osmotic water permeability. However, further increase in the PLR reduced the osmotic water permeability probably due to the occurrence o...
TL;DR: A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules.
Abstract: A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules. The electrical switching behavior of a less-studied molecular switch, dihydroazulene/vinylheptafulvene, is described, which is used as a test case.
TL;DR: A short review on the recent development of membrane contactor technology is presented in this paper, where the state-of-the-art of highly hydrophobic microporous membranes, novel liquid absorbents and membrane module design and process simulation are presented.
Abstract: Gas–liquid membrane contactor, which integrates the absorption process with membranes, is an emerging membrane technology that is of particular interest to acid gas absorption. This article presents a short review on the recent development of membrane contactor technology. With the analysis of key challenges being addressed for membrane contactor development, the state-of-the-art of highly hydrophobic microporous membranes, novel liquid absorbents and membrane module design and process simulation are presented. The future opportunities for achieving breakthrough in membrane contactor that can lead to large-scale practical applications are also summarized.
TL;DR: In this article, a layer-by-layer (LBL) polyelectrolyte assembly technique has been successfully applied onto a microporous polyethersulfone (PES) hollow fiber substrate to make novel LBL hollow fiber membranes suitable for forward osmosis (FO) applications.
TL;DR: In this paper, the authors directly measured the denitrification potential and the fractions of nitrogenous gases as products of the process in laboratory, and investigated the effects of the nitrate (NO) concentration on emissions of denitification gases, and test the hypothesis that denitization can be a major pathway of N2O and NO production in calcic cambisols under conditions of simultaneously sufficient supplies of carbon and nitrogen substrates and anaerobiosis.
Abstract: The direct measurement of denitrification dynamics and its product fractions is important for parameterizing process-oriented model(s) for nitrogen cycling in various soils. The aims of this study are to a) directly measure the denitrification potential and the fractions of nitrogenous gases as products of the process in laboratory, b) investigate the effects of the nitrate (NO
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) concentration on emissions of denitrification gases, and c) test the hypothesis that denitrification can be a major pathway of nitrous oxide (N2O) and nitric oxide (NO) production in calcic cambisols under conditions of simultaneously sufficient supplies of carbon and nitrogen substrates and anaerobiosis as to be found to occur commonly in agricultural lands. Using the helium atmosphere (with or without oxygen) gas-flow-soil-core technique in laboratory, we directly measured the denitrification potential of a silt clay calcic cambisol and the production of nitrogen gas (N2), N2O and NO during denitrification under the conditions of seven levels of NO
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concentrations (ranging from 10 to 250 mg N kg−1 dry soil) and an almost constant initial dissolved organic carbon concentration (300 mg C kg−1 dry soil). Almost all the soil NO
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was consumed during anaerobic incubation, with 80–88 % of the consumed NO
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recovered by measuring nitrogenous gases. The results showed that the increases in initial NO
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concentrations significantly enhanced the denitrification potential and the emissions of N2 and N2O as products of this process. Despite the wide range of initial NO
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concentrations, the ratios of N2, N2O and NO products to denitrification potential showed much narrower ranges of 51–78 % for N2, 14–36 % for N2O and 5–22 % for NO. These results well support the above hypothesis and provide some parameters for simulating effects of variable soil NO
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concentrations on denitrification process as needed for biogeochemical models.
TL;DR: This paper aims to demonstrate the efforts towards in-situ applicability of EMMARM, which aims to provide real-time information about the physical and chemical properties of EMT in animals and its application in humans.
Abstract: the National Natural Science Foundation of China (nos. 91213302;20932003;21272102);the Key National S&T Program “Major New Drug Development” of the Ministry of Science and Technology (2012ZX09504001-003)
TL;DR: In this article, a comparison study of nanofiltration (NF)-like and reverse osmosis (RO)-like thin film composite (TFC) OMs in terms of flux performance and fouling behavior is presented.
TL;DR: In this article, a carbon nanotube/graphene nanoplatelet (MWCNT/GNP) hybrid membrane with lower liquid permeability and better barrier effect compared to MWCNT membranes was successfully synthesized by vacuum filtering.
Abstract: Carbon nanotube/graphene nanoplatelet (MWCNT/GNP) hybrid membranes with lower liquid permeability and better barrier effect compared to MWCNT membranes were successfully synthesized by vacuum filtering. Their morphologies, water permeability, and pore structures were characterized by a scanning electron microscope (SEM) and nitrogen adsorption isotherms. Furthermore, MWCNT/GNP membranes were used to improve the flame retardancy of carbon fiber reinforced polymer (CFRP) composites, and the influence of weight percentage of GNPs on the permeability and flame retardancy of MWCNT/GNP membranes was systematically investigated. Results show that incorporation of MWCNT/GNP membranes on CFRP composite plates can remarkably improve the flame retardancy of CFRP composites. Specifically, the incorporation of hierarchical MWCNT/GNP membrane with 7.5 wt% of GNP displays a 35% reduction in the peak heat release rate (PHRR) for a CFRP composite plate with the epoxy as matrix and a 11% reduction in PHRR compared with the incorporation of MWCNT membrane only. A synergistic flame retarding mechanism is suggested to be attributed to these results, which includes controlling the pore size and penetrative network structure.
TL;DR: The physical origin of the shape resonance effect of second-harmonic generation from periodic arrays of subwavelength rectangular air hole with various aspect ratios perforated in gold thin films is clarified and a nonlinear coupled-mode theory is set up to solve energy conversion within the nanoscale air hole.
Abstract: Second-harmonic generation (SHG) from periodic arrays of subwavelength rectangular air hole with various aspect ratios perforated in gold thin films can get resonantly enhanced for some specific geometric shapes. Here we clarify the physical origin of this shape resonance effect. A nonlinear coupled-mode theory is set up to solve energy conversion from fundamental wave (FW) mode to second-harmonic wave (SHW) mode within the nanoscale air hole. It reveals that several physical mechanisms, including the FW mode excitation amplitude, FW-SHW modal spatial overlap, FW-SHW mode phase mismatch, and SHW mode attenuation, are all geometric shape sensitive and altogether act to induce the SHG shape resonance effect. The theory agrees well with experimental observations and provides an accurate and complete explanation for the long-emphasized but elusive shape effect. The study may stimulate deeper insights to visualize general nonlinear nanophotonic processes and pave the way to engineering high-efficiency nonlinear nanophotonic devices.
TL;DR: In this paper, dual-layer ultrafiltration (UF) dual layer hollow fibers have been successfully fabricated by dry jet-wet spinning technique and two different polymers of poly(amide-imide) (PAI) and polyethersulfone (PES) were utilized as the selective layer on the outer side and the porous support layer on inner side, respectively.
TL;DR: A multifunctional hybrid platinum(iv) drug which has both DCA and Pt in one molecule was synthesized and tethered to polymers to further self-assemble into micelles to target both nuclear DNA and mitochondria.
Abstract: A multifunctional hybrid platinum(IV) drug which has both DCA and Pt in one molecule was synthesized and tethered to polymers to further self-assemble into micelles. This micelle-mediated delivery of platinum(IV) prodrug aims to target both nuclear DNA and mitochondria.
TL;DR: In this paper, a simple and efficient technique to deposit a regenerable coating of silver nanoparticles/multi-walled carbon nanotubes (Ag/MWNTs) on the surface of hollow fiber membrane by filtration was reported.
TL;DR: In this article, a needle-like structure was observed on the membrane surface while there was no significant change in pore size and pore distribution, FTIR and XPS data showed Si peak and composition.
Abstract: This work investigates the membrane modification to enhance hydrophobicity aiming for applications as membrane contactors. The PVDF membranes were activated by NaOH and by plasma activation followed by grafting using three organosilanes. For the NaOH, the contact angle of original membranes (68°) was decreased from 44° to 31° with increasing NaOH concentration from 2.5M to 7.5M at 60°C for 3 h. The contact angle of NaOH treated membranes was increased to 100° after modification with 0.01M FAS-C8 for 24 h. A needle-like structure was observed on the membrane surface while there was no significant change in pore size and pore size distribution. Moreover, FTIR and XPS data showed Si peak and composition. The mechanical strength was improved. The surface modified membranes under helium plasma activation followed by grafting with 0.01M FAS-C8 for 24 h showed higher contact angle, mechanical strength and surface roughness than that obtained by NaOH activation method while other physical properties did not change. The long-term performance test for 15 days of operation was conducted. The modified membranes exhibited good stability and durability for CO2 absorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013