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Direct Three-Dimensional Visualization of Membrane Fouling by Confocal Laser Scanning Microscopy
摘要： Membrane-based separation is an important technique for removing emulsified oil from water. However, the mechanisms of fouling are complex because of the deformability and potential for coalescence and break-up of the oil droplets. Here, we report for the first time direct, three-dimensional (3D) visualization of oil droplets on electrospun fiber microfiltration membranes after a period of membrane-based separation of oil-in-water emulsions. High-resolution 3D images were acquired by a dual-channel confocal laser scanning microscopy (CLSM) technique in which both the fibers and the oil (dodecane) were fluorescently labeled. The morphology of dodecane as the foulant was observed for two different types of fibers, an oleophobic nylon (PA6(3)T), and oleophilic polyvinylidene fluoride (PVDF). Through direct visualization, the rejected oil was found to form droplets of clam-shell shape on the PA6(3)T fibers, whereas the oil tended to wet the PVDF fibers and spread across the membrane. The morphology was also analyzed as a function of separation time (i.e., "4D" imaging), as the oil accumulated within and upon the membranes. The observations are qualitatively consistent with a transition from blocking of individual pores in the membrane to coalescence of oil droplets into coherent liquid films with increasing filtration time. Analysis of permeate flux using blocking filtration models corroborate the transition of fouling modes indicated by the 3D images. This direct, 3D visualization CLSM technique is a powerful tool for characterizing the mechanisms of fouling in membranes used for liquid emulsion separations.
关键词： membrane fouling,3D imaging,oil emulsion,microfiltration,direct visualization
更新于2025-11-21 11:08:12
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Monitoring of polycyclic aromatic hydrocarbon contamination at four oil spill sites using fluorescence spectroscopy coupled with parallel factor-principal component analysis
摘要： Fluorescence spectroscopy analysis of oil and environmental samples collected from four oil spill incidents in Canada—a 2016 pipeline spill into the North Saskatchewan River (NSR), Saskatchewan; a 2015 train derailment in Gogama, Ontario; the 1970 sinking of the SS Arrow ship in Chedabucto Bay, Nova Scotia; and the 1970 sinking of the Irving Whale barge in the Gulf of St. Lawrence—permitted assessment of the PAH content of environmentally weathered samples. A recently developed fluorescence fingerprinting model based on excitation–emission matrix-parallel factor analysis-principal component analysis (EEM-PARAFAC-PCA) was applied to (i) evaluate the intensity of the abundant PAH groups in the samples, (ii) investigate changes in the PAH composition of environmental samples over time due to weathering, and (iii) classify the original spilled oil and environmental samples within the already established classes of the fingerprinting PCA model. The environmental sediment samples collected from the Husky Energy spill site show loss of PAHs occurring over the course of 15 months post-spill. However, the extent of weathering depends on several environmental factors rather than solely the time of weathering, the PAH loss was maximum at 15 months. There was a decrease in the PAH content of the environmental samples of Gogama spill collected 20 months post-spill. Almost all of Gogama environmental sediment samples underwent substantial weathering, making PCA classification impractical. The SS Arrow and Irving Whale samples fell within adjacent PCA groups, as they both had a similar type of spilled oil (Bunker C) with similarity in chemical composition.
关键词： EEM-PARAFAC-PCA,fluorescence spectroscopy,environmental monitoring,oil spill,PAH contamination
更新于2025-11-19 16:56:42
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Photocatalytic Activation of C-H Bonds by Spatially Controlled Chlorine and Titanium on the Silicate Layer
摘要： Owing to the economic and environmental benefits, photocatalytic organic transformation via C-H activation is a crucially important, while still challenging area. We report photocatalytic process for partial cyclohexane oxidation with enhanced catalytic activity that exploits chlorine and titanium atoms spatially arranged on a silica substrate. Silica-based catalysts bearing grafted titanium that effectively interacts with photochemically adsorbed chlorine were prepared. The catalysts were synthesized by reacting a layered silicate with titanium(IV) acetylacetonate and subsequent chlorination treatment. Characterization by a variety of techniques revealed that the organic ligand of the titanium species that is grafted onto the silicate layer surface is converted into chlorine while maintaining its coordination state. However, upon subsequent hydration, the chlorine existed as HCl. We investigated the performance of the catalyst for the production of cyclohexanol and cyclohexanone from cyclohexane with molecular oxygen under solar light irradiation. The chlorinated layered silicate photocatalyst exhibited a remarkably high production rate (0.7 mmol g-1 h-1) and large amount of product formed (0.8 mmol), while the over-oxidation of cyclohexane was inhibited. The enhanced catalytic ability could be explained by the presence of a radical mediator (chlorine) located at a position neighboring an isolated titanium atom. The high surface density of these active species (both titanium and chlorine) on the silicate layer provided suitable electron transfer to form chlorine radicals.
关键词： Photocatalysis,partial oxidation,C-H activation,KA oil,layered silicate,titanosilicate,chlorine,cyclohexane oxidation
更新于2025-11-19 16:51:07
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S, N-codoped Oil-soluble Fluorescent Carbon Dots for High Color-rendering WLED
摘要： Carbon dots (CDs) have attracted widespread attention in light-emitting-diode (LED) applications owing to their environmental friendliness, easy processing and unique optical properties. For the practical use of CDs in LEDs, the controllable synthesis of high performance oil-soluble carbon dots are still in urgent demand. In this study, S, N-codoped oil-soluble carbon dots (S, N-OCDs) with average size of 3.38 nm were prepared by solvothermal reaction of acetone, dimethyl trithiocarbonate (DMTTC) and nitric acid. Characterization results reveal that both the conjugated aromatic π systems from aldol condensation and highly active free radicals from DMTTC essentially dominate the development of this yellow-green emitting S, N-OCDs which possess high carbonization, quantum yield (21.08 %) and oil-solubility. Furthermore, a white light-emitting-diode (WLED) was fabricated through mixing the obtained S, N-OCDs and epoxy and drop-casting the mixure on the surface of gallium nitride (GaN) based blue chips. The as-prepared WLED showed excellent color rendering properties (CCT of 5389 K, CIE coordinates of (0.33,0.30), CRI of 88.38).
关键词： oil-soluble carbon dots,color rendering index,WLED,heteroatom doping
更新于2025-11-19 16:46:39
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A molecular-based design of RGO/TiO2-PAM composite flocculant with photocatalytic self-degrading characteristics and the application of the oil sand tailings flocculant
摘要： Polymer flocculation technology has a very broad application in the flocculation industry of oil sand tailings at present. Nevertheless, the most commonly used commercial polyacrylamide flocculant has problems of low flocculation efficiency and secondary pollution. In this paper, we proposed an organic-inorganic composite flocculant with self-degrading properties for the flocculation treatment of oil sand tailings, which was prepared by photocatalytic surface initiation technique. Further, the functional groups of the materials before and after polymerization composites were characterized by infrared spectrum to explore the polymerization mechanism, the structure was observed by transmission electron microscope, and the molecular weight of polyacrylamide was measured by gel permeation chromatography. Then, the flocculation performance was characterized by the flocculation experiment (tested with simulated oil sand tailings). Subsequently, the flocculation mechanism was explored by testing the zeta potential of the organic-inorganic composites and analyzing images of sediment observed by transmission electron microscope and atomic force microscope. Finally, the test of self-degradation performance was carried out under illumination. Based on the above experiments, the following conclusions were obtained. First, the structural characterization results indicate the polymerization mechanism is that under the condition of light, the surface of the inorganic photocatalyst generates free radicals to initiate the radical polymerization of the monomers, so that the monomers successfully grow on the surface of the inorganic particles into comb structure. And then, the flocculation experiment shows that reduced graphene oxide/titanium dioxide-polyacrylamide(2:40) has the best flocculation effect, of which the supernatant transmittance is 21.4 higher and the sedimentation ratio is 8.9% higher than those of the commercial polyacrylamide. The reason for its excellent flocculation performance is that the zeta potential of the organic-inorganic composite increases, reducing repulsion of particles and flocculant molecules, simultaneously, the formed comb structure is beneficial to the expansion of the polymer chain and increases the contact area, thereby improving the flocculation effect. Ultimately, the degradation results indicates that the new organic-inorganic composite had good degradation effect, with the degradation rate up to 75.9% within 4 hours. Therefore, this work has made great contributions to solving the oil sand tailings pollution field.
关键词： Flocculant,Oil sand tailings,Photocatalytic Self-degrading,Organic-inorganic composite,Comb structure
更新于2025-11-14 17:03:37
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UV/thermal dual curing of tung oil-based polymers induced by cationic photoinitiator
摘要： With the increasing shortage of petroleum-based resources, the exploitation and application of the polymers derived from the renewable resources has becomes increasingly important for the industrial development. In this work, in order to promote the direct application of tung oil in the coating ?eld, the tung oil-based polymers with the excellent mechanical properties by using cationic photoinitiator as the “green” initiator were prepared. The cationic polymerization mechanism and the optimal polymerization conditions of methyl eleostearate (ME) induced by triarylsulfonium salt (TAS) are characterized via the nuclear magnetic resonance spectroscopy. The e?ects of di?erent monomers on the properties of tung oil-based polymers and the post curing behaviors of the polymers are studied by dynamic mechanical test and microtensile test. The results display that the heating treatment after UV irradiation is necessary and favorable for the cationic polymerization of ME induced by TAS. And the optimal reaction condition is 500 W of irradiation energy, 5 wt% of initiator concentration, 60 min of irradiation time, 100 °C of heating temperature and 3 h of heating time. Moreover, tung oil-based polymers with good hydrophobicity can be obtained under the optimal reaction condition. In addition, adding 20 wt% divinylbenzene and 10 wt% styrene to the tung oil can e?ectively increase the mechanical properties and glass transition temperatures (Tg) of tung oil-based polymers.
关键词： Dual curing,Triarylsulfonium salts,Cationic polymerization,Tung oil-based
更新于2025-11-14 15:14:40
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Study of oil-particle-aggregation by digital inline holograph
摘要： This study was performed to visually analyse the relationship between particles and oil in seawater by digital holograph technology. Two types of particles with different sizes were chosen to form oil-particle aggregates (OPAs) in the laboratory to determine whether these particles may be a good approach to safely and harmoniously recover marine environment after an oil spill. The processes were recorded by a digital inline holographic system, which could facilitate a continuous real-time three-dimensional in situ observation of oil droplets and OPAs without touching these particles. The visual results showed that, in the micro scale, the particles formed two different types of OPA after breaking the oil film and transported oil into the bottom of the water, while some OPAs could be resuspended.
关键词： spatial distribution,oil droplet,oil particle aggregation,marine oil spill,digital holographic,digital generated hologram
更新于2025-09-23 15:23:52
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Diode Array Near Infrared Spectrometer Calibrations for Composition Analysis of Single Plant Canola (Brassica napus) Seed
摘要： A canola breeder needs an accurate, rapid, non-destructive method for analyzing seeds from a single plant to select the most promising samples for further breeding trials. Near Infrared Spectroscopy (NIRS) is widely used for quantitative analysis of oilseeds in a non-destructive manner. This research was aimed at developing NIRS calibration models for single plant canola seed using a diode array NIRS (950-1650 nm wavelength range), multivariate prediction models, and a mirrored sample cup. Eighteen different NIRS calibration models were developed using 100 samples for each constituent with different pre-processing techniques (mean center, derivatives, variates) and models (PLS, PCR). The relative performance of different calibration models for each constituent was compared using R2, SEP, and ratio performance deviation (RPD) values obtained from the validation set of 30 samples. NIRS models developed using the PLS regression algorithm for moisture content (R2 = 0.97, SEP = 0.32, RPD = 6.13) and oil content (R2 = 0.84, SEP = 0.61, RPD = 4.16) were successful. However, acceptable NIRS models were not obtained for fatty acid and glucosinolates content likely due to limited variability and low levels of the constituent and a narrow wavelength range of the DA-NIR instrument.
关键词： Moisture content,Diode array,Fatty acid composition,Mirrored cup,DA-NIRS,Oil content,Oleic acid,Stearic acid,NIRS calibration model,Palmitic acid
更新于2025-09-23 15:23:52
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Skin friction measurements on structured surfaces using Clauser-chart method and Oil film interferometry
摘要： Measurements of skin friction have been performed on flat and hexagonal concave surfaces using the conventional Clauser-chart method and the Oil film interferometry. The values of shear stress coefficients measured by the conventional Clauser-chart method on a flat plate were found to be up to 13 % higher from the ones deduced by the Oil film interferometry. The velocity profiles required for the Clauser-chart were obtained by using hot wire anemometry. The analysis of the results suggested that the conventional Clauser-chart method cannot be used to predict shear stresses acting on the hexagonal concave surfaces due to the existence of strong pressure gradients. Oil film interferometry not only provides accurate and direct values of shear stress coefficients but also helps to visualize the flow above the surface.
关键词： Oil film interferometry,skin friction,Clauser-chart
更新于2025-09-23 15:23:52
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Analysis of impacting factors on polarimetric SAR oil spill detection
摘要： Polarimetric synthetic aperture radar (SAR) oil spill detection parameters conformity coefficient (μ), Muller matrix parameters (|C|, B0), the eigenvalues of simplified coherency matrix (λnos) and the influence of SAR observing parameters, ocean environment and noise level are investigated. Radarsat-2 data are used to make systematic analysis of polarimetric parameters for different incidences, wind speeds, noise levels and the ocean phenomena (oil slick and look likes). The influence of the SAR observing parameters, the ocean environment and the noise level on the typical polarimetric SAR parameter conformity coefficient has been analyzed. The results indicate that conformity coefficient cannot be simply used for oil spill detection, which represents the image signal to the noise level to some extent. When the signals are below the noise level for the oil slick and the look likes, the conformity coefficients are negative; while the signals above the noise level corresponds to positive conformity coefficients. For dark patches (low wind and biogenic slick) with the signal below the noise, polarization features such as conformity coefficient cannot separate them with oil slick. For the signal above the noise, the oil slick, the look likes (low wind and biogenic slick) and clean sea all have positive conformity coefficients, among which, the oil slick has the smallest conformity coefficient, the look likes the second, and the clean sea the largest value. For polarimetric SAR data oil spill detection, the noise plays a significant role. So the polarimetric SAR data oil spill detection should be carried out on the basis of noise consideration.
关键词： oil spill,conformity coefficient,multi-polarimetric SAR,noise
更新于2025-09-23 15:23:52