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Interfacial Tensions and Viscosities in Multiphase Systems by Surface Light Scattering (SLS)
摘要： Hypothesis Multiphase systems are relevant in many fields of process engineering. For process and product design in connection with multiphase systems, knowledge on the thermophysical properties of the individual phases such as viscosity and on the interfacial tension between these is required but often lacking in literature. Experiments In the present study, the applicability of surface light scattering (SLS) for the simultaneous measurement of interfacial tensions and viscosities in multiphase systems in macroscopic thermodynamic equilibrium is demonstrated. For two model systems consisting of n-decane and methanol as well as n-dodecane and methanol forming a vapor-liquid-liquid equilibrium at atmospheric pressure, surface fluctuations which show an oscillatory behavior at the vapor-liquid and liquid-liquid interface could be associated with hydrodynamic modes. Findings From an exact theoretical description of the dynamics of the surface fluctuations, absolute data for the dynamic viscosities of the two liquid phases as well as the vapor-liquid and liquid-liquid interfacial tensions could be determined at temperatures between (333 and 358) K with total measurement uncertainties (k = 2) down to about 2%. For both systems studied at temperatures close to the upper critical solution temperature, the viscosities of the two liquid phases approach each other and the liquid-liquid interfacial tension tends to zero.
关键词： liquid-liquid systems,interfacial tension,multiphase systems,interfaces,upper critical solution temperature,vapor-liquid systems,viscosity,surface light scattering
更新于2025-09-23 15:21:21
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Photoresponsive Structured Liquids Enabled by Molecular Recognition at Liquida??Liquid Interfaces
摘要： Using the host-guest molecular recognition at the oil-water interface, a new-type photo-responsive nanoparticle surfactant (NPS), is designed and prepared to structure liquids. With the help of a polymeric surfactant, the interfacial host-guest interactions can be significantly enhanced, leading to a rapid formation and assembly of a NP monolayer, and offering sufficient binding energy to hold the NPs in a jammed state. The assembly of the NPSs can be reversibly manipulated via a photo-switchable jamming to unjamming transition, endowing the interface, as well as the macroscopic assemblies, with responsiveness to the external trigger (photons). This study, for the first time, opens the pathway for the construction of multi-responsive, structured all-liquid systems by introducing host?guest chemistry, showing promising potential applications in encapsulation, delivery systems, and unique microfluidic devices.
关键词： self-assembly,liquid-liquid interfaces,host-guest chemistry,Structured liquid,nanoparticle surfactants
更新于2025-09-23 15:19:57
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Phase-equilibrium measurement of a carbon dioxide/toluene/polystyrene ternary system using laser turbidimetry
摘要： The phase behavior of a carbon dioxide (CO2)/toluene (Tol)/polystyrene (PS) ternary system was measured. The measurements were performed using a synthetic method combined with a reflected light intensity measurement. The bubble points were determined by visual observation, and the cloud points were determined from the change in the reflected light intensity. The phase boundaries were measured at temperatures ranging from 313.2 K to 373.2 K and CO2 weight fractions ranging from 0.10 to 0.41. The homogeneous phase area decreased when the molecular weight of PS and/or the ratio of PS to Tol increased. It was found that the phase behavior of ternary systems, especially the liquid-liquid phase separation behavior, was altered by a change in the mutual solubility between the three components.
关键词： Toluene,Synthetic method,Carbon dioxide,Vapor-liquid equilibrium,Vapor-liquid-liquid equilibrium,Polystyrene,Laser turbidimetry,Liquid-liquid equilibrium
更新于2025-09-16 10:30:52
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Determination of prostate cancer marker Zn2+ with a highly selective surface-enhanced Raman scattering probe on liquid–liquid self-assembled Au nanoarrays
摘要： As the concentration of Zn2+ in patients with prostate cancer is much less than that in healthy persons, Zn2+ concentration can be used as a marker to expediently screen prostate cancer. In this study, a sensitive and highly selective surface-enhanced Raman scattering (SERS) method to detect Zn2+ concentration in human prostatic fluids by utilizing water-insoluble 2-carboxyl-2′-hydroxyl-5′-sulfoformazylbenze (Zincon) as a SERS probe based on self-assembled Au nanoarrays at a liquid–liquid interface between n-hexane and Au colloids was proposed. Zincon showed remarkably different SERS bands before and after coordinating Zn2+ in the controlled conditions (70 μL of ethanol, 500 μL of n-hexane, pH value of 7.1 and 10 s of vortex mixing time), which can be used in quantifying Zn2+ with characteristic peaks. The proposed SERS method presented a good linear relationship ranging from 0.5 to 10 μmol/L and a satisfactory detection limit of 0.1 μmol/L as well as low interference with other metal ions. Moreover, the detection results are close to those of the conventional standard atomic absorption spectroscopy (AAS) method.
关键词： SERS,Au nanoarray,Zincon,Zn2+,Liquid-liquid self-assembly,Prostate cancer
更新于2025-09-12 10:27:22
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Synthesis of Silver Sulfide Quantum Dots Via the Liquid–Liquid Interface Reaction in a Rotating Packed Bed Reactor
摘要： We developed the high-gravity coupled liquid–liquid interface reaction technique on the basis of the rotating packed bed (RPB) reactor for the continuous and ultrafast synthesis of silver sulfide (Ag2S) quantum dots (QDs) with near-infrared (NIR) luminescence. The formation of Ag2S QDs occurs at the interface of microdroplets, and the average size of Ag2S QDs was 4.5 nm with a narrow size distribution. Ag2S QDs can disperse well in various organic solvents and exhibit NIR luminescence with a peak wavelength at 1270 nm under 980-nm laser excitation. The mechanism of the process intensification was revealed by both the computational fluid dynamics simulation and fluorescence imaging, and the mechanism is attributed to the small and uniform droplet formation in the RPB reactor. This study provides a novel approach for the continuous and ultrafast synthesis of NIR Ag2S QDs for potential scale-up.
关键词： Liquid–liquid interface reaction,Rotating packed bed,Ag2S quantum dots,Near-infrared luminescence,Process intensification
更新于2025-09-12 10:27:22
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Quantification of TiO <sub/>2</sub> and ZnO nanoparticles in wastewater using inductively coupled plasma optical emission spectrometry
摘要： The applicability of inductively coupled plasma optical emission spectrometry has been examined for determination titanium dioxide and zinc oxide nanoparticles in industrial wastewater samples. The extraction and preconcentration of the nanoparticles were achieved using ligandless ultrasound-assisted surfactant-based dispersive liquid–liquid microextraction. Under optimized conditions, the developed method had limits of detection (LOD) of 2.7 ng L?1 for Ti and 3.6 ng L?1 for Zn resulting from dissolved TiO2 and ZnO nanoparticles. The relative standard deviation values for intraday precision were 2.5% and 3.1% for TiO2 and ZnO, while the interday precision was 4.5% and 5.0%. Percentage recoveries ranging from 98% to 100% were obtained. Finally, the applicability of the method was examined by analyzing spiked samples and wastewater samples collected from textile, cosmetic and paint industries.
关键词： Surfactant-based dispersive liquid–liquid microextraction,emerging contaminant,desirability function,engineered nanoparticles,wastewater
更新于2025-09-11 14:15:04
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Determination of Ciprofloxacin in Fish by Surface-Enhanced Raman Scattering Using a Liquid-Liquid Self-Assembled Gold Nanofilm
摘要： Trace detection of antibiotic ciprofloxacin by surface-enhanced Raman scattering (SERS) remains a challenge, because this compound is water-insoluble and amphoteric and it has no functional groups to combine with gold nanoparticles. Herein, ciprofloxacin was physically adsorbed on a self-assembly gold nanofilm for realizing quantitative SERS detection of ciprofloxacin in fish. A gold nanofilm containing ciprofloxacin spontaneously formed at the interface of gold colloids/n-hexane by vortex mixing in a few seconds without ethanol or other organic additives. The density of the gold nanoparticles on the interface which influences the SERS effect was controlled by varying the vortex mixing time and the volume of n-hexane. Furthermore, the proposed substrates with an enhancement factor of 2.7 (cid:1) 106 were successfully applied for the determination of ciprofloxacin in fish samples with a linear range from 0.5 to 10.0 lg/mL and a detection limit of 0.19 lg/mL. The recovery measurements showed that the proposed SERS method had satisfactory precision and accuracy.
关键词： Ciprofloxacin,interface,gold nanofilm,liquid-liquid,surface-enhanced Raman scattering
更新于2025-09-11 14:15:04
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DLLME-GC/ECD Method for the Residual Analysis of Parathion-Methyl and its Application in the Study of the UV-Photodegradation Process
摘要： A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 μg L-1, respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1, the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 μg L-1.
关键词： UV radiation,degradation,gas chromatography,pesticide,dispersive liquid-liquid microextraction
更新于2025-09-11 14:15:04
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Optimization of the liquid–liquid interfacial precipitation method for the synthesis of $$\hbox {C}_{60}$$C60 nanotubes
摘要： Tubular fullerene nanowhiskers called ‘fullerene nanotubes’ are composed of C60 fullerene molecules (C60 NTs) are synthesized at room temperature using the liquid–liquid interfacial precipitation method in the pyridine and isopropyl alcohol (IPA) system. The growth control of fullerene nanotubes is important for their chemical and physical properties as well as for their future applications. In the present study, we investigated the effect of light, water, solvent ratio and temperature on the synthesis of C60 nanotubes. A marked development in the yield of C60 NTs was achieved using dehydrated solvents, a solution with a volume ratio of 1:9 for pyridine: IPA, a growth temperature equal to 5?C and by illuminating the C60-pyridine solution with ultraviolet light (wavelength 302 nm) for 102 h. The synthesized fullerene nanotubes were characterized by different analytical techniques including Raman and Fourier transform infrared spectroscopy, optical microscopy, focussed ion beam scanning electron microscopy and transmission electron microscopy.
关键词： solution growth,liquid–liquid interfacial precipitation method,light,temperature,solvent,Fullerene nanotubes
更新于2025-09-09 09:28:46