Organic Droplets Research Articles

The presence of nanoparticles in aqueous droplets containing plant-derived biopolymers plays a role in heterogeneous ice nucleation.

Organic matter can initiate heterogeneous ice nucleation in supercooled water droplets, thereby influencing atmospheric cloud glaciation. Predicting the ice nucleation ability of organic matter-containing cloud droplets is challenging due to the unknown mechanism for templating ice. Here, we observed the presence of nanoparticles in aqueous samples of known ice-nucleating biopolymers cellulose and lignin, as well as in newly identified ice-nucleating biopolymers xylan and laminarin. Using our drop Freezing Ice Nuclei Counter (FINC), we measured the median ice nucleation temperature (T50) of xylan and of laminarin droplets of 2 μl to be -14.2 and -20.0 °C, respectively. Next, we characterized these samples using nanoparticle tracking analysis, and we detected and quantified nanoparticles with mean diameters between 132 and 267nm. Xylan contained the largest nanoparticles and froze at higher temperatures. Xylan also dictated the freezing in a 1:1:1:1 mixture with cellulose, lignin, laminarin, and xylan. Filtration experiments down to 300 kDa with the xylan sample indicated that the presence of nanoparticles triggered freezing. Overall, only samples with mean diameters above 150nm froze above -20 °C. Furthermore, we determined the ice-active site densities normalized to particle concentrations, surface area, and mass of the nanoparticles to show that the samples' nucleation site densities are similar to sea spray aerosols and nanometer-sized dust. The identification and characterization of xylan and laminarin as nanometer-sized ice-nucleating substances expands the growing list of organic matter capable of impacting cloud formation and thus climate.

Solvent-Focused Gas Chromatographic Determination of Thymol and Carvacrol Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction through Solidifying Floating Organic Droplets (USA-DLLME-SFO).

An ultrasound-assisted dispersive liquid-liquid microextraction by solidifying floating organic droplets, coupled to a form of temperature-programmed gas chromatography flame ionization detection, has been developed for the extraction and determination of thymol and carvacrol. This method utilizes undecanol as the extraction solvent, offering advantages such as facilitating phase transfer through solidification and enhancing solvent-focusing efficiency. The optimal gas chromatography conditions include a sample injection volume of 0.2 µL, a split ratio of 1:10, and a flow rate of 0.7 mL min-1. The extraction conditions entail an extraction solvent volume of 20 µL, a disperser solvent (acetone) volume of 500 µL, pH 7.0, 7.0% NaCl (3.5 M), a sample volume of 5.0 mL, an ultrasound duration of 10 min, and a centrifuge time of 7.5 min (800 rpm). These conditions enable the achievement of a high and reasonable linear range of 3.5 to 70. 0 μg mL-1 for both thymol and carvacrol. The detection limits are found to be 0.95 and 0.89 μg mL-1, respectively, for thymol and carvacrol. The obtained relative standard deviations, 2.7% for thymol and 2.6% for carvacrol, demonstrate acceptable precision for the purpose of quantitative analysis.

Organic suspension droplet solid-phase dispersive liquid–liquid microextraction ultra-high performance liquid chromatography tandem mass spectrometry determination of antibiotic residues in water samples

A method was developed for the simultaneous detection of 38 antibiotic residues, which included 8 sulfonamides, 14 fluoroquinolones, 9 macrolides, and 7 anthelminthics, in drinking water, tap water, and environmental water. The method involved organic suspension droplet solid-phase dispersive liquid–liquid microextraction, followed by ultra-high performance liquid chromatography tandem mass spectrometry for the analysis of the water samples. Hypersil GOLD C18 chromatography column (100 × 2.1 mm, 1.9 μm) be used for separation of target analytes that were eluted by a gradient mobile phase composition of 0.2 % formic acid–water as mobile phase A and acetonitrile as mobile phase B at a flow rate of 0.2 mL min−1. Using 0.2 mL of octanoic acid as the extractant and 0.3 mL of acetonitrile as the dispersant. Under optimal conditions, the standard curve exhibits a good linear relationship within the range of 1–50 μg L−1. The spiked recovery rate of the method ranges from 63 % to 96 %, with a relative standard deviation of 0.6 % to 7.3 % (n = 6). The detection limit of the method is between 0.1 and 0.2 μg L−1. This method is characterized by its simplicity, speed, and high sensitivity, which sets the groundwork for investigating the exposure levels and environmental behavior of antibiotics.

Dispersive liquid–liquid microextraction based on solidification of floating organic droplet and spectrophotometric determination of Allura red using green deep eutectic solvent as disperser solvent: Green profile assessment

In this study, dispersive liquid–liquid microextraction based on the solidification of a floating organic drop (DLLME-SFO) was investigated for allura red (AR) preconcentration from water and food samples using green deep eutectic solvent (DES) as a disperser solvent. Compared to the conventional disperser solvents, the DES, which consists of choline chloride and citric acid (1:1), exhibited a higher AR recovery with simple preparation, being eco-friendly and low expense. The proposed protocol showed relatively high recovery values of AR in real samples (97.0–99.5 %). The optimum conditions for AR extraction were pH=3.0, 250.0 µl DES volume, CTAB (4.0 × 10−4 mol L−1), KCl (0.10 mol L−1), 100 µl of 1-dodecanol, and centrifugation: 4.0 min. at 4000 rpm. The validated method showed linearity from 100 to 5000 µg L−1 with 14.4 enrichment factor for 10.0 mL sample. The limit of detection was 29.9 µg L−1 and the relative standard deviation was 3.7 % for five replicate analysis of 300.0 µg L−1. The AR content in studied food samples was determined by spectrophotometry and high-performance liquid chromatography (HPLC). Our proposed method is simple and fast, as the whole process for AR extraction requires only 9.0 min. The analytical eco-scale AGREEnness calculator (AGREE), the blue applicability grade index (BAGI), and the ChlorTox scale were evaluated.

Kinetic monitoring of molecular interactions during surfactant-driven self-propelled droplet motion by high spatial resolution waveguide sensing

Hypothesis: Self-driven actions, like motion, are fundamental characteristics of life. Today, intense research focuses on the kinetics of droplet motion. Quantifying macroscopic motion and exploring the underlying mechanisms are crucial in self-structuring and self-healing materials, advancements in soft robotics, innovations in self-cleaning environmental processes, and progress within the pharmaceutical industry. Usually, the driving forces inducing macroscopic motion act at the molecular scale, making their real-time and high-resolution investigation challenging. Label-free surface sensitive measurements with high lateral resolution could in situ measure both molecular-scale interactions and microscopic motion.Experiments: We employ surface-sensitive label-free sensors to investigate the kinetic changes in a self-assembled monolayer of the trimethyl(octadecyl)azanium chloride surfactant on a substrate surface during the self-propelled motion of nitrobenzene droplets. The adsorption–desorption of the surfactant at various concentrations, its removal due to the moving organic droplet, and rebuilding mechanisms at droplet-visited areas are all investigated with excellent time, spatial, and surface mass density resolution.Findings: We discovered concentration dependent velocity fluctuations, estimated the adsorbed amount of surfactant molecules, and revealed multilayer coverage at high concentrations. The desorption rate of surfactant (18.4 s−1) during the microscopic motion of oil droplets was determined by in situ differentiating between droplet visited and non-visited areas.

Application of hydrophobic superparamagnetic nanoparticles in the solvent extraction of nickel aiming to accelerate phase disengagement

This study investigated the application of a magnetic organic phase containing hydrophobic superparamagnetic nanoparticles to accelerate phase disengagement in solvent extraction processes. For this purpose, stearate-modified magnetite nanoparticles were prepared, characterized, and dispersed in 20 vol.% D2EHPA extractant diluted in kerosene to obtain the intended organic phase. The magnetic solvent extraction process of nickel was conducted using the as-prepared magnetic organic phase containing varying concentrations of hydrophobic magnetite nanoparticles in a sulfate medium. The results implied significant decrements of up to four times in the aqueous/organic phase disengagement duration in an external magnetic field with 10 g.L−1 nanoparticles determined as the optimum concentration. Such magnetically accelerated separation was revealed to be the result of colliding and coalescing the size-heterogeneous magnetic organic droplets moving unevenly through the continuous aqueous solution in a separating system. It is also worth mentioning that applying magnetic solvent extraction did not affect the equilibrium extraction behavior of nickel by D2EHPA.

Development of an ecofriendly dispersive liquid phase microextraction method for the preconcentration of β-blockers in waste and environmental samples

Effective sample preparation is crucial in instrumental analysis to enhance selectivity, sensitivity, and instrument protection. The current trend of miniaturization in liquid–liquid extraction aims to conserve solvents and promote environmental sustainability. Liquid phase microextraction, requiring only small volumes of the extractant, facilitates sample preconcentration without the need for evaporation and reconstitution. This study presents the development of an eco-friendly dispersive liquid–liquid microextraction method employing solidification of floating organic droplets for the determination of five β-blocker drugs in waste and environmental samples. The optimization of key variables affecting extraction efficiency, including extractant type and volume, pH of the diluent, dispersion technique, vortexing, and centrifugation time, was carried out. Optimal results were achieved using 50 μL of dodecanol as the extractant, 1 min of vortexing for dispersion, followed by 2 min of centrifugation for phase separation. The sample was then subjected to a 5 min cooling in an ice bath to solidify the dodecanol before UHPLC/UV analysis. The method yielded enrichment factors within the range of 23–55. The applicability of this approach was demonstrated in laboratory waste and environmental water analysis, with acceptable % recoveries ranging from 98.07 % to 101.83 % and %RSD below 1.96. Moreover, we assessed the method’s performance and greenness with ComplexGAPI, BAGI, and carbon footprint. This method not only provides high efficiency and reliability but also aligns with the principles of sustainablility.

Effect of Surfactants on 1,2-Dichloroethane-in-Water Droplet Impacts at Electrified Liquid-Liquid Interface

In this work, we used the electrified liquid-liquid interface (eLLI) to study the fusion of DCE-in-water organic droplets (soft particles) upon coming into contact with the soft interface. Our focus was to define the effect of the neutral (1-tetradodecanol) and ionic (cetyltrimethylammonium bromide and sodium dodecylsulfonate) surfactants that stabilize the colloidal solution on the electroanalytical output of the impact events. The electrochemically and interfacially active salt used in our work (tetramethylammonium tetrakis(4-chlorophenyl)borate) was always initially dissolved in the organic phase droplets. When the potential drop at the interface was set below the formal Galvani potential of the tetramethylammonium cation ion transfer, we observed ionic current events upon the fusion of the droplets at the eLLI, as studied by chronoamperometry. This phenomenon was found to be severely affected by the surfactants. Our system was investigated with several methods, including cyclic voltammetry, chronoamperometry, interfacial tension measurements, and finally zeta potential and droplet size distribution measurements based on dynamic light scattering.

Separation-dependent near-field effects in Mie scattering spectra of two optically trapped aerosol droplets

The backscattering of ultraviolet and visible light by a model organic (squalane) aerosol droplet (1.0<r<1.4 μm) is investigated upon approach of a second isolated droplet at varying separations. Illumination and collection of light is along the interparticle axis. The conditions replicate typical broadband light spectroscopy studies of atmospheric aerosol. T-Matrix near-field modelling, which includes near-field effects, predicts separation-dependent changes in the intensity of the backscattered light on close approach of neighbouring spheres. However, the experimental results show no evidence of separation-dependent near-field effects on the scattering. The results are best replicated by modelling the droplets as individual Mie scatterers.

A fast, simple and efficient surface floating organic droplet–based air–assisted liquid–liquid microextraction for simultaneous extraction of multiclass pesticides from environmental water, mineral water and soft drink samples by HPLC–DAD

A fast, simple, efficient and selective surface floating organic droplet–based air–assisted liquid–liquid microextraction method coupled with high performance liquid chromatograph–diode array detector was developed for simultaneous extraction of six multiclass pesticides. The developed method was validated for the extraction, enrichment and quantitative determination of trace level multiclass pesticides from environmental water, mineral water and soft drink samples. The effect of experimental parameters such as type and volume of extraction solvent, addition of salt, solution pH and extraction number were successfully optimized. Under the optimum conditions, the method showed good linearity for all the six multiclass pesticide residues with coefficient of determination within the range of 0.9979–0.9994. The limit of detection and quantification were in the range 0.01 to 0.07 µg L−1 and 0.03 to 0.25 µg L−1, respectively. The reproducibility and repeatability study in terms of %RSD were in the range of 0.88–5.28 and 1.35–6.08, respectively, indicating good precision of the method. The method exhibited acceptable mean relative recovery (%RR) in the range of 71.82 to 110.16 % with %RSDs (n = 3) less than 8 % for all the samples. Thus, the developed method could be utilized as selective extraction and preconcentration of multiclass pesticides from environmental water samples, mineral water and soft drink samples, as well as samples with similar matrices.

Efficient Separation of Methanol Single-Micron Droplets by Tailing Phenomenon Using a PDMS Microfluidic Device.

Microdroplet-based fluidic systems have the advantages of small size, short diffusion time, and no cross-contamination; consequently, droplets often provide a fast and precise reaction environment as well as an analytical environment for individual molecules. In order to handle diverse reactions, we developed a method to create organic single-micron droplets (S-MDs) smaller than 5 μm in diameter dispersed in silicone oil without surfactant. The S-MD generation microflow device consists of a mother droplet (MoD) generator and a tapered separation channel featuring multiple side channels. The tapered channel enhanced the shear forces to form tails from the MoDs, causing them to break up. Surface treatment with the fluoropolymer CYTOP protected PDMS fluid devices from organic fluids. The tailing separation of methanol droplets was accomplished without the use of surfactants. The generation of tiny organic droplets may offer new insights into chemical separation and help study the scaling effects of various chemical reactions.

Ultrafast self-transportation and efficient separation of organic droplets on semi-conical asymmetric structure

Manipulating oil droplets in an aqueous solution is highly desirable for organic multiphase liquid separation. Despite substantial works in the realm of organic multiphase liquid manipulation and separation, the ultrafast transportation and efficient and precise separation of these liquids, especially those with varied surface tensions, encounters significant challenges due to little driving forces. To address this issue, a semi-conical structure with pine-needlelike features and incorporated wedge-shaped grooves is fabricated, which could support the ultrafast transport and separation of organic droplets. For pre-wetted superhydrophobic surfaces, organic liquids with lower surface tension can be transported at a speed of 305.6 mm/s. The Laplace pressure difference caused by the conical structure determines the direction of transport of organic liquids, and the capillary force caused by flat wedge-shaped grooves increases the transport speed of organic droplets on the surface. Based on the characteristics of “differential” transportation and directional transportation, the separation of mixed organic liquids is realized. This biomimetic design concept will pave a path for microfluidics, liquid manipulation, and the separation of various organic liquids.

Ultrasonic–microwave synergistic liquid–liquid microextraction based on solidified floating organic droplets for extraction of histamine in beer and fish and exploration of the extraction process

It is important to detect the presence of histamine (His) for indicating food quality. To improve the precision and accuracy of histamine detection, this study developed a novel ultrasonic–microwave synergistic liquid–liquid microextraction based on solidified floating organic droplets (UMS-SFO-LLME) to determine His in beer and fish combined with visible spectrophotometry. Through single-factor experiments and response surface Box–Behnken design, the key extraction conditions affecting UMS-SFO-LLME were systematically optimized. The results for the extraction kinetics and thermodynamics indicated that UMS-SFO-LLME is a spontaneous endothermic diffusion extraction process. The linear range of this method in combination with visible spectrophotometry for the determination of His in beer and fish is 0.3–15 mg L−1 and 1–300 mg kg−1, limit of detection is 0.1 mg L−1 and 0.3 mg kg−1, the intra-day precision is 0.86%–1.22% and 0.98%–2.11%, and the inter-day precision is 0.81%–1.75% and 1.45%–2.32%, respectively. UMS-SFO-LLME is an efficient, green and economical sample pretreatment method for determination of His in beer and fish samples.

Air-agitated liquid–liquid microextraction method based on solidification of a floating organic droplet (AALLME-SFO) followed by UPLC-MS/MS for trace analysis of steroids in water samples: Assessment of the method environmental impact using Analytical Eco-Scale, green Analytical procedure Index and the Analytical GREEnness metric

In the present study, we developed and optimized an air-agitated liquid–liquid microextraction method, employing the solidification of a floating organic droplet (AALLME-SFO), for the effective and rapid identification of specific steroids in water samples using UPLC-MS/MS. The methodology relies on the utilization of 1-dodecanol as the extractant.Initial microextraction trials were carried out to identify an appropriate study space within the experimental conditions. The factors influencing extraction efficiency, including the type and volume of extractant, sample pH, salt concentration, and centrifugation time, were investigated and optimized using experimental designs. The method was carried out using 1-dodecanol as the extractant solvent, the centrifugation time was 15 min and no requirement for the addition of salt or adjustment of pH. Under optimized conditions, the method exhibited favorable linearity, with correlation coefficients higher than 0.9990. Detection limits fell within the range of 0.0025–0.034 µg/L. The proposed method effectively determined the targeted steroids in water samples, yielding satisfactory recoveries ranging from 90.14 % to 98.90 % and relative standard deviations (RSDs) of ≤ 4.10. The environmental impact of the method was assessed through the Analytical Eco-Scale (AES), Green Analytical Procedure Index (GAPI), and the Analytical GREEnness (AGREE) metric, affirming its ecological compatibility. The AALLME-SFO method, as proposed, offers advantages over established methods for steroid detection in water, such as simple preparation, cost-effectiveness, improved extraction efficiency, and environmental friendliness, establishing it as a practical alternative to conventional methods.

Characteristics of Oil-in-Oil Emulsions under AC Electric Fields.

Emulsions have been applied in a number of industries such as pharmaceutics, cosmetics, and food, which are also of great scientific interest. Although aqueous emulsions are commonly used in our daily life, oil-in-oil (o/o) emulsions also play an irreplaceable role in view of their unique physics and complementary applications. In this paper, we investigate typical behaviors of organic droplets surrounded by organic medium (o/o emulsions) with different functional groups controlled by the AC electric field. Droplet behaviors can be catalogued into five types: namely, "no effect", "movement", "deformation", "interface rupture", and "disorder". We identify the key dimensionless number Wee·Ca, combined with the channel geometry, for characterizing the typical behaviors in silicon oil/1,6-hexanediol diacrylate and mineral oil/1,6-hexanediol diacrylate emulsions. Unlike aqueous emulsion, the Maxwell-Wagner relaxation inhibits the electric effect and leads to an effective frequency, ranging from 0.5 to 3 kHz. The increasing viscosity of the droplet facilitates the escalation by promoting the shearing effect under the same flow conditions. Ethylene glycol droplets primarily show the efficient coalescence even at a low Wee·Ca, which is attributed to the attraction of free charges induced by the increasing conductivity. In 1,6-hexanediol diacrylate/silicon oil emulsion, the droplet tends to form a liquid film that expands into the entire channel due to the affinity of the droplet to the channel wall. A variety of elongated columns are observed to oscillate between the electrodes at high voltages. These findings can contribute to understanding the electrohydrodynamic physics in o/o emulsion and controlling droplet behaviors in a fast response, programmable, and high-throughput way. We expect that this droplet manipulation technology can be widely adopted in a broad range of chemical synthesis and biological and material science.

Simultaneous Determination of Steroids and NSAIDs, Using DLLME-SFO Extraction and HPLC Analysis, in Milk and Eggs Collected from Rural Roma Communities in Transylvania, Romania.

This research aims to determine five steroids and four non-steroidal anti-inflammatory drugs in milk and egg samples collected from rural Roma communities in Transylvania, Romania. Target compounds were extracted from selected matrices by protein precipitation, followed by extract purification by dispersive liquid-liquid microextraction based on solidification of floating organic droplets. The extraction procedure was optimized using a 24 full factorial experimental design. Good enrichment factors (87.64-122.07 milk; 26.97-38.72 eggs), extraction recovery (74.49-103.76% milk; 75.64-108.60% eggs), and clean-up of the sample were obtained. The method detection limits were 0.74-1.77 µg/L for milk and 2.39-6.02 µg/kg for eggs, while the method quantification limits were 2.29-5.46 µg/L for milk and 7.38-18.65 µg/kg for eggs. The steroid concentration in milk samples was <MDL up to 4.30 µg/L, decreasing from 17α-ethinyl estradiol, 17β-estradiol, and estrone to estriol. The NSAID concentration was <MDL up to 3.41 µg/L, decreasing from ibuprofen, diclofenac, and ketoprofen to naproxen. The steroid concentration in the egg samples was <MDL to 2.79 µg/kg, with all steroids detected, while the concentration of NSAIDs was <MDL to 2.28 µg/kg, with only ibuprofen, ketoprofen, and naproxen detected. The developed protocol was successfully applied to the analysis of target compounds in real milk and egg samples.

Voltammetry in Microemulsion Formed by Electron Donor Solution in Organic Solvent|Ionic Liquid Microdroplets in Aqueous Electrolyte

Oxygen reduction reaction (ORR)1 or hydrogen evolution reaction (HER)2 at liquid|liquid interface provide the possibility of separation of their products: hydrogen peroxide or hydrogen.3,4 Typically, these reactions are studied at single interface formed between immiscible electrolyte solutions in quiescent conditions. In such geometry the frequency of successful reaction events when highly hydrophobic electron donor (i.e. decamethylferrocene (DMFc) or excited form of decamethylruthenocene (DMRc)) dissolved in organic phase meet proton from aqueous phase is rather limited. Importantly, electrochemical recycling of electron donor at electrode positioned close to the liquid|liquid interface increases efficiency of this reaction.5,6 The use of microemulsion is promising higher efficiency alternative, because of extended interfacial area of numerous organic droplets. As efficient electron exchange between oxidized form of electron donor and the electrode is crucial for biphasic ORR and HER one has to focus on electrochemical studies of DMFc or DMRc in emulsions.are important. Voltammetric signal of various redox probes as ferrocene or ferrocene surfactants in quiescent emulsions is similar to that in single phase with some variation of peak density currents or redox potential.7-11 Other studies focused on chronoamperometric experiments to detect collisions of redox probe (e.g. ferrocene12) containing droplets with the electrode surface. It was found that the addition of an hydrophobic ionic liquid, typically trihexyltetradecyl-phosphonium bis(trifluoro-methylsulfonyl) amide to the organic phase as stabiliser and electrolyte, does not influence the magnitude of the electrochemical signal.13 Here we will report results of electrochemical studies of emulsion prepared from aqueous HClO4 and DMFc or DMRc and trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) imide (IL-PI) solution in toluene. As aqueous phase acid solution was selected, because in biphasic ORR or HER it serves as a source of protons. During the measurements the microemulsion was stirred to achieve faster droplets transport towards the electrode surface. Results will be compared with these obtained in a single organic phase.Voltammograms obtained with glassy carbon disc electrode indicate reversible oxidation/reduction of the redox probe similar to the seen with an electrode immersed in single organic phase. During continuous scanning redox only small change of peak currents is seen. Importantly, when after experiment in emulsion working electrode was transferred to aqueous HClO4, the voltammetric signal is still seen, but the peak currents are significantly smaller. This may indicate the redox reaction in liquid film formed on the electrode surface. Formation of liquid organic film is confirmed by the results of chronoamperometric experiments. When the electrode is set at potential corresponding to the oxidation of the redox probe, of the current is seen after c.a. 100 s drop, what may indicate the gradient of redox probe concentration. As DMFc is insoluble in water this points out on gradient of organic phase close to the glassy carbon surface.14 In turn voltammetric current related to electroreduction of highly hydrophilic hexacyanoferrate(III) is significantly diminished in emulsion as compared to pure aqueous electrolyte indicating partial coverage of the GC surface by hydrophobic film.Other effects related with electrochemical behavior of studied emulsions will be also presented and discussed.

Measuring Liquid-into-Liquid Diffusion Coefficients by Dissolving Microdroplet Electroanalysis.

Diffusion is a fundamental process in various domains, such as pollution control, drug delivery, and isotope separation. Accurately measuring the diffusion coefficients (D) of one liquid into another often encounters challenges stemming from intermolecular interactions, precise observations at the liquid interface, convection, etc. Here, we present an innovative electrochemical methodology for determining the diffusion coefficient of a liquid into another liquid. The method involves precisely tracking the lifetime of a nonaqueous droplet. An organic droplet is placed on an ultramicroelectrode surrounded by an aqueous solution of potassium hexacyanoferrate(II/III). The droplet initially blocks the reduction or oxidation of the redox species. As the droplet dissolves, giving access to the conductive microelectrode surface, a continuously increasing current is observed in voltammetry and the amperometric i-t response. The electrochemical response thus directly reports on the flux of redox species on the electrode surface, allowing us to precisely determine the lifetime of the droplet. D values are directly determined through a combination of electrochemical analysis and the principles of droplet dissolution. We demonstrate the quantification of 1,2-dichloroethane and nitrobenzene into water, yielding diffusion coefficients of (11.3 ± 1.2) × 10-6 cm2/s and (5.2 ± 1.1) × 10-6 cm2/s, respectively. This work establishes a reliable electrochemical approach for quantifying diffusion coefficients based on droplet lifetime analysis.

Extraction of platinum at high phase ratio via a rotating packed bed integrated with falling film

The recovery of platinum is an urgent requirement because of its limited resources and wide application in catalysis, electrochemistry, and so forth. Liquid-liquid extraction is an efficient process in metal recovery due to high product selectivity and purity. However, the extraction of platinum was challenging at a high aqueous-to-organic phase ratio (R), restricted by insufficient contact between phases. This work developed a rotating packed bed integrated with falling film (FF-RPB) to intensify the platinum extraction process. The organic phase consisting of TOA, TBP, and kerosene was broken into droplets by rotating packing. The aqueous phase, the Pt(IV) acidic chloride solution, flowed downward as liquid film on the FF-RPB’s inner wall. The organic micro droplets impacted on the aqueous film, and the extraction was gradually completed during the coflowing process. Results indicated that the extraction efficiency was improved with the increment of rotational speed and TOA concentration and reduced with the enlargement of pH value, Pt(IV) concentration and aqueous-to-organic phase ratio. The extraction efficiency and enrichment factor reached 0.993 and 14.9 at R = 15 and aqueous phase flowrate of 300 L·h−1, respectively. Compared with batch apparatus and microreactors, the FF-RPB showed great advantages, which realized prominent extraction of platinum at a higher aqueous-to-organic phase ratio and a larger throughput.

Ultrasonic-microwave synergistic supramolecular solvent liquid-liquid microextraction of trace biogenic amines in fish and beer based on solidification of floating organic droplet.

It is important to detect the presence of biogenic amines (BAs) as indicators of food freshness. The purpose of this study was to develop a novel ultrasonic-microwave synergistic supramolecular solvent liquid-liquid microextraction based on solidification of floating organic droplet (UMS-SUPRAS-SFO-LLME) combined with high-performance liquid chromatography for the determination of BAs. The physical properties and microstructure of SUPRAS based on 1-dodecanol and tetrahydrofuran were studied, and the extraction conditions such as the SUPRAS volume, the UMS process, and the centrifugal conditions were optimized. The results for the extraction kinetics and thermodynamics showed that UMS-SUPRAS-SFO-LLME is a spontaneous, endothermic diffusion process. The linear ranges of this method are 0.1-2.0×105 ng·mL-1 (R2>0.994), the limits of detection are 4.0×10-3-6.0×10-2 ng·mL-1, and the recoveries were 96.28-103.15%. Compared with existing analysis methods, UMS-SUPRAS-SFO-LLME is a sensitive, green and economical sample pretreatment method for analyzing the enrichment of BAs in beer and fish.