Water Mixtures Research Articles

Experimental investigation of the effects of aqueous ammonia and water mixtures on the efficiency and emissions of a compression ignition engine

In this study, different concentrations of aqueous ammonia and pure water were fumigated and aspirated into the cylinder from the engine intake manifold. Aqueous ammonia (NH4OH) with 5 %, 10 % and 15 % ammonia (NH3) concentration was used in the experiments. Both aqueous ammonia and pure water were converted into cold vapor using an ultrasonic evaporator and conveyed to the combustion chamber as fume. Experiments were carried out at a constant engine speed of 660 rpm. Torque values of 25 %, 50 %, and 100 % (386 Nm) were used in the experiments, respectively. As a result of the experiments, it was seen that as the ammonia percentage increased, the engine efficiency was negatively affected. At 100 % torque, when comparing the BTE value of pure diesel fuel with the BTE values of experiments with 5 %, 10 %, and 15 % ammonia addition, decreases of 0.09 %, 2.27 %, and 3.57 % were observed, respectively. In experiments conducted with pure water, although the thermal efficiency increased significantly as the torque ratio increased, it still could not reach the thermal efficiency of pure diesel fuel. On the other hand, it has been observed that water vapor improves NO and HC emissions. While the NOx value tends to increase with the increase in ammonia concentration at low and medium load values, the NOx value tends to decrease relatively as the ammonia concentration increases at 100 % torque value. The highest NOx emission value, 534 ppmvol, occurred in the experiments with 15 % NH4OH addition. It was observed that the NOx emission value of all experiments conducted with aqueous ammonia additive at 100 % torque was lower than pure diesel. In this study, the effects of NH4OH and H2O on engine performance and emissions were investigated.

Determination of free formaldehyde in cosmetics products through derivatization with 2,4-DNPH using an optimized and validated HPLC-PDA method

AbstractFormaldehyde plays a significant role in the global economy due to its unique chemical properties and widespread use in both the medical field and various industrial sectors. However, formaldehyde (HCHO) is classified as a persistent organic pollutant and is known to be harmful. Exposure to formaldehyde, both direct and prolonged, can cause severe health issues and potentially lead to death. It is recognized as a human carcinogen by numerous organizations and can negatively impact the endocrine system, as well as having mutagenic or teratogenic effects. Formaldehyde has been detected in various matrices at levels exceeding those permitted by international health regulatory bodies. Chromatography, particularly high-performance liquid chromatography (HPLC) coupled with detection methods, is an analytical technique frequently used to determine volatile organic molecules, including formaldehyde. This investigation aimed to develop and validate an assay method to identify and quantify formaldehyde in cosmetic products using HPLC-PDA. The chosen isocratic system consisted of a ZORBAX RX-C8 column (250 mm × 4.6 mm; 5 μm) and a mobile phase mixture of acetonitrile and water in a 55:45 (v/v) ratio, with a flow rate of 1.5 mL min−1. Formaldehyde was detected at 353 nm after derivatization with a 0.1N 2,4-dinitrophenylhydrazine solution, with a retention time of approximately 5.0 min and a total run time of 7.0 min for formaldehyde. The method was validated according to ICH Q2 (R1) guidelines. The validation parameters demonstrated high selectivity, precision (RSD <2%), accuracy (mean recovery of 101.3%), linearity (r > 0.995 in the 1,000–2,400 ppm range), and a limit of quantification (LOQ) of 0.1 ppm. The validated analytical method was applied to 35 cosmetic products. None of these products were labeled as containing formaldehyde, although 6 imported products were labeled as containing formaldehyde-releasing preservatives. The results indicated that 88.6% of the samples tested positive for formaldehyde, with free formaldehyde levels ranging from 20 to 981 ppm. All samples contained formaldehyde levels below the 2000 ppm threshold.

Preparation, Characterization and Sustained-release Study of Encapsulated Cinnamon Essential Oil Microcapsules

Aims: The aim of this study is to study preparation, characterization and sustained release of Encapsulated Cinnamon Essential Oil Microcapsules. Background: In this work, encapsulated cinnamon essential oil (CEO) microcapsules were prepared, characterized, and analyzed for their sustained-release properties. CEO microcapsules were encapsulated from an alginate polymer using homogenization and extrusion, and the encapsulation mechanism used was ionic gelation. The potent antibacterial properties of natural cinnamon oil extracts and their shelf-life activity can be reduced or eliminated as a result of deterioration caused by light, heat, and oxygen exposure during production. High-speed homogenization was utilized for the encapsulation, which encloses and protects the volatile compounds from degradation. Objective: The objective of this study is to synthesize sustained-release encapsulated cinnamon essential oil (CEO) microcapsules. Method: The preparation of encapsulated cinnamon oil was achieved through homogenization. The extrusion method was employed to obtain microcapsules encapsulating liquid active ingredients (AI) with alginate polymer to induce ionic gelation. Results: SEM and Optical images reveal that all microcapsules maintain their spherical shape with clearly defined membranes. XPS analysis indicates the presence of oxygen (O), carbon (C), and sodium (Na) on the surface, suggesting the presence of an alginate-based ionic gelation. Chromatographic studies demonstrate a high encapsulation efficiency of 99%. The average microcapsule size is 261.5 nm for the fresh sample and 278 nm after 3.5 months. The zeta potential is -29.8 mV for the fresh sample and -28.2 mV after 3.5 months. Notably, there is no evidence of microcapsule agglomeration during the 3.5-month storage period as observed in the study. TGA data reveals that only 7.5% of the adsorbed water and essential oil mixture is lost at 40°C over 4 hours, in contrast to 11.7% for the adsorbed water material, indicating a sustained release of the encapsulated CEO from the microcapsules. Conclusion: The microcapsules exhibited an impressive encapsulation efficiency of 99%, demonstrating stability over the 3.5-month investigation period and showcasing sustained-release properties.

Two-dimensional refractive index distribution using polarization phase shifting interferometry and total internal reflection

An effective method to measure the 2-D refractive index distribution of homogeneous liquids: acetic acid and glycerol- water mixture at different concentration and a non- homogeneous mixture of liquids: water, acetic acid, acetone and glycerin but not limited to these liquids is presented. In the present setup a combination of polarization phase shifting interferometry (PPSI) and total internal reflection (TIR) is used. The s-polarized light strikes the boundary of a right angle prism and a tested liquid droplet. When TIR occurs on the interface, the incident light has a phase variation which depends on the refractive index of adhered liquid on prism surface. Two-dimensional index distributions can be easily calculated using the relation among reflection phase shift difference and the liquid index. The results of the tested mixed liquid by proposed technique show the refractive index and its distribution in range 1.433 ± 0.031 to 1.433 ± 0.124.

Solubility of sildenafil citrate in acetonitrile + water mixture at different temperatures

ABSTRACT The study involved the determination of the equilibrium mole fraction solubility of sildenafil citrate in aqueous binary mixtures of acetonitrile across a range of temperatures (from 293.15 K to 313.15 K). To represent this data numerically, both linear and non-linear cosolvency models were employed, and their performances were assessed through mean relative deviations or MRD%. Additionally, this study calculated the apparent thermodynamic properties (Gibbs energy, entropy, and enthalpy) for the dissolution processes using the van’t Hoff and Gibbs equations. Moreover, the study determined the density values of sildenafil citrate saturated solutions and presented them through the van’t Hoff equation.

Effect of Antisolvent Used to Regenerate Cellulose Treated with Ionic Liquid on Its Properties.

The solvolysis reaction with ionic liquids is one of the most frequently used methods for producing nanometer-sized cellulose. In this study, the nanocellulose was obtained by reacting microcrystalline cellulose with 1-ethyl-3-methylimidazolium acetate (EmimOAc). The aim of this research was to determine the influence of various antisolvents used in the regeneration of cellulose after treatment with ionic liquid on its properties. The following antisolvents were used in this research: acetone, acetonitrile, water, ethanol and a mixture of acetone and water in a 1:1 v/v ratio. The nanocellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and elemental analysis (EA). The results show that the antisolvent used to regenerate cellulose after the solvolysis reaction with EmimOAc affects its properties. Water, ethanol and a mixture of acetone and water successfully removed the used ionic liquid from the cellulose structure, while acetone and acetonitrile were unable to completely remove EmimOAc from the cellulosic material. The results of the XRD analysis indicate that there is a correlation between the ionic liquid content in the regenerated cellulose and its degree of crystallinity. Among the tested solvents, water leads to the effective removal of EmimOAc from the cellulose structure, which is additionally characterized by the smallest particle size and non-formation of agglomerates.

Effect of Water on Wear of DLC Coatings in High Temperature and Pressurized Ethanol

The friction and wear characteristics of a-C:H:Si and a-C:H coatings in an ethanol environment at 120 °C and 10 MPa focusing on the effects of water and dissolved oxygen in ethanol were investigated. The friction tests were conducted using an autoclave chamber, with gases (oxygen or nitrogen) and ethanol–water mixtures (0 and 6 vol.%). The wear acceleration of a-C:H:Si took place when it slid in ethanol with 6 vol.% water and pressurized by oxygen, thus the specific wear rate was the highest, approximately 1.8 × 10−7 mm3/Nm. The reason of this wear acceleration was assumed the effect of hardness reduction due to oxidation of the a-C:H:Si, so the O/C ratio by AES and the hardness of topmost surface by AFM nano-scratch were investigated. As a result, the higher O/C ratio showed higher specific wear rate due to the hardness reduction from 13.3 to 6.0 GPa. These findings highlight the role of water and dissolved oxygen in accelerating wear of a-C:H:Si coatings.Graphical abstract

Effect of particle size on SiO2 nanofluid viscosity determined by a two-step method

AbstractAccording to review of the literature, the influence of nanoparticle diameter with irregular shapes on viscosity requires further research since there is no relation between particle size and nanofluid stability. In this study, SiO2/EG–water-based nanofluid samples were prepared, and their viscosities were experimentally determined. SiO2 nanoparticles had sizes of 7, 15, and 40 nm, and the base fluid was a 50% ethylene glycol and 50% water mixture. Nanofluid samples were prepared using a two-step technique. Viscosity change was measured every 10 °C from 20 to 60 °C. The maximum viscosity values were observed for 7, 15, and 40 nm particles over an entire concentration range. Considering all measurements, the highest viscosity increase was 60.51% for 3% SiO2 (7 nm) at 60 °C, and the lowest viscosity change was 7.72% for 1% SiO2 (40 nm) at 40 °C. The most stable sample of the current study was 1% SiO2 (15 nm), and its Zeta potential was − 35.6 mV. Finally, a new empirical equation that included temperature, particle diameter, and concentration terms is suggested to predict dynamic viscosity, with R adj 2 = 0.98. It was also compared with previous correlations.

Evaluation of a prototype variable frequency mode soil moisture and EC probe for its final development

AbstractA prototype dielectric probe developed by the Daiki Rika Kogyo Co., Ltd, Japan, was evaluated by controlled laboratory experiments. The probe simultaneously measures the real and imaginary parts of the dielectric permittivity, which are comparable to the measurements obtained with a vector network analyser (VNA) at frequencies ranging from 10 to 160 MHz. The probe accurately (±2% error) measures the real parts of the dielectric permittivity of oil–ethanol and ethanol–water mixtures over a wide range of real permittivities (3.26 ~ 79) at frequencies ranging from 70 to 90 MHz. The imaginary parts of the dielectric permittivity of aqueous solutions are related to the electrical conductivity (EC) through a unique rational model (±2.5% error) over 80–90 MHz. Dielectric measurements by probes at the desired frequencies can eliminate/reduce the limitations of fixed‐frequency measurements, such as the effects of EC, clay composition, porosity, and organic matter, of currently available probes.

Catalyst Free Synthesis of 4‐Aryl/Alkylamino‐1,2‐Naphthoquinones: Applications in Fluorescence Microscopy

AbstractAn efficient one‐step reagent‐free synthesis of 4‐Aryl/alkylamino‐1,2‐naphthoquinones in water and iPrOH (1 : 1) mixture was carried out at room temperature (RT) using 4‐amino‐3‐hydroxynaphthalene‐1‐sulfonic acid and various primary and secondary aryl and alkyl amines. The reaction did not proceed in the absence of air or oxygen. In all cases, good yields (isolated yield: ≥65 %) were observed. The compounds exhibited fluorescence emission bands (400–470 nm) in the visible region upon excitation at their respective λmax values (330–350 nm). We evaluated in vitro cytotoxicity of some of the derivatives against two human breast cancer cell lines (MCF‐7, and MDA‐MB‐231) using the WST‐1 assay. The naphthoquinone derivatives did not show any cytotoxic effects at concentration levels relevant to cellular fluorescence imaging. The imaging experiments revealed that a few of the derivatives hold the potential to be used as cellular fluorescent imaging probes.

Effect of two-phase viscosity difference and natural fractures on the wormhole morphology formed by two-phase acidizing with self-diverting acid in carbonate rocks

Different types of acids are needed in the field to achieve various acidizing goals. Currently, there are no reliable acidizing models for multiphase flows and complex multiphysics coupling. This paper derives mathematical formulas for the oil–water acidizing process of a situ self-diverting acid combined with thermal–chemical–fracture interactions and discusses the influence of two-phase oil–water mixture and fractures on the wormhole morphology produced by self-diverting acid. The results show that the spent acid following the acid–rock reaction forms a high-viscosity sealing zone, causing the injected acid to be redirected. The self-diverting acid forms more numerous and longer branches than a conventional acid during single-phase acidizing. In the case of two-phase acidizing, the high viscosity difference produces distinct effects when using self-diverting acid compared with conventional acid. Specifically, the self-diverting acid extends the breakthrough time and forms a wormhole morphology with longer and more complex branches, whereas the conventional acid accelerates the breakthrough of the rock. As the viscosity difference decreases, the wormhole morphology of the self-diverting acid gradually approaches that of a single-phase acid. Large-aperture fractures completely determine the wormhole morphology, while smaller apertures determine the branch morphology of the wormhole. Fractures have a negative acidizing effect in the case of the self-diverting acid, unlike conventional acid. The proposed model accurately simulates the complex acidizing process of a self-diverting acid.

Eco-friendly bionic superwetting Janus membranes prepared from paper-based laser-induced graphene for photothermal anti-icing and on-demand oil–water separation

Laser-induced graphene (LIG) from carbon precursors is used in the manufacture of semiconductors, energy and biomedical devices. To expand its field of applications, there is a strong need to explore LIG conversion of eco-friendly precursors. An approach combining bionic structures and surface modification on paper-based LIG was investigated for producing asymmetric superwetting Janus membranes. Molecular dynamic simulation illustrates the paper-based LIG conversion mechanism. The Octadecanethiol-modified bionic crescent-shaped LIG surface exhibited superhydrophobic performance, the water contact angle (WCA) is 157° and the water sliding angle (WSA) is 3.5°. The plasma-modified LIG surface was superhydrophilic with the WCA of 0°. The Janus membranes were demonstrated for high-efficient separation of light oil–water and heavy oil–water mixtures. Furthermore, the superhydrophobic surface of the Janus membranes with excellent photothermal properties exhibited superior anti-icing capability. The proposed approach for fabrication of bionic Janus membranes would provide an eco-friendly solution to LIG applications.

Acceleration of Final Residual Solvent Extraction From Poly(lactide-co-glycolide) Microparticles.

The removal of the residual solvent dichloromethane from biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) microparticles was investigated by aqueous or alcoholic wet extraction or vacuum-drying. Microparticles were prepared by the O/W solvent extraction/evaporation method. The solidified microparticles were separated by filtration and the effect of subsequent drying and wet extraction methods were investigated. The residual solvent content was analysed with gas chromatography (organic solvents) and Karl Fischer titration (water). The effect of extraction conditions on microparticle aggregation, surface morphology and encapsulation of the drugs dexamethasone and risperidone was investigated. Residual dichloromethane was reduced to 2.43% (w/w) (20°C) or 0.03% (w/w)(35°C) by aqueous wet extraction. With vacuum-drying, residual dichloromethane only decreased from about 5% (w/w) to 4.34% (w/w) (20°C) or 3.20% (w/w) (35°C) due to the lack of the plasticizing effect of water. Redispersion of filtered, wet microparticles in alcoholic media significantly improved the extraction due to an increased PLGA plasticization. The potential of different extractants was explained with the Gordon-Taylor equation and Hansen solubility parameters. Extraction in methanol: or ethanol:water mixtures reduced residual dichloromethane from 4 - 7% (w/w) to 0.5 - 2.3% (w/w) within 1 h and 0.08 - 0.18% (w/w) within 6 h. Higher alcohol contents and higher temperature resulted in aggregation of microparticles and lower drug loadings. The final removal of residual dichloromethane was more efficient with alcoholic wet extraction followed by aqueous wet extraction at elevated temperature and vacuum drying of the microparticles.

Automatic characterization of capillary flow profile of liquid samples on μTADs based on capacitance measurement

Capillary flow profile of liquid samples in porous media is closely related to the important properties of liquid samples, including the viscosity and the surface energy. Therefore, capillary flow profile can be used as an index to differentiate liquid samples with different properties. Fast and automatic characterization of capillary flow profile of liquid samples is necessary. In this work, we develop a portable and economical capacitance acquisition system (CASY) to easily obtain the capillary flow profile of liquid samples on microfluidic thread-based analytical devices (μTADs) by measuring the capacitance during the capillary flow. At first, we validate the accuracy of this method by comparing with the traditional method by video analysis in obtaining the capillary flow profiles in μTADs of cotton threads or glass fiber threads. Then we use it to differentiate liquid samples with different viscosity (mixture of water and glycerol). In addition, capillary flow profile on μTADs with chemical valves (chitosan or sucrose) can also be obtained on this device. Lastly, we show the potential of this device in measurement of hematocrit (HCT) of whole blood samples. This device can be used to catalog liquid biological samples with different properties in point-of-care diagnostics in the near future.

Spectroscopic, anti-cancer, anti-bacterial and theoretical studies of new bivalent Schiff base complexes derived from 4-bromo-2,6-dichloroaniline

In this paper, four new mono-nuclear Ni(II), Pd(II), Pt(II) and Zn(II) complexes were prepared by using a bi-dentate Schiff base ligand, (E)-2-(((4-bromo-2,6-dichlorophenyl)imino)methyl)-5-chlorophenol (BrcOH), with bivalent ions in a methanol and distil water mixture as solvent in presence of NaOH as base. The structures of the prepared compounds were characterized by spectroscopic techniques (IR and 1H NMR), CHN analysis, and molar conductivity. The M(II) (Ni, Pd and Pt) ions are four-coordinated by a bi-dentate N2O2 donor ligand, forming square planar geometry, whereas the Zn(II) is coordinated as a tetrahedral geometry. The newly synthesized compounds, which include the Schiff base ligand and its complexes, underwent antibacterial screening against E. coli and S. aureus. The results demonstrated a remarkable and noteworthy biological activity of these compounds against these pathogenic bacterial strains. Different binding energies showed good correlation, with Pd showing the strongest binding. Small energy differences indicated high reactivity, with Ni and Pd complexes being the most reactive. Electrophilicity index exhibited electron-accepting properties, with Zn showing the highest reactivity. The dipole moments showed polarity and charge separation, with Pt having the highest polarity. We evaluated the pharmacokinetic properties (ADME) of a ligand and its metal complexes using the Swiss ADME website. The results of the in-silico prediction of physicochemical properties revealed that ten compounds in total adhered to Lipinski's rule.

Liquid–Liquid Equilibria in Mixtures of 2-Ethylhexanoic Acid, Ethanol, and Water

Liquid–Liquid Equilibria in Mixtures of 2-Ethylhexanoic Acid, Ethanol, and Water

Experimental Forced Convection Study Using a Triply Periodic Minimal Surface Porous Structure with a Nanofluid: Comparison with Numerical Modeling

Triply periodic minimal surfaces (TPMSs) show potential as porous materials in different engineering applications. Amongst them, heat sink is the subject of this paper. The advantage of such a structure is the ability to design it based on the intended applications. In the present paper, an attempt is made to experiment with a better understanding of the performance of TPMSs in heat sink applications. The experiment was conducted for different flow rates, and two heat sink materials, aluminum and silver, were used. In addition, two fluids were used experimentally: The first was water, and the second was a mixture of water containing 0.6% aluminum nanoparticles and identified as a nanofluid. The applied heat flux was maintained constant at 30,800 W/m2. The results reveal experimentally and confirm numerically that the TPMS structure secures a uniform heat extraction in the system. The development of the boundary layer in the porous structure is reduced due to the current structure design. A higher Nusselt number is obtained when the nanofluid is used as the circulating fluid. The performance evaluation criteria in the presence of the nanofluid exceed 100.

Superhydrophobic Stainless Steel Mesh through Chemical Vapour Deposition of TMCS for Effective Oil-Water Separation

Aim: To Fabricate the superhydrophobic Stainless Steel (SS) mesh using Trimethylchlorosilane (TMCS) through a Chemical Vapor Deposition (CVD) method for the oil-water mixture separation Background: The frequent oil spills have a devastating impact on marine ecosystems and the environment. The porous materials with superhydrophobic properties have been created to separate oil and water effectively. Due to their ability to effectively separate oil and water, superhydrophobic coatings have gained significant attention. Methods: The cleaned stainless-steel mesh was put on a stand and covered with a glass container. Within the container, 50 mL of hexane, which contained 1 mL of TMCS, was added. The mesh was then left for 3 h to undergo the CVD process Results: The silane content with low surface energy creates a highly rough structure on the mesh surface. The optimal mesh coating is superhydrophobic, having a strong affinity to oil and a water contact angle of 162 ± 2°. The coated mesh has shown a separation efficiency of over 97.8% for different oil-water mixtures. The coatings sustain their superhydrophobicity up to 30 tape peels and 40 times sandpaper abrasion, indicating good mechanical durability. Conclusion: The study concludes that the S-3 sample is mechanically stable and can withstand various tests such as adhesive tape peeling, sandpaper abrasion, bending, folding, and twisting. It efficiently separates oil and water mixtures on a large scale with high efficacy

The surface tension of Martini 3 water mixtures.

The Martini model, a coarse-grained forcefield for biomolecular simulations, has experienced a vast increase in popularity in the past decade. Its building-block approach balances computational efficiency with high chemical specificity, enabling the simulation of organic and inorganic molecules. The modeling of coarse-grained beads as Lennard-Jones particles poses challenges for the accurate reproduction of liquid-vapor interfacial properties, which are crucial in various applications, especially in the case of water. The latest version of the forcefield introduces refined interaction parameters for water beads, tackling the well-known artifact of Martini water freezing at room temperature. In addition, multiple sizes of water beads are available for simulating the solvation of small cavities, including the smallest pockets of proteins. This work focuses on studying the interfacial properties of Martini water, including surface tension and surface thickness. Employing the test-area method, we systematically compute the liquid-vapor surface tension across various combinations of water bead sizes and for temperatures from 300 to 350K. These findings are of interest to the Martini community as they allow users to account for the low interfacial tension of Martini water by properly adjusting observables computed via coarse-grained simulations to allow for accurate matching against all-atom or experimental results. Surface tension data are also interpreted in terms of local enrichment of the various mixture components at the liquid-vapor interface by means of Gibbs' adsorption formalism. Finally, the critical scaling of the Martini surface tension with temperature is reported to be consistent with the critical exponent of the 3D Ising universality class.

Fructose-mediated single-step synthesis of copper nanofluids with enhanced stability and thermal conductivity for advanced heat transfer applications

A precisely controlled solution-phase approach was employed to synthesize copper nanofluid through the reduction of copper sulfate by fructose in the presence of cetyltrimethylammonium bromide, utilizing a mixture of water and ethylene glycol in 1:1 ratio as the base fluid. We delved into the nanofluid’s thermal conductivity and rheological properties, with a keen interest on particle size and reaction rates that exhibited significant sensitivity to variations in reaction parameters. The homogeneous dispersion of nanoparticles in the base fluid resulted in an augmentation of thermal conductivity to 2.31 Wm−1K−1 for particle loading fraction of 0.19%, with a never before achieved stability of 9 months. This method has proven to be not only straightforward and dependable but also efficient for the rapid synthesis of highly stable Newtonian nanofluids, underscoring the nanofluid’s potential for highly powerful cooling applications.