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Keywords = ethoxylated alcohol solutions

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23 pages, 4426 KiB  
Article
Laser Microinterferometry for API Solubility and Phase Equilibria: Darunavir as a Case Example
by Veronika Makarova, Mark Mandrik and Sergey Antonov
Pharmaceutics 2025, 17(7), 875; https://doi.org/10.3390/pharmaceutics17070875 - 3 Jul 2025
Viewed by 417
Abstract
Background: The solubility and phase behavior of APIs are crucial for the development of medicines and ensuring their stability. However, conventional experimental approaches often do not allow for the precise determination of phase transitions and solubility limits, especially for poorly soluble compounds. Purpose: [...] Read more.
Background: The solubility and phase behavior of APIs are crucial for the development of medicines and ensuring their stability. However, conventional experimental approaches often do not allow for the precise determination of phase transitions and solubility limits, especially for poorly soluble compounds. Purpose: The aim of this study was to demonstrate the possibility of using the laser microinterferometry method, traditionally used to define the phase equilibria of polymer systems, to determine the thermodynamic solubility of the APIs. Methods: Using laser microinterferometry, the thermodynamic solubility and phase behavior of amorphous darunavir were determined in various pharmaceutical solvents, including vaseline and olive oils, water, glycerol, alcohols (methanol, ethanol, isopropanol), glycols (propylene glycol, polyethylene glycol 400, polypropylene glycol 425, polyethylene glycol 4000), and ethoxylated polyethylene glycol ether obtained from castor oil in the temperature range of 25–130 °C. Dissolution kinetics was estimated at 25 °C. Hansen solubility parameter calculations were also performed for comparison. Results: Darunavir is practically insoluble in olive and vaseline oils. In water and glycerol, an amorphous equilibrium with an upper critical solution temperature was observed, and phase diagrams were constructed for the first time. In alcohols, glycols, and ethoxylated polyethylene glycol ether obtained from castor oil, darunavir showed high solubility, accompanied by the formation of crystalline solvates. Kinetic evaluation showed that the dissolution rate of darunavir in methanol is four times faster than in ethanol and thirty times faster than in isopropanol. Comparison of the obtained data with previously published and calculated values of solubility parameters demonstrates a good correlation. Conclusions: Laser microinterferometry has been demonstrated as a potential tool for determining the thermodynamic solubility of APIs. This method allows for directly observing the dissolution process, determining the solubility limits, and detecting phase transitions. These studies are necessary for selecting appropriate excipients, preventing the formation of undesirable solvates and predicting formulation stability, which are all critical factors in early-stage drug development and pharmaceutical formulation design. Full article
(This article belongs to the Section Physical Pharmacy and Formulation)
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17 pages, 2381 KiB  
Article
Wettability of the Plant Growth Regulator 28-HB on Pepper Leaves at Different Developmental Stages
by Xiaoya Dong, Kaiyuan Wang, Zhouming Gao, Cuicui Zhu, Xianping Guan and Baijing Qiu
Horticulturae 2025, 11(6), 661; https://doi.org/10.3390/horticulturae11060661 - 10 Jun 2025
Viewed by 360
Abstract
Studying the wettability of plant growth regulators on crop leaf surfaces is essential for enhancing crop yield. In this study, the wetting behavior of the plant growth regulator 28-homo-brassinolide (28-HB), supplemented with different surfactants, was investigated on the adaxial and abaxial surfaces of [...] Read more.
Studying the wettability of plant growth regulators on crop leaf surfaces is essential for enhancing crop yield. In this study, the wetting behavior of the plant growth regulator 28-homo-brassinolide (28-HB), supplemented with different surfactants, was investigated on the adaxial and abaxial surfaces of pepper leaves at the seedling, early flowering, and fruiting stages. The microstructure of the leaf surface was characterized using an ultra-depth field microscope. The surface free energy (SFE) of the leaves was calculated using the Owens-Wendt-Rabel-Kaelble (OWRK) method. Additionally, the surface tension of the 28-HB solutions containing various surfactants, as well as the contact angles on pepper leaves at different growth stages, were measured. The experimental results indicate that the surface free energy (SFE) of pepper leaves significantly decreases with plant maturation. Specifically, the SFE of the adaxial leaf surface declined from 43.4 mJ/m2 at the seedling stage to 26.6 mJ/m2 at the fruiting stage, while the abaxial surface decreased from 27.5 mJ/m2 to 22.5 mJ/m2. At all growth stages, the relative polar component (RP) of the adaxial surface was consistently higher than that of the abaxial surface and showed a gradual decline from 94.70% to 57.34% as development progressed. The contact angle measurement showed that the addition of surfactant decreased the contact angle of 28-HB on the leaf surface and increased the wetting area. Among the tested formulations, the addition of fatty alcohol ethoxylates (AEO-9) significantly reduced the contact angle to below 45°, and resulted in an adhesion tension below 30 mN/m and adhesion work lower than 105 mJ/m2. These values indicate superior wetting performance compared to formulations containing sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). This study integrates the surface free energy characteristics of pepper leaves at different growth stages with the wetting performance of various surfactant systems, providing a quantitative basis for the selection and optimization of surfactants in agricultural spray formulations. The findings offer theoretical support for precise pesticide application strategies, enhancing pesticide adhesion and absorption on leaf surfaces, thereby improving pesticide utilization efficiency throughout the crop growth cycle. Full article
(This article belongs to the Special Issue New Technologies Applied in Horticultural Crop Protection)
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21 pages, 5031 KiB  
Article
Interaction Between Nonionic Surfactants and Alkyl Amidoamine Cationic Collector in the Reverse Flotation of Iron Ore
by José Tadeu Gouvêa Junior, Flávia Paulucci Cianga Silvas, Christian Lariguet Taques Bittencourt, Vantuir Jorge de Morais, Ali Asimi Neisiani and Laurindo de Salles Leal Filho
Minerals 2024, 14(12), 1298; https://doi.org/10.3390/min14121298 - 22 Dec 2024
Cited by 1 | Viewed by 1470
Abstract
This paper evaluates the performance of four ethoxylated nonionic surfactants (nonyl phenol vs. C13 alcohols) to act as ancillary collectors with Alkyl Amidoamine (AAA) in the reverse flotation of quartz at pH8 to concentrate iron ores. Compared to 100% AAA, the blend [...] Read more.
This paper evaluates the performance of four ethoxylated nonionic surfactants (nonyl phenol vs. C13 alcohols) to act as ancillary collectors with Alkyl Amidoamine (AAA) in the reverse flotation of quartz at pH8 to concentrate iron ores. Compared to 100% AAA, the blend composed of 80% AAA (Flotinor®5530) plus 20% of isotridecyl alcohol ethoxylated with five groups of ethylene oxide (DP-210 RO) improved quartz recovery (from 54% to 63%, p < 0.05) by increasing contact angle (from 55° to 56°, p < 0.05) and decreasing induction time (26 ms to 23 ms, p < 0.05). Compared to 100% AAA (200 g/t), the blend (160 g/t of AAA + 40 g/t of DP-210 RO) improved the flotation performance of iron ore, yielding richer hematite concentrate (65.3% Fe × 61.4% Fe) and less contaminated with quartz (4% SiO2 × 10.2% SiO2), coupled with an increase in Fe recovery from 79.8% × 81.6% in the sunken product as well as SiO2 recovery from 91.7% to 96.9% in the froth. Results from zeta potential, the hydrodynamic diameter of reagent droplets, and the surface tension of the solution provide insights into the synergism between AAA and DP-210 RO. Full article
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20 pages, 5602 KiB  
Article
Adsorption Properties and Wettability of Ethoxy- and Propoxy- Derivatives of 2-Ethylhexanol as Sterically Specific Surfactant Structures
by Wiesław Hreczuch, Beata Konopczyńska, Marcin Stasiak, Adam Andrzejewski and Krystyna Prochaska
Molecules 2024, 29(3), 690; https://doi.org/10.3390/molecules29030690 - 2 Feb 2024
Cited by 1 | Viewed by 2070
Abstract
2-ethylhexanol, an oxo alcohol competitively priced on the global market, has not been explored intensively as a raw material for surfactants, due to its weak hydrophobic character. However, its sequenced propoxylation and ethoxylation yield an innovative amphiphilic structure, which exhibits unique interfacial activity. [...] Read more.
2-ethylhexanol, an oxo alcohol competitively priced on the global market, has not been explored intensively as a raw material for surfactants, due to its weak hydrophobic character. However, its sequenced propoxylation and ethoxylation yield an innovative amphiphilic structure, which exhibits unique interfacial activity. The paper presents the differences in the fractional composition of innovative surfactants derived from 2-EH alcohol prepared using alkali and dimetalcyanide catalysts, as well as examples of excellent adsorption and interfacial properties of the latter. The adsorption behavior of the synthesized compounds was explored using equilibrium surface tension (the du Noüy ring method), dynamic surface tension (the maximum gas bubble pressure method) and static/dynamic contact angle (the sessile drop method). The results from the adsorption tests conducted at the air/aqueous surfactant solution interface underwent comprehensive qualitative and quantitative analyses. Moreover, based on the experimentally obtained dynamic surface tension isotherms and the developed algorithm, the diffusion coefficients for these preparations were estimated, and it was shown that the diffusivity of these surfactants is higher compared to the commercial formulations. The study’s outcomes in the testing of wettability indicate that new synthesized nonionic and anionic surfactants constitute an interesting group of amphiphiles with a wide application potential as effective wetting agents, especially in relation to the polymer surface. It should therefore be emphasized that the innovative surfactants described in this article, derived from 2-EH alcohol and prepared using dimetalcyanide catalysts, can successfully compete with conventional preparations such as ABS (Dodecylbenzenesulfonic Acid) or AES (Alcohol Ethoxysulphate) acid salts. Full article
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12 pages, 4166 KiB  
Article
Synergy Effect between Sodium Oleate and Alcohol Ethoxylates on the Reverse Flotation of Quartz
by Na Zhang, Jiajia Li, Jue Kou and Chunbao Sun
Minerals 2023, 13(1), 93; https://doi.org/10.3390/min13010093 - 7 Jan 2023
Cited by 10 | Viewed by 2705
Abstract
In this study, an optimized method was presented for the reverse quartz flotation in iron ore purification where sodium oleate (NaOL) was always selected as the collector due to its accessibility and economic benefits. Three alcohol ethoxylates, octylphenol ethoxylate (OP-10), nonylphenol ethoxylate (NP-10) [...] Read more.
In this study, an optimized method was presented for the reverse quartz flotation in iron ore purification where sodium oleate (NaOL) was always selected as the collector due to its accessibility and economic benefits. Three alcohol ethoxylates, octylphenol ethoxylate (OP-10), nonylphenol ethoxylate (NP-10) and fatty alcohol ethoxylates (AEO-9) were introduced to improve the collecting performance of NaOL in the reverse flotation of quartz. It turned out that the addition of alcohol ethoxylates was helpful to increase the recovery of quartz in the flotation with the order of OP-10 > NP-10 > AEO-9. To characterize the adsorption of NaOL on activated quartz in different surfactant systems, Fourier-Transform Infrared Spectroscopy (FTIR) and Quartz Crystal Microbalance with Dissipation (QCM-D) were employed. Furthermore, the contact angles of the quartz surface that interacted with different surfactant systems were measured to investigate the synergy effect of NaOL and alcohol ethoxylates on the hydrophobicity of quartz. It turned out that alcohol ethoxylates promoted the adsorption of NaOL on the activated quartz, resulting in an increase in the hydrophobicity of quartz also in the order of OP-10 > NP-10 > AEO-9, which well explained the flotation results. Regular Solution Theory (RST) and the dilution effect based on the surface tension analysis were utilized to elucidate the synergy mechanism between NaOL and the alcohol ethoxylate. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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10 pages, 4372 KiB  
Article
Degreasing Efficiency of Electroplating Pretreatment Process Using Secondary Alcohol Ethoxylate as Nonionic Surfactant
by Su-Byung Jeon, Byung-Ki Son, Ji-Won Choi and Injoon Son
Appl. Sci. 2022, 12(21), 11285; https://doi.org/10.3390/app122111285 - 7 Nov 2022
Cited by 1 | Viewed by 4018
Abstract
In this study, the effect of the hydrophilic–lipophilic balance (HLB) number and cloud point (CP) of a secondary-alcohol ethoxylated nonionic surfactant on degreasing efficiency was investigated. A degreasing process was conducted for steel samples with different surfactants in a degreasing solution. The HLB [...] Read more.
In this study, the effect of the hydrophilic–lipophilic balance (HLB) number and cloud point (CP) of a secondary-alcohol ethoxylated nonionic surfactant on degreasing efficiency was investigated. A degreasing process was conducted for steel samples with different surfactants in a degreasing solution. The HLB number and CP increased with the increasing n of the hydrophilic ethylene oxide (OCH2CH2)n group. For a constant temperature of the degreasing solution (30–80 °C), the degreasing efficiency was investigated as a function of degreasing time. The highest degreasing efficiency was observed near the cloud point of the surfactant, and the degreasing efficiency decreased significantly at temperatures lower and greater than the cloud point. A Hogaboom test was carried out to observe oil stains on the surface of samples. Additionally, the contact angle of the surface with water droplets was measured after degreasing with various surfactants. Full article
(This article belongs to the Section Surface Sciences and Technology)
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11 pages, 701 KiB  
Article
The Accumulated Effect of the Number of Ethylene Oxide Units and/or Carbon Chain Length in Surfactants Structure on the Nano-Micellar Extraction of Flavonoids
by Karolina Śliwa and Paweł Śliwa
J. Funct. Biomater. 2020, 11(3), 57; https://doi.org/10.3390/jfb11030057 - 7 Aug 2020
Cited by 14 | Viewed by 3758
Abstract
Classical extraction methods used for isolation of active substances from plant material are expensive, complicated and often environmentally unfriendly. The ultrasonic assistance micelle-mediated extraction method (UAMME), based on green chemistry principles, seems to be an interesting alternative. This work aimed to find a [...] Read more.
Classical extraction methods used for isolation of active substances from plant material are expensive, complicated and often environmentally unfriendly. The ultrasonic assistance micelle-mediated extraction method (UAMME), based on green chemistry principles, seems to be an interesting alternative. This work aimed to find a connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process. The effect of hydrophobic chain length and number of ethoxy groups on the quality of Bidens tripartite extracts was investigated. Several ethoxylated fatty alcohols were used: Ceteareth-20, Steareth-20, Oleth-20, Oleth-10, Oleth-5, C12-C13 Pareth-12, C12-C15 Pareth-12 and Ceteareth-12. The bioflavonoid compositions with the HPLC method was determined. The hydrophilic lipophilic balance (HLB) of studied surfactants, as well as the surface tension of surfactant solutions, were compared, to determine the explanation for the obtained differences in bioflavonoids concentration. The structural changes influenced by polyphenol extraction were monitored using Dynamic Light Scattering (DLS) measurements. In this work, probably for the first time, the connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process was found. The experimental and theoretical approach rationalized the choice of an appropriate eluent. We propose some structurally dependent factors, whose optimal value gave a high efficiency to the UAMME. Full article
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13 pages, 1224 KiB  
Communication
The Potential of Non-Ionic Surfactants for Extraction of Lactic Acid from Aqueous Solution
by Remil Aguda, Shayla LeBoeuf, Cody Stelly, Samantha Bonilla, Brandon LeBlanc, William Holmes, Rafael Hernandez, Mark E. Zappi and Emmanuel D. Revellame
Appl. Sci. 2020, 10(15), 5315; https://doi.org/10.3390/app10155315 - 31 Jul 2020
Cited by 3 | Viewed by 4819
Abstract
Lactic acid, an important commodity chemical for various applications, is mainly produced through fermentation. In this study, the potential of non-ionic surfactants (an alcohol ethoxylate (AE) and two alcohol alkoxylates (AAs)) as solvents for the extraction of lactic acid from aqueous solutions is [...] Read more.
Lactic acid, an important commodity chemical for various applications, is mainly produced through fermentation. In this study, the potential of non-ionic surfactants (an alcohol ethoxylate (AE) and two alcohol alkoxylates (AAs)) as solvents for the extraction of lactic acid from aqueous solutions is reported for the first time. Ternary mixtures containing lactic acid, water, and surfactants were prepared for the assessment. The results indicated that for all the systems, the water–surfactant binary pair exhibits partial immiscibility. Furthermore, the results suggested that with respect to the size of the two-phase region and stability of phases developed, the AE is the suitable solvent for the targeted extraction process. Thus, tie-lines for the system lactic acid + water + AE were then determined to establish the phase diagram of the system at 308.15 K. From the tie-lines, distribution coefficients and separation factors were estimated, which indicated that a compromise between the size and number of extraction units is necessary if AE is to be used as a solvent for lactic acid extraction. The extraction efficiency was estimated to be only about 37–48%. Nevertheless, the biodegradability and non-toxicity of AE makes it a viable solvent for the development of the extractive lactic acid fermentation process. Full article
(This article belongs to the Section Environmental Sciences)
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21 pages, 10099 KiB  
Article
Investigating the Fluid–Solid Interaction of Acid Nonionic Nanoemulsion with Carbonate Porous Media
by Cláudio Regis dos Santos Lucas, Yanne Katiussy Pereira Gurgel Aum, Edson de Andrade Araújo, Tereza Neuma de Castro Dantas, Elayne Andrade Araújo, Talles Nóbrega Sousa and Pedro Tupã Pandava Aum
Molecules 2020, 25(6), 1475; https://doi.org/10.3390/molecules25061475 - 24 Mar 2020
Cited by 15 | Viewed by 3598
Abstract
The subject of rock–fluid interaction is important in cases where flow through porous media is occurring. One special case is when the fluid reacts with the porous matrix. In this case, the mass transfer and reaction rate control the dissolution pattern. This article [...] Read more.
The subject of rock–fluid interaction is important in cases where flow through porous media is occurring. One special case is when the fluid reacts with the porous matrix. In this case, the mass transfer and reaction rate control the dissolution pattern. This article aimed to study the interaction between an acid nanoemulsion system and a carbonate porous media. Nanoemulsions were developed to retard the rock’s dissolution and to promote the formation of conductivity channels. Nanoemulsions were prepared using ALK100 (alkyl alcohol ethoxylate) and RNX110 (alkylphenol ethoxylate) (nonionic surfactants), sec-butanol (co-surfactant), xylene isomers (oil phase), and a solution of HCl (aqueous phase). The obtained systems were characterized in terms of surface tension, droplet diameter, and reactivity. X-ray fluorescence/diffraction (XRF/XRD) and X-ray microtomography (microCT) were performed on carbonate porous media samples treated with the acid systems in order to observe the effects of the fluid–rock interaction. The results showed that the acid nanoemulsion, presenting a low oil content formulation, showed the low surface tension and droplet size characteristic of nanoemulsions. It was experimentally verified that the reactivity in the nanoemulsion media was mass-transfer-retarded, and that the wormhole pattern was verified under the studied conditions. Full article
(This article belongs to the Section Molecular Liquids)
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17 pages, 598 KiB  
Article
The Effect of Liquid Crystalline Structures on Antiseizure Properties of Aqueous Solutions of Ethoxylated Alcohols
by Marian Wlodzimierz Sulek and Anna Bak
Int. J. Mol. Sci. 2010, 11(1), 189-205; https://doi.org/10.3390/ijms11010189 - 12 Jan 2010
Cited by 14 | Viewed by 13975
Abstract
Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the [...] Read more.
Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester) and characterized by scuffing load (Pt), seizure load (Poz) and limiting pressure of seizure (poz). Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the Pt values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value. Full article
(This article belongs to the Special Issue Liquid Crystals)
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