Amount Of Surfactant Research Articles

Interaction and micellar behavior of ternary mixture of amphoteric amino sulfonate surfactant with traditional anionic and nonionic surfactants: Effect of hydrophilicity

The micellization and the molecular interaction behaviors for two ternary mixtures constituted by an amphoteric sodium 3-(n-dodecyl ethylenediamino)-2-hydroxypropyl sulfonate (C12AS), an anionic sodium dodecylbenzene sulfonate (SDBS) and a nonionic octylphenol polyoxyethylated ether with the number (n) of oxyethylene glycol ethers OP-n (n = 10 or 7) in aqueous solution were investigated using the tensiometry and the effect of hydrophilicity on them was also discussed. In the framework of pseudophase separation model and based on the regular solution theory, the related micellization parameters including the mixed critical micelle concentration (cmc) values in the ideal and real cases, the activity coefficients and the compositions in mixed micelle, etc. and thermodynamic parameters were estimated by the Clint’s model and the Rubingh’ model. The mixed cmc value is dependent on the composition in aqueous solution and influenced by the hydrophilicity of nonionic surfactant. With increasing the nonionic in ternary mixture, the mixed cmc value is initially decreased and then slightly rise. An increasing in the hydrophilicity of nonionic will make the minimum value of mixed cmc be increased from 1.299 mM to 1.705 mM. The resulting phenomena can be explained reasonably by the electrostatic effect, the steric hindrance, the hydrogen bonding, etc. Thermodynamic data indicate that the contribution of entropy or enthalpy plays a vital role on the spontaneous process of micellization and the share of entropy or enthalpy in free energy change is dependent largely on the amount of nonionic surfactant and the hydrophilicity. In ternary mixtures of C12AS/SDBS/OP-10, an increase in an amount of OP-10 will induce the change from the enthalpy-driven micellization process to the entropically favorable process. Once an abundant amount of OP-7 is added, while, the enthalpy will make a main contribution on the micellization process, which can be described by the drop in the share of entropy at the composition (0.6970/0.0000/0.3030) of ternary mixture from 0.6478 to 0.4901. These findings will help with understanding the molecular interaction behavior for the ternary surfactant mixture and the effect of the addition of nonionic surfactant and its hydrophilicity.

Hierarchical Macroporous PolyDCPD Composites from Surface-Modified Calcite-Stabilized High Internal Phase Emulsions

High Internal Phase Emulsions (HIPEs) of dicyclopentadiene (DCPD) were prepared using mixtures of surface-modified calcite (mCalcite) and a non-ionic surfactant. Twelve different emulsion formulations were created using an experimental design methodology. Three distinctive levels of the internal phase ratio, the amount of mCalcite loading, and the surfactant were used to prepare the HIPEs. Accordingly, macroporous polyDCPD composites were synthesized by performing ring-opening metathesis polymerization (ROMP) on the HIPEs. The variations in the morphological and physical properties of the composites were investigated in terms of experimental parameters. In the end, five different model equations were derived with a confidence level of 95%. The main and binary interaction effects of the experimental parameters on the responses, such as the average cavity size, interconnecting pore size, specific surface area, foam density, and compression modulus, were demonstrated. The synergistic interaction between the amount of surfactant, the amount of mCalcite loading, and the internal phase ratio appeared to have a dominant role in the average cavity diameter. The solo effect of the internal phase ratio on the interconnecting pore size, foam density, and compression modulus was confirmed. In addition, it was demonstrated that the specific surface area of the composites was mainly changed depending on the amount of mCalcite loading.

Influence of surfactant on glass transition temperature of poly(lactic-co-glycolic acid) nanoparticles.

Poly(D,L-lactic-co-glycolic acid) (PLGA) is one of the most commonly used drug carriers in nanomedicines because of its biodegradability, biocompatibility and low toxicity. However, the physico-chemical characterization and study of drug release are often lacking the investigation of the glass transition temperature (Tg), which is an excellent indicator of drug release behavior. In addition, the residual surfactant used during the synthesis of nanoparticles will change the glass transition temperature. We thus prepared PLGA nanoparticles with polymeric (poly(vinyl alcohol) (PVA)) and ionic (didodecyldimethylammonium bromide (DMAB)) surfactant to investigate their influence on the glass transition temperature. Determination of Tg in dry and wet conditions were carried out. The use of concentrated surfactant during synthesis resulted in a larger amount of residual surfactant in the resulting particles. Increasing residual PVA content resulted in an increase in particle Tg for all but the most concentrated PVA concentrations, while increasing residual DMAB content resulted in no significant change in particle Tg. With the presence of residual surfactant, the Tg of particle and bulk samples measured in wet conditions is much lower than that in dry conditions, except for bulk PLGA containing the ionic surfactant, which may be related to the plasticizing effect of the DMAB molecules. Notably, the Tg of both particles in wet conditions is approaching physiological temperatures where subtle changes in Tg could have dramatic effects on drug release properties. In conclusion, the selection of surfactant and the remaining amount of surfactant are crucial parameters to utilize in designing the physico-chemical properties of PLGA particles.

Optimized synthesis of polyacrylic acid-coated magnetic nanoparticles for high-efficiency DNA isolation and size selection.

Solid-phase reversible immobilization (SPRI) bead technology is widely used in molecular biology for convenient DNA manipulation. However, commercial SPRI bead kits lack cost advantages and flexibility. It is, therefore, necessary to develop new and alternative cost-effective methods of on-par or better quality. Herein, an easy and cost-effective method is proposed for synthesizing polyacrylic acid-coated iron oxide nanoparticles (PAA-IONPs) through in situ polymerization at lab scale for high-efficiency nucleic acid extraction and size selection. A design of experiment (DoE) approach was used to investigate the influence of iron oxide nanoparticles (IONPs), acrylic acid (AA) monomer, and sodium dodecyl sulfate (SDS) surfactant amounts on the sizes and carboxyl group densities of PAA-IONPs. Thorough characterization by thermogravimetric analysis (TGA), attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and vibrating sample magnetometry (VSM) highlights the importance of a low starting pH achieved by a high ratio of AA/IONPs, to yield the largest sizes (554 nm) and highest carboxyl group densities (2.13 mmol g-1) obtained in this study. An efficient DNA purification strategy is then presented using homemade beads-suspension buffer and optimized bead concentrations (17% PEG 8000, 2.5 M NaCl, and 3 mg mL-1 PAA-IONPs). This method shows comparable performance to the control (AMPure XP beads) for DNA recovery. An adjustable PAA-IONPs DNA purification system was also developed to be used for DNA-size selection at low DNA amounts (50-100 ng) with a high degree of resolution and recovery. In conclusion, this work offers an optimized PAA-IONPs synthesis protocol and a flexible DNA purification approach that will enable researchers to manipulate DNA under various conditions, holding the significant potential to benefit future molecular biology research and diagnostics.

Fetal main pulmonary artery Doppler and prediction of lung maturity

Background Respiratory distress syndrome (RDS) in newborns occurs owing to surfactant deficiency. Decrease in quantity and quality of surfactant in lungs results in diminished surfactant activity. It affects not only preterm neonates but also term ones. RDS is a serious condition as it can lead to many neonatal comorbidities and even death. Doppler ultrasound is a noninvasive tool used for assessment of fetal biometry, so Doppler of pulmonary artery can be used safely in assessment of fetal lung maturity. Aim The purpose of our study was to assess the significance of fetal pulmonary artery Doppler in predicting lung maturity. Patients and methods A total of 50 pregnant women participated in this study with gestational age ranging from 34 to 39 weeks who were referred to the Diagnostic Radiology Department at Tanta University Hospitals during the period between December 2019 and December 2021. Results From the 50 pregnant women included in this study, six fetuses developed RDS. The greatest correlation was found with acceleration time/ejection time (AT/ET) ratio and resistive index (RI) with high sensitivity and specificity (P=0.000 and P<0.001, respectively). A cutoff value AT/ET less than 0.297 and RI more than 0.889 predicted RDS with sensitivity of 94.8 and 89.1%, respectively, and specificity of 83.5 and 78.2%, respectively. Conclusion Neonatal RDS can be predicted by pulmonary artery AT/ET ratio and RI with high sensitivity and specificity.

Instability and rupture of surfactant-laden bilayer thin liquid films.

The stability of surfactant-laden bilayer thin films, where the top layer is subject to van der Waals driven breakup, is of particular relevance to applications where one thin liquid layer is spread on another, such as film-forming firefighting foams and multilayer coatings. Although there has been much prior modeling work on the stability of thin liquid bilayers, additional physical effects and assumptions were incorporated in those studies, making it difficult to isolate the influence of surfactant on the rupture of the top layer. The present work addresses this issue through application of the lubrication approximation to derive a coupled system of nonlinear evolution equations describing the perturbations to the liquid-liquid and liquid-air interfaces and the surfactant interfacial concentrations. The surfactant is assumed to be insoluble and can be present at each interface. Linear stability analysis suggests, and nonlinear simulations confirm, that by using surfactant that adsorbs to both interfaces, the rupture time can be increased by an order of magnitude relative to the surfactant-free case. However, we find it crucial to have the right amount of surfactant to generate strongly stabilizing Marangoni stresses without reducing the interfacial tension too much. Nonlinear simulations and linear stability analysis provide insight into the mechanisms of the delayed rupture and show how the direction and strength of the Marangoni stresses strongly depend on the viscosity ratio of the layers. These results can help guide the choice and design of surfactants to achieve more effective firefighting foams and more stable liquid coatings.

Equilibrium state model for surfactants in oils: Colloidal assembly and adsorption

An equilibrium state model addressing the aggregation and adsorption of colloidal assemblies in apolar solvents (oils) via monomer exchange is presented. The model is based on the previously reported step-wise aggregation response of fatty acids and monoglycerides in bio-oils, and captures surface crowding via scaled particle theory (SPT). The sensitivity of key observables - mean aggregation number, adsorbed surfactant amount, and free monomer concentration - to model parameters is demonstrated. Fits to molecular modelling based aggregation and adsorption data of oleic acid and monoolein reveal that the model accurately reproduces chemically specific aggregate exponential distributions in both bulk and surface phases, even outside of its parameterization conditions. A biased state model, where the initial bulk aggregation step (dimer formation) differs from other steps results in a notable improvement in accuracy. Fits to various phospholipid adsorption isotherms demonstrate the applicability of the model to isotherm type experimental data. The fits reveal either monolayer or aggregate like adsorption structures, depending on surfactant head group charge. The presented model provides an easily accessible, computationally feasible means to estimate colloidal assembly and adsorption in oil environments, and enables assessment of surfactant aggregation propensity and adsorption energetics.

Influence of the Type and the Amount of Surfactant in Phillipsite on Adsorption of Diclofenac Sodium

Modified phillipsite samples were prepared with two different amounts (monolayer and bilayer coverage) of surfactants octadecyldimethylbenzylammonium chloride (O) and dodecylamine (D). Composites were characterized by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), thermal analysis and determination of zeta potential, and subsequently tested for removal of diclofenac sodium (DCF). Drug adsorption experiments were performed under different initial DCF concentrations and different contact times. In order to investigate the influence of the chemical structure of surfactants used for modification of phillipsite on the preparation and properties of composites and DCF adsorption, experimental data were compared with previously published results on DCF adsorption by composites containing phillipsite and the same amounts of surfactants cetylpyridinium chloride (C) and Arquad®2HT-75 (A). DCF adsorption isotherms for O and D composites showed a better fit with the Langmuir model with maximum adsorption capacities between 12.3 and 38.4 mg/g and are similar to those for C and A composites, while kinetics run followed a pseudo-second-order model. Composites containing either benzyl or pyridine functional groups showed higher adsorption of DCF, implying that surfactant structure has a significant impact on drug adsorption. Drug adsorption onto O, D, C and A composites was also confirmed by FTIR–ATR spectroscopy and zeta potential measurements.

EMULSION ELECTROSPINNING OF PVA NANOFIBERS CONTAINING HYPERICUM PERFORATUM OIL

The aim of this study is to produce essential oil loaded nanofiber wound dressings from PVA, which is a biodegradable and biocompatible polymer, by emulsion electrospinning method. Hypericum Perforatum oil, known for its antibacterial, antioxidant and anti-inflammatory properties on skin disorders, was used and Kolliphor RH40 surfactant was added to emulsify oil in polymer solution. In order to examine the effect of surfactant amount on nanofiber morphology, surfactant was used at 2%, 4% and 6% (w/w) ratios. The effect of surfactant concentration on solution viscosity and fibre morphology were investigated by viscosity measurements and SEM analysis. To confirm the presence of Hypericum Perforatum oil in nanofibers structure FT-IR spectroscopy analysis were carried out. According to the results, the solution viscosity increased as the amount of surfactant increased. Additionally, it was observed that the average diameters of nanofibers, containing 2%, 4%, and 6% surfactant (w/w), increased compared to the pristine PVA nanofiber. In conclusion, the fiber morphology of Hypericum Perforatum oil-containing PVA nanofibers has been changed with the effect of surfactant.

Controlled Synthesis and Growth Mechanism of Two-Dimensional Zinc Oxide by Surfactant-Assisted Ion-Layer Epitaxy

Two-dimensional (2D) zinc oxide (ZnO) has attracted much attention for its potential applications in electronics, optoelectronics, ultraviolet photodetectors, and resistive sensors. However, little attention has been focused on the growth mechanism, which is highly desired for practical applications. In this paper, the growth mechanism of 2D ZnO by surfactant-assisted ion-layer epitaxy (SA-ILE) is explored by controlling the amounts of surfactant, temperature, precursor concentration, and growth time. It is found that the location and the number of nucleation sites at the initial stages are restricted by the surfactant, which absorbs Zn2+ ions via electrostatic attraction at the water-air interface. Then, the growth of 2D ZnO is administered by the temperature, precursors, and growth time. In other words, the temperature is connected with the diffusion of solute ions and the number of nucleation sites. The concentration of precursors determines the solute ions in solution, which plays a dominant role in the growth rate of 2D ZnO, while growth time affects the nucleation, growth, and dissolution processes of ZnO. However, if the above criteria are exceeded, the nucleation sites significantly increase, resulting in multiple 2D ZnO with tiny size and multilayers. By optimizing the above parameters, 2D ZnO nanosheets with a size as large as 20 μm are achieved with 10 × 10−5 of the ratio of sodium oleyl sulfate to Zn2+, 70 °C, 50 mM of precursor concentration, and 50 min of growth time. 2D ZnO sheets, are confirmed by scanning electron microscope (SEM), energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectrum. Our work might guide the development of SA-ILE and pave the platform for practical applications of 2D ZnO on photodetectors, sensors, and resistive switching devices.

Study of a high efficient composite foam drainage surfactant for gas production

Abstract The foam drainage technique for gas production has the disadvantage of requiring a large amount of surfactant and having low resistance to salt and oil. In this study, a new surfactant mixture (composite surfactant) of lauramidopropyl betaine (LAB-35), α-olefin sulfonate (AOST), sodium alkyl sulfonate (SASE) and cetyltrimethylammonium bromide (CTAB) was tested and its foaming properties were investigated in detail. The foaming properties were determined using high-speed measurements and the Ross-Miles method. The results show that the foaming volume of the composite surfactant can reach 563 mL, indicating that the foaming behaviour of the composite surfactant is more effective than that of the individual surfactants used for the mixture. In addition, the results show that the composite surfactant has a resistance to salt, methanol and condensate oil that most foam drainage agents do not have. However, the stability of the composite surfactant gradually decreases with increasing temperature and concentration. The surface tension was measured and the critical micelle concentration of the composite surfactant is 0.023 g/L.

Solvent Free Twin Screw Processed Silybin Nanophytophospholipid: In Silico, In Vitro and In Vivo Insights.

Silybin (SIL) is a polyphenolic phytoconstituent that is commonly used to treat liver disorders. It is difficult to fabricate an orally delivered SIL product due to its low oral bioavailability (0.95%). Therefore, the current research focusses on the development of a novel composition of a phospholipid complex, termed as nanophytophospholipid, of SIL by employing a unique, solvent-free Twin Screw Process (TSP), with the goal of augmenting the solubility and bioavailability of SIL. The optimised SIL-nanophytophospholipid (H6-SNP) was subjected to physicochemical interactions by spectrometry, thermal, X-ray and electron microscopy. The mechanism of drug and phospholipid interaction was confirmed by molecular docking and dynamics studies. Saturation solubility, in vitro dissolution, ex vivo permeation and preclinical pharmacokinetic studies were also conducted. H6-SNP showed good complexation efficiency, with a high practical yield (80%). The low particle size (334.7 ± 3.0 nm) and positively charged zeta potential (30.21 ± 0.3 mV) indicated the immediate dispersive nature of H6-SNP into nanometric dimensions, with good physical stability. Further high solubility and high drug release from the H6-SNP was also observed. The superiority of the H6-SNP was demonstrated in the ex vivo and preclinical pharmacokinetic studies, displaying enhanced apparent permeability (2.45-fold) and enhanced bioavailability (1.28-fold). Overall, these findings indicate that not only can phospholipid complexes be formed using solvent-free TSP, but also that nanophytophospholipids can be formed by using a specific quantity of lipid, drug, surfactant, superdisintegrant and diluent. This amalgamation of technology and unique composition can improve the oral bioavailability of poorly soluble and permeable phytoconstituents or drugs.

Osmotic Pressure as Driving Force for Reducing the Size of Nanoparticles in Emulsions.

We describe here a method to decrease particle size of nanoparticles synthesized by miniemulsion polymerization. Small nanoparticles or nanocapsules were obtained by generating an osmotic pressure to induce the diffusion of monomer molecules from the dispersed phase of a miniemulsion before polymerization to an upper oil layer. The size reduction is dependent on the difference in concentration of monomer in the dispersed phase and in the upper oil layer and on the solubility of the monomer in water. By labeling the emulsion droplets with a copolymer of stearyl methacrylate and a polymerizable dye, we demonstrated that the migration of the monomer to the upper hexadecane layer relied on molecular diffusion rather than diffusion of monomer droplets to the oil layer. Moreover, surface tension measurements confirmed that the emulsions were still in the miniemulsion regime and not in the microemulsion regime. The particle size can be tuned by controlling the duration during which the miniemulsion stayed in contact with the hexadecane layer, the interfacial area between the miniemulsion and the hexadecane layer and by the concentration of surfactant. Our method was applied to reduce the size of polystyrene and poly(methyl methacrylate) nanoparticles, nanocapsules of a copolymer of styrene and methyl methacrylic acid, and silica nanocapsules. This work demonstrated that a successful reduction of nanoparticle size in the miniemulsion process can be achieved without using excess amounts of surfactant. The method relies on building osmotic pressure in oil droplets dispersed in water which acts as semipermeable membrane.

Effect of dispersant added graphene nanoplatelets with diesel–Sterculia foetida seed oil biodiesel blends on diesel engine: engine combustion, performance and exhaust emissions

In this experimental study, the effect of graphene nanoplatelets (GNPs) on the performance, combustion, and emissions of a diesel engine using Sterculia foetida seed oil biodiesel (SFOME20) was investigated. The novelty of the present study is the surface modification of GNPs with a lipophilic surfactant at different ratios to achieve stable dispersion of GNPs in fuel blends. The homogeneity of the nano-additives in the fuel was tested by ultraviolet spectrometry, and an optimized amount of surfactant was found. The GNPs are dispersed in SFOME20 in different compositions such as 25, 50 and 75 ppm. The experiments were performed at a constant speed under different load conditions. Significant improvements in performance were oberved: brake thermal efficiencywas increased by 8.48%, and brake-specific fuel consumption was decreased by 16.53%. Emission levels Hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx)) were reduced by 28.3%, 24.16% and 10.43%, respectively, at 50 ppm in SFOME20. Significant improvement in combustion parameters was noted in the form of reduced ignition delay (ID), decreased combustion duration, and improved peak pressure and heat release rate under full load conditions. The GNPs were found to be promising additives for biodiesel blends to improve the overall performance, combustion and emission characteristics of the engine.

Effect of different types of surfactants adsorption characteristics on the wettability of coking coal dust

To investigate the effect of different types of surfactants adsorption characteristics on the wettability of coking coal dust, Guoyang coking coal and three different surfactants - dodecyl dimethyl benzyl ammonium chloride (DDBAC), sodium alcohol ether sulphate (AES), coconut diethanolamide (CDEA) - were used. Firstly, the amount of surfactant adsorbed on coal dust were determined using spectrophotometry. Secondly, the contact angles of surfactants on coal tablets was determined. Subsequently, the relationship between the amount of surfactant adsorbed on the coal dust surface and the contact angle was analysed. Finally, the influence mechanism of the amount of the surfactant adsorbed on the coking coal dust surface on wettability was discussed. The experimental results suggest that the adsorption isotherm of cationic surfactant DDBAC on the coal dust surface is bilayer LS-type, while the adsorption isotherm of anionic surfactant AES and non-ionic surfactant CDEA are L-type and S-type, respectively. Additionally, when the concentration of the solution was 0.05%, the amount of AES adsorbed on the coking coal dust surface was estimated to be 64.9 mgg−1, which was 4.19-fold higher than DDBAC (i.e. to 15.5 mgg−1) and 2.2-fold higher than CDEA (i.e. to 29.5 mgg−1), nearly reaching adsorption saturation. The R2 of the amount of DDBAC, AES, and CDEA adsorbed on the coal dust surface affecting the contact angle was 0.9944, 0.99238, and 0.9923, respectively. The adsorption amount of anionic surfactant AES on the coal dust surface at 0.05% is 64.9 mgg−1, and the adsorption isotherm of surfactant on the coal dust surface is L-type, which is more conducive to enhancing the wettability of coking coal dust. Thus, the amount and adsorption isotherm form of the surfactant adsorbed on the coal dust surface are critical factors affecting the coal dust wettability, which provides a theoretical basis for the reasonable selection of surfactants to improve the coal dust suppression efficiency.

States of Aggregation and Phase Transformation Behavior of Metallosurfactant Complexes by Hexacyanoferrate(II): Thermodynamic and Kinetic Investigation of ETR in Ionic Liquids and Liposome Vesicles.

Electronic absorption spectroscopy was used to study the ETR of surfactant-cobalt(III) complexes containing imidazo[4,5-f][1,10]phenanthroline, dipyrido[3,2-d:2'-3'-f]quinoxaline and dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine ligands by using ferrocyanide ions in unilamellar vesicles of dipalmitoylphosphotidylcholine (DPPC) and 1-butyl-3-methylimidazolium bromide ((BMIM)Br), at different temperatures under pseudo-first-order conditions using an excess of the reductant. The reactions were found to be second-order and the electron transfer is postulated as occurring in the outer sphere. The rate constant for the electron transfer reactions was found to increase with increasing concentrations of ionic liquids. Besides these, the effects of surfactant complex ions on liposome vesicles in these same reactions have also been studied on the basis of hydrophobicity. We observed that, below the phase transition temperature, there is an increasing amount of surfactant-cobalt(III) complexes expelled from the interior of the vesicle membrane through hydrophobic effects, while above the phase transition temperature, the surfactant-cobalt(III) complexes are expelled from the interior to the exterior surface of the vesicle. Kinetic data and activation parameters are interpreted in respect of an outer-sphere electron transfer mechanism. By assuming the existence of an outer-sphere mechanism, the results have been clarified based on the presence of hydrophobicity, and the size of the ligand increases from an ip to dpqc ligand and the reactants become oppositely charged. In all these media, the ΔS# values are recognized as negative in their direction in all the concentrations of complexes employed, indicative of a more ordered structure of the transition state. This is compatible with a model in which these complexes and [Fe(CN)6]4- ions bind to the DPPC in the transition state. Thus, the results have been interpreted based on the self-aggregation, hydrophobicity, charge densities of the co-ligand and the reactants with opposite charges.

A new drag model for CFD modeling of bubble columns with surfactant

It is well known that a small amount of surfactant may significantly affect the flow stability in bubble columns, which cannot be interpreted by the slight variation of the liquid physical properties, e.g., surface tension, viscosity or density. The underlying mechanism is relevant to the interfacial dynamics due to surfactant concentration gradient. However, direct resolution of the micro-scale dynamics is challenging, as this requires complicated coupling of direct numerical simulation of interfacial dynamics and surfactant migration. In this study, a simplified correlative model was developed to take into account the surfactant effect on the average drag coefficient in the two-fluid model of CFD simulation. This novel drag model can improve the prediction of gas holdup in the homogeneous regime. By considering both the surfactant effect and swarm effect, the model can also reasonably estimate the gas holdup in the heterogeneous regime. A notable feature of this model is the reproduction of the peak of gas holdup at certain surfactant concentration in the experiments. Furthermore, although the model is based on the experimental data of ethanol solution, it can also predict the gas holdup in the bubble columns of other types of surfactants, e.g., butanol solution.

Insights into the relation of crude oil components and surfactants to the stability of oily wastewater emulsions: Influence of asphaltenes, colloids, and nonionic surfactants

Large amounts of asphaltenes, colloids, and surfactants in the oily wastewater emulsions produced during the resource utilization of oily sludge make the treatment of oily wastewater emulsions difficult. In this study, the crude oil components were separated by solvent separation method, characterized by SEM, XRD, FT-IR, and EDS for crude oil components, suspended solids, and “oil-particulate aggregates”, and compared the emulsification performance of each crude oil component according to the oil–water wetting angle. In addition, the static stability and coalescence stability of different surfactant emulsions were determined, and the kinetic parameters of emulsion decomposition and oil–water interfacial film strength parameters were calculated based on the stability model of emulsion two-phase separation. The mechanisms of active components such as asphaltenes and colloids in crude oil and surfactants on the emulsion stability of oily wastewater were analyzed. It was found that the polar components in crude oil consisted of asphaltenes and colloids, and with the increase of asphaltenes and colloids, the oil–water wetting angle decreased significantly and the emulsion stability increased, and the emulsion stability of nonionic surfactants was better than that of cationic and anionic surfactants, among which octylphenol polyoxyethylene ether (10) (OP-10) had the best emulsion stability. The results of the study provide a theoretical basis for the demulsification and oil removal of oily wastewater emulsions.

The 1,3-Dioctadecyl-1H-imidazol-3-ium Based Potentiometric Surfactant Sensor for Detecting Cationic Surfactants in Commercial Products

A low-cost and fast potentiometric surfactant sensor for cationic surfactants, based on the new ion-pair 1,3-dioctadecyl-1H-imidazol-3-ium-tetraphenylborate (DODI-TPB), is presented. The new cationic surfactant DODI-Br was synthesized and characterized by NMR, LC-MS, and elemental analysis, and was used for synthesis of the DODI-TPB ionophore. The DODI-TPB surfactant sensor was obtained by implementation of the ionophore in PVC. The sensor showed excellent response characteristics with near-Nernstian slopes to the cationic surfactants DMIC, CPC, CTAB, and Hyamine 1622. The highest voltage responses were obtained for DMIC and CPC (58.7 mV/decade of activity). DMIC had the lowest detection limit (0.9 × 10-6 M) and the broadest useful linear concentration range (1.8 × 10-6 to 1.0 × 10-4 M). An interference study showed remarkable stability. Potentiometric titration curves for the titration of cationic surfactants (DMIC, CPC, CTAB, and Hyamine 1622), with DDS and TPB used as titrants, showed sigmoidal curves with well-defined inflexion points and a broad signal change. The standard addition method was successfully applied with recovery rates from 98.9 to 101.2 at two concentrations. The amount of cationic surfactant found in disinfectants and antiseptics was in good agreement with the referent two-phase titration method and the surfactant sensor on the market. This new surfactant sensor represents a low-cost alternative to existing methods for cationic surfactant detection.

Modelling the partitioning equilibria of nonionic surfactant mixtures within the HLD framework

Commercial non-ionic surfactants are usually blends of species differing in the degree of ethoxylation, characterised by a distribution of surfactants with different affinity for the oil and the aqueous phases. This leads to an unexpected concentration dependence of the phase behaviour and the rationalization of such deviations is necessary for their exploitation in surfactant-based formulations. In this work, the phase behaviour of commercial Novel® nonionic surfactants in presence of brine and oil was studied fixing equal volumes of organic and aqueous phases and changing the amount of surfactant and brine salinity (fish cut). The conditions for the balanced state (microemulsion solubilizing equals amount of water and oil) have been determined for different alkanes. The phase behaviour of the surfactant mixture was described, without a priori information about its actual chemical composition, in terms of two pseudo-components: one hydrophilic, entirely at the interface, and the other lipophilic, able to partition itself between the interface and the oil bulk according to a partition constant P. The pseudo-components effect on the interface is quantified through surfactant characteristic parameters (SCPs), according to the Hydrophilic-Lipophilic-Difference (HLD) model. SCPs and P can be experimentally determined by fitting the dependence of the balanced state on the surfactant concentration. The model is successfully applied to the tested surfactants and can quantitively predict the behaviour of their mixtures.