Aqueous Solutions Of Nonionic Surfactants Research Articles

Ionic liquids and non-ionic surfactants: a new marriage for aqueous segregation

The aqueous nature of aqueous biphasic systems has boosted their use in downstream stages in biotechnological processes. Since aqueous solutions of non-ionic surfactants are widely used for different metabolites' purification, we have demonstrated for the first time their segregation capacity in the presence of ionic liquids.

Photochemical properties of substituted tetraazachlorins

The photochemical properties of water-insoluble metal-free tetraazachlorin derivatives in organic solvents and aqueous micellar solutions of nonionic surfactants were investigated. The quantum yields of fluorescence, singlet oxygen generation and photodegradation were evaluated in benzene. The highest photostability and singlet oxygen quantum yield (ΦΔ = 0.7) was found for 2,2,3,3-tetramethyl-7,8,12,13,17,18-hexaphenyltetraazachlorin. The moderate ΦΔ values (0.21–0.35) of triarenotetraazachlorins in benzene were established. Expansion of tetraazachlorin π-system by fusion of three aromatic rings leads to reduction of efficiency of singlet oxygen generation. The study of photodegradation mechanism shows that radical photooxidation apparently is most plausible, though 1 O 2 may partly contribute to photodestruction of some tetraazachlorins. In aqueous colloidal solution of nonionic surfactant (Cremophor EL) the same, as in benzene, effect of sensitizer structure upon efficacy of singlet oxygen production was observed. It was shown that 1 O 2 diffusion from micelle core into solution and then to target slows its oxidation rate substantially in comparison to the case where sensitizer and target are localized in the same micelle.

5-[4-(N,N-Dimethylamino)Phenyl]-2-(4-Pyridyl)-1,3-Oxazole as a Fluorescent Probe for Monitoring Microheterogeneous Media

The N,N-dimethylamino-γ-pyridine analog of 2,5-diaryl-1,3-oxazole has been synthesized. Quantum-chemical modeling was carried out for the electronic absorption spectra and the effect of hydrogen bonding between the pyridine nitrogen atom and the water molecule on these spectra. The calculation results were compared with the experimental data for the solvent effect on the spectra of this compound. The feasibility of practical application of this derivative as a fluorescent probe was tested for determining the critical micelle concentration in aqueous solutions of nonionic, zwitterionic, cationic, and anionic surfactants.

Synthesis and Interfacial Activity of Nonyl Phenol Polyoxyethylene Ether Carboxylate

In order to study the interfacial activity of the anionic-nonionic surfactant, five nonyl phenol polyoxyethylene ether carboxylates were synthesized and mass spectra were used to characterize their structures. The tensions of the anionic–nonionic surfactant aqueous solutions against crude oil were measured and the effects of the surfactant structure, concentration, and salinity on the interfacial activities were discussed. It was shown that nonyl phenol polyoxyethylene (6) ether carboxylate can produce ultralow interfacial tension when the concentrations are not lower than 0.10%, exhibiting a high interfacial activity and a good anti-dilution resistance. Moreover, it was proved that there exists synergism between NaCl and MgCl2 (or CaCl2), which is crucial to achieve the ultralow interfacial tension.

213 非イオン性界面活性剤の実用化に向けた抵抗低減水溶液の劣化特性に関する実験的研究(OS13-1 乱流現象の実験と数値シミュレーション(1),OS13 乱流現象の実験と数値シミュレーション)

213 非イオン性界面活性剤の実用化に向けた抵抗低減水溶液の劣化特性に関する実験的研究(OS13-1 乱流現象の実験と数値シミュレーション(1),OS13 乱流現象の実験と数値シミュレーション)

Enhancement of heat transfer rate in air-atomized spray cooling of a hot steel plate by using an aqueous solution of non-ionic surfactant and ethanol

Air-atomized spray cooling, where compressed air atomizes water into fine droplets, is an efficient alternative to conventional cooling techniques. The present work deals with the air-atomized spray cooling of a 6 mm thick stainless steel plate having an initial surface temperature of 900 °C, using surfactant Tween 20 and ethanol additives. The main difficulty in achieving a high cooling rate at elevated surface temperatures is the Leidenfrost phenomenon. The metallurgical properties of steel are highly affected by the run-out table cooling rate between the temperature range of 900–600 °C. Another important cooling region, particularly to achieve the high strength martensite microstructure in steel, is 900 °C–200 °C. Therefore, in this study, the heat transfer studies have been done over those temperature regions. The physical properties of the coolant mixture were measured to understand the heat transfer enhancement mechanism. The results show that increasing the ethanol fraction in pure water (with or without surfactant) enhances the critical heat flux, heat transfer coefficient and cooling rate of a hot surface in the nucleate and transition boiling regimes. A maximum cooling rate of 183 °C/s has been obtained with the ethanol–water mixture; whereas ethanol–water–surfactant mixture gives a cooling rate of 235 °C/s, both of which lie in ‘ultrafast cooling’ regime.

Preparation of SiO2 /epoxy nanocomposite via reverse microemulsion in situ polymerization

Reverse water/oil (w/o) microemulsions composed of epoxy resin (EP) (the oil phase) and nonionic surfactant and ammonia aqueous solutions (the water phase) were used in the synthesis of SiO2/EP nanocomposites. The stability of reverse microemulsion was evaluated by measuring water solubilization of the microemulsion. Effects of surfactant type and content, ammonia concentration and temperature on the water solubilization were systematically investigated. Higher water solubilization capacity was obtained by nonionic surfactant TX-100 compared with other two surfactants, Span-80 and Tween-80. Ammonia concentration of 5 wt% and preparation temperature at 35°C were favorable for forming a stable microemulsion and enabling the subsequent hydrolysis and condensation reaction of inorganic precursor tetraethoxysilane (TEOS). SiO2/ epoxy nanocomposites were prepared via in situ polymerization of TEOS within the nanoscale reverse microemulsion “water pool”. FTIR, SEM, and universal testing machine were used to characterize the structural and mechanical properties of the composite. The results revealed that the optimal mechanical properties were obtained at 3 wt% TEOS content. Compared with neat epoxy resin, the tensile and flexural strength of the composite were 40% and 12% higher, respectively. The formation of the silica structure in the hybrid was investigated with FTIR. The SEM and optical observations showed a ductile fracture morphology and good miscibility between inorganic and organic phases. POLYM. COMPOS., 35:1388–1394, 2014. © 2013 Society of Plastics Engineers

Tube radial distribution phenomenon observed in an aqueous micellar solution of non-ionic surfactant fed into a microspace and an attempt of capillary chromatographic application

A new type of tube radial distribution phenomenon was observed in an aqueous micellar solution of non-ionic surfactant that was fed into a microspace. A homogeneous aqueous solution containing 2 wt % Triton X-100 and 2.0 M sodium chloride was fed into a microchannel (40 μm in depth and 200 μm in width) in a microchip at a flow rate of 4.0 μL/min, where the microchip was maintained at a temperature of 34°C. The homogeneous aqueous solution changed to a heterogeneous solution with two phases in the microchannel; the surfactant-rich phase was generated around the middle of the channel, while the aqueous phase containing little surfactant was formed near the wall. The radial distribution of the surfactant was observed through Rhodamine B dissolved in the aqueous micellar solution with a bright-field microscope — CCD camera system. An open-tubular capillary chromatographic system was also tried to develop using the fusedsilica capillary tube (75 μm inner diameter and 120 cm length) as a separation column and the aqueous micellar solution as a carrier.

Phase segregation in aqueous solutions of non-ionic surfactants using ammonium, magnesium and iron salts

Aqueous Biphasic Systems (ABS) are suggested as a separation technique for a great diversity of compounds, making it necessary to characterise fully the solubility data of these kinds of systems. In this study, the non-ionic surfactants Tween 20 and Triton X-100 are proposed as candidates to form ABS, with different inorganic and organic salts ((NH4)2Fe(SO4)2, MgSO4, (NH4)2HPO4, (NH4)2SO4, (NH4)2C4H4O6) at T=298.15K. All the solubility data were obtained by means of the cloud point method and the salting-out ability of salts was also evaluated in terms of the Gibbs free energy of hydration (ΔhydG) and molar entropy of hydration (ΔhydS). The Merchuk equation and some variations of this model have been used for correlating the solubility curve. The extraction capacity k was evaluated in terms of tie-lines (TL) data.

Effect of Microbubble Mixtures on the Washing Rate of Surfactant Solutions in a Swirling Flow and an Alternating Flow

Abstract Wastewater from laundry cleaning contributes to water pollution, and the amount of detergent used needs to be reduced. In the present study, water, four types of surfactants, and their microbubble mixtures were used, and washing rates were measured in swirling flows and alternating flows. The microbubble/water mixtures (average particle diameter: 25 μm; mixed with air at 1.5 vol % in water) achieved washing rates higher than those of water alone. Furthermore, microbubbles mixed with an aqueous surfactant solution had a washing rate that depended on the ionization of the surfactant: the mixtures with microbubbles and non-ionic and anionic surfactants had a washing rate that was higher than that of aqueous non-ionic and anionic surfactant solutions without microbubbles. The surface tensions of microbubble/water mixtures and mixtures of microbubbles with non-ionic and anionic surfactants were lower than those without microbubbles. These results provide evidence of an enhanced washing effect for microbubble mixtures in laundry cleaning.

Study of Hydrophobic VOCs Absorption Mechanism in a Bubble Column: Bubble Hydrodynamic Parameters and Mass Transfer Coefficients

The absorption mechanism of hydrophobic Volatile Organic Compounds (benzene) was investigated in a small bubble column. Effects of gas spargers (orifice size), gas flow rates, and absorbents (tap water, aqueous solution with non-ionic surfactant, and lubricant oily-emulsion) were analyzed in terms of absorption efficiency, bubble hydrodynamic, and mass transfer parameters. The results showed that the presence of non-ionic surfactant and lubricant oil affected the bubble hydrodynamic phenomena and the interfacial area (a) and the mass transfer parameters (volumetric mass transfer coefficient, kLa, and liquid-side mass transfer coefficient, kL). Absorption efficiencies of aqueous solutions with the previous substances as absorbents were significantly greater than those of tap water. These experimental results relate to the augmentation of benzene solubility in the liquid phase (absorbents) due to the presence of oily-particles and surfactant molecules. Moreover, high gas flow rates can decrease the VOCs absorption efficiency due to desorption mechanisms, associated with the mixing power in the liquid phase. Finally, it has been suggested that gas spargers with an orifice size smaller than 0.65 mm, 1 cm/s gas superficial velocity, and 50 mg/l lubricant oily-emulsion or 5 CMC non-ionic surfactant aqueous solutions are of optimal design and operation for hydrophobic VOCs absorption in the bubble column used in this study.

Pressure Reentrant Assembly: Direct Simulation of Volumes of Micellization

Surfactants exhibit maxima in their critical micelle concentrations upon application of hydrostatic pressure, which is attributable to changes in their volumes of micellization from positive to negative values with increasing pressure. We present a direct molecular simulation analysis of the volumes of micellization of an anionic, cationic, and nonionic surfactant in aqueous solution at pressures up to 2500 bar. Excellent agreement with experiment is observed. A Kirkwood-Buff theory analysis based on proximal solvent distributions permits the breakdown of the volumes of micellization into constituent surfactant headgroup and tailgroup contributions. Although the micellization volume crossover is analogous to the transfer of an alkane from water to its pure liquid, significant differences are observed, including lower compressibilities of micelle volumes compared to that of the alkane liquid, negative partial compressibilites for anionic sulfated surfactant monomers, and large nonionic ethoxy headgroup contributions to the micellization volume.

Comparative study on coating CdSe nanocrystals with surfactants

We have synthesized CdSe nanocrystals (NCs) in sizes from 2.2 to 5.1 nm passivated with hydrophobic trioctylphosphine oxide (TOPO) in combination trioctylphosphine (TOP) or tributylphosphine (TBP) to obtain particles of the type CdSe/TOPO/TOP or CdSe/TOPO/TBP. These NCs were then dispersed in aqueous solution of ionic or non-ionic surfactants (such as stearate, oleic acid, Tween) using a biphase (water and chloroform or hexane) transfer method. It is found that both the structure of the surfactant and the native surface of the ligand govern the coating of the NCs with surfactants. More specifically, the hydrophobicity-hydrophilicity balance of the surfactant regulates the coating efficacy, thereby transferring the NC from the organic to the aqueous phase. The type of ligand on the NCs and the kind of coating surfactant also affect photoluminescence (PL). The ratio of PL and absorbance unit (defined as PL per 0.1 AU) was implemented as a tool to monitor changes in PL intensity and wavelength as a function of size, coatings and surface defects. Finally, the distribution of CdSe nanocrystals between pseudophases in cloud point extraction was discussed based on experimental results. It was concluded that the size of CdSe nanocrystal present in an appropriate pseudophase is correlated with the way in which the non-ionic surfactant coats CdSe nanocrystals. FigureCoating of CdSe semiconductor nanocrystals with surfactants impacts nanocrystals’ spectral features. Absorbance of first exciton absorption band was used to estimate ability of surfactant to disperse CdSe nanocrystals. Photoluminescence (PL) intensity and position of PL band were analysed in terms of nanocrystal’s surface phenomena via surfactants applied for coating. Electronic supplementary materialThe online version of this article (doi:10.1007/s00604-013-1062-z) contains supplementary material, which is available to authorized users.

Evaluation of interactions between metal ions and nonionic surfactants in high-concentration HCl using low-pressure high-performance liquid chromatography with low-flow-resistance polystyrene-based monolithic column

A method for evaluating the interactions between metal ions and nonionic surfactants in aqueous solutions containing high-concentration HCl, using gas pressure-driven low-pressure high-performance liquid chromatography (LP-HPLC) as a highly acid-resistant HPLC system, was developed. To construct the LP-HPLC for this purpose, poly(styrene-co-divinylbenzene)-based low-flow-resistance monolithic columns tolerant to highly acidic conditions were prepared using low-conversion thermal polymerization. Thermal polymerization at 65 °C for 1.5 h (monomer conversions, 33% for styrene and 59% for divinylbenzene) allowed preparation of a column with both high separation efficiency (around 60,000 plates m(-1) for alkylbenzenes) and a quite low back pressure of 0.14 MPa at a linear flow rate of 1 mm s(-1) (2.8 × 10(-13) m(2) in permeability). The base column prepared under the above conditions was coated with a nonionic surfactant, polyoxyethylene nonylphenyl ether (PONPE, average oxyethylene unit numbers (n) = 3, 7.5, 15, and 20), and used for evaluation of the interactions between PONPEs and metal ions in 6 M HCl. The interactions between PONPEs and Au(III), Ga(III), Fe(III), Zn(II), and Cu(II) were successfully evaluated using both breakthrough and chromatographic methods. Furthermore, a study of the effect of the polyoxyethylene (POE) chain length revealed that the use of PONPE with the longer POE moiety enhanced the magnitude of the interaction together with the increase in the amount of oxyethylene (OE) units coated on the monolith. Moreover, the interactions of metal ions with a single OE unit were almost constant in the range of n = 7.5-20, whereas the suppression of the interaction between Au(III) with the shortest PONPE chain (n = 3) was also observed.

Altering Phase Separation in Aqueous Nonionic Surfactant Solutions by Power Ultrasound

Cloud point extraction (CPE) is an efficient and green separation technology as an alternative to conventional organic solvent extractions. How to accelerate the phase separation of aqueous surfactant solutions conveniently is of great importance. In this study, the effect of power ultrasound on the phase separation of aqueous solutions of a nonionic surfactant, Triton X-114 [(1,1,3,3-tetramethylbutyl) phenyl-polyethylene glycol], has been studied as a function of temperature by means of rheo-small angle light scattering. It is found that anomalous viscosity enhancements and micron-sized scattering aggregates are observed for the surfactant solutions after ultrasound irradiation. The aggregate growth is quantified by the characteristic length of the aggregates. It is proposed that ultrasonic cavitation can promote the aggregation or transition of surfactants in the aqueous solutions, resulting in the formation of micrometer-scale phase-separated droplets. This work may advance further understanding of the controlled transformation of aggregates in surfactant solutions via power ultrasound and promote its applications in CPE.

Tube Radial Distribution Phenomenon Observed in an Aqueous Micellar Solution of Non-ionic Surfactant Fed into a Microspace and an Attempt Of Capillary Chromatographic Application

Tube Radial Distribution Phenomenon Observed in an Aqueous Micellar Solution of Non-ionic Surfactant Fed into a Microspace and an Attempt Of Capillary Chromatographic Application

Partition coefficients of ionizable solutes in aqueous micellar two-phase systems

The potential of micellar cloud point systems for extraction processes has been demonstrated for a broad range of different applications. The extraction is based on the phenomenon that aqueous non-ionic surfactant solutions split into two phases if the temperature is increased beyond a certain temperature, the so called cloud point temperature (CPT). Recently, aqueous micellar two-phase systems have been implemented in a counter current extraction. However, almost equally important for large scale applications is the recovery of the solute from micellar solutions, which remains a serious concern considering micellar cloud point systems as alternative to conventional solvents. In conventional solvent extraction processes the influence of the pH on the partitioning of ionizable solutes is an important parameter to control the extraction and back extraction efficiency. However, the partitioning of ionizable solutes such as organic acids and bases in micellar two-phase systems has not been studied so far. In this work the partitioning of various ionizable solutes including phenolic as well as pharmaceutical active compounds has been investigated. Lipophilicity profiles of all solutes were analyzed for the system TritonX-114/water in a pH range between 2 and 12. Further, the influence of temperature, solute concentration, as well as different salt concentrations on the partitioning of charged solutes was investigated. Experimental results are verified by means of predicted values using the thermodynamic model COSMO-RS. The results reveal that COSMO-RS can be applied to predict the partitioning of ionizable solutes in micellar biphasic systems, when the phase behavior of the pure surfactant is known.Based on these data optimal strategies for large scale micellar extraction processes are proposed and validated by means of a continuous pilot plant micellar extraction column.

Studies on Surfactant–Ionic Liquid Interaction on Clouding Behaviour and Evaluation of Thermodynamic Parameters

AbstractThe present study investigates the effect of tetraethyl ammonium tetrafluoroborate [TEA(BF4)] ionic liquid (IL) on the cloud point (CP) of the following nonionic surfactants in aqueous solution: ter‐octylphenol ethoxylates with 9.5 and 4.5 ethylene oxide groups (abbreviated TOPEO9.5 and TOPEO4.5, respectively), cetyl alcohol ethoxylate with 10 ethylene oxide groups (C16EO10), and sorbitan monolaurate and monooleate both with 20 ethylene oxide groups (SMLEO20 and SMOEO20, respectively) in aqueous solutions. The thermodynamic parameters of these mixtures were calculated at different IL concentrations. The CP of most of the tested nonionic surfactants increased with the increment of IL concentrations with the exception of C16EO10 for which it decreased. The solubility of a nonionic surfactant containing polyoxyethylene (POE) hydrophilic chain was considered as maximum at the CP, hence the thermodynamic parameters were calculated at the same temperature. The results showed that the standard Gibbs free energy (∆GCP0), the enthalpy (∆HCP0) and the entropy (∆SCP0) of the clouding phenomenon were found to be positive for ethoxylated octylphenol and sorbitan esters, whereas ∆HCP0 and ∆SCP0 were found to be negative for C16EO10. It was found that the overall clouding process is endothermic for ethoxylated octylphenol and sorbitan esters and exothermic for C16EO10. For all the studied systems, ∆HCP0 > T∆SCP0 indicated that the process of clouding is guided by both enthalpy and entropy. The positive value of standard Gibbs free energy (∆GCP0) for the all mixed systems indicated that the process proceeds non‐spontaneously. The ∆GCP0 decreased with increasing IL concentration for all the nonionic surfactants; however, it decreased with increasing surfactant concentration for TOPEO9.5, C16EO10, and SMOEO20, and increased with increasing surfactant concentration for TOPEO9.5 and SMLEO20.

Effect of t-octylphenoxylpolyethoxyethanol (TX-100) on the dilute aqueous solution phase diagrams, surface activity and micellization behavior of non-ionic silicone surfactants (SS) in aqueous media

Dilute aqueous solution phase diagrams, surface tension, dynamic light scattering (DLS) and dilute solution viscosity measurements have been made in aqueous solutions of nonionic silicone surfactants (SS) in presence of t-octylphenoxylpolyethoxyethanol (TX-100). Critical micelle concentration, thermodynamic parameters of association, interfacial characteristics such as pC20, surface excess, Γmax , area per adsorbed molecule, a1s along with the size and shape and intrinsic viscosities of the associates have been determined and discussed to ascertain the effect of TX-100 as an additive in SS aqueous solutions. The importance of hydrophobic/hydrophilic (hp/hl) ratio of the SS rather than their molecular architecture and molar mass on their overall interaction with TX-100 micelles has been reflected in the above parameters for the mixture solutions. It was observed that the mixed species in SS aqueous solutions in TX-100 are more hydrophilic in nature and the overall association process in the mixture solutions is entropy driven. TX-100 addition to SS micellar solutions induces the dissociation of SS micelles. As compared to the room temperature, the mixed micelles at elevated temperatures were large in size suggesting that the ellipsoidal micelles in mixed state grow along their major axis that is typically characteristic of the micelles of the individual nonionic SS or TX-100 surfactants at temperatures close to the turbid point.

Determination of cadmium and zinc in waters by flame atomic absorption spectrometry after cloud-point extraction

Phase separation of nonionic surfactants in aqueous solutions was used to extract cadmium and zinc. After complexation with 6-(4-nitrophenyl)-2,4-diphenyl-3,5-diazabicyclo[3.1.0]hexene-2 (pH 1), cadmium and zinc were quantitatively transferred into the phase rich with the nonionic surfactant octylphenoxypolyethoxyethanol. After the addition of tetrahydrofuran and HCl to the extract, the elements were determined by flame atomic absorption spectrometry.