Salt Surfactant Research Articles

Synergism Effect of Surfactant and Inorganic Salt on the Properties of Starch/Poly(Vinyl Alcohol) Film

The starch/PVA films with the addition of 30 wt.% Ca(NO3)2 and different content of Tween 20 are prepared by solution casting. The effect of Ca(NO3)2 on the crystalline, thermal, and mechanical properties of starch/PVA film is studied by X‐ray diffraction measurement, differential scanning calorimetry and tensile testing, respectively. The effect of Tween 20 on the properties of Ca(NO3)2 doped starch/PVA film is studied. The water sorption properties and the water vapor barrier properties of starch/PVA films are studied. The results shows that Ca(NO3)2 can effectively destroy the crystals of starch and PVA. The Ca(NO3)2 doped starch/PVA film shows a high water sorption rate and low water vapor barrier properties. Tween 20 can increase the water resisting properties and increase the flexibility of Ca(NO3)2 doped starch/PVA film. With the combination of Ca(NO3)2 and Tween 20 the flexible starch/PVA film with a high water resisting ability is obtained.

Synthesis of Hierarchically Porous Zeolite Composites with Enhanced Catalytic Activity: Effect of Different Long-Chain Structure Directing Agents

A two-section temperature strategy was employed to achieve micromesoporous composites with five kinds of long-chain alkyl quaternary ammonium salts as single template. Zeolites with an ordered two-dimensional hexagonal mesopore and crystallized MFI domain were successfully obtained. Gemini quaternary ammonium salt surfactants C18N2 and C22N2 are effective in directing the structure of MCM-41 than CTAB at 100 °C and will transform to lamellar MFI structures at 150 °C gradually. While single quaternary ammonium salts C18N and C22N direct lamellar M41s at 100 °C and transform to mesoporous structure at a higher temperature of 150 °C, it is possible to get a composite of microporous and mesoporous material with a surface area as high as 1046 m2 g–1. Catalytic performance of typical hierarchical zeolites was evaluated by Claisen-Schmidt condensation of bulky reactants. The excellent conversion suggested the synergy effects of improved large molecule diffusion in mesopores and highly separated MFI domains as ca...

Facile synthesis of core–shell Cu2O@ ZnO structure with enhanced photocatalytic H2 production

Core–shell Cu2O@ZnO composites were synthesized successfully based on a one-pot hydrothermal method in the presence of dioctyl sulfosuccinate sodium salt (AOT) surfactant. The Cu2O can be converted to rough core–shell Cu2O@ZnO structure by adjusting the amount of zinc powder added. The as-synthesized Cu2O@ZnO composites exhibited excellent photocatalytic activity and the amount of H2 generated using these composites was 4.5-fold more than that produced with Cu2O cubes. A possible photocatalytic mechanism for the Cu2O@ZnO composites with enhanced photocatalytic activity could be the separation by ZnO of the effective charge carriers.

Self-Assembly of Lysine-Based Dendritic Surfactants Modeled by the Self-Consistent Field Approach.

Implementing a united atom model, we apply self-consistent field theory to study structure and thermodynamic properties of spherical micelles composed of surfactants that combine an alkyl tail with a charged lysine-based dendritic headgroup. Following experiments, the focus was on dendron surfactants with varying tail length and dendron generations G0, G1, G2. The heads are subject to acetylation modification which reduces the charge and hydrophilicity. We establish a reasonable parameter set which results in semiquantitative agreement with the available experiments. The critical micellization concentration, aggregation number, and micelle size are discussed. The strongly charged dendronic surfactants micelles are stable for generation numbers G0 and G1, for progressively higher ionic strengths. Associates of G2 surfactants are very small and can only be found at extreme surfactant concentration and salt strengths. Micelles of corresponding weaker charged acetylated variants exist up to G2, tolerate significantly lower salt concentrations, but lose the spherical micelle topology for G0 at high ionic strengths.

Liquid chromatography with micelles in open-tube capillaries

Open-tubular liquid chromatography with interfacial micelles.

Interpreting the interfacial and colloidal stability of bulk nanobubbles.

This paper elucidates parts of the mystery behind the interfacial and colloidal stability of the novel bubble system of bulk nanobubbles. Stable bulk nanobubble suspensions have been generated in pure water using hydrodynamic cavitation in a high-pressure microfluidic device. The effects of pH adjustment, addition of different types of surfactant molecules and salts on the nanobubble suspensions have been studied. Results show that nanobubble interfaces in pure water are negatively charged, suggesting the formation of an electric double layer around the nanobubbles. It is presumed that the external electrostatic pressure created by the charged nanobubble interface, balances the internal Laplace pressure; therefore, no net diffusion of gas occurs at equilibrium and the nanobubbles are stable. Such stability increases with increasing alkalinity of the suspending medium. The addition of mono- and multi-valent salts leads to the screening of the electric double layer, hence, destabilizing the nanobubbles. Different surfactant molecules (non-ionic, anionic, cationic) affect the stability of bulk nanobubbles in different ways. Calculations based on the DLVO theory predict a stable colloidal system for bulk nanobubbles in pure water and this could be a further reason for their observed longevity. All in all, in pure water, the long-term stability of bulk nanobubbles seems to be caused by a combination of ion-stabilisation of their interface against dissolution and colloidal stability of the suspension.

Ti0.85Sn0.15O2 nanocomposite: an efficient semiconductor photocatalyst for degradation of pesticides under solar light

Heterogeneous semiconductor photocatalyst (Ti0.85Sn0.15O2) was synthesized by addition of TiO2 solution into Sn(OH)4 solution via sol–gel method using docusate sodium salt surfactant as model controlling agent while annealing at 800 °C. The structural, morphological and crystalline features of the synthesized sample were explored by using different microscopic and spectrophotometric techniques. The quantitative phase analysis and Rietveld refinement of XRD spectra was done to confirm the formation of Ti0.85 Sn0.15O2 nanocomposite. Optical electronegativity and refractive index was determined by using band gap energy. Their photocatalytic activity was estimated by using chlorpyrifos (CP) a class of organophosphorus pesticides, as a model of organic pollutants under solar light irradiations.

Morphology-controllable Cu2O supercrystals: Facile synthesis, facet etching mechanism and comparative photocatalytic H2 production

Monodisperse Cu2O-cubes, Cu2O-concave cubes and Cu2O-octapods supercrystals have been synthesized successfully using a self-assembly approach in the presence of dioctyl sulfosuccinate sodium salt (AOT) surfactant. Specifically, the supercrystals can be prepared by adding aqueous Cu(Ac)2 solution into butyl alcohol solution of AOT to first assemble nanoreactors and then perform hydrothermal reactions. The structures of the supercrystals can be tailored by simply varying the amount of Cu (Ac)2 with the same ratio of the Cu(Ac)2 to ascorbic acid. AOT surfactant was crucial to precisely control the supercrystal morphology. It was demonstrated that the ratio of growth rate along different planes varied by adjusting the amount of Cu(Ac)2 and the volume ratio of alcohol to water, thus Cu2O crystals with cubes, concave cubes, and octapods with the size of 1.2–2.2 μm were obtained. The morphology evolution from cubes, concave cubes to octapods was systematically studied and a facet etching mechanism is proposed. Hence, precise control of the amount of Cu(Ac)2 enables this facet etching, novel Cu2O with concave {100} facets can be fabricated. Photocatalysis investigation on the morphology-controlled Cu2O indicates that the Cu2O-octapods supercrystals showed the highest amount of H2 and the best cyclic-stability. This work reveals that morphology-control of supercrystals is important to the development of novel photocatalysis.

A Low Energy Route to DNA-Wrapped Carbon Nanotubes via Replacement of Bile Salt Surfactants.

DNA-wrapped carbon nanotubes are a class of bionano hybrid molecules that have enabled carbon nanotube sorting, controlled assembly, and biosensing and bioimaging applications. The current method of synthesizing these hybrids via direct sonication of DNA/nanotube mixtures is time-consuming and not suitable for high-throughput synthesis and combinatorial sequence screening. Additionally, the direct sonication method does not make use of nanotubes presorted by extensively developed surfactant-based methods, is not effective for large diameter (>1 nm) tubes, and cannot maintain secondary and tertiary structural and functional domains present in certain DNA sequences. Here, we report a simple, quick, and robust process to produce DNA-wrapped carbon nanotube hybrids with nanotubes of broad diameter range and DNA of arbitrary sequence. This is accomplished by exchanging strong binding bile salt surfactant coating with DNA in methanol/water mixed solvent and subsequent precipitation with isopropyl alcohol. The exchange process can be completed within 10 min and converts over 90% nanotubes into the DNA wrapped form. Applying the exchange process to nanotubes presorted by surfactant-based methods, we show that the resulting DNA-wrapped carbon nanotubes can be further sorted to produce nanotubes with defined handedness, helicity, and endohedral filling. The exchange method greatly expands the structural and functional variety of DNA-wrapped carbon nanotubes and opens possibilities for DNA-directed assembly of structurally sorted nanotubes and high-throughput screening of properties that are controlled by the wrapping DNA sequences.

Spontaneous vesicle formation and vesicle-to-micelle transition of sodium 2-ketooctanate in water

Single-tailed short-chain alkyl keto-acids/salts, a class of fatty acid/salt derivatives, such as sodium 2-ketooctanate (KOCOONa), are a kind of weakly acid/salt type amphiphiles and plausible prebiotic molecules, and the current understanding of their aggregation behavior in aqueous solutions is still limited. Herein, the aggregation behavior of KOCOONa in aqueous solution was studied by changing its concentration (C), using equilibrium surface tension, conductivity, and fluorescence measurements. The aggregates formed were characterized using freeze-fracture and cryogenic transmission electron microscopy, dynamic light scattering, atomic force microscopy, and confocal laser scanning microscopy. A concentration-driven stepwise aggregation was identified in the KOCOONa solution. Vesicles can spontaneously form from the single-component aqueous solution, with a critical vesicle concentration (CVC) of ∼15mM, which is obviously lower than that of octanoic acid/salt (120–200mM). With increasing C, a vesicle-to-micelle transition can occur, showing a critical micelle concentration (CMC) of ∼80mM. In addition, the membrane permeability of the KOCOONa vesicles was examined using small-size Calcein and large-size FITC-BSA as fluorescence probes, showing a size-selective permeability, similar to short-chain (C8-C11) fatty acid vesicles. For the first time, the aggregation behavior of single-tailed keto-acid salt surfactant is reported.

Rheological Properties and Microstructure Transition in Mixture of Zwitterionic Surfactant, Anionic Surfactant and Salts in Sorbitol/H2O Solvent: 2. Effect of Salts and Sorbitol

AbstractThe impact of mixed salts and sorbitol on the viscoelastic properties of a multi‐component system, made of a zwitterionic surfactant cocoamidopropyl betaine (CAPB), an anionic surfactant sodium lauryl sulfate (SLSS) and mixed salts (tetrasodium pyrophosphate, sodium acid pyrophosphate, saccharin and sodium fluoride) in sorbitol/H2O mixed solvent are systematically investigated by steady state and dynamic rheology. As reported previously, the viscosity of the mixed system passes through a maximum with increase in the SLSS mass fraction (XSLSS) at a fixed total surfactant concentration, salt concentration (Csalt) and mass ratio of sorbitol in mixed solvent (R). The shape of the XSLSS‐dependent viscosity curve does not change regardless of Csalt and R, but adding salts or sorbitol has different effects on the rheological properties of this system. The former due to a high screening effect plays an important role in the elongation and entanglement of the wormlike micelles, facilitating the enhancement of rheological properties and the formation of Maxwell fluids. The latter has a dual effect on the rheological properties and phase behavior of the mixtures. A certain amount of sorbitol can promote the formation entangled wormlike micelles, while the effect is reversed if the sorbitol content is too large. The electrostatic and hydrophobic interaction between CAPB and SLSS are the prerequisite for the aggregate formation and transition. Meanwhile, the aggregation behaviors are strongly influenced by the balance between low dielectric constant, strong solvophobic interaction and steric effect of sorbitol with the ability to form hydrogen bonds which favors the growth of micelles, and appearance of aqueous two‐phase systems with smaller amounts of wormlike micelles in CAPB‐rich regions which oppose enhancement of rheological properties. Our findings provide a new insight and approach to control and adjust the phase behavior of such a complicated applied multi‐component system.

A Novel Bola‐Type Rosin‐Based Functional Surfactant and Its Synergistic Effect with Natural Surfactant Saponin

AbstractA novel bola‐type acrylic‐modified rosin ester tertiary ammonium salt surfactant (AETAS) with two hydrophilic groups and a rigid hydrophobic group was synthesized through a simple method from rosin acid, which is a natural raw material. The chemical structure of the synthesized surfactant was confirmed by infrared spectroscopy and nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). The critical micelle concentration (CMC) of the AETAS was 0.44 g/L, and the surface tension at the CMC (γcmc) was 45.02 mN/m. Self‐assembly behavior of the AETAS in aqueous solution was characterized by transmission electron microscopy. The micelle diameter of the AETAS was about 150 nm in aqueous solution. We also explored the synergy of the AETAS and soapnut saponin. The binary surfactant compound systems of the AETAS and soapnut saponin had obvious synergistic effect in enhancing surface activity when the mass ratio of AETAS/soapnut saponin was 1:1. The γcmc of soapnut saponin was 47.70 mN/m when the concentration reached 0.46 g/L, but the γcmc of mixtures decreased to 44.26 mN/m at 0.30 g/L. The emulsification ability of the mixtures was significantly improved and the emulsion performance increased from 245 to 595 s when the mass ratio of AETAS/soapnut saponin was 1:1.

π-π stacking interaction in mixed surfactant solutions assembled by cationic surfactant and organic salt with a naphthalene nucleus

Wormlike micellar solutions (WLMs) on the basis of ionic surfactants customarily show only one peak in curves of viscosity versus concentration of organic salt. Here, we report the highly viscoelastic states of wormlike micelles obtained in the solution, which contain a cationic surfactant N-hexadecane-N-methylpyrrolidinium bromide (C16MPB) and an organic salt, Sodium 2-naphthalenesulfonate (SNphS). It manifests an unusual double-hump with increasing concentration of SNphS while surfactant concentration remains constant. A possible mechanism for the formation of wormlike micellar gel, which does not flow when inverted due to having higher viscoelasticity, is proposed. The π-π aromatic interactions from hydrotrope with naphthalene nucleus induce the wormlike micelles to become more closely packed. Thus, this work shows that π-π stacking interactions represent an effective means of enhancing viscosity of WLMs.

Physicochemical properties and effect of organic and inorganic electrolytes on surface properties of C12 and C16 alcohol-based bis-sulfosuccinate anionic gemini surfactants

Current communication reports the inorganic and organic salt behavior towards the surface active properties of lauryl and cetyl alcohol-based bis-sulfosuccinate anionic gemini surfactant (BSGSLA’s and BSGSCA’s) having different spacer and alkyl chain lengths by means of tensiometric measurements. The results revealed the enhanced surface activity and reduced critical micelle concentration (CMC) of gemini surfactants with the interaction of different salts as well as with increased salt concentration. The CMC reduction pattern reflects the profound influence of different salts of bis-sulfosuccinate anionic gemini surfactants and considerably noticed as sodium salicylate > sodium benzoate > potassium chloride > sodium chloride. This finding divulged the superior interaction behavior of organic salts in contrast to inorganic salts. The outcome of these investigations pointed out towards the improvement scrutinized in surface activity of bis-sulfosuccinate gemini surfactants with different salts which evidently supported with the eyecatching reduction in CMC with various factors including, viz. enhanced salt concentration, elongated spacer group as well as enlarged alkyl chains of gemini surfactants. The results also confirmed that the synthesized anionic bis-sulfosuccinate gemini surfactants, viz. BSGSLA’s and BSGSCA’s, exhibited promising performance properties.

Mixed micelle formation of cationic gemini surfactant with anionic bile salt: a PAH solubilization study

Aqueous mixed micelle formation between cationic gemini surfactant (butanediyl-1,4-bis (N,N-alkyl ammonium) dibromide, m-4-m; or ethane-1,2-diyl (N,N-dimethyl-N-dodecyl-alkyl ammoniumacetoamide) dichloride, m-Eda-m, where m=12,14 and 16) and bile salt (sodium cholate, SC or sodium deoxycholate, SDC) has been investigated by conductivity measurements and the critical micelle concentration values are compared with individual gemini surfactant or bile salt. Surfactant–bile salt interactions (interaction parameter, βm) have been compared using theoretical models of Clint, Rubingh and Motomura. cmc values, with varying mole fractions of CG or bile salt, were used to obtain composition of binary mixture for PAH solubilization. Solubilization studies of polycyclic aromatic hydrocarbons PAHs, fluorene, anthracene and pyrene, have also been performed spectrophotometrically in aqueous cationic gemini (CG) with or without bile salt (SC or SDC). Individual bile salt nearly failed to solubilize any amount of PAHs. The solubilization potential has been discussed in the light of molar solubilization ratio (MSR) and compared with other similar CG-anionic surfactant systems. This is the first study in which oppositely charged CG-bile salt binary mixtures are used to enhance aqueous solubility of PAHs. The study may find potential use in biomedical applications.

Agglomeration and capture of fine particles in the coupling effect of pulsed corona discharge and acoustic wave enhanced by spray droplets

Fine particles from industrial processes are considered to be potentially harmful to humans and environment, and massive amounts of fine particles are continuously emitted into the air due to the low removal efficiency of current conventional dust capture devices. A novel pretreatment process using the coupling effect of pulsed corona discharge and acoustic waves enhanced by spray droplets for fine particle agglomeration and capture was investigated in this study. The application of pulsed corona discharge in an acoustic field led to an increase in the efficiency of fine particle agglomeration to 74.7%, and the improvement was much more obvious for low frequency acoustic waves. The spray flow rate delivered by the spray nozzles with a size of 0.30mm or 0.40mm was incrementally increased. Furthermore, the penetration efficiency initially decreased, then increased, and finally decreased when droplets were sprayed in either a pulsed corona discharge field or an acoustic wave field. The penetration efficiency of fine particles substantially decreased to 10% with the enhancement of spray droplets coupled with both a pulsed corona discharge and an acoustic wave, both at their most efficient settings. The penetration efficiency further decreased with the addition of sodium dodecyl sulfonic salt surfactant to the spray droplets, in particular, at a concentration of 0.3%.

Effects of Temperature, Time and Composition on Food Oil Surface Tension

Equilibrium and time-dependent surface tension properties at the lipid-vapor interface were investigated, due to their importance in many food applications. Common cooking oils and triglycerides, with or without added oil-soluble amphiphiles, were studied as a function of time and temperature. Surface tension was found to decrease linearly as temperature was increased, and this linear dependence was analyzed to yield thermodynamic information on the surface excess energy and entropy. The different types of cooking oils were nearly indistinguishable with regard to their surface entropy and energy, but an effect of acyl chain length was observed from data for different purified triglyceride oils. These results were consistent with separate results on pure fatty acids of different chain lengths and degree of unsaturation. Lipid amphiphiles, natively present or deliberately added at low concentration to oil, did not cause a change in either dynamic or equilibrium surface tension of corn or olive oil. We conclude that such amphiphilic molecules, despite their presence within the food oil, lack significant surface activity at their native concentration when presented with the surface between oil and air. A decrease in tension in corn oil was seen when mixed in solution with the short-chain caprylic acid (octanoate), but the decrease was notable (>4%) only when this short-chain fatty acid was added at high concentration (≥ 1 M). Added sorbitan monooleate (Span 80) or dioctyl sulfosuccinate sodium salt (AOT) surfactants, on the other hand, decreased equilibrium surface tension by up to 12% and 18%, respectively, at low concentrations (<0.125 M).

Comparison of Salt Cations in the Design of Nonionic Surfactant Based Aqueous Biphasic Systems: Application in Polyphenol Separations

New aqueous biphasic systems (ABSs) composed of a nonionic surfactant, Brij 35, and sulfate salts of Na, Mg, and Zn were designed. Ternary phase diagrams were constructed together with respective tie lines. The tie line lengths and slope of tie lines were calculated, and the results were validated using Othmer-Tobias and Bancroft equations. The binodals plotted for the three individual salts indicate their respective biphasic regions which follows the order MgSO4 > ZnSO4 > Na2SO4. All three ABSs were checked for their binary separation ability for the two polyphenols catechin and hesperidin. A pH dependent study indicates the possibility of separation of the two polyphenols using MgSO4 as the salt rich phase.

The interation of Gemini biquaternary ammonium salt surfactant and coal tar pitch

ABSTRACT Coal pitch is the main product of coking process, which has a huge production. Ways to make full use of coal pitch could have broad appeal because of its unsatisfactory utilization rate presently. Learning from the technology of coal water slurry, our team developed the concept of coal pitch water slurry (CPWS), it was prepared based on a certain particle size of coal pitch powders and dispersant. The adsorption quantity and zeta potential of Cn-m-Cn on the surface of coal pitch have been studied, and the appropriate dispersants were selected. Cn-m-Cn Gemini surfactants could significantly change the wettability of the coal pitch surface. With the increase in surfactant concentration, zeta potential on the surface of the coal pitch was increased, from negative to positive, and finally leveled off. The adsorption capacity also increased rapidly at the beginning and then trended to flatten out. The concentration at the zero potential was lower than critical micelle concentration, at least an order of magnitude. The apparent viscosity of CPWS was decreased with the increase of shear rate, and when the shear rate remained unchanged, the viscosity would increase with the increase of slurry concentration. The stability of the CPWS prepared by Gemini surfactants of Cn-8-Cn was better than that of the CPWS prepared by Gemini surfactants of C12-m-C12.

Equilibrium and dynamic surface tension properties of Gemini quaternary ammonium salt surfactants with ester groups

Two series of quaternary ammonium salt Gemini surfactants with ester groups (n-m-n, where n represents hydrocarbon chain lengths of 10, 12, 14 and 16, m represents spacer group lengths of 2 and 6) were synthesized and characterized by 1H NMR. Surface activity and adsorption of these cationic Gemini surfactants were investigated by methods of measuring equilibrium surface tension and dynamic surface tension. The critical micelle concentration (CMC) decreased with an increase in chain length, while increased with the length of spacer group. Moreover, data obtained were analyzed in accordance with Word-Tordai equation, and the diffusion coefficients for ionic liquid molecular adsorption in the initial stage and final stage under different concentration were figured out respectively. The results indicated that the adsorption process was controlled by a diffusion step at low surfactant concentration while by a mixed kinetic-diffusion adsorption mechanism at high surfactant concentration.