Elemental composition and bioactivity of morphological parts extracts of winter savory (Satureja montana L.)

Steady state and time-resolved fluorescence spectroscopy of quinine sulfate dication in ionic and neutral micelles: Effect of micellar charge on photophysics

The influence of Sodium dodecyl sulfate and Triton X-100 surfactants on the two-phase pressure drop and two phase flow regime of water-air and gas condensate-air in upward vertical pipe were investigated for various gas/liquid flow rates. Sodium dodecyl sulfate and Triton X-100 reduced the pressure drop of single phase water flow by 11% and 29% compared with that of pure water single phase flow at water velocity of 13 m/s. For condensate single phase flow, Sodium dodecyl sulfate and Triton X-100 reduced the pressure drop by 9% and 17% compared with that of condensate single phase flow with no surfactant at gas condensate velocity of 13 m/s. The maximum efficiency of Sodium dodecyl sulfate and Triton X-100 in reducing the pressure drop of water-air system were 67.1% and 79.8%, respectively, compared with that of pure water-air two-phase flow. For gas condensate-air system, the maximum efficiency of Sodium dodecyl sulfate and Triton X-100 in reducing the pressure drop was 57.1% and 36.7%, respectively, compared to that of pure condensate-air two-phase flow.

We have demonstrated the size-dependent charge specific surfactant induced aggregation and subsequent deaggregation of allylamine-capped silicon quantum dots (Si-QDs) by means of photoluminescence (PL) spectroscopy, dynamic light scattering (DLS), and imaging techniques. The heterogeneous size distribution of allylamine-capped Si-QDs results in differential interaction with negatively charged sodium dodecyl sulfate (SDS) surfactant. Initial aggregation and subsequent deaggregation have been observed for both smaller and bigger size Si-QDs in the presence of SDS. These aggregates dissociated slowly beyond 1 mM SDS concentration due to formation of spherical micelles. It has been observed that the smaller size QDs get incorporated inside the micellar Stern layer while the larger size QDs remain in aqueous phase. No such effect has been observed for cationic cetyltrimethylammonium bromide (CTAB) and neutral Triton X-100 (TX-100) surfactant. The results at pH 4.5 and pH 7.1 indicate the involvement of specific electrostatic as well as hydrogen-bonding interaction between the amine groups and negatively charged sulfate headgroups. The extent of aggregation is more at pH 4.5 than pH 7.1 due to favorable electrostatic interaction between cationic Si-QDs and anionic SDS surfactant. The effect of local surface pH around the SDS micelles is considered to interpret the PL behavior at pH 7.1. We have performed PL microscopy of individual allylamine-capped Si-QDs to get further information about their inherent PL properties at single dot resolution.

A new and simple determination method for critical micelle concentration (CMC) has been developed based on surface plasmon resonance (SPR) technique. In the current work, the CMCs for sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and Triton X-100 (TX-100) were determined in aqueous media by SPR of silver nanoparticles (AgNPs). The variation of the absorbance of AgNPs in respect of bulk water is a consequence of the micelles formation from the surfactants monomer, here, SDS, CTAB, and TX-100. Under the optimal experimental conditions, CMCs for SDS, CTAB, and TX-100 using SPR technique were 8.6 × 10−3, 9.1 × 10−4, and 2.6 × 10-4 mol L−1, respectively. The potential application of SPR technique for the CMC determination has been demonstrated in this work. Comparing to the other CMC determination methods, this SPR method is universal, sensitive, and nonadditive; it can be used for the direct measurements of CMC without adding any dyes or fluorescent probes. CMC values of various surfactants including SDS, CTAB, and TX-100 determined by this method are in agreement with those determined by the other methods. The results obtained by our simple method have comparable accuracy with those obtained from more elaborate experiments.

Sequential Adsorption of Triton X-100 and Sodium Dodecyl Sulfate onto Positively and Negatively Charged Polystyrene Latexes

Removal of Cd(II) by MEUF-FF with anionic-nonionic mixture at low concentration

Micellar-enhanced ultrafiltration of soft drink wastewater using anionic and mixed anionic/nonionic surfactants

This work reports the refinement of nanoporous copper (NPC) ligaments by introducing the sodium dodecyl sulfate (SDS) surfactant in the dealloying process. The Al80Cu20 (at%) alloy precursor is chemically dealloyed in a mixed solution of NaOH and SDS surfactant, producing NPC with a hierarchical microstructure. Micron-scaled skeletons that build up higher level networks consist of geometrically similar nano-scaled bi-continuous ligament-pore networks at the lower level. It has been found that the size of the ligaments in the lower level networks reduces from ∼32 nm to ∼24 nm with increasing SDS concentration to 1 mM. Further increasing the SDS concentration to 5 mM only leads to a slight ligament size decrease to ∼21 nm. Remarkably, nano-sized cones are formed on the lower level network surface in the dealloying solution containing 1 mM SDS, and the cone number greatly rises when the SDS concentration increases to 5 mM. The surface diffusivity of Cu adatoms is evaluated based on the experimental data, and the refinement of the ligament as well as the formation of cones are associated with the decreased surface diffusivity and the retarded Cu adatom motions with the addition of SDS. Quantum chemical calculations and molecular dynamics simulations are performed to model the adsorption behavior of SDS. It has been found that the SDS-substrate interaction increases with the number of SDS molecules before SDS reaches saturation.

Achieving reversible and tunable assembly of silica nanoparticles at liquid-liquid interfaces is vital for a wide range of scientific and technological applications including sustainable subsurface energy applications, catalysis, drug delivery and material synthesis. In this study, we report the mechanisms controlling the assembly of silica nanoparticles (dia. 50 nm and 100 nm) at water-heptane and water-toluene interfaces using sodium dodecyl sulfate (SDS) surfactant with concentrations ranging from 0.001-0.1 wt% using operando ultrasmall/small-angle X-ray scattering, cryogenic scanning electron microscopy imaging and classical molecular dynamics simulations. The results show that the assembly of silica nanoparticles at water-hydrocarbon interfaces can be tuned by controlling the concentrations of SDS. Silica nanoparticles are found to: (a) dominate the interfaces in the absence of interfacial SDS molecules, (b) coexist with SDS at the interfaces at low surfactant concentration of 0.001 wt% and (c) migrate toward the aqueous phase at a high SDS concentration of 0.1 wt%. Energetic analyses suggest that the van der Waals and electrostatic interactions between silica nanoparticles and SDS surfactants increase with SDS concentration. However, the favorable van der Waals and electrostatic interactions between the silica nanoparticles and toluene or heptane decrease with increasing SDS concentration. As a result, the silica nanoparticles migrate away from the water-hydrocarbon interface and towards bulk water at higher SDS concentrations. These calibrated investigations reveal the mechanistic basis for tuning silica nanoparticle assembly at complex interfaces.

Synergistic enhancement of oil recovery: Integrating anionic-nonionic surfactant mixtures, SiO2 nanoparticles, and polymer solutions for optimized crude oil extraction

Study the influence of surfactants on the particle diameter, viscosity and polydispersity index of Solid Lipid Nanoparticles in manufacturing (SLN) of the cocoa butter. Intended use of surfactants (lecithin and sodium dodecyl sulfate) in generating particle diameter, viscosity and polydispersity index suitable for the manufacture of Solid Lipid Nanoparticles of cocoa butter. Preparation of Solid Lipid Nanoparticles made by homogenizing a mixture of cocoa fat, distilled water and a surfactant (sodium dodecyl sulfate, and lecithin) using Ultra Thurax, speed of 1500 rpm with some formulations. Further characterized by means of Particle size analyzer (PSA). The results showed that Formula Solid Lipid Nanoparticles and surfactant lecithin produced polydispersity index is 0302-0389 and is monomodal compared to surfactant sodium dodecyl sulfate with a higher polydispersity index is above 0.5 for 0848-1215 and are polymodal. For lecithin surfactant particle diameter on particle diameter 426.2 - 654.3 nm corresponding to the diameter of Solid Lipid Nanoparticles range is 50-1000 nm. While the surfactant sodium dodecyl sulfate particles with a diameter of 2813.5 to 3976.7 nm diameter beyond the range of Solid Lipid Nanoparticles, on the use of surfactant lecithin viscosity of 0.8980 and 0.8878 and the surfactant sodium dodecyl sulfate at 0.8878.

A computer aided analysis of both cw-and pulsed-Electron Paramagnetic Resonance (EPR) spectra of 5doxylstearic acid (5DXSA) as a probe was carried out to compare the aggregation process of Sodium Dodecyl Sulfate (SDS) surfactants in the absence and in the presence of Starburst Dendrimers (SBDs), and to provide information on the interactions between SDS and SBDs. Mobility and polarity parameters were extracted from the cw-EPR analysis whereas the analysis of the Electron Spin Echo Envelope Modulation (ESEEM) signal provided details about the doxyl environment in the SDS micelles. In the absence of SBDs, the formation of SDS micelles was revealed by the decrease in mobility of the probes inserted in the micelles. The high packing of SDS chains in the micelles prevented the water permeability at the doxyl site. In the presence of the dendrimers, the analysis of the EPR spectra suggested the formation of SDS aggregates at the dendrimer surface (cooperative interaction). The larger the size of the dendrimers and the protonation of their surface, the stronger the interactions resulted between the SDS surfactants and the SBD surface. The analysis of the ESEEM pattern indicated that the cooperative interaction of the surfactant with the SBD surface led to a less packed structure of the aggregates. A schematic view was proposed to describe the local structure of the doxyl group and its environment in the absence and in the presence of the dendrimers.

Separation of sodium lactate from Span 80 and SDS surfactants by ultrafiltration

In the present work the effect of three different surfactants Triton X-100, cetyltrimethylammonium bromide (CTAB) and sodium dodecylesulfate (SDS) on the spectrophotometric determination of sulfide based on phenothiazine dye production from phenyl-p-diamine (PPD) is studied. The main step for phenothiazine dye production is the oxidation of aromatic p-substituted amine to yield iminoquinone free-radical intermediary. Fe3+ in acidic media is used for oxidation purposes. Electron donor groups in the p-position of aromatic ring of amines are decisive for free-radical stabilization, leading to an increased dye production rate and the analytical sensitivity. Preliminary studies showed that, the analytical signal was increased in the presence of SDS, CTAB and Triton X-100; but among the surfactants studied, SDS and Triton X-100 had a significant effect on the spectrophotometric determination of sulfide based on phenothiazine dye production. The effects of various experimental parameters in this reaction was investigated using central composite design. The experimental design was done at five levels of operating parameters. As a model surfactant, the concentration of SDS, amine, Fe3+ and H2SO4 were optimized simultaneously. The effects of Triton X-100 and CTAB as non-ionic and cationic surfactant, respectively, were investigated using a one variable at a time optimization method. The linear range for the determination of sulfide in the presence of SDS and Triton X-100 was 0.1–2 μg ml−1 and that in presence of CTAB was 0.2–2.0 μg ml−1. The proposed method was applied successfully for the determination of sulfide in different spiked real samples.

The performance of copper ion removal using sodium dodecyl sulfate (SDS) and its mixtures with Brij 35, Tween 80 (TW80) and Triton X-100 (TX100) by micellar-enhanced ultrafiltration (MEUF) was investigated. The effects of the molar ratio of nonionic surfactant to SDS on the critical micelle concentration (CMC) of SDS/Brij 35, SDS/TW80 and SDS/TX100, the removal efficiency of Cu(2+), the residual concentration of SDS in the permeate solution and the permeate flux were tested. The results showed that the CMCs of the mixed surfactants were sharply less than that of pure SDS. The removal efficiencies of Cu(2+) were up to the maximum values 98.3 and 95.8% when the molar ratios of Brij 35 and TW80 to SDS were 0.3, and it was 93.5% given 0.7 molar ratio of TX100 to SDS. The concentration of SDS in the permeate decreased dramatically with the addition of nonionic surfactant, and the permeate flux decreased slightly as the molar ratio increased. Compared with the performance by single SDS, the mixed SDS/Brij 35, SDS/TW80 and SDS/TX100 at an optimum composition could result in not only higher rejection of Cu(2+) but also much less dosage of surfactant and concentration of SDS in the permeate.