Aqueous Solutions Of Sodium Dodecyl Sulfate Research Articles

Optical properties of chiral single-walled carbon nanotubes thin films

This work contains experimental results of optical properties for thin films containing Single-Walled Carbon Nanotubes. Thin films concerning 0.5, 1 and 2 mg of low dimension chiral (10,6) Single-Walled Carbon Nanotubes dispersed in low concentration aqueous sodium dodecyl sulfate solution (2 mL) were successfully fabricated by spin-coating technique on transparent substrates at ambient atmosphere. Optical properties of these thin films were examined using Transmission, Raman and Photoluminescence Spectroscopies. We find that investigated chiral Single-Walled Carbon Nanotubes show transmission and emission bands not only in infrared range but also ultraviolet and visible range.

Modulation of Surface-Catalyzed Secondary Nucleation during Amyloid Fibrillation of Hen Egg White Lysozyme by Two Common Surfactants.

Amyloid fibrillation by hen egg white lysozyme (HEWL) under the influences of two common surfactants, sodium dodecyl sulfate (SDS) and Triton X-100 (TX-100), was investigated with atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. Detailed AFM investigations indicated that both SDS and TX-100 were able to induce some significant morphological changes of HEWL amyloid fibrils. Both SDS and TX-100 could induce a morphological change which was characterized with alternating fibril regions with increased thicknesses along the fibril axis. In addition, TX-100 was also able to induce a morphological change which was characterized with fibril branching. In contrast, the positively charged cetyltrimethylammonium bromide displayed no such effect as compared with the negatively charged SDS and the nonionic TX-100. These intriguing modulation effects of SDS and TX-100 on amyloid fibrillation were hypothesized to be due to surfactant-induced surface-catalyzed secondary nucleation owing to the noncovalent interaction between the surfactants and HEWL. The proposed hypothesis was further supported by FTIR spectroscopic investigation, which demonstrated the formation of a SDS-amyloid fibril complex and TX-100-amyloid fibril complex. Detailed FTIR analysis suggested that the tail group of SDS associated with amyloid fibrils is more disordered similar to that of SDS in aqueous solution, while the headgroup of SDS appears to interact with amyloid fibrils strongly similar to that of SDS in the solid state, and the ether groups of TX-100 associated with amyloid fibrils experienced a different microenvironment as compared with that of neat TX-100. Additional control experiments with FTIR spectroscopy revealed that the interactions of SDS/TX-100 with HEWL amyloid fibrils were different from those of SDS/TX-100 with HEWL amorphous aggregates. In addition, the β-sheet structures of the HEWL amyloid fibrils were found to be increased due to the influences of SDS and TX-100. Our work provides new insight into the modulation effects of surfactants on amyloid fibrillation.

Experimental and modelling studies on the effects of nanofluids (SiO2, Al2O3, and CuO) and surfactants (SDS and CTAB) on CH4 and CO2 clathrate hydrates formation

Sodium dodecyl sulfate (SDS) with concentrations of 300 ppm and 500 ppm; cetyl trimethylammonium bromide (CTAB) with concentrations of 220 ppm and 700 ppm; and water-based nanofluids of SiO2, Al2O3, and CuO with concentrations of 0.1, 0.3, and 0.5 wt% were used as kinetic promoters in methane hydrate formation process at initial conditions of 274.15 K and 5.5 MPa and carbon dioxide hydrate formation process at initial conditions of 274.15 K and 3 MPa. Englezos and Bishnoi model was utilized for calculating the apparent rate constant of hydrate growth and van der Waals-platteeuw model coupled with CPA equation of state was used to model hydrate phase equilibrium conditions. SDS with a concentration of 500 ppm and CTAB with a concentration of 700 ppm are the most effective promoters in increasing the average apparent rate constant and water to hydrate conversion. SiO2 nanofluid with a concentration of 0.3 wt% shows the most promising promotion effects by reducing the induction times of CO2 and CH4 hydrates formation by 70 and 74%, respectively. Aqueous solution of SDS with a concentration of 500 ppm is the most effective promoter that can enhance the average apparent rate constant of CO2 and CH4 by 350 and 200%, respectively.

Fabrication of MoS2 decorated reduced graphene oxide sheets from solid Mo-precursor for electrocatalytic hydrogen evolution reaction

Contemporary research on electrochemistry revolves around fabricating cost effective catalysts using non-precious compounds for environmentally benign energy storage and production. Aiming at the engineering of such a proficient catalyst we report a novel synthesis of molybdenum disulfide (MoS2) particle decorated on reduced graphene oxide (rGO) sheets. We used low cost precursors like graphene oxide (GO), sodium dodecyl sulfate (SDS) thioacetamide (Tha) and an inexpensive Keggin compound, ammonium phosphomolybdate (APM) powder, in aqueous medium using simple hydrothermal procedures at the different stage of the synthesis. The as-prepared MoS2/rGO exhibits high catalytic ability for hydrogen evolution electrochemical reaction with ∼140 mV overpotential for a current density of 10 mA cm−2 for a catalyst loading of 0.1 mg cm−2 and a Tafel slope of 50 mV dec−1 measured in glassy carbon electrode. The low charge transfer resistance value Rct 26.56 Ω, is manifested in the enhanced HER performance due to faster electron transfer. In-house reduction of APM to MoS2 on in situ reduced rGO by Tha in aqueous medium, produced the effective 2D catalyst. This is the first report of one-pot synthesis of an in situ produced electrocatalyst i.e. MoS2 onto rGO from aqueous SDS solution using solid phase dispersion of the simplest Keggin compound.

Modeling detergent applications using molecular dynamics

The molecular dynamics group at Fairmont State University models detergent systems with interdisciplinary applications. Simulations currently underway include octane interacting with sodium dodecyl sulfate (SDS) in aqueous solution as well as micelle formation in systems of cetyltrimethylammonium bromide and chloride (CTAB and CTAC, respectively). The simulation of octane and SDS in aqueous solution is designed to model the process of washing away grease with a detergent commonly found in dish soap. It is intended for use as a web-based educational tool to provide a dynamic visualization of micelle formation, e.g. in freshman chemistry classes. CTAB was chosen as a target because of literature evidence that low concentrations of the detergent cause a 100-fold increase in fluorescence of a small organic molecule. This organic molecule is a localized photosensitizer, which is useful in improving photodynamic light therapy that is currently being used as treatment for some cancers. Bromide ion parameters were adapted from the well parameterized chloride ion in the CHARMM forcefield; the comparison is interesting because CTAC and CTAB are known to have different aggregation numbers. Initial simulation results indicate that micelle formation from a random assembly of detergent molecules (n=20-130) occurs rapidly for both species. This research has been supported by the Fairmont State University College of Science and Technology as well as the NASA WV Space Grant Consortium.

Kinetics of Spreading over Porous Substrates

The spreading of small liquid drops over thin and thick porous layers (dry or saturated with the same liquid) is discussed in the case of both complete wetting (silicone oils of different viscosities over nitrocellulose membranes and blood over a filter paper) and partial wetting (aqueous SDS (Sodium dodecyl sulfate) solutions of different concentrations and blood over partially wetted substrates). Filter paper and nitrocellulose membranes of different porosity and different average pore size were used as a model of thin porous layers, sponges, glass and metal filters were used as a model of thick porous substrates. Spreading of both Newtonian and non-Newtonian liquid are considered below. In the case of complete wetting, two spreading regimes were found (i) the fast spreading regime, when imbibition is not important and (ii) the second slow regime when imbibition dominates. As a result of these two competing processes, the radius of the drop goes through a maximum value over time. A system of two differential equations was derived in the case of complete wetting for both Newtonian and non-Newtonian liquids to describe the evolution with time of radii of both the drop base and the wetted region inside the porous layer. The deduced system of differential equations does not include any fitting parameter. Experiments were carried out by the spreading of silicone oil drops over various dry microfiltration membranes (permeable in both normal and tangential directions) and blood over dry filter paper. The time evolution of the radii of both the drop base and the wetted region inside the porous layer were monitored. All experimental data fell on two universal curves if appropriate scales are used with a plot of the dimensionless radii of the drop base and of the wetted region inside the porous layer on dimensionless time. The predicted theoretical relationships are two universal curves accounting quite satisfactorily for the experimental data. According to the theory prediction, (i) the dynamic contact angle dependence on the same dimensionless time as before should be a universal function and (ii) the dynamic contact angle should change rapidly over an initial short stage of spreading and should remain a constant value over the duration of the rest of the spreading process. The constancy of the contact angle on this stage has nothing to do with hysteresis of the contact angle: there is no hysteresis in the system under investigation in the case of complete wetting. These conclusions again are in good agreement with experimental observations in the case of complete wetting for both Newtonian and non-Newtonian liquids. Addition of surfactant to aqueous solutions, as expected, improve spreading over porous substrates and, in some cases, results in switching from partial to complete wetting. It was shown that for the spreading of surfactant solutions on thick porous substrates there is a minimum contact angle after which the droplet rapidly absorbs into the substrate. Unfortunately, a theory of spreading/imbibition over thick porous substrates is still to be developed. However, it was shown that the dimensionless time dependences of both contact angle and spreading radius of the droplet on thick porous material fall on to a universal curve in the case of complete wetting.

Investigation of functionalized carbon nanotubes' performance on carbon dioxide hydrate formation

Abstract In this work, the impact of functional group on the thermodynamics and kinetics of CO2 hydrates are investigated experimentally. The hydroxylated multi-wall carbon nanotubes (OH-MWCNT) and carboxylated carbon nanotubes (COOH-MWCNT) along with pristine carbon nanotubes (MWCNT) are selected for this study. The carbon nanotubes are suspended in a 0.03 wt% sodium dodecyl sulfate (SDS) aqueous solution and the results are compared with SDS aqueous solution at the same concentration of 0.03 wt% and deionized water. The CO2 hydrate phase boundary and kinetic parameters of CO2 hydrate formation including induction time, the initial rate and amount of gas consumed, gas uptake, storage capacity, and water to hydrates conversion are studied. The results show that the nanofluids studied do not affect the equilibrium conditions of CO2 hydrates. In addition, 0.01 and 0.05 wt% of COOH-MWCNT mixed with 0.03 wt% SDS showed highest initial hydrate formation rate and gas uptake. Furthermore, a comparison between SDS and COOH-MWCNT (without stabilizer SDS) at 0.03 wt% revealed that addition of COOH-MWCNT to the water enhance the initial hydrates formation rate compared to SDS.

Dancing performance of organic droplets in aqueous surfactant solutions

Droplet systems remain the subject of a constant fascination in science and technology. Here we focus on organic droplets floating on the surface of aqueous surfactant solutions. These droplets can exhibit intriguing interactions. Recently we have found independently in two laboratories that we can observe almost the same complex collective behaviour in two different droplet systems. The aim of this paper is to compare both droplets systems, present their differences and show their similar oscillatory behaviour. The first system consists of decanol droplets floating on a sodium decanoate solution. In the second one, the droplets consist of a mixture of ethyl salicylate and liquid paraffin and they are placed on the surface of an aqueous sodium dodecyl sulphate solution. Although the mechanism of these spatio-temporal interactions of droplets is not fully understood yet, we believe that this behaviour is based on the same phenomena.

Bubaline Diaphragm Matrix: Development and Clinical Assessment into Cattle Abdominal Hernia Repair

Abstract The purpose of the study was to develop a xenogenic bubaline diaphragm matrix (BDM) for abdominal hernia repair. A fresh diaphragm was decellularized using aqueous sodium dodecyl sulfate (SDS) solutions (0.5-4% w/v) over a period. Acellularity was confirmed histologically and characterized by Masson’s trichrome staining, scanning electron microscopy (SEM), DNA quantification, agarose gel electrophoresis, and Fourier-transform infrared spectroscopy. The BDM was used for clinical abdominal hernia repair in six cattle. Clinical, hemato-biochemical and antioxidant parameters were evaluated to assess biocompatibility of xenogenic BDM. Histologically, the diaphragm treated with 2% SDS for 48 h showed complete acellularity and orderly arranged collagen fibers. The SEM confirmed preservation of collagen structure and integrity. The DNA content was significantly (P < 0.05) reduced in BDM (33.12 ± 5.40 ng/mg) as compared to the native diaphragm (443.96 ± 162.60 ng/mg). DNA extracts from BDM show considerable removal of DNA material, with absence of DNA band in agarose gel. The FTIR spectrum of BDM has shown all characteristic transmittance peaks of bovine skin collagen indicating preserved collagen structure. Six cattle with BDM implant recovered uneventfully and remained sound at least upto 6 months. Hemato-biochemical and antioxidant findings were unremarkable. Bubaline diaphragm matrix shows excellent repair efficiency and biocompatibility for abdominal hernia repair in cattle without complications.

Minimum film boiling temperature and minimum heat flux in pool boiling of high-temperature cylinder quenched by aqueous surfactant solution

The use of surfactant has been known as one of effective ways to improve the boiling heat transfer. However, the most of boiling research using the surfactant has focused on the nucleate boiling regime, and the surfactant effect on the MFB (minimum film boiling) point, identified with MFBT (minimum film boiling temperature) and MHF (minimum heat flux) has rarely been studied. In the present study, the effects of surfactant and liquid subcooling on MFB point of vertical stainless steel cylinder were investigated experimentally using the quenching method. As the test fluids, the aqueous SDS (sodium dodecyl sulfate) solutions (1000 wppm and 2000 wppm), known to enhance the nucleate boiling heat transfer, were tested with pure water, where their liquid subcoolings covered from 0 °C to 39 °C. Based on the present experimental data, it was revealed that the SDS surfactant can impede the MFB point, while the increase of liquid subcooling leads to accelerating the MFB point. In addition, the influence of contact angle on MFB point was examined and discussed in detail. It was found that it could be insufficient and limited to explain the general trends of MFB point using contact angle alone and the fundamental factors responsible for changing the contact angle and thermal-hydraulic conditions should be considered.

Development of a 3D-printed modified Scheludko-cell: Potential application for adsorption and thin liquid film study

A systematic study on the formation of thin liquid films (TLFs) of n-dodecane, as an intervening liquid phase in aqueous surfactant solution, was performed using a modified 3D-printed Scheludko-cell (MSC). The formation and stability of TLFs are electrically detected using the current density-voltage (J-Ψ) characteristics of the system, and it is confirmed by in-situ visualization of TLFs. The conductivity of the TLFs is measured using the J-Ψ curve and resistors in a series model of the system. The induced conductivity of the film is measured for different concentrations of potassium chloride (KCl) and sodium dodecyl sulfate (SDS) aqueous solutions. We monitored an increase in TLF conductivity due to the accumulation of inorganic hydrophilic ions like (K+ or Cl−) and adsorption of amphiphilic anion of dodecyl sulfate to the interface. The higher rate of increase in the TLF conductivity in the case of SDS is attributed to the ability of amphiphilic ions to pass through a so-called unscreened potential in the vicinity of oil-aqueous solution interface leading to an unscreenable potential at the boundary of the TLF. The predicted adsorption time-scale of surfactants using the MSC cell in ionic liquid (IL) phase, at O/W interface, is found to be in good agreement with the dynamic interfacial tension test results.

Molecular models for Sodium Dodecyl Sulphate in aqueous solution to reduce the micelle time formation in molecular simulation

In this work two Sodium Dodecyl Sulphate (SDS) molecular models are proposed; one based on the Explicit-Atom (EA) approach while the other on the United-Atom (UA) approach. A SDS aqueous solution was simulated using the TIP4P/ε potential for water. With the EA model the micellar aggregate spent less than 1 ns of simulation time to be formed. This is a quite low simulation time compared to the 23 ns spent by existing SDS models to attain the same micellar formation. When both proposed models are compared, micellar formation from EA model is 10 times faster than the UA model. The time reduction is due to the implementation of two repulsive sites in the carbon atoms on the hydrophobic tails. To validate the models, density, radial distribution functions, radius of gyration and shear viscosity were calculated; results were in good agreement with those reported in literature.

Effect of water hardness on the interaction of cationic dye with anionic surfactants

ABSTRACTThe effect of water hardness causing ions on the critical micelle concentration (cmc) of surfactants was studied using conductivity measurement. Spectrophotometric and conductometric studies of dye and surfactant interaction under the influence of water hardness causing ions were also investigated. It was found that with increasing hardness in water, cmc of the surfactants tends to decrease. The change in the colour of the solution was observed as the degree of hardness increases. Hardness of water can consider as a major contributor of fading or change in colour during washing and cleaning of dyed material. Dye in a surfactant solution containing varying amount of hardness causing ions undergoes a blue shift in the visible region and red shift in ultraviolet region. The comparison between sodium dodecylsulphate (SDS) and saponin natural surfactant showed that turbidity was observed only in the aqueous solution of SDS in the presence of very hard water.

Synthesis and characterization of silver nanoparticles in aqueous solutions of surface active imidazolium-based ionic liquids and traditional surfactants SDS and DTAB

This article reports synthesis and characterization of silver nanoparticles (AgNPs) in different concentrations of aqueous solutions of 1-octyl-3-methylimidazlium chloride ([C8mim]Cl), 1-octyl-3-methylimidazlium bromide ([C8mim]Br), 1-decyl-3-methylimidazlium bromide ([C10mim]Br), 1-dodecyl-3-methylimidazlium bromide ([C12mim]Br), sodium dodecyl sulfate (SDS) and dodecyltrimethyl ammonium bromide (DTAB) as stabilizer at 298.15 K. The effects of type, alkyl chain length and concentration of surfactants on the size, concentration and stability of AgNPs were investigated by Ultraviolet-Visible spectroscopy (UV–Vis), Transmission Electron Microscopy (TEM), Small Angle X-ray Scattering (SAXS) and Dynamic Light Scattering (DLS). The length of alkyl chain of surfactants is determining factor in stability of nanoparticles so that the surfactants with 8 or less carbon atoms have no enough protecting effects and the synthesized AgNPs tend to coalesce immediately. Increase in the alkyl chain length from C8 to C12 led to increase in stability and concentration of AgNPs. It seems that, the hydrophobic interactions between surfactants and surface of AgNPs have more important role in the stability of silver nanoparticles and the order of stabilizing effect of the investigated surfactants is as: SDS > DTAB > [C12mim]Br > [C10mim]Br.

Molecular insights into sodium dodecyl sulphate mediated control of size for silver nanoparticles

A specific condition directing the formation of silver nanoparticles (AgNPs) with narrow size-distribution in aqueous sodium dodecyl sulphate (SDS) solutions, using trisodium citrate (TSC) is investigated. The peculiar control in distribution of size for AgNPs in presence of 35 mM (~1 wt%) aqueous SDS solution as stabilizing agent is evident. Water penetration through packed PTFE powder and dynamic surface tension measurements demonstrate formation of stable aggregates at the given condition and accordingly reduced numbers of free SDS monomers diffusing to the growing AgNP interface. The smaller size of AgNPs was also confirmed by TEM images, which illustrates mixed morphologies for the nanoparticles in an aggregated state. The NMR experiments reveal strong hydrophobic interactions between the alkyl chains of SDS molecules adsorbed on AgNPs. These results also indicate that TSC is molecularly distributed in bulk phase without binding to the SDS micellar aggregates. A plausible molecular mechanism is proposed based on diffusion of Ag+ ions to the growing AgNP surface along with SDS monomers and submicellar aggregates, subsequently forming bigger size AgNPs. The narrow distribution of size for AgNP in presence of 35 mM SDS is arguably driven by the capping of stable SDS micelles or monomers around growing nuclei and restricted number of SDS monomers and submicellar aggregates responsible for supply of Ag+ at the growing AgNP nuclei.

Electrospinning of casein nanofibers with silver nanoparticles for potential biomedical applications

Casein, a major protein content in the milk has been extensively used in drug delivery due to its unique structural features. Fabrication of nanofibers from casein along with nanoparticles for tissue engineering applications has been explored in this study. Nanofibers fabrication is achieved by co-electrospinning of casein with poly (ethylene oxide) in sodium dodecyl sulphate (SDS) aqueous solution. Stabilization of silver nanoparticles has been achieved by the presence of SDS in the nanofiber matrix. The influence of conductivity on the nanofiber fabrication has also been studied. The nanofibrous mats have been characterized using techniques such as scanning electron microscope (SEM) and high resolution-transmission electron microscope (HR-TEM). Antimicrobial properties of the nanofibers have been assessed and the cellular biocompatibility of the material has been evaluated using cultured fibroblast (NIH-3T3) cells. Silver nanoparticles incorporated nanofibers showed good antimicrobial property against both gram negative and gram positive bacteria. In addition, the nanofiber matrix exhibited good biocompatibility for the fibroblast cell proliferation. These results pave the way for extending the use of casein based nanofibers in the skin care applications.

Improvement of the Color Stability of Cyanidin-3-glucoside by Fatty Acid Enzymatic Acylation.

Anthocyanins are water-soluble pigments with limited application in lipophilic matrices such as lipid-based foods and cosmetic formulations. In this work, the liposolubility improvement of cyanidin-3-glucoside (cy3glc) was performed by enzymatic esterification with saturated fatty acids with variable chain lengths, and their thermostabilities were evaluated at different pH values in a lipophilic medium (an aqueous sodium dodecyl sulfate solution) by means of UV-vis spectroscopy. Overall, lipophilic cy3glc derivatives showed improved color stability and lowered sensitivity to thermal degradation than nonmodified cy3glc in an SDS micellar solution between pH 3 and 7.

Determination of Physicochemical Parameters of Sodium Dodecyl Sulfate in Aqueous Micellar Solutions Containing Short-Chain Alcohols

Herein, the concentration effect of ethanol (in the molality range 0–9.5 mol·kg–1), 1-propanol (in the molality range 0–7 mol·kg–1), and 2-propanol (in the molality range 0–13 mol·kg–1) on the micellization of sodium dodecyl sulfate (SDS) in aqueous solutions has been studied at 298 K. The aggregation properties of SDS in aqueous solutions were investigated earlier in the presence of these alcohols but in the alcohol concentration range used in this work the micellization parameters (i.e., the critical micellar concentration, CMC, the dissociation degree of micelles), and especially, the molar conductance of micelles and monomers, the alcohol partition between micelles and the intermicellar solution have not been reported in such detail as here. Moreover, the published CMC values are often considerably different. For the systems studied here, the Gibbs energy of alcohol solubilization in the micelles, foaming properties, and refractive indices were determined. The studies presented here provide informatio...

Effect of temperature on thermo-acoustical parameters of arginine in colloidal solutions

Volumetric and acoustic studies of l‑arginine in water and in aqueous sodium dodecyl sulphate (SDS) solutions were carried out to understand intermolecular interactions in solutions of arginine with water and colloidal solutions containing anionic micelles. Density and ultrasonic velocity data for arginine in water and in aqueous colloidal solutions were measured over a temperature range (288.15 K–308.15 K). The experimental data have been used to calculate apparent and partial molar volume (Φv, Φvο), apparent and partial molar compressibility (Φk, Φko), transfer volume (Φνto), partial molar expansibility (ΦE°), acoustic impedance (Z) and relative association (τ) etc. to comprehend inter and intra molecular interactions. The above mentioned parameters have been used to explore the arginine-surfactant interactions among ions of arginine and water molecules. The trends of transfer volumes have been interpreted by the cosphere overlap model. Moreover, the expansibility factor showed the structure making the behavior of arginine both in water and in aqueous SDS solutions.

Effects of Sodium Dodecyl Sulfate on a Single Cavitation Bubble**Supported by the National Natural Science Foundation of China under Grant Nos 11334005 and 11574150.

Dynamics of a single cavitation bubble in sodium dodecyl sulfate (SDS) aqueous solutions is investigated experimentally and theoretically. The bubble pulsation is measured by a phase-locked integrated imaging technique, and the ambient radius is obtained by fitting the numerical calculation based on the Rayleigh–Plesset bubble dynamics model to the experimental data. The results show that, under the same driving condition, the ambient radius of the cavitation bubble decreases correspondingly with the increase of SDS concentration within the critical micelle concentration, while the compression ratio of the radius increases, which indicates that the addition of SDS decreases the internal molecular number of the cavitation bubble and increases the power capability of the cavitation bubble. In addition, bubble oscillation increases the concentration of the surfactant molecules on the bubble wall, so that the effect of SDS on a single cavitation bubble is reduced when the SDS concentration is greater than 0.8 mM.