Aqueous Solutions Of Sodium Dodecyl Sulfate Research Articles

Hierarchical Microphase Behaviors of Chiral Block Copolymers under Kinetic and Thermodynamic Control

Hierarchical Microphase Behaviors of Chiral Block Copolymers under Kinetic and Thermodynamic Control

Enormous Promotion of Photocatalytic Activity through the Use of Near-Single Layer Covalent Organic Frameworks

Enormous Promotion of Photocatalytic Activity through the Use of Near-Single Layer Covalent Organic Frameworks

Contribution of Different Molecules and Moieties to the Surface Tension in Aqueous Surfactant Solutions. II: Role of the Size and Charge Sign of the Counterions.

Understanding the role of the counterion species in surfactant solutions is a complicated task, made harder by the fact that, experimentally, it is not possible to vary independently bulk and surface quantities. Here, we perform molecular dynamics simulations at constant surface coverage of the liquid/vapor interface of lithium, sodium, potassium, rubidium, and cesium dodecyl sulfate aqueous solutions. We investigate the effect of counterion type and charge sign on the surface tension of the solution, analyzing the contribution of different species and moieties to the lateral pressure profile. The observed trends are qualitatively compatible with the Hofmeister series, with the notable exception of sodium. We point out a possible shortcoming of what is at the moment, in our experience, the most realistic nonpolarizable force field (CHARMM36) that includes the parametrization for the whole series of alkali counterions. In the artificial system where the counterion and surfactant charges are inverted in sign, the counterions become considerably harder. This charge inversion changes considerably the surface tension contributions of the counterions, surfactant headgroups, and water molecules, stressing the key role of the hardness of the counterions in this respect. However, the hydration free energy gain of the counterions, occurring upon charge inversion, is compensated by the concomitant free energy loss of the headgroups and water molecules, leading to a negligible change in the surface tension of the entire system.

A Novel Hydrate Form of Sodium Dodecyl Sulfate and Its Crystallization Process.

A novel hydrate form of sodium dodecyl sulfate (SDS) was firstly discovered through a hydrate screening with the use of organic solvents, while SDS is generally prepared solely in aqueous media. Surprisingly, a novel SDS hydrate form with needle-shaped crystals produced by adding acetonitrile to a 20 wt % SDS aqueous solution at a ratio of 3:1 (v/v) and further cooling to around 5 °C could be found with a trace amount in one of the two purchased SDS products that we examined. After comprehensive solid-state characterizations by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Raman spectroscopy, dynamic vapor sorption (DVS), and elemental analysis (EA), it is also successfully made directly from the synthesis of SDS through esterification and saponification. Four times the equal proportion of acetone was added into the reaction solution at an interval of 5 min to separate the side product, sodium sulfate, from the mother liquor. The desired novel hydrate form of SDS was then obtained by cooling the filtered mother liquor to 5 °C and aged for 8 h for a preferential growth.

Degradation of trichloroethene by citric acid chelated Fe(II) catalyzing sodium percarbonate in the environment of sodium dodecyl sulfate aqueous solution

In this study, the common chlorinated solvent trichloroethene (TCE) was selected as the target contaminant. The aqueous solution after solubilization treatment (containing TCE and sodium dodecyl sulfate (SDS)) was used as the research object to carry out the remediation technology research of citric acid (CA) enhanced Fe(II) activation in sodium percarbonate (SPC) system. In 0.15 mM TCE and 1 critical micelle concentration (CMC) SDS solution, CA chelating Fe(II) activated SPC could effectively promote 93.2% degradation of TCE when the dosages of SPC, Fe(II) and CA were 3.0, 6.0 and 3.0 mM, respectively. SDS had a significant inhibitory effect on the degradation of TCE, and the surface tension changed after the reaction. The addition of CA greatly increased the generation of hydroxyl radicals (HO) in the system, while the removal of TCE was mainly attributed to HO, and the removed TCE was almost completely dechlorinated. The pH range from 3 to 7 could keep the TCE degradation above 80.0%. In the actual groundwater remediation, this technique could also efficiently degrade TCE (including SDS), showing a great application potential and development prospective in practice.

Energetically efficient and electrochemically tuneable exfoliation of graphite: process monitoring and product characterization

In this work, graphene oxide was prepared by electrochemical exfoliation of graphite in sodium dodecyl sulphate and sodium dodecylbenzene sulphonate aqueous solution. Two different working electrodes were investigated: an electrode prepared from natural graphite flakes and a commercial natural graphite rod. The working electrode was polarized in a two-electrode system by using platinum counter electrode and by a multistep change of polarity or by single anodic and cathodic polarization. The voltage value ranged from 2.5 to 3.2 V. By monitoring the current transients and the colour of the resultant solutions, it was shown that the exfoliation process depends on the type of working electrode, surfactants and applied voltage value. The multistep change of polarity was more effective compared to single polarization. The ultraviolet–visible spectrophotometry and Raman spectroscopy indicated the presence of defects within the graphene structure, while FTIR spectroscopy indicated the presence of oxygen functional groups, which is characteristic of graphene oxide (GO). Dynamic light scattering revealed that the solutions obtained in this work contained GO sheets within the size of 10–600 nm. Atomic force microscopy measurements proved that the obtained product contains multilayer sheets. The energy consumption for the process carried out in this work ranges from 0.084–0.038 kWh g−1, and therefore this process is considered to be a low-energy and cost-effective process.

Synergistic Action of Temperature and pH Factors in the Cleaning of Fatty Acids Soils; Analyzed by Probability Density Functional Method.

In this study, the interaction between the temperature and the pH of soil containing fatty acids with sodium dodecyl sulfate (SDS) aqueous solution was investigated to elucidate their synergistic effect in cleaning. A tergotometer was used for the cleaning test, and the cleaning results were analyzed by the probability density functional method, using the calculated parameter, µ rl , as an index of the cleaning power. The increase in µ rl by one of the factors was defined as ΔX or ΔY and the increase in µ rl by the both factors was defined as Δ(X + Y). It is assumed that there is a synergistic effect when Δ(X + Y) > ΔX + ΔY. The cleaning of fatty acid stains followed the addition rule pertaining to mechanical force and the pH effect. However, synergy was observed between the temperature and the pH effect. This was also supported by the plot of µ rl vs 1/T and observations using a phase-contrast microscope.

Corrosion Protection of Self-Healing Coating Contained Fiber/Spherical Shaped Capsules Formed on Substrate Metal

Coating is one of the most useful techniques for corrosion protection of metallic materials, however, if coating is damaged, local corrosion will occur. It is important to repair the damaged area of coating soon, however it needs much cost. From these, our research group develop the coating with self-healing property, called by self-healing coating. In this coating capsules containing healing-agent of coating are dispersed. If the coating is damaged, capsules will be broken at the same time. The healing-agent containing in capsules will flow out. The healing-agent reacts with the water vapor in the air to form a healing-structure and cover the damaged area of coating. The capsules contained healing-agent are produced as follows. First, the prepolymer, this is precursor of shell of capsules, drip into the aqueous solution dissolved glycerol, it hardly dissolves in the aqueous solution since the prepolymer is the oil phase. A mixture of oil droplets dispersed in the aqueous solution is formed. When this mixture is agitated with high speed, the oil droplets become micro spheres and emulsion forms. Furthermore, the reaction between prepolymer and glycerol occurs only at this interface between oil phase and water phase, spherical shaped capsules contained a healing-agent in a polyurethane shell can be produced. From our previous study, the coating with these spherical capsules has a self-healing property, because healing-structure could be observed at the damaged area of coating, but this structure covered damaged area, incompletely. It is necessary to improve self-healing property of coating. From the self-healing mechanism of the coating, the self-healing property of the coating will be strongly depended on the amount of healing-agent flowing to the damaged area. Therefore, we start the development of the coating with capsules with other shape such as fiber shape are dispersed in order to develop an advanced self-healing coating with higher healing property. Considering the procedure of capsule formation, the shape of capsules can be controlled by the agitation speed and viscosity of prepolymer solution. The shape of capsules will be related to the amount of healing-agent flow from capsules to the damaged area of coating, when coating is damaged. e.g. more amount of healing-agent will flow from fiber shaped capsules than that from spherical shaped capsules, because fiber capsules will be arranged horizontally to the metal substrate due to the flow during the formation of coating, and the more capsules will be broken, when vertical damage was formed in the coating. In this paper, the shape of capsules produced from prepolymer solution with high viscosity and self-healing property of coating dispersed with these capsules were discussed.The procedure synthesizing capsules is follows. The prepolymer prepared by reaction between TDI and glycerol in cyclohexanone as a solvent under 75 ℃, 600 rpm. In order to increase the prepolymer concentration and viscosity of solution, the heat treatment of prepolymer solution were performed under 140 ℃, 8 min. After heat treatment, IPDI as a healing-agent, and xylene as inhibiter solidification inside of capsules were added. First, this prepolymer solution drip into the sodium dodecyl sulfate and glycerol aqueous solution with low agitation speed (200 rpm). The prepolymer solution was not dissolved in the aqueous solution and small oil droplets were dispersed in the aqueous solution. The shape of some of droplets will be changed from spherical to long spheroidal or fiber by agitation of solution. Furthermore, the shell formation reaction take place only at the interface between oil and water phases, the spherical, spheroidal and fiber shaped capsules could be formed. For comparison, the capsules produced under high agitation speed (600 rpm) and those from prepolymer solution without heat treatment were also prepared. These capsules were observed by a scanning electron microscope SEM.Fig. 1-a show the shape of capsules prepared from prepolymer solution without heat treatment under high agitation speed, 600 rpm. From this image, only spherical with 20 - 60 µm of diameter can be observed. The shape of capsules from same prepolymer under low agitation speed, 200 rpm, also only spherical however the size of capsules is bit larger, the maximum diameter is about 80 µm, as shown in Fig. 1-b. The shape of the capsule the produced from prepolymer with heat treatment with high agitation speed, shown in Fig. 1-c, are similar to that without heat treatment. In contrast to these, the capsules produced from prepolymer with heat treatment under low agitation speed have some kinds of shape, such as spherical, spheroidal and long fiber. The coating dispersed with these shaped capsules will be also discussed. Figure 1

Experimental study on pool boiling regime transitions of vertical rod quenched in aqueous surfactant solutions using inverse heat transfer analysis

In this study, the effect of surfactants and liquid temperature on boiling regime transitions of high-temperature rod during quenching was examined using inverse heat transfer analysis. Liquid pools of the aqueous sodium dodecyl sulfate (SDS) and Triton X-100 solutions were used with pure water. In the present experimental range, the critical heat flux (CHF) and minimum film boiling (MFB) point for all test fluids increased as the liquid temperature decreased. On the other hand, the SDS and Triton X-100 surfactants suppressed the CHF and MFB point, which might be due to the enhancement of vapor film stability caused by reduced surface tension. Some previous experimental studies have reported that the surfactants enhance the boiling regime transitions, but their results seem to be contradictory to the present ones. Considering the present study with the previous works, the surfactants seem to have different effect on boiling phenomena depending on the boiling regime. In other words, in the aqueous surfactant solution, the boiling regime transition points seem to be markedly influenced by a path of boiling regime. In addition, boiling mode diagrams were presented for pure water and aqueous surfactant solutions.

Antimicrobial Activity of Microgels with an Immobilized Copper(II) Complex Linked to Cross-Linking and Composition.

The resistance of many bacteria against currently available antimicrobial agents is increasing worldwide at an alarming pace. The described structure-activity relationship study was prompted by the extraordinary ability of water-dispersed microgels to hydrolyze glycosidic bonds similar to building blocks of the peptidoglycan layer of Gram-positive bacteria. The results establish polyacrylate microgels with embedded copper(II) complex as antimicrobial agents. The systematic study reveals that Staphylococcus aureus is susceptible to the microgels, while common commercial agents are found intermediate or resistant. In particular, a microgel with 60 mol % of cross-linking, Cu2LP60%, shows intriguing bactericidal activity at 1 μg/mL, while vancomycin requires a 4-fold higher dose, i.e., 4 μg/mL, for the same effect. The minimum inhibitory concentration of Cu2LP60% was determined as low as 0.64 μg/mL. Excellent stability of the poly(acrylate) microgels was observed by negative zeta potentials in nanopure water and aqueous sodium dodecyl sulfate solution. The composition of the microgel matrix with embedded binuclear metal complex was shown to be responsible for the antimicrobial activity, while the aqueous buffer-surfactant solution is not.

Positive/Negative Phototropism: Controllable Molecular Actuators with Different Bending Behavior

Herein, a series of molecular actuators based on the crystals of (E)-2-(4-fluorostyryl)benzo[d]oxazole (BOAF4), (E)-2-(2,4-difluorostyryl)benzo[d]oxazole (BOAF24), (E)-2-(4-fluorostyryl)benzo[d]thi...

Pure and mixed aqueous micellar solutions of Sodium Dodecyl sulfate (SDS) and Dimethyldodecyl Amine Oxide (DDAO): Role of temperature and composition

Aqueous mixtures of anionic and nonionic/cationic surfactants can form non-trivial self-assemblies in solution and exhibit macroscopic responses. Here, we investigate the micellar phase of pure and mixed aqueous solutions of Sodium Dodecyl Sulfate (SDS) and Dimethyldodecyl Amine Oxide (DDAO) using a combination of Small Angle Neutron Scattering (SANS), Fourier-Transform Infrared Spectroscopy (FTIR) and rheological measurements. We examine the effect of temperature (0–60 °C), on the 20 wt% SDS micellar solutions with varying DDAO (⩽5 wt%), and seek to correlate micellar structure with zero-shear solution viscosity. SANS establishes the formation of prolate ellipsoidal micelles in aqueous solutions of pure SDS, DDAO and SDS/DDAO mixtures, whose axial ratio is found to increase upon cooling. Elongation of the ellipsoidal micelles of pure SDS is also induced by the introduction of the non-anionic DDAO, which effectively reduces the repulsive interactions between the anionic SDS head-groups. In FTIR measurements, the formation of elongated mixed ellipsoidal micelles is confirmed by the increase of ordering in the hydrocarbon chain tails and interaction between surfactant head-groups. We find that the zero-shear viscosity of the mixed surfactant solutions increases exponentially with decreasing temperature and increasing DDAO content. Significantly, a master curve for solution viscosity can be obtained in terms of micellar aspect ratio, subsuming the effects of both temperature and DDAO composition in the experimental range investigated. The intrinsic viscosity of mixed micellar solutions is significantly larger than the analytical and numerical predictions for Brownian suspensions of ellipsoidal colloids, highlighting the need to consider interactions of soft micelles under shear, especially at high concentrations.

Synthesis of hierarchical porous ZIF-8/3DCNTs composite sensor for ultrasensitive detection of DA and DFT studies

Abstract A hybrid nanocomposite of hierarchical porous zeolitic imidazolate framework-8 / three-dimensional carbon nanotubes (HP-ZIF-8/3DCNTs) has been successfully fabricated by constructing micelle by sodium dodecyl sulfate (SDS) and deep eutectic solvent (DES) aqueous solution to grow HP-ZIF-8 in situ on the 3DCNTs template. The electrochemical performance for detecting dopamine (DA) is greatly improved owing to the synergism of highly conductive CNTs and hierarchical porous ZIF-8. At the same time, the electrochemical reaction of DA on HP-ZIF-8/3DCNTs/GCE is an adsorption control process, and density function theory (DFT) calculation was performed to analysis the charge distribution and interaction force of DA and dopaminophenone in the material, forming a molecular complex with adsorption energy of −19.11 and − 25.21 kJ/mol−1. In addition, the response current is linear when the DA content is 1.0 × 10−7 to 1.0 × 10−4 M, the LOD is 2.7 × 10−8 M at S/N = 3. The electrode material has excellent selectivity, sterling reproducibility of 2.21% and satisfactory repeatability with a RSD of 1.96%, and splendid long-term stability with peak current maintained 96.03% of the initial value after 14 days. The results indicate that HP-ZIF-8/3DCNTs composite has broad application prospects in the field of electrochemical sensing, and its modification methods and theoretical concepts can potentially be applied to the research of other sensors.

Design of Optimized PEDOT-Based Electrodes for Enhancing Performance of Living Photovoltaics Based on Phototropic Bacteria

Living photovoltaics represent a growing class of microbial devices that are based on whole cell-electrode interactions [1-3]. The limited charge transfer at the cell-electrode interface represents a significant bottleneck in realizing an efficient technology [4]. This study focuses on the development of poly(3,4-ethylenedioxythiophene) (PEDOT)-based electrodes with enhanced charge transfer properties at the interface [5,6]. This is accomplished by the electrosynthesis of PEDOT layers from aqueous sodium dodecyl sulfate (SDS) solutions. Potentiodynamic and potentiostatic electrochemical techniques, as well as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, and theoretical modelling of the electropolymerization transient, were employed to assembly and characterize PEDOT electrodes under various conditions. The produced electrodes are able to capture photosynthetically derived current under multiple light-dark cycles when interfaced with Synechocystis sp. PCC 6803. In the presence of the Synechocystis, the PEDOT electrodes show a six-fold and two-fold enhancement over conventional graphite electrodes for both mediatorless and K3Fe(CN)6 mediated conditions, respectively. The ability of these electrodes to enhance extracted photocurrent for both direct and indirect electron transfer mechanisms provides a versatile platform for improving various microbial devices.[1] Zou, Y., Pisciotta, J., Billmyre, R. B., & Baskakov, I. V. (2009). Photosynthetic microbial fuel cells with positive light response. Biotechnology and Bioengineering, 104(5), 939-946.[2] Pisciotta, J. M., Zou, Y., & Baskakov, I. V. (2010). Light-dependent electrogenic activity of cyanobacteria. PloS one, 5(5), e10821.[3] Schuergers, N., Werlang, C., Ajo-Franklin, C. M., & Boghossian, A. A. (2017). A synthetic biology approach to engineering living photovoltaics. Energy & environmental science, 10(5), 1102-1115.[4] Mouhib, M., Antonucci, A., Reggente, M., Amirjani, A., Gillen, A. J., & Boghossian, A. A. (2019). Enhancing bioelectricity generation in microbial fuel cells and biophotovoltaics using nanomaterials. Nano Research, 1-16.[5] Tamburri, E., Orlanducci, S., Toschi, F., Terranova, M. L., & Passeri, D. (2009). Growth mechanisms, morphology, and electroactivity of PEDOT layers produced by electrochemical routes in aqueous medium. Synthetic metals, 159(5-6), 406-414.[6] Zajdel, T. J., Baruch, M., Méhes, G., Stavrinidou, E., Berggren, M., Maharbiz, M. M., ... & Ajo-Franklin, C. M. (2018). PEDOT: PSS-based multilayer bacterial-composite films for bioelectronics. Scientific reports, 8(1), 15293.

Exploring the effect of hydrophobic ionic liquid on aggregation, micropolarity and microviscosity properties of aqueous SDS solutions

Ionic liquid (IL)-modified surfactant systems have versatile applications in several technological areas. Therefore, it is utmost need to achieve full understanding of interactions existing in such systems before their further uses. Here, the effects of IL, 1-ethyl-3-methylimidazolium hexafluorophospahte, [emim][PF6] on the physicochemical properties of aqueous sodium dodecyl sulfate (SDS) solutions has been studied using multi-technique approach. Various micellar parameters such as critical micelle con-centration (cmc), degree of counter ion dissociation (α), aggregation number (Nagg) as well as some thermodynamic parameters such as standard free energy of micellization (G°m), standard enthalpy of micellization (H°m) and standard entropy of micellization (S°m) and surface properties from surface tension measurement have been evaluated. A significant decrease in cmc, and increase in degree of counter ion dissociation along with increase in Nagg is observed. The aggregation behaviour of SDS is also studied in presence of ILs having different alkyl chain length in their imidazolium cations. A decrease in CMC of SDS observed, and trend of decrease in CMC is reported as [hmim][Cl] > [bmim][PF6] > [emim][PF6]. The micropolarity and microviscosity of micellar media are accessed with fluorescence probe studies. The effect of chain length of IL cation has been also explored on aggregation behaviour. The FTIR technique is employed to evaluate possible interactions between SDS and IL [emim][PF6] molecules, the information regarding size of SDS micelle in presence of IL [emim][PF6] has been explored by DLS technique.

Adsorption of the Cationic Dye Methylene Blue on Anodic Porous Alumina in Sodium Dodecyl Sulfate Solutions.

Dyeing of anodic porous alumina (APA) prepared by aluminum anodization is generally achieved by dipping the positively charged APA surface into a negatively charged dye solution. We have proposed a new method to adsorb dyes and molecules onto APA using negatively charged sodium dodecyl sulfate (SDS). In this study, we found that cationic methylene blue (MB) can be adsorbed onto the positively charged APA surface using SDS aqueous solutions. We investigated two adsorption methods: dipping APA into aqueous solutions containing both MB and SDS (method 1) and successive dipping of APA into SDS and then MB aqueous solutions (method 2). The two methods produced different adsorption characteristics. Method 1 adsorption profile reflected formation of dye-rich induced micelles below the critical micellar concentration (CMC) and electrostatic interaction of micelles with MB above CMC. Method 2 adsorption was explained by electrostatic interaction of preadsorbed SDS with APA and MB.

Highly stretchable and thermally healable polyampholyte hydrogels via hydrophobic modification

Aqueous solutions or gels of polyampholytes attract interest for more than half a century due to their several attractive properties. We present here thermally healable hydrophobically modified physical polyampholyte (PA) hydrogels based on oppositely charged 2-acrylamido-2-methylpropane-1-sulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC) monomers. PA hydrogels were prepared via micellar polymerization technique in the presence of the hydrophobic monomer n-octadecyl acrylate (C18A) in aqueous sodium dodecyl sulfate (SDS) solutions. Charge-balanced PA hydrogels containing 60–90% water exhibit a high tensile strength and stretchability of up to 202 kPa and 1239%, respectively. Above 7 mol% C18A, swollen hydrogels containing around 90% water exhibit much better mechanical properties as compared with the corresponding as-prepared ones because of the stronger hydrophobic interactions in the absence of SDS micelles. Cut-and-heal tests conducted at 50 °C reveal a complete healing efficiency with respect to Young’s modulus for all as-prepared PA hydrogels within 1–4 h.

Reproducible Crystallization of Sodium Dodecyl Sulfate·1/8 Hydrate by Evaporation, Antisolvent Addition, and Cooling.

Sodium dodecyl sulfate (SDS)·1/8 hydrate (NaC12H25SO4·1/8H2O) crystals were successfully produced by evaporation, antisolvent addition, cooling crystallization, and isothermal aging in a common stirred tank. A clear 33.3 wt % SDS aqueous solution was concentrated by evaporation to a 60 wt % coagel consisting of numerous SDS hydrates and water. The coagel was transformed to a clear solution when two times the volume of acetone relative to the water remaining were added. By this fluid property, a controlled crystallization was made possible in a homogeneous solution. Moreover, acetone with a water-to-acetone volume ratio of 1:15 was then added as an antisolvent to induce crystallization of SDS·1/8 hydrate by cubic addition. Finally, cooling crystallization and isothermal aging were carried out to further increase the yields and gave monodispersed particle size. The stability test showed that the produced SDS·1/8 hydrate could be stored at various relative humidity environments for at least 5 days.

BACTERIAL NANOCELLULOSE BIOMEMBRANE AS A SUPPORT FOR HUMAN INSULIN AIMING AT TRANSDERMAL PERMEATION

Production of bacterial nanocellulose was pursued as a matrix system for the stabilization of human insulin. The biomembranes produced by Gluconacetobacter hansenii were washed with 2% aqueous sodium dodecylsulfate solution, rinsed with ultrapure water and immersed in 1 mol L-1 NaOH aqueous solution at 60 °C for 90 min until neutralization. For the insulin adsorption assays, the biomembranes were soaked in a buffered solution of human insulin until no protein could be detected in the supernatant. The membranes with adsorbed insulin were characterized via mechanical resistance (resilience, relaxation, perforation), Differential Scanning Calorimetry (DSC), Thermal Gravimetrical Analysis (TGA), Fourier Transform Infrared Spectrophotometry (FTIR), X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) analyses. The FESEM photomicrographs of the surface of the biomembranes showed a rugged surface without cracks. The biomembranes exhibited adequate mechanical characteristics. The infrared spectra indicated that the chemical aspect of the protein moiety was preserved during adsorption onto the BNC biomembranes. According to the XRD analyses, the biomembranes showed a generalized amorphous behavior. Thermal analyses indicated an adequate thermal stability for a pharmaceuticals product. Hence, an elastic and malleable biomembrane was produced, suitable for incorporation of human insulin, aiming at transdermal delivery.

A comparative study on the effects of Fe3O4 nanofluid, SDS and CTAB aqueous solutions on the CO2 hydrate formation

In this study, the effects of water-based Fe3O4 nanofluids containing 400 ppm sodium dodecyl sulfate (SDS) and 400 ppm cetyltrimethylammonium bromide (CTAB) in different concentrations of nanoparticles (0.05 wt%, 0.09 wt%, 0.15 wt%, 0.20 wt% and 0.25 wt%) on the kinetic parameters of carbon dioxide hydrate formation have been investigated and the results are compared with other aqueous solutions including pure water, aqueous solution of 400 ppm SDS, aqueous solution of 400 ppm CTAB and suspension of 0.15 wt% Fe3O4 nanoparticles. The kinetic parameters studied in this work included the mole of gas consumption, induction time and apparent rate constant. The experiments were performed at the initial pressure of 2.5 MPa and two temperatures of 274.15 K and 276.15 K. The experimental results showed that by increasing the concentration of nanoparticles up to 0.15% by weight, the effect of nanoparticles on the carbon dioxide hydrate formation increases. However, a further increase in nanoparticle concentration will reduce this effect. It was observed that the effect of the suspension of 0.15 wt% Fe3O4 nanoparticle on the carbon dioxide hydrate formation is more than the 400 ppm CTAB aqueous solution and less than the 400 ppm SDS aqueous solution. Results also showed that among different aqueous solutions, Fe3O4 nanofluid containing SDS with a concentration of 0.15 wt% nanoparticle is the best aqueous solution for carbon dioxide hydrate formation. In this nanofluid at 274.15 K, the induction time decreased by 70.6% and the mole of gas consumption and the apparent rate constant increased about 160% and 120.5%, respectively compared to pure water.