Addition Of Sodium Dodecyl Sulfate Research Articles

Effects of surfactant on Bacillus mucilaginosus adsorption characteristics during vanadium bioleaching process

Bioleaching is a sustainable and economical technology for extracting valuable elements from low-grade ores or refractory resources. Adsorption of bacteria on mineral surface is the usual basic condition for the deep interaction between bacteria and minerals, thereby improving the bioleaching efficiency of target elements. The addition of surfactants in bioleaching process is an efficient and promising method for improving the bacteria adsorption on mineral surface. Therefore, effects of surfactant SDS (Sodium Dodecyl Sulfate) on bacterial adsorption characteristics were investigated during the bioleaching process from vanadium-bearing shale by Bacillus mucilaginosus (B.M). The optimal vanadium bioleaching conditions were 0.5 g/L of SDS, 2 g/L of yeast dip powder, and 7.0 of the initial pH. The B.M adsorption equilibrium on the surface of the vanadium-bearing shale with and without addition of surfactant SDS fitted a Freundlich equation, and the addition of surfactant SDS could significantly enhance the B.M absorption on the vanadium-bearing shale. The Pseudo-first-order adsorption kinetics was more suitable to be selected for the demonstration of the B.M adsorption on the surface of the vanadium-bearing shale with and without addition of surfactant SDS, and the addition of surfactant SDS could accelerate the B.M adsorption rate on the surface of the vanadium-bearing shale.

Surfactant-sodium dodecyl sulfate enhanced degradation of polystyrene microplastics with an energy-saving electrochemical advanced oxidation process (EAOP) strategy

Microplastics have been identified as a kind of emerging pollutant with potential ecological risks, and it is an urgent endeavor to find proper technologies for their remediation. Electrochemical advanced oxidation process (EAOP) technology has exhibited robust performance in the removal of various refractory organic pollutants. In this study, we explored a new remediation strategy for polystyrene microplastics (PS MPs), introducing sodium dodecyl sulfate (SDS) to enhance its degradation performance in boron-doped diamond (BDD) anode adopted EAOP. At first, we investigated the degradation behaviors of SDS in the BDD electrolysis. According to the SDS half-life under various current densities, the SDS addition strategy into EAOP is proposed; that is, supplement SDS to 500 mg/L at every half-life during electrolysis except the last cycle. Results indicated that SDS addition greatly enhanced MPs degradation rate in 72 h of EAOP, about 1.35–2.29 times higher than that in BDD electrolysis alone. The SDS assisted EAOP also led to more obvious changes in the particle size, morphology, and functional groups of the MPs. After treatment, a variety of alkyl-cleavage and oxidation products were identified, which attributed to the strong attack of oxidants (i.e., persulfate) on the MPs. The enhanced persulfate generation and oxidants adsorption on MPs can explain the enhancement effect in the EAOP strategy. Cost analysis results showed the surfactant only accounts for < 0.05% of the total operating costs in the SDS assisted EAOP. In general, the current study provided new insight into the effective way to improve the EAOP efficiency of microplastics.

Evaporative Deposition of Surfactant-Laden Nanofluid Droplets over a Silicon Surface.

Morphologies of evaporative deposition, which has been widely applied in potential fields, were induced by the competition between internal flows inside evaporating droplets. Controlling the pattern of deposition and suppressing the coffee-ring effect are essential issues of intense interest in the aspects of industrial technologies and scientific applications. Here, evaporative deposition of surfactant-laden nanofluid droplets over silicon was experimentally investigated. A ring-like deposition was formed after complete evaporation of sodium dodecyl sulfate (SDS)-laden nanofluid droplets with an initial SDS concentration ranging from 0 to 1.5 CMC. In the case of initial SDS concentrations above 1.3 CMC, no cracks were observed in the ring-like deposition, indicating that the deposition patterns of nanofluid droplets could be completely changed and cracks could be eliminated by sufficient addition of SDS. With the increase of the initial concentration of hexadecyl trimethylammonium bromide (CTAB), the width of the deposition ring gradually decreased until no ring-like structure was formed. On the contrary, with the increase of the initial Triton X-100 (TX-100) concentration, the width of the deposition ring gradually increased until a uniform deposition was generated. Moreover, when the initial TX-100 concentration was high, a "tree-ring-like" pattern was discovered. Besides, morphologies of evaporative pattern due to the addition of surfacants were qualitatively analyzed.

Circular Dichroism Spectra of α-Chymotrypsin-SDS Solutions Depend on the Procedure of Their Preparation.

We recorded the far- and near-UV circular dichroism (CD) spectra of solutions of α-chymotrypsin and sodium dodecyl sulfate (SDS) with the final surfactant concentration significantly above the critical micellization concentration. Solutions were prepared using three different procedures. The reference procedure was to mix the chymotrypsin solution with the SDS solution once, immediately achieving the final SDS concentration. In alternative procedures, the protein solutions initially contained some SDS and were mixed with pure SDS solutions at a concentration to provide the same final surfactant as the reference mixing. We demonstrate that the supplementation to the selected final concentration of SDS of the pure chymotrypsin solution leads to different CD spectra than the supplementation to this final concentration of SDS in the chymotrypsin solution containing a small concentration of a few millimolar SDS. These differences disappear when the initial concentration of SDS in the protein solution, which we then supplement to the indicated final concentration, is higher. This suggests the irreversibility of the processes caused by the addition of SDS to chymotrypsin and the influence of the initial amount of this surfactant on the processes occurring with its further addition to the solution. For quantitative analysis of far-UV CD spectra in terms of populations of protein secondary structure elements, we used four well-established software packages. All programs consistently indicate that the observed differences in the far-UV CD spectra can be explained by the differences in the increase in the population of helical forms in chymotrypsin under the influence of SDS.

Degradation of tetracycline by visible light over ZnO nanophotocatalyst

BackgroundZnO material can only absorb ultraviolet light. However, tetracycline (TC) can sensitize semiconductors to produce visible light activity. The application of intrinsic ZnO for visible light degradation of TC is a new discovery. MethodsThe ZnO nanostructures were synthesized by the precipitation method with sodium dodecyl sulfate (SDS) as the structure guide. The catalytic activity of intrinsic ZnO to degrade high concentrations of TC under visible light irradiation was investigated. Significant findingsThe addition of SDS changed the morphology of ZnO and reduced its average size to 55.5 nm. In the visible light photocatalytic degradation, SDS also enhanced the adsorption of TC on the surface of ZnO and promoted the formation of TC-SDS/ZnO surface complexes at the defects. The results showed that the degradation rate of TC by SDS/ZnO is 49.0%, which is 2.51 times that of commercial ZnO. UV-Vis DRS proves that TC-SDS/ZnO has visible light response, TC as a photosensitizer absorbs visible light and excites ZnO with visible light response. Radical trapping experiments combined with ESR tests jointly proved that •O2− and •OH play vital roles in the degradation of TC, finally the degradation mechanism was proposed.

Line Patterns and Fractured Coatings in Deposited Colloidal Hydrochar on Glass Substrates after Evaporation of Water

Patterns of assembled colloidal particles can form on substrates due to solvent evaporation, and here we studied such phenomena in the drying of monodispersed colloidal hydrochar dispersions prepared by the hydrothermal carbonization of glucose and purified by dialysis. During the evaporation of water, line patterns or, in some cases, mud-like patterns formed. The line formation was investigated as a function of the pH of the dispersion, substrate shape, particle concentration, and concentration of sodium dodecylsulfate (SDS). The lines comprised dense assemblies of hydrochar particles. The line width increased with the successive evaporation of water. Sharper lines formed with the addition of SDS, which was ascribed to the effects of solubilization or moderated interactions. At greater particle concentrations, we also observed a continuous layer of colloidal particles between the lines. A mechanism for the line pattern formation derived from the literature on other colloids was proposed. Mud-like patterns formed on the substrate in concentrated samples without SDS addition and were put in the context of the formation of cracks in the drying of colloidal coatings. Hydrochars belong to carbon-rich colloids, which are of fundamental and technological importance. This research could be useful for in situ line printing within microfluidic devices, for example.

Influence of pectin and drying conditions on the structure, stability and swelling behaviour of casein microparticles

Casein microparticles with adjustable swelling properties and stabilities, which are produced under gentle pH and temperature conditions, are of interest as encapsulation systems for bioactive compounds. In the process investigated here, the volume exclusion of pectin causes casein micelles to form aggregates under neutral pH conditions, from which casein microparticles can be produced by film drying. The type of pectin used and the drying conditions significantly influence the stability and swelling behaviour of the casein microparticles. With increasing drying time, the microparticles become more stable and show greater deviations from mono-exponential decomposition after addition of sodium-dodecylsulphate. They are also more stable when dried in pure pectin films rather than in mixed pectin films. While the microparticles from beet and citrus pectin films swell the fastest and the slowest, respectively, those from mixed films show a moderate swelling behaviour with only a weakly pronounced two-step swelling process.

Poly(N-isopropylacrylamide) copolymer nanogels with thermogelling ability prepared by a single step of dispersion polymerization

The copolymer nanogels composed of two N-substituted acrylamides with different water solubility, N-isopropylacrylamide (NIPAM, water-soluble) and N-t-butylacrylamide (TBAM, water-insoluble), were prepared by free-radical polymerization in the presence of sodium dodecyl sulfate (SDS) as a dispersant and found to exhibit thermogelling ability at very low concentrations. To investigate the structure of the P(NIPAM-TBAM) nanogel and its formation mechanism in dispersion polymerization, we prepared the nanogels by changing the conditioning time, which is the time between the addition of SDS to the monomer solution and the start of polymerization, and compared the thermogelling properties of the resultant nanogels. As the conditioning time increased, (i) the hydrodynamic diameter of the nanogel decreased, (ii) the sol–gel and gel-syneresis transition temperatures of the nanogel dispersion decreased, and (iii) the storage moduli of the nanogel dispersion in a gel state increased. These results indicate that the P(NIPAM-TBAM) nanogel has a block-like structure composed of the TBAM-rich brushes and the NIPAM-rich core with three-dimensional polymer network, and that the TBAM ratio in the brushes increases with an increase in the conditioning time. It should be noted that the critical gelation concentration of the P(NIPAM-TBAM) nanogel dispersion was very low (∼1.3 wt%), compared with other thermogelling polymers reported in literatures. This low gelation concentration can be attributed to the gel structure of the nanogel core because the NIPAM-rich core can retain water inside even when the TBAM-rich brushes are dehydrated and crosslink with each other to induce gelation of the system.

Synthesis and temperature-sensitive lubrication behavior of PNIPAM microgels for titanium alloy

PurposeThis paper aims to offeri novel nano-additives polymer microgels to precisely improve the lubrication properties of titanium alloy under different temperatures.Design/methodology/approachThe surfactant-free emulsion polymerization method was used to prepare Poly(N-isoprolylacrylamide) (PNIPAM) microgels. A ball-on-disk tribometer was applied to investigated the temperature-sensitive lubrication behavior of PNIPAM microgels.FindingsThe results show that the as-prepared microgels are ball-like nanoparticles with the size of 50–900 nm. In addition, potassium persulfate as initiator, complete mixing technic and high sodium dodecyl sulfate (SDS) concentration contribute to the formation of microgels with small size. The tribosystem shows a lower friction coefficient with the lubrication of PNIPAM microgels as aqueous solution additives when the temperature exceeding the critical temperature.Originality/valueThis work reports the temperature-sensitive lubrication of PNIPAM microgels. The critical temperature of PNIPAM microgels could be regulated by the addition of SDS in the solutions. This offers an effective and facile strategy for regulation of the critical temperature of smart microgels, which is helpful for the smart lubrication in the future.

On the association between poly(vinyl alcohol) and sodium dodecyl sulfate and its effect on liquid–liquid interfacial tension: A mathematical model

AbstractAssociation between poly(vinyl alcohol‐co‐vinyl acetate) copolymer (PVA) and sodium dodecyl sulfate (SDS) was studied experimentally and theoretically. It was found that, for the ethyl acetate‐aqueous phase interface in which PVA was previously adsorbed, the interfacial tension (γ) increases abruptly to a maximum and then exhibits a relatively mild decay with the addition of SDS to the aqueous phase. The theoretical results indicate that vinyl acetate (VAc) segments determine γ. However, for relatively low concentrations of SDS (CSDS), this latter plays a major role because through its association with the VAc segments it modulates the extent to which PVA is adsorbed at the interface, indirectly determining the value of γ. As CSDS approaches to the CMC value for SDS, its influence on γ decreases because SDS tends to self‐assembly rather than associates with VAc. These model predictions are consistent with experimental findings reported in the literature.

Stability and thermal conductivity of TiO2/water nanofluids: A comparison of the effects of surfactants and surface modification

In this study, Surface modification technique is applied to prepare γ-glycidoxypropyltrimethoxysilane (GPTMS) modified TiO2/water nanofluids. Three surfactants and unmodified nanoparticles are added into de-ionized water to prepare surfactant added nanofluids. The characteristics of modified nanoparticles are firstly investigated. The results show that the grafting efficiency of GPTMS increases with reacting temperature and reactant mass ratio of GPTMS to nanoparticles. The stability and thermal conductivity of prepared nanofluids are investigated. The results show that the nanofluids prepared by adding Sodium dodecyl sulfate (SDS) and unmodified nanoparticles have moderate stability. The nanofluids prepared by GPTMS modified nanoparticles show excellent stability, which can be stable for 49 days and have the largest zeta potential. For all prepared nanofluids, thermal conductivity increases with temperature and nanoparticle concentration. The addition of SDS has limited contributions in thermal conductivity of nanofluids, while GPTMS modified nanofluids have higher thermal conductivity and long term thermal conductivity consistency.

Influences of different co-promoters on the mixed methane hydrate formation with salt water at moderate conditions

Effects of co-promoters on the mixed methane-THF hydrate formation in the presence of 3.5 wt% NaCl and 5.56 mol% THF solution were investigated at 8 MPa and 288.2 K in an unstirred reactor. The addition of NaCl resulted in the two-step hydrate formation, and it is the first stage that adversely affected the hydrate formation rate. However, the final gas uptake in this system was similar to that without NaCl. The synergistic effects on the kinetic promotion by adding a co-promoter including sodium dodecyl sulfate (SDS) and amino acids (valine, leucine, and methionine) were then studied. The results showed that the addition of the co-promoters reduced the induction time, minimized the length of the first stage formation, and increased the hydrate formation rate. Moreover, the induction time and the length of the first stage formation decreased along with the increase in the co-promoter concentration. However, the addition of SDS had the adverse effects by decreasing about half of the final gas uptake and the water to hydrate conversion for the system without SDS. Moreover, the addition of methionine resulted in the best performance as a kinetic promoter on the hydrate formation in the system with THF and NaCl. Up to 95 % of methane gas can be recovered from the hydrates formed with and without the co-promoters. The hydrate formation morphology illustrated the same pattern in all cases.

Effect of sodium dodecyl sulphate on Cu electrodeposition: interaction with hydrophobic substrate and Cu ions

ABSTRACT In this study, the effect of sodium dodecyl sulphate (SDS) on Cu electrodeposition was evaluated using cyclic voltammetry. With the weak adsorption of SDS on Cu and Au surfaces, SDS slightly altered the cyclic voltammogram for Cu electrodeposition on these surfaces. However, the cyclic voltammogram on glassy carbon (GC) and pyrolytic graphite significantly changed with the addition of SDS, indicating that the hydrophobic interactions are critical for SDS adsorption. SDS adsorbed on the GC surface exhibiting an increase in current response, an indication of the enhancement of Cu nucleation, confirmed by the increase in the nuclei density on the GC surface. Moreover, the addition of SDS splits the voltammetric wave on GC, indicating that SDS might stabilise Cu+ intermediates that are probably associated with SDS micelles. In addition, the micellar association might lower the diffusion coefficient of Cu2+ leading to a depression in the reduction peaks in the cyclic voltammograms.

Effects of different surfactants on the conjugates of soybean protein-polyphenols for the preparation of β-carotene microcapsules.

In this study, we investigated the spray-drying microencapsulation of β-carotene in oil co-stabilized by soy protein isolate-epigallocatechin-3-gallate conjugate (SPE) and small molecule surfactants [sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide (CTAB), and tea saponin (TS)] of different concentrations [0.1, 0.5, and 1.0% (w/v)], as a prospective approach to stabilize β-carotene. The results show that different surfactant types and concentrations significantly affect the encapsulation efficiency, water dispersibility, microstructure, and digestion of the microcapsules. Interactions between the surfactants and the SPE at the interface were found to include both synergistic and competitive effects, and they depended on the surfactant type and concentration. Moreover, the addition of SDS and TS before spray drying significantly improved the microencapsulation performance of the microcapsules and the water dispersion behavior of the corresponding spray-dried powders. The highest encapsulation efficiency was achieved for the SPE-0.1TS-encapsulated β-carotene microcapsules. In contrast, the addition of CTAB was not conducive to microcapsule formation, resulting in poor encapsulation efficiency, water dispersibility, thermal stability, β-carotene retention rate, and oxidation stability. In vitro gastrointestinal digestion results revealed that the addition of CTAB promotes the release of β-carotene and improves the bioaccessibility of β-carotene. In contrast, except for SPE-1.0SDS, the addition of SDS and TS inhibited β-carotene release and reduced β-carotene bioaccessibility. This study demonstrated that this novel β-carotene encapsulation formulation can overcome stability limitations for the development of β-carotene supplements with a high bioaccessibility.

Sodium dodecyl sulfate modulates the structure and rheological properties of Pluronic F108-poly(acrylic acid) coacervates).

Micelles formed within coacervate phases can impart functional properties, but it is unclear if this micellization provides mechanical reinforcement of the coacervate whereby the micelles act as high functionality crosslinkers. Here, we examine how sodium dodecyl sulfate (SDS) influences the structure and properties of Pluronic F108-polyacrylic acid (PAA) coacervates as SDS is known to decrease the aggregation number of Pluronic micelles. Increasing the SDS concentration leads to larger water content in the coacervate and an increase in the relative concentration of PAA to the other solids. Rheological characterization with small angle oscillatory shear (SAOS) demonstrates that these coacervates are viscoelastic liquids with the moduli decreasing with the addition of the SDS. The loss factor (tan δ) initially increases linearly with the addition of SDS, but a step function increase in the loss factor occurs near the reported CMC of SDS. However, this change in rheological properties does not appear to be correlated with any large scale structural differences in the coacervate as determined by small angle X-ray scattering (SAXS) with no signature of Pluronic micelles in the coacervate when SDS concentration is >4 mM during formation of the coacervate, which is less than that observed (6 mM SDS) in initial Pluronic F108 solution despite the higher polymer concentration in the coacervate. These results suggest that the mechanical properties of polyelectrolyte-non-ionic surfactant coacervates are driven by the efficicacy of binding between the complexing species driving the coacervate, which can be disrupted by competitive binding of the SDS to the Pluronic.

Secondary Structure Transitions for a Family of Amyloidogenic, Antimicrobial Uperin 3 Peptides in Contact with Sodium Dodecyl Sulfate.

Secondary structure changes are an inherent part of antimicrobial (AMP) and amyloidogenic peptide activity, especially in close proximity to membranes, and impact the peptides' function and dysfunction roles. The formation, and stability of α-helical components are regarded as essential 'intermediates' for both these functions. To illuminate the conformational transitions leading to amyloid formation we use short cationic AMPs, from an Australian toadlet, Uperoleia mjobergii, (Uperin 3 family, U3) and assess the impact on secondary structural elements in the presence of a membrane mimetic surfactant, sodium dodecyl sulfate (SDS). Specifically, Uperin 3.x, where x=4, 5, 6 wild-type peptides and position seven variants for each, R7A or K7A, were investigated using a combination of experimental and simulation approaches. In water, U3 peptides remain largely unstructured as random coils, with the addition of salts initiating structural transitions leading to assembly towards amyloid. Solution NMR data show that an unstructured U3.5 wt peptide transitions in the presence of SDS to a well-defined α-helical structure that spans nearly the entire sequence. Circular dichroism (CD) and ThT fluorescence studies show that all six U3 peptides aggregate in solution, albeit with vastly varying rates, and a dynamic equilibrium between soluble aggregates rich in either α-helices or β-sheets may exist in solution. However, the addition of SDS leads to a rapid disaggregation for all peptides and stabilisation of predominantly α-helical content in all the U3 peptides. Molecular dynamics (MD) simulations show that the adsorption of U3.5 wt/R7A peptides onto the SDS micelle is driven by Coulombic attraction between peptide cationic residues and the negatively charged sulfate head-groups on SDS. Simulating the interactions of various kinds of β-sheet dimers (of both U3.5 wt and its variant U3.5 R7A) with SDS micelles confirmed β-sheet content decreases in the dimers after their attachment to the SDS micelle. Adsorbed peptides interact favourably with the hydrophobic core of the micelle, promoting intramolecular hydrogen bonds leading to stabilisation of the α-helical structure in peptides, and resulting in a corresponding decrease in intermolecular hydrogen bonds responsible for β-sheets.

ISOLATION AND IDENTIFICATION OF LACTIC ACID BACTERIA (LAB) PRODUCING BACTERIOSIN-LIKE FROM SMOKED GIANT CATFISH (Arius thalassinus)

Bacteriocin was bacterial metabolite that have antimicrobial properties, so it had the potential to be used as food bio preservatives. Bacteriocin was produced by lactic acid bacteria (LAB), one of the sources of which was from smoked fish products. Some regions in Indonesia produce various types of smoked fish from various types of fish, which were thought to contain bacteriocin-producing lactic acid; one of them was giant cathfish (Arius thalassinus). This study aims to obtain LAB isolates that have strong antimicrobial activity and have the potential to produce bacteriocin-like from smoked giant catfish (Arius thalassinus). The research method used an experimental method that analyzed descriptively. Based on the results, there were 15 isolates LAB isolated from smoked giant catfish. Three selected isolates showed strong antimicrobial activity inhibiting E. coli and S. aureus bacteria, and the most effective inhibiting Salmonella sp. One selected LAB isolates identified Pediococcus acidilactici suspected to produce pediocin bacteriocin-like, while the other two isolates identified Lactobacillus plantarum sp 1 and Lactobacillus plantarum sp 2 which suspected to produce plantaricin bacteriocin. Bacteriocin from the three isolates of LAB had characteristics stable to temperatures up to 121oC, stable in pH range 2-6, and bacteriocin activity increased with the addition of SDS (Sodium Dodecyl Sulfate) and EDTA (Ethylenediaminetetraacetic acid) surfactants. The conclusion was that the bacteriocin produced was stable at high temperature, low pH, and resistence in the presence of surfactants, so it had the potential to be developed as biopreservatives material in preserving fish-based foods

Dilute sodium dodecyl sulfate droplets impact on micropillar-arrayed non-wetting surfaces

Impinging dilute sodium dodecyl sulfate (SDS) droplets on micropillar-arrayed polydimethylsiloxane surfaces were experimentally investigated. It was found that the behaviors of impinging droplets greatly depend on surface roughness and SDS concentration. Similar to pure water droplets, there exists a narrow range of dimensionless Weber number, We, for the complete rebound of impacting SDS droplets. The lower and upper limits of impact velocity were theoretically analyzed and compared with experimental data. The addition of SDS could greatly shorten the contact time of bouncing droplets. Besides, surface roughness has little influence on the maximum spreading factor while SDS concentration has an obvious influence and the maximum spreading factor nearly follows a scaling law of We1/4.

Spectrophotometric study of the sodium dodecyl sulfate in the presence of methylene blue in the methanol–water mixed solvent system

The methylene blue (MB) dye is very sensitive to changes in the polarity of its surroundings. The interaction of MB with sodium dodecyl sulfate (SDS) was studied spectrophotometrically in 0.1, 0.2, 0.3 and 0.4 vol fractions of methanol in an aqueous medium. The dielectric constant value decreases with the addition of methanol in the water and hence there is the lower stabilization of the lowest unoccupied molecular orbital which results in the hypsochromic shift in the monomeric form of methylene blue. In a 0.1 vol fraction of methanol, the peaks are seen at 665 and 612 nm, which are monomeric and dimeric MB peaks, respectively. The dimerization of MB is reduced with the increasing volume fraction of methanol in the solvent and ceases at/above 0.3 vol fraction of methanol. In the 0.4 vol fraction of methanol, the turbidity appears with the addition of SDS and there were no significant changes in the absorbance. In the presence of methanol, MB prefers to stay with the sulfate groups of SDS at the peripheral regions of the premicelle and micelle. At very low surfactant concentrations, far below their critical micelle concentration (CMC), the formation of MB-MB dimers and/or MB-SDS ion pairs or clusters occurs, and a corresponding shift in absorption and decrease in absorbance is observed. On increasing the concentration of SDS, micellization occurs, which disrupts the MB-MB dimers and MB-SDS ion pairs are incorporated with the micelles. On further addition of SDS, lone MB monomers become associated with these micelles and the absorbance increases slightly higher than those of the original dye in the solvent. This is the case of dye solubilization where monomers are completely incorporated or bounded by micelles. The CMC of SDS decreases in the presence of dye suggesting the strong interaction between the oppositely charged dye-surfactant ion pairs. The value of binding constant and partition coefficient decreased with the increasing volume fraction of methanol. The negative value of ΔGb indicates that the interaction between SDS and MB is spontaneous but the negative values of ΔGb decreased with the increasing volume fraction of methanol.

Interlayer expanded nickel-iron layered double hydroxide by intercalation with sodium dodecyl sulfate for enhanced oxygen evolution reaction

Layered double hydroxides (LDH), a typical two-dimensional nanomaterial, has received vigorous attention in water splitting for its typically weak van der Waals interactions that can tunable for its interlayer spacing. Opening LDH with expanded interlayer is highly desirable to expose more active sites for electrocatalysis and more accessible surface for ion transfer in the interlayer, which can greatly boost the performance of LDH. Herein, interlayer expanded nickel-iron layered double hydroxide (NiFe-LDH) was fabricated by the intercalation with sodium dodecyl sulfate (SDS) using a one-pot hydrothermal route. For compassion, the NiFe-LDH without SDS were also prepared as hierarchical hollow spheres (NiFe-LDH HSs), while hollow spheres were transformed into hierarchical nanosheets (NiFe(SDS)-LDH NSs) with the addition of SDS. Moreover, the interlayer spacing of NiFe(SDS)-LDH NSs was effectively enlarged to 2.36 nm contrast to 0.77 nm of NiFe-LDH HSs. As expected, a highly enhanced oxygen evolution reaction (OER) performance was obtained on NiFe(SDS)-LDH NSs with a current density of 10 mA cm−2 at overpotential of 115 mV, while 225 mV for NiFe-LDH HSs. The intercalation of SDS in NiFe-LDH plays an indispensable role in boosting OER. It indicates the importance of enlarging the interlayer space of LDH for high-performance OER.