Sodium Dodecyl Sulfate Concentration Research Articles

Diffusiophoretic Transport of Charged Colloids in Ionic Surfactant Gradients Entirely below versus Entirely above the Critical Micelle Concentration.

When placed in an ionic surfactant gradient, charged colloids will undergo diffusiophoresis at a velocity, uDP = MDP∇ ln S, where MDP is the diffusiophoretic mobility and S is the surfactant concentration. The diffusiophoretic mobility depends in part on the charges and diffusivities of the surfactants and their counterions. Since micellization decreases surfactant diffusivity and alters charge distributions in a surfactant solution, MDP of charged colloids in ionic surfactant gradients may differ significantly when surfactant concentrations are above or below the critical micelle concentration (CMC). The role of micelles in driving diffusiophoresis is unclear, and a previously published model that accounts for micellization suggests the possibility of a change in the sign of MDP above the CMC [Warren, P. B.; . Soft Matter 2019, 15, 278-288]. In the current study, microfluidic channels were used to measure the transport of negatively charged polystyrene colloids in sodium dodecyl sulfate (SDS) surfactant gradients established at SDS concentrations that are either fully above or fully below the CMC. Interpretation of diffusiophoresis was aided by measurements of the colloid electrophoretic mobility as a function of SDS concentration. A numerical transport model incorporating the prior diffusiophoretic mobility model for ionic surfactant gradients was implemented to elucidate signatures of positive and negative diffusiophoretic mobilities and compare with experiments. The theoretically predicted sign of the diffusiophoretic mobility below the CMC was determined to be particularly sensitive to uncertainty in colloid and surfactant properties, while above the CMC, the mobility was consistently predicted to be positive in the SDS concentration range considered in the experiments conducted here. In contrast, experiments only showed signatures of a negative diffusiophoretic mobility for these negatively charged colloids with no change of sign. Colloid diffusiophoretic transport measured in micellar solutions was more extensive than that below the CMC with the same ∇ ln S.

Molecular simulation of the regulation mechanism of surfactant on microscopic chemical wetting of coal

To explore the influence mechanism of surfactants on the wettability of coal, elemental analysis, Fourier-transform infrared spectroscopy, 13C nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy were applied to characterize the chemical structure of coal before and after modification with solutions having different concentrations of sodium dodecyl sulfate. Macromolecular models of four different coal samples before and after modification were constructed, and the mechanism of the change in the chemical structure of the coal before and after modification on its wettability was then studied with molecular dynamics (MD) simulations. The molecular formulas of the four coal samples were determined to be C160H114O34N2S, C203H144O44N3S, C196H137O42N3S, and C242H171O56N3S. Aromatic carbon accounts for a relatively high proportion of these formulas, mainly in the form of benzene rings and naphthalene. The ratios of aromatic bridge carbons to pericarbons are 0.3, 0.23, 0.21, and 0.22, respectively. Nitrogen (N) and sulfur (S) are present as pyrrole nitrogen and thiol thiophenol, respectively. MD simulations show that compared with the original coal sample, the thickness of the absorption layer between the modified coal and water molecules increases, and the interaction energy is enhanced. The maximum electrostatic potential of the surface of coal molecules in the four systems (−0.07826, −0.07915, −0.08511, and −0.10711 a.u.) is concentrated around the oxygenated functional groups. After the modification, the distribution of oxygenated functional groups is more extensive, and the content of water molecules adsorbed on the surface of the coal increases because of static electricity, which promotes the wettability of the coal. This research reveals the microscopic wetting mechanism of coal dust at the molecular level and provides a research path that offers important guidance for the reduction of coal dust that is generated during mining.

Manipulating the monomers supply of interfacial polymerization towards the ultrathin polyamide composite membrane for CO2 capture

Preparing polyamide (PA) composite membranes with high gas separation performance requires rational control for the interfacial polymerization (IP) process. In this study, the monomer supply of piperazine (PIP) and trimesoyl chloride (TMC) in the IP process was precisely manipulated to generate an ultrathin PA film on the polydimethylsiloxane (PDMS) gutter layer for CO2 separation. Concretely, the PIP supply was regulated from the homogeneous, slow, and excess mode to the inhomogeneous, fast, and small mode by constructing a sodium dodecyl sulfate (SDS) array at the phase interface; subsequently, the TMC supply was increased by elevating the TMC concentration. Therefore, the amine-to-acid chloride concentration ratio in the reaction zone was optimized and, as a consequence, the IP reaction rate was significantly increased. As a result, the thickness of the PA film was reduced from ∼92 nm to ∼37 nm through the optimization of SDS and TMC concentrations, and accordingly, the CO2 permeance was increased from 501 GPU to 1498 GPU under 0.1 MPa without sacrificing selectivity. Moreover, the membrane preparation efficiency was greatly improved with an IP reaction time of less than 30 s. The insights provided could promote the industrial application of interfacial polymerization in the scale-up preparation of high-performance CO2 separation membranes.

Solubilization and physicochemical parameters of 2-chloro and 4-chlorophenol in micellar media of cetyltrimethylammonium bromide and sodium dodecyl sulphate at different temperatures

Solubilization and thermodynamic parameters of 2-chloro and 4-chlorophenol in micellar media of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS) are elaborated in this study. The effect of the addition of 2-chloro and 4-chlorophenol on the critical micelle concentrations (CMCs) of CTAB and SDS was investigated by using the conductivity method at different concentrations (5 mmolL−1 to 25 mmolL−1) and temperatures (25 °C to 45 °C). The plot of specific conductance versus concentration of surfactant was used to determine CMC value. The CMC values of CTAB and SDS were observed to decrease, and thus the addition of 2-chloro and 4-chlorophenol favors micellization. In addition, it was observed that the CMC values of CTAB and SDS gradually increased with an increase in temperature. Various types of thermodynamic parameters such as standard Gibbs free energy of micellization (ΔGm°), standard enthalpy of micellization (ΔHm°) as well as standard entropy of micellization (ΔSm°) were determined and explained thoroughly to investigate the interactions between additives and surfactant. The magnitudes of ΔGm°andΔHm° were shown to be negative in the whole system, which shows that the processes of micellization were energetically spontaneous and exothermic. The thermodynamic parameters of transfer (ΔGm.tr°, ΔHm.tr° and ΔSm.tr°) from water to 2-chloro and 4-chlorophenol were also calculated and discussed with appropriate reasoning.

Axisymmetric Compression of a Circular Particle Raft Driven by the Diffusion of Surfactant.

Particle rafts are a new kind of soft matter formed by self-organization on the interface, which possesses mechanical properties between fluid and solid, and they have been widely used in many industrial fields. In the present study, the compression experiment of a circular particle raft is first performed, where an SDS (sodium dodecyl sulfate)-coated metal ring is placed around its periphery. When the surfactant diffuses, the particle raft shrinks, and its shrinkage ratio increases with the increase in the surfactant concentration, where the experimental results are consistent with the numerical simulation. Next, the relationship between the initial surface tension difference of SDS and the radius shrinkage of the particle raft is obtained by dimensional analysis. In what follows, the diffusion model is built to quantify the diffusion process of SDS at the liquid-gas interface, and then the analytical concentration solution of the concentration of SDS at the periphery of particle raft is given. The particle raft is viewed as an elastic circular plate under the action of the radial pressure, which originates from the surface tension difference, which has been verified by the experimental result. These explorations cast a new light on how to apply loads to measure mechanical properties of soft matter, which also provide some inspirations on the design of microsensors and microfluidics.

Application of Alcohols to Inhibit the Formation of Ca(II) Dodecyl Sulfate Precipitate in Aqueous Solutions.

The presence of alkaline earth cations, in particular, Ca2+ and Mg2+ ions in brine, causes undesired effects in solutions containing anionic surfactants because of precipitate formation. In the present study, an anionic surfactant, sodium dodecyl sulfate (SDS), was investigated, focusing on the determination of various properties (surface tension, critical micelle concentration, micelle size, turbidity) in the presence of alcohols and, in particular, the inhibition of the precipitation of SDS with calcium ions. The calcium ions were added to the surfactant in increasing concentrations (3.0-10.0 g/L), and short-carbon-chain alcohols (methanol, ethanol, n-propanol and n-butanol) were used to shift the onset of precipitate formation. The critical micelle concentration (CMC) of SDS in the presence of alcohols was also determined. It was established that among these alcohols, methanol and ethanol did not exert significant effects on the solubility of the Ca(DS)2 precipitate, while n-propanol and n-butanol were found to be much more efficient inhibitors. In addition, all the alcohols in the applied concentration range (up to 20 V/V%) were found to decrease the critical micelle concentration of SDS.

Effect of sodium dodecyl sulfate (SDS) on the co-deposition and frictional behavior of carbon nanotube/nickel composite layer

In this paper, the effects of sodium dodecyl sulfate (SDS) concentrations in the electroplating solution on the morphology, nucleation rate, nucleation mode, and frictional behavior of the CNT/Ni composite layers were investigated. The results showed that the electrodeposition of Ni was in a three-dimensional nucleation/growth mode. In addition, the x-ray diffraction (XRD) of the deposited layers showed that adding SDS changed the preferred growth direction of Ni from (2 0 0) to the (2 2 0) crystallographic plane. When the carbon nanotube (CNT) content was 0.1 g l−1, and the SDS content was 0.05 g l−1, the deposition potential was the most negative, increasing the number of Ni nucleation sites on the electrode and resulting in the grain size refinement of the deposited layer. It also reduced the friction coefficient of the composite simultaneously.

Preparation of Three Component PVDF‐Bi4V2O11‐SDS Composites with Enhanced Dielectric and Electrical Properties

AbstractIn this work, poly(vinylidene fluoride) (PVDF)‐bismuth vanadate (Bi4V2O11; BVO)‐sodium dodecyl sulfate (SDS) composite films are fabricated by the solution casting method. The frequency dependence of the dielectric and electric performances of the resultant PVDF‐BVO‐SDS composites on various weight percentages of SDS contents is investigated. The results demonstrate that the three‐component PVDF‐BVO‐SDS composites have a superior dielectric constant (96) and suppressed dielectric loss (<1) at 102 Hz for 20 wt% of SDS contents. The surface morphology of the PVDF‐BVO‐SDS composites shows that SDS is successfully reinforced on the PVDF‐BVO matrix with better homogeneity. The ac conductivity of the PVDF‐BVO‐SDS composites is also improved, which is helpful for the enhancement of the dielectric constant and relatively low loss in the composites. Moreover, the PVDF‐BVO‐SDS composite also exhibits a larger value of the dielectric constant (96) than the pristine PVDF matrix, which is 15 times higher than that of the pristine one. These significantly enhanced dielectric and electrical characteristics of PVDF‐BVO‐SDS composites will fulfill the practical criteria for their use in high dielectric‐constant capacitors and energy storage devices.

Wetting and evaporation behavior of dilute sodium dodecyl sulfate droplets on soft substrates under a direct current electric field

Wetting and evaporation behavior of dilute sodium dodecyl sulfate (SDS) droplets on planar polydimethylsiloxane (PDMS) surfaces under a direct current (DC) electric field were experimentally investigated. Two characteristic voltages—actuation voltage and saturation voltage were observed in the electrowetting of dilute SDS droplets on PDMS surfaces. It was found that for dilute SDS droplets with a fixed SDS concentration substrate elasticity has an obvious influence on actuation voltage, and saturation voltage increased with the increase of mass ratio of PDMS surfaces. SDS concentration was also found to obviously influence actuation voltage and saturation voltage when SDS concentration was in a certain range. For the case of evaporation of sessile dilute SDS droplets on PDMS surfaces with the application of a DC electric field, substrate elasticity, SDS concentration and the magnitude of applied voltage were all found to have an influence on the duration of CCR stage. Moreover, contact angle hysteresis for dilute SDS droplets on a planar PDMS 10:1 surface under different applied voltage was measured and it was found that the magnitude of applied voltage greatly influenced contact angle hysteresis, which also depends on SDS concentration and KCl concentration.

Ultrasonication‐assisted alkali treatment of hemp fibers to improve the fiber/matrix interface of hemp/epoxy composites: The influence of sodium dodecyl sulfate surfactant

AbstractAlkali pretreatment of fibers is an efficient technique to enhance fiber/matrix bonding in natural fiber composites. This study investigates if the addition of sodium dodecyl sulfate (SDS) surfactant increases the efficacy of alkali treatment of hemp fibers. SDS concentrations ranging between 2 and 10% wt/wt were used with a constant (10% wt/wt) NaOH concentration. Fiber surfaces were observed with scanning electron microscopy (SEM). Fiber surfaces were cleaner when SDS was used compared with alkali treatment with no SDS added indicating the elimination of substances such as lignin, waxes, hemicelluloses, and pectin. Fourier‐transform infrared spectroscopy and TGA studies also confirmed the removal of these substituents. Mechanical performance of the composites was evaluated via static and dynamic tests. The tensile strength and modulus improved 24.9% and 13.6% respectively with the addition of 10 wt% SDS. The flexural strength and modulus also showed an improvement of 22.4% and 26.3% respectively when 10 wt% SDS was added to alkali solution. Dynamic mechanical tests showed that the storage and loss modulus of the composites increase with SDS/alkali treatment. Results indicated that the use of SDS in alkali treatment notably improves the composite performance which is attributable to more efficient elimination of noncellulosic constituents from fiber structure.Highlights Sodium dodecyl sulfate (SDS) improves the efficacy of NaOH treatment of hemp. Removal of noncellulosic substances from fibers was facilitated by SDS. Ultrasound/SDS assisted alkalization of fibers improved composite properties.

Effect of sodium dodecyl sulfate (SDS) on microbial community structure and function in lake–terrestrial ecotones: A simulation experiment

Even a low concentration of sodium dodecyl sulfate (SDS), a widely used bactericidal surfactant, can significantly change the species, quantity and genetic functions of microorganism communities in natural waters. Lake–terrestrial ecotones are areas where microorganisms are highly active, and they are also the lake areas most vulnerable to SDS pollution. Because microorganisms are very sensitive to environmental changes, their activities vary greatly among lakes and laboratories, so it is difficult to simulate their real dynamics using small-scale experiments. To study the interaction between SDS and microorganisms in a lake–terrestrial ecotone, a large artificial simulation device was used to analyse microbial community structure, phospholipid fatty acid (PLFA) content, gene function and ability to degrade SDS in a lake–terrestrial ecotone contaminated with SDS. The results showed that (1) the period from 2 to 4 days after the beginning of the experiment was the key stage for the biodegradation of SDS. The biodegradation cycle of SDS in the natural environment is shorter than that in small-scale experimental setups, and more than 90% of SDS was removed within 4 days in the simulation device. (2) Low-level SDS pollution (≤ 6 mg/L) has different effects on different types of lacustrine microorganisms. The presence of SDS can lead to a significant decrease in microbial diversity and biomass in lake–terrestrial ecotones with a high density of aquatic plants, but the opposite is true in ecosystems with degraded aquatic plant communities. (3) After SDS pollution occurred, pollution-resistant bacteria such as Chitinophaga and Flavobacterium became dominant. The relative abundance of carbon cycle functional genes increased rapidly in microorganisms, while the relative abundance of nitrogen cycle functional genes decreased. These changes were not readily reverse even after 20 days, although the communities recovered to a certain extent.

Interaction of sodium dodecyl sulfate and triton X-100 with ofloxacin drug using conductivity and UV–visible spectroscopic techniques in aqueous alcohols media at several temperatures

The current investigation explores the association and complexation of the mixture of anionic surfactant, sodium dodecyl sulfate (SDS), and antibiotic drug, ofloxacin (OFC) as well as nonionic surfactant, Triton X-100 (TRX) and OFC drug respectively in several additive solutions. The investigations were performed by applying conductivity and UV-Visible spectroscopic techniques. The impacts of drug concentration, types of solvents, and composition of aq. solutions of alcohols (methanol (MeOH), ethanol (EtOH), and 1-propanol (1-PrOH)) as well as temperature change have been investigated on the micelle formation of SDS + OFC mixture. The micellization of SDS + OFC and TRX + OFC systems has been characterized by the determination of critical micelle concentration (CMC) from conductivity vs. SDS concentration (conductivity technique) and Absorbance vs log[TRX] (UV-Visible spectroscopic technique) plots respectively. The micellization of SDS was delayed owing to the introduction of the OFC drug while the effect has been intensified as a function of OFC concentration. At a fixed OFC concentration and temperature, the CMC values were acquired to be augmented with the upsurge of alcohol concentration. The enhancement of the CMC changes has been perceived with the escalation of temperature at a definite concentration of OFC in water and 5% (w/w) aq. alcohols media. The disfavor of micellization of TRX in aq. EtOH solutions in comparison to aqueous solution also detected from UV-Visible spectroscopic technique. The binding constant (Kb) for the complexation of TRX with OFC drug was determined using the Benesi-Hildebrand plot. The Kb values were obtained to be affected by the change of solvent and temperature. The negative free energy change (∆Gmo/ ∆Gbo) of the micellization and complexation demonstrate the spontaneous occurrence of micelle formation and complex development. The enthalpy changes (∆Hmo) of micellization were negative (exothermic process) and entropy changes (∆Smo) were positive (highly disordered and entropy-dominated micellization). Other thermodynamic properties ((∆Hbo and ∆Sbo) and thermodynamics of transfer) have been evaluated and illustrated as well, for the working systems.

Pulsed electrodeposition of homogenous and heterogeneous solid solution layered structure in high strength nanocrystalline Co[sbnd]Cu alloys

A supersaturated solid solution nanostructure of an immiscible CoCu system is among the promising nanocrystalline (NC) alloys offering enhanced thermal and mechanical stability. In this paper, experiments were conducted to study the phase transformation and tailoring microstructure from a homogeneous/single-phase to a heterogeneous/dual-phase solid solution layered CoCu nanostructure via pulsed electrochemical deposition (PED). The increasing concentration of sodium dodecyl sulfate (SDS) in electrolyte played a crucial role in stabilizing a homogeneous solid solution CoCu nanostructure. On the other hand, the opposite approach led to the formation of heterogeneous solid solution CoCu alloys in the form of multilayered nanostructure consisting of the primary and secondary solid solution CoCu differing in 10–15 at.% Cu. The separation of primary and secondary phase is more prominent with the extended pulsed periods. The mechanical properties of selected single- and dual-phase alloys were investigated through micro-pillar compression, revealing that a combination of a high yield strength and an elevated strain hardening can be achieved in NC materials through a combined solid solution strengthening and hardening through nano-twin (NT).

Molecular Interactions of Sodium Dodecyl Sulphate with a Sulpha Drug and its Nanoaggregates in Aqueous System

AbstractInteraction study between sulfanilamide (SM) and sodium dodecyl sulfate (SDS) in an aqueous environment has been conducted using electrical conductivity, emission, and absorption spectroscopy techniques. Conductivity measurements were performed over the temperature range of (288.15 to 318.15) K and SM concentrations ranging from (c=0.005 to 0.03) mol ⋅ L−1. Thermodynamic parameters: Gibbs free energy (ΔGom), enthalpy (ΔHom), and entropy (ΔSom) associated with micellization have been calculated. To further investigate the interactions between (SM and SDS), the absorption and emission spectroscopy were employed at premicellar concentrations of SDS. Resulting SM‐SDS conjugate was then utilized to examine its interaction behavior with electrolytes and vitamins commonly found in biofluids namely chlorides and sulfates of sodium, potassium, magnesium, and calcium, along with L‐ascorbic acid (LAA) and nicotinic acid (NA). Moreover, SM drug has been transformed into its nanoaggregates (SMNA). These nanoaggregates have been characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Interactions between SMNA‐SDS conjugates were also studied in the presence of the above‐mentioned electrolytes and vitamins. The findings of this study have been interpreted within the context of the interactions occurring in the solution phase. This research provides valuable insights into the complicated interactions between SM, SDS, electrolytes, and vitamins in aqueous system.

Robust cooperative of cadmium sulfide with highly ordered hollow microstructure coordination polymers for regulating the photocatalytic performance

Accurately controlling and achieving selective reactivity at difficult-to-access reaction sites in organic molecules is challenging owing to the similar local and electronic environments of multiple reaction sites. In this work, we regulated multiple reaction sites in a highly selective and active manner using cobalt coordination polymers (Co-CP) 1 and 1a with various particle sizes and morphologies ranging from large granular to ordered hollow hemispheres by introducing sodium dodecyl sulfate (SDS) as a surfactant. The size and morphology of the catalysts could be tuned by controlling the amount of SDS. An SDS concentration of 0.03 mmol generated 1a having a highly ordered hollow hemispherical microstructure with a well-defined platform as a pre-made building unit. Cadmium sulfide (CdS), as a typical photocatalyst, was subsequently uniformly anchored in-situ on the premade building unit 1a to produce CdS@1a composites, that inherited the originally ordered hollow hemispherical microstructure while integrating CdS as well-dispersed catalytic active sites. Furthermore, the well-established CdS@1a composites were used as photocatalysts in selective oxidation reactions under air atmosphere with blue irradiation. The CdS0.109@1a composite with unique structural characteristics, including uniformly distributed and easily accessible catalytic sites and excellent photoelectrochemical performance, served as a highly efficient heterogeneous photocatalyst for promoting the selective oxidation of sulfides to sulfoxides as the sole products. This work presents an approach for fabricating CPs as premade building units that function as well-defined platforms for integration with photocatalysts, enabling tuning of the structure-selectivity-activity relationships.

The investigation of sorption-desorption performance and mechanism of copper by surfactant-modified zeolite in aqueous solutions.

As the most common filler in stormwater treatment, zeolite (NZ-Y) has good cation exchange capability and stabilization potential for the removal of heavy metal from aqueous solutions. In this study, sodium dodecyl sulfate (SDS) and NZ-Y were selected to preparing new adsorbent (SDS-NZ) by using a simple hydrothermal method. The sorption-desorption performance and mechanism of Cu(II) onto SDS-NZ were investigated. The results showed that the sorption of Cu(II) on SDS-NZ was in accordance with the pseudo-second-order kinetic model with an equilibrium time of 4h. The sorption behavior fitted Langmuir isotherm with a saturation sorption capability of 9.03mg/g, which was three times higher than that of NZ-Y. The modification of SDS increases the average pore size of NZ-Y by 3.96nm, which results in a richer internal pore structure and more useful sorption sites for Cu(II) sorption. There was a positive correlation between solution pH values and sorption capability of Cu(II) in the range of 3.0-6.0. With the ionic strength increased, the sorption capability of Cu(II) onto SDS-NZ first decreased and then increased, which may be attributed to competitive sorption and compression of the electronic layer. The desorption of Cu(II) on SDS-NZ was favored by the increase in SDS concentration and ionic strength and decrease in solution pH values. The application of SDS-NZ in runoff improved the leaching risk of Cu(II). After several cycles, the ability of reused SDS-NZ to efficiently adsorb most heavy metals was verified with removal rates above 99%.

Electrostatic self-assembly effect of Fe3O4 nanoparticles on performance of carbon nanotubes in cement-based materials

Abstract The beneficial effect of carbon nanotubes (CNTs) to enhance the electrical conductivity and piezoresistivity of cement-based materials was highly contingent upon its dispersion. To achieve an appropriate dispersion of CNTs, ultrasonication, high-speed stirring, and chemical dispersion were commonly used, which raises the risk of structural damage of CNTs caused by the excessive energy. In this study, electrostatic self-assembly of Fe3O4 nanoparticles on CNTs was employed to efficiently disperse CNTs. To optimize the dispersion effect of conductive fillers in cement paste, the mix proportions including sodium dodecyl sulfate (SDS) concentration, CNTs concentration, and Fe3O4/CNTs ratios were adjusted. The dispersion degree and electrical property were evaluated by UV–vis absorption and zeta potential. In addition, the effect of self-assembled conductive filler dosage on the electrically conductive property of cement pastes was examined. The results show that the occurrence of electrostatic self-assembly was proved by the change of zeta potential, and the grape-bunch structure was observed by transmission electron microscopy. Further, the optimal proportions of self-assembled conductive fillers were 0.20 wt% SDS concentration, 0.05 wt% CNTs concentration, and 1:1 Fe3O4/CNTs ratio. The self-assembled conductive filler dosage between 0.02 and 0.10 wt% can effectively improve the electrical conductivity of cement paste with up to 68% reduction of resistivity.

Control of the Colloidal and Adsorption Behaviors of Chitin Nanocrystals and an Oppositely Charged Surfactant at Solid, Liquid, and Gas Interfaces.

Chitin has a unique hierarchical structure, spanning the macro- and nanoscales, and presents chemical characteristics that make it a suitable component of multiphase systems. Herein, we elucidate the colloidal interactions between partially deacetylated chitin nanocrystals (cationic ChNC) and an anionic surfactant, sodium dodecyl sulfate (SDS). We investigate charge neutralization and association (electrophoretic mobility, surface tensiometry, and quartz crystal microgravimetry) and their role in the stabilization of Pickering emulsions. We find SDS adsorption and association with ChNC under distinctive regimes: At low SDS concentration, submonolayer assemblies form on ChNC, driven by the hydrophobic effect and electrostatic interactions. With the increased SDS concentration, bilayers or patchy bilayers form, followed by adsorbed hemimicelles and micelles. We further suggested the role of hydrophobic effects in the observed colloidal transitions and complex conformations. At the highest SDS concentration tested, charge neutralization and SDS/ChNC flocculation take place. Remarkably, at given concentrations, adsorbed SDS endows the chitin nanoparticles with an effective hydrophobicity that opens the opportunity to achieve tailorable Pickering stabilization. Hence, a facile route is proposed by in situ modification by SDS physisorption, which extends the potential of renewable nanoparticles in the formulation of complex fluids, for instance, those relevant to household and healthcare products.

The interfacial tension at the liquid junction of petrol and Sodium dodecyl sulphate solution

The precise measurements of petrol interfacial tension (IFT) in the presence of Sodium dodecyl sulphate (SDS) at room temperature by Mansingh Survismeter are reported. The concentration of sodium dodecyl sulphate was varied from above and below the critical micelle concentration (CMC) to cover the minimum and maximum concentrations of the investigated surfactant. Petrol was taken from the dealer in Nepal and used without purification. Therefore, when surfactant is added to the system, the surfactant decreases its free energy, thus decreasing its surface tension

Qualitative and Quantitative Analysis of Sodium Dodecyl Sulphate (SDS) Degradation by Pseudomonas Species

Sodium dodecyl sulphate (SDS), an anionic surfactant widely used in cleaning and cosmetic products, poses significant environmental risks when untreated effluents are discharged into terrestrial and aquatic ecosystems. In this study, a potential bacterial isolate identified as Pseudomonas sp. FD-2aii, which could grow in the presence of SDS, was successfully isolated from industrial wastewater. Bacteria were used in the SDS degradation study based on their ability to utilise SDS as the sole carbon source. Isolate FD-2aii showed growth after incubating at 30 °C with shaking at 150 rpm for 24 h. The residual SDS concentration and percentage of SDS degradation in the bacterial cultures were quantified using a methylene blue active substances (MBAS) assay. This study focused on the reduction in SDS concentration over a ten-day period and provided a clear indicator of the degradation efficacy of isolate FD-2aii.