Cetyltrimethylammonium Bromide Micelles Research Articles

Surfactant Molecules and Nano Gold on HOPG: Experiment and Theory

Excessive surfactant molecules within the solution adhere to highly ordered pyrolytic graphite (HOPG) when a droplet containing gold nanorods evaporates, leading to the emergence of a unique coffee-ring pattern. The combination of surface hydrophobicity and evaporation of the aqueous phase results in a stick-slip motion, which enhances the convective hydrodynamics of suspended particles. This phenomenon initiates interactions that influence the deposition and flow dynamics inside the droplet. High-resolution scanning electron microscopy (HRSEM) does not provide significant insights into regions potentially linked to cetyltrimethylammonium bromide (CTAB) molecules, whereas the atomic force microscope (AFM) displays the presence of gold nanoparticles arranged by CTAB within specific CTAB patches. The layers forms with varying heights and gaps between them, indicating diverse adhesion of CTAB. The analytical focus lies on the quantitative assessment of CTAB molecules, stripe dimensions, and energy profiles influenced by concentration and the effective positioning of CTAB-coated gold nanorods in CTAB-covered regions. AFM examination reveals CTAB molecular stripes on HOPG, showing a binding energy of -20 kJ/mol with the surface, -10 kJ/mol for nitrogen bonding with HOPG, and a total binding energy (BE) of -60 kJ/mol, considering various contributing factors. Completely parallel aligned molecules (CPAM) exhibit higher binding energy than non-perfectly aligned molecules (NPAM) due to maximum Van der Waals (VdW) interactions, ideal electrostatic interactions, and minimal steric repulsion. The difference in binding energy between perfectly and non-perfectly aligned molecules is around 20kJ/mol, emphasizing the importance of molecular orientation. As temperature rises from 298K to 348K, the likelihood of NPAM desorption increases significantly, with the binding energy shifting from 2.5kJ/mol to 4.1kJ/mol. Temperature significantly influences the equilibrium of molecules on HOPG surfaces. The emphasis is on elucidating the alterations in energy levels during nanorod aggregation on CTAB areas compared to bare HOPG surfaces, underscoring the impact of nanorods on CTAB micelle deformation energy. Observations on the variation in CTAB desorption rates with temperature changes underscore the dynamic nature of molecular binding energy associated with surface properties, underscoring the importance of molecular configuration and energy transfers in nanoscale systems.

The role of presence of wormlike micelles of ionic surfactants on the sterilization efficiency of sodium hypochlorite

Abstract This paper describes an attempt to increase the sterilising efficacy of sodium hypochlorite (SH) by prolonging its shelf life in gel mode through the presence of wormlike micelles. No effect was observed on the presence of SH on the ratio of highest viscosity peak of 20:80 of 3 % (w/w) sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB). On the other side, the presence of SH has a relatively negative effect on transformation process from spherical (three-dimensional, 3D) micelles to wormlike (one-dimensional, 1D) micelles. The gel state of the aqueous SH solution is maintained even at a ratio of 20:80 SDS:CTAB 3 % (w/w). Measurements of the biological activity of the gel using Staphylococcus aureus bacteria show that the sterilizing efficiency of SH is enhanced by the presence of 1D micelles. In contrast, the stability of SH using the kinetic method shows a sudden decrease in its stability due to the presence of 1D micelles, and the same is the case when both SDS and CTAB micelles are present. It was concluded that the increase in the biological activity of SH due to presence of micelles in gel or liquid mode resulted from their chemical interference, which acts as an antibacterial formulation.

Cationic surfactant-assisted assembly of water-dispersible MnO2 onto indoor textiles for anti-bacterial and HCHO removal

Nowadays, the applications of nanoparticle-decorated textiles for environmental governmental governance have aroused great concerns, while the poor fastness and uncontrolled aggregation of the nanoparticles negatively influenced its practical use. Herein, an environmental-friendly synthesis strategy of water-dispersible MnO2 was demonstrated by using the reductant of 2-(N-morpholino) ethanesulfonic acid (MES) and template of cetyltrimethylammonium bromide (CTAB), and then the as-prepared MnO2 was further employed as a multifunctional textile coating. In all the procedures under room temperatures, three effects of cationic CTAB micelles were thoroughly explored, from optimizing MnO2 to uniform micro/nanoscale through template strategy, to bridging the gaps between electronegative particles and fabrics, and even providing stable antibacterial effect. Consequently, without any additional binding agents, multifunctional cotton textile was obtained by simply immersing cotton into a MnO2-CTAB aqueous solution, and appeared antibacterial rates (over 99 %) to both E. coli and S. aureus. Meanwhile, HCHO removal and ultraviolet blocking (UVA<0.1 %) properties as well as high durability of the nanoparticles are also introduced to the textiles. We believe as-presented cationic surfactant-templated strategy for regulating synthesis and deposition of functional particles onto cotton textiles has broad application prospects in green and sustainable functionalization of decoration textiles.

Interaction between methyl red and cetyltrimethylammonium bromide under the influence of sodium polystyrene sulphonate in ethanol-water binary solvent systems: A spectrophotometric investigation

This research aims to comprehensively investigate and analyze the UV–visible spectroscopic behavior of the methyl red (MR)-cetyltrimethylammonium bromide (CTAB) system under the influence of sodium polystyrene sulfonate (NaPSS) in aqueous and different volume fractions (v.f.) of ethanol (EtOH)–H2O (0.1, 0.2, and 0.3) at 298.15 ± 0.2 K. In EtOH–H2O solvent systems, the triple interactions of dyes-surfactants-polyelectrolyte (DSP) complex systems are entirely novel. MR interacts with CTAB in NaPSS in the binary solvent media (0.1, 0.2, and 0.3 v.f. of EtOH–H2O) resulting in the formation of ion-pairs at very low CTAB concentrations, far below their apparent critical micelle concentration (CMC*) reducing the absorbance, and the new complexes above the CMC* due to solubilization of the MR into CTAB micelles observed by distinct spectral shifts. The CMC* values obtained from spectroscopic data increase in the order: (CMC*)water< (CMC*)0.1< (CMC*)0.2< (CMC*)0.3. This is because of the reduced polarity or dielectric constant and increased degree of water structure disruption around the hydrophobic chains of CTAB, where micelle formation occurs at somewhat higher concentrations. The Gibbs energy of micellization (ΔGmo) increases in the order: (ΔGmo=−16.89)water <(ΔGmo=−16.17)0.1<(ΔGmo=−15.62)0.2<(ΔGmo=−15.38)0.3, which further supports the inhibitory effect of increasing ethanol content towards micellization. In the post-micellar region, the decrease in hydrophobic interactions and an increase in electrostatic interactions lead to a rise in the overall binding constant value. This means that, when NaPSS is present, the stronger electrostatic interactions in the post-micellar region contribute significantly to the increased binding of CTAB micelles with MR. The tautomeric activity of MR and the solvent composition played a prime role in affecting the interaction mechanism, as evidenced by the blue and red spectral shifts.

Insights into the role of ionic surfactants on the morphology of gold and gold@silver nanoparticles

Cyanidin-3, 5-di-O-glycoside (anthocyanin) was extracted from the red rose flower petals in an aqueous media. Anthocyanin was used as reductant to the preparation of gold nanoparticles with cationic and anionic surfactants. UV–visible absorption spectroscope, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray spectroscope were employed to determine absorption bands of anthocyanin, surface Plasmon resonance (SPR) band, and morphology of the gold and gold@silver nanoparticles. Anthocyanin exhibited two absorption peaks at 284 and 518 nm, and one shoulder at 328 nm in the UV–visible spectrum. The intensity of these peaks decreases with time after the addition of HAuCl4. The color and the position of SPR band of gold nanoparticles depend on the concentration of gold salt with and without cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS). The anionic and cationic head groups of SDS and CTAB micelles have significant impact of the morphology of gold nanoparticles. Seedless co-reduction method was used for the synthesis of gold@silver nanoparticles. TEM images clearly indicate the formation of bimetallic gold@silver core-shell nanoparticles. The antioxidant power of AuNPs and gold@silver nanoparticles were tested in terms of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity as a function of different concentrations of nanoparticles.

Effect of CTAB premicelle and micelle formation on Bromophenol Blue spectra

AbstractThe interactions between surfactants and dyes in aqueous solutions are essential for gaining insights into dyeing processes across various industries and for driving advancements in chemical research. This paper investigates the interaction between the anionic dye bromophenol blue (BPB) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in aqueous solutions. It was observed that the absorbance value at the maximum absorption peak of BPB changes systematically with increasing CTAB concentration, revealing the critical premicelle concentration (cpc) and critical micelle concentration (cmc) of CTAB. Employing a micellization model and measuring the electric conductivity across different concentrations of CTAB, the micellization thermodynamic parameters of CTAB, both in the absence and presence of BPB, were determined. The findings indicate that the associative interaction between BPB and CTAB significantly influences the formation of CTAB micelles.

Kinetics and mechanism of methyl linoleate oxidation in cetyltrimethylammonium bromide micelles

Kinetics and mechanism of methyl linoleate oxidation in cetyltrimethylammonium bromide micelles

Surfactant-induced alterations in optoelectronic properties of perylene diimide dyes: modulating sensing responses in the aqueous environment.

The compartmentalization effect of microheterogeneous systems, like surfactant aggregates, showcases altered optoelectronic properties of a perylene diimide-based chromogenic dye (PDI-Ala) compared to bulk water. The relatively hydrophobic microenvironment, poor hydration, and exceptionally large local concentration of dye molecules in the confined environment affect their interaction with target analytes. This realization intrigued us to investigate if micellization can modify the sensing properties (selectivity, sensitivity, response kinetics, output signal, etc.) of the encapsulated dye molecules in the aqueous medium. Response comparisons of PDI-Ala to the ionic analyte (Fe3+) and biomolecule (heparin) in aqueous and surfactant-bound states highlighted significant variations. Fe3+ interaction exhibited a "turn-off" fluorescence response in a water medium, while surfactant-bound conditions triggered "turn-on" fluorescence, enhancing selectivity at the micelle-water interface. Conversely, the native probe showed no interaction with heparin in water but displayed a turn-on fluorescence response in cetyltrimethylammonium bromide (CTAB) micelles, indicating the transformation of a silent molecule into a turn-on fluorescence sensor. This study underscores the influence of micellar environments on dye molecules, altering the sensing responses and selectivity toward analytes, crucial for applications in understanding cellular pathways and toxicity mechanisms.

Micelle-mediated chemiluminescence of 6-aza-2-thiothymine-protected gold nanoclusters for carbazochrome sodium sulfonate detection

Chemiluminescence (CL) intensity of luminol-H2O2 system was dramatically enhanced by cetyltrimethylammonium bromide (CTAB) micelle-mediated 6-aza-2-thiothymine-protected gold nanoclusters (ATT-AuNCs). It is proved that spherical micelles of CTAB in aqueous solution improved the dispersity of ATT-AuNCs, thus enhancing their catalytic activity, which brought in the increased CL intensity of luminol-H2O2 system. Carbazochrome sodium sulfonate (CSS) with a hemostatic containing tetrahydroindole structure broke the spherical micelles and notably quenched the CL intensity of luminol-H2O2-CTAB-ATT AuNCs system. Based on these results, a simple, fast, and sensitive CL method has been developed for the detection of CSS with a linear range of 0.25–25 μM and a detection limit of 0.11 μM. The method has also been successfully applied to the determination of CSS in serum with satisfied recoveries in the range of 89.6 % to 103.7 %. This study not only provides an effective approach for CSS detection but also paves the way for AuNCs-based CL applications.

Synergistic effect of a fluorinated azobenzene for transforming spherical micelles into thread-like micelles with a disk-like cross-section

The free energy in solutions of amphiphilic molecules leads to the formation of supramolecular structures, often making spherical aggregates, worm-like micelles, vesicles, and lamellae. In this work, we add a fluorinated azobenzene, 4-(4-trifluoromethoxy phenyl azo) phenol (Azo-3F) to a solution mainly made of spherical and rodlike micelles of CetylTrimethylAmmonium Bromide (CTAB) and sodium salicylate (NaSal). These structures transform to disk-like micelles, which concatenate through hydrogen bridges to form long thread-like structures highly similar to worm-like micelle structures. This conclusion was reached after observing that NMR results suggest the formation of aggregates in solution with Azo-3F molecules inside them. Viscosity increases by three orders of magnitude at low shear rates when Azo-3F is added, and it shear-thins as the shear rate increases. The viscoelastic spectra show that the fluid changes from viscous to viscoelastic. Cole-Cole plots follow semicircles, typical of Maxwellian behavior below ∼ 35 °C. Cryo-TEM micrographs of the solution with Azo-3F show giant thread-like structures, and cross-sectional analysis of SAXS and WAXS profiles predict oblate ellipsoidal structures. In addition, MD simulations show that the disk-like micelles interact mainly through hydrogen bonds and electrostatics, forming micellar strings. These strings behave similarly to worm-like micelles, explaining why the solution behaves as a Maxwellian fluid at relatively low temperatures. Consequently, when some specific molecules are introduced in supramolecular structures, such as a spherical micelle, they can be transformed into disk-like micelles that assemble into thread-like micelles.

Effect of Substituents on Solubility, Medicinal, Absorption, Emission and Cationic/Anionic Detection Properties of Anthraquinone Derivatives.

Anthraquinones constitute an important class of compounds with wide applications. The solubility of derivatives at 298.15K was discussed in ethanol-water solution and at atmospheric pressure, the solubility of 1-amino-4-hydroxy-9,10-anthraquinone (AHAQ) in binary solvents (ethanol-water combinations) was determined. Colour strength and fastening properties depend upon the kind and position of a hydrophobic group connected to the phenoxy ring of Anthraquinone moiety. There is a continuing interest in the creation of novel anthraquinone derivatives with biological activities since they have demonstrated potential for treating multiple sclerosis. For this purpose, by utilizing voltammetric and absorption studies, interactions of various derivatives with calf thymus DNA (ct-DNA) and the cationic surfactant cetyltrimethylammoniumbromide (CTAB) were examined. Here prominent Hydrophobic interaction and electron transfer resulting in binding to CTAB micelles were observed. The polarity index of the media was assessed and associated with the electrochemical parameters. The medicinal behaviour of Anthraquinone derivatives was a result of electron transfer reactions with DNA. UV-Visible and fluorescence properties were due to the transitions between n* and π* orbitals. Large absorption band with low dichroic ratio was characteristic of various derivatives of Anthraquinone. Presence of -NH group proves various derivatives remarkable calorimetric and anionic sensors.

Super-enrichment of ultra-low concentration rhenium via synergistic co-flocculation precipitation using CTAB and ferric salt hydrolysis micelles

Super-enrichment and recovery of associated Rhenium (Re) in sandstone-type uranium deposits is challenging due to its sparse distribution and ultra-low contents in raw ores. Conventional industrial processes are extremely difficult to achieve economic recovery of Re with a concentration below 0.1 mg/L from in-situ leaching solutions of sandstone-type uranium deposits. This study proposes a novel approach for achieving super-enrichment ultra-low concentration of Re using a synergistic co-flocculation precipitation system composed of cetyltrimethylammonium-bromide (CTAB) and ferric salt (FeCl3) hydrolysis micelles. Experimental results reveal that the enriched content of Re in the co-flocculation precipitates is as high as 503 g/t, nearly 3353 times higher than that in the in-situ leaching solutions. The synergistic precipitation percentage of Re can reach more than 60%, which is larger than the sum of using CTAB micellar flocculation (30.16%) and FeCl3 hydrolysis micellar flocculation (5.43%) separately. Furthermore, the synergistic co-flocculation and precipitation mechanism of Re is examined by SEM, turbidity, Fourier transform infrared spectroscopy, Zeta potential analysis, and DTF calculations. Results demonstrate that the ReO4- anions first form ion associations with CTA+ cations through electrostatic force, which are subsequently captured to forms insoluble co-flocculating precipitate via weak intermolecular hydrogen bond force between Fe(OH)3 and ReO4-, which promotes the super-enrichment of the ultra-low concentration Re. In summary, this process presents great potential for the efficient recovery Re from a large amounts of sandstone-type uranium deposits leaching solution, and provides new insights into the enhancement mechanism of synergistic co-flocculation precipitation.

Surfactant micellar induced aggregation control of an anionic fluorescent dye in Langmuir-Blodgett film

This work reports the formation of stable Langmuir monolayer of an anionic water soluble fluorescent dye 5(6)-carboxyfluorescein (abbreviated as CFS) by electrostatic interaction with a cationic monolayer. Formation of non-fluorescent H-dimeric sites of CFS molecules in Langmuir monolayer and Langmuir Blodgett films has been controlled by using cationic surfactant micelles of cetyltrimethylammonium bromide (CTAB). Thus the film can act as efficient fluorescence marker. Langmuir monolayer has been investigated by Surface Pressure versus Area per molecule (π-A) isotherm and in situ Brewster Angle Microscope (BAM) studies. Mono and multilayered Langmuir Blodgett films were characterized by using UV–vis absorption and steady state fluorescence spectroscopy.

Enhancement of Fluorescence Mediated by Silver Nanoparticles: Implications for Cell Imaging.

In this study, we report the surface enhanced fluorescence (SEF) of a biologically important organic dye, fluorescein (FL), by silver nanoparticles (Ag NPs) in an aqueous medium and its implications for human cell imaging. The as-synthesized Ag NPs were characterized by dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), and UV-vis absorption spectroscopic studies. The interaction and aggregation of FL dye with Ag NPs and a cationic surfactant, namely, cetyltrimethylammonium bromide (CTAB), were explored by UV-vis absorption and steady-state and time-resolved fluorescence spectroscopic methods. The distance-dependent fluorescence enhancement of FL due to Ag NPs in the solution was also theoretically correlated by three-dimensional finite-difference time-domain (3D-FDTD) simulation. The plasmonic coupling between neighboring NPs facilitated the augmentation of the local electric field, thereby producing various "hotspots" that influence the overall fluorescence of the emitter. J-type aggregates of FL in the presence of the CTAB micelles and Ag NP mixed solution were confirmed by electronic spectroscopy. The density functional theoretical (DFT) study revealed the electronic energy levels associated with different forms of FL dye in the aqueous solution. Most interestingly, the Ag NP/FL mixed system used in fluorescence imaging of human lung fibroblast cells (WI 38 cell line) showed a significantly stronger green fluorescence signal compared to that of FL after an incubation period of only 3 h. This study confirms that the Ag NP mediated SEF phenomenon of the FL dye is also manifested in the intracellular medium of human cells giving a brighter and more intense fluorescence image. The cell viability test after exposure to the Ag NP/FL mixed system was confirmed by the MTT assay method. The proposed study may have an implication as an alternate approach for human cell imaging with higher resolution and more contrast.

Quantitative Analysis of Drug Supersaturation Region by Temperature-Variable Nuclear Magnetic Resonance Measurements, Part 2: Effects of Solubilizer

This study utilized temperature-variable nuclear magnetic resonance (NMR) spectroscopy to investigate the effects of a solubilizing agent on the ketoprofen (KTP) supersaturation region. Quantitative NMR analysis showed that the solubilizing agent cetyltrimethylammonium bromide (CTAB) increased both the crystalline and amorphous solubilities of KTP, shifting the KTP supersaturation region to a higher KTP concentration range. The amorphous solubility of KTP was found to be independent of the enantiomeric composition of KTP, even in the presence of CTAB. However, the supersaturation region of the S-enantiomer of KTP (s-KTP) in CTAB solutions was smaller than that of the racemic form of KTP (rac-KTP), likely because of the higher crystalline solubility of s-KTP. When KTP formed a KTP-rich phase via liquid-liquid phase separation from KTP-supersaturated solutions, CTAB was observed to be distributed into the KTP-rich phase, decreasing the chemical potential of KTP and the maximum thermodynamic activity of KTP in the aqueous phase. Additionally, the incorporation of CTAB into the KTP-rich phase diminished the solubilization effect of CTAB micelles in the aqueous phase, narrowing the KTP supersaturation region to a greater extent at higher KTP dose concentrations. Furthermore, the upper-temperature limit of the supersaturated dissolvable region of KTP was lowered in the presence of CTAB, which was rationalized by the melting point depression of the KTP crystal upon mixing with CTAB. The findings of this study highlight the importance of considering the molecular-level impact of solubilizing agents on the drug supersaturation region to fully exploit the potential benefits of supersaturated formulations.

Tuning of distinguished fluorescent responses to methylmercury and Hg2+ ions: Selective detection of methylmercury over Hg2+ ions by fluorescent sensor using micelle system

Although CH3Hg+ is highly toxic, reversible fluorescent sensors for detecting CH3Hg+ over Hg2+ are rare. In this study, we synthesized a reversible fluorescent sensor (1) based on tryptophan amino acid and 6-membered cyclic amine as an electron-donating unit of the fluorophore for turn-on monitoring of Hg2+ in H2O and developed a fluorescent sensing method for selective sensing CH3Hg+ over Hg2+ using 1 and the micelles with a different surface charge. 1 in triton X-100 (TX-100) micelles differentiated between CH3Hg+ and Hg2+ by fluorescent response types (turn-on vs red-shifted emission), whereas 1 in cetyltrimethylammonium bromide (CTAB) micelles detected only CH3Hg+ among 16 metal ions by turn-on response. 1 in the micelles exhibited remarkable detection ability for CH3Hg+ such as ultrafast response (<30 s), high sensitivity and/or selectivity for CH3Hg+, low detection limits (107 nM), and large enhancement of the fluorescence. We proposed the plausible binding mode of 1 in the micelles for selective sensing CH3Hg+ based on fluorescence and NMR and IR study. The 6-membered cyclic amine group of the fluorophore part of 1 might play a critical role to distinguish between CH3Hg+ and Hg2+ by fluorescent response types in TX-100 micelles. 1 detected sensitively Hg2+ and CH3Hg+ in live cells through significant enhancement of green and red fluorescence. 1 with and without the micelles successfully quantified CH3Hg+ and Hg2+ in groundwater and tap water. The combination of the sensor with the micelles provided a selective detection of CH3Hg+ over Hg2+ or distinguished between CH3Hg+ and Hg2+ by fluorescent response types.

Surfactant Assisted One-Pot Method for Preparation of Polyethylene-Clay Nanocomposites (PECN) and Study of their Viscoelastic Behaviour

This work demonstrates a one-pot soft template-assisted technique for developing polyethylene clay nanocomposite (PECN) using cetyltrimethylammonium bromide (CTAB) micelle as structure directing agent. Linear and shear viscosities of the composite were studied in the oscillatory and rotational modes. The effect of clay content, temperature and gallery space on the storage modulus and steady-state viscosities were analyzed. The composite exhibited enhanced storage modulus over the pristine polymer, confirming strong interaction between the clay platelet and polymer molecules. The prepared PECN showed superior thermal stability, phase transition temperature, flame retardancy and mechanical properties as compared to the conventional composite. Morphological studies using SEM and TEM also confirmed the formation of the nanocomposite. This one step surfactant-assisted emulsion method offers a broad scope in designing polymer clay nanocomposites with exciting properties and consequent applications.

How Micelles Influence the Optical Limiting Properties of Zinc Porphyrins and J-Aggregates for Picosecond Pulse Trains

In this work, we studied nonlinear dynamics and optical limiting (OL) effects of pulse trains in zinc porphyrins meso-tetrakis methylpyridiniumyl (Zn2+TMPyP) and meso-tetrakis sulfonatophenyl (Zn2+TPPS) and porphyrin J-aggregates. The environments of zinc porphyrins were selected as aqueous solutions and micelles of sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB). Our numerical results show that both Zn2+TMPyP and Zn2+TPPS are good optical limiters in all solutions. Zn2+TPPS in aqueous solutions shows the best OL effect. Micelles of SDS and CTAB produced less OL effects than the aqueous solutions. The main reason lies in the first excited singlet state and intersystem crossing depending on the electronic structures in different environments.

Role of ionic surfactants on the activation of K2S2O8 for the advanced oxidation processes

Effects of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate were studied to elucidate the persulfate based in-situ chemical oxidation of subsurface contamination. Advanced oxidation processes (AOP) utilizing Fenton’s like reagent was investigated for the degradation of acid orange 7 (AO7) with and without ionic surfactants. The new findings are that the CTAB and SDS retarding the S2O82− activation to some extent. The kinetics of S2O82− assisted decomposition of AO7 were performed under different reaction parameters such as [S2O82−], [Fe2+], [AO7], pH, and temperature. The rate constants (kψ) were decreased markedly in presence of both surfactants. CTAB showed the most potential deactivation than that of SDS. The stability of both surfactants were determined in presence of S2O82−, and no drastic changes was observed in the critical micellar concentration (CMC). The columbic attraction and repulsion between the reactants (S2O82−, and AO7) with ionic head groups of CTAB and SDS are responsible to deactivating the S2O82− decomposition. AO7 and S2O82−, respectively, solubilized and transferred from bulk phase to micellar surface through electrostatic interactions, which may contribute to the inhibitory role of CTAB micelles in the AOP of AO7. Finally the role of surfactants in the Fenton’s like oxidation of AO7 based on the micellar-pseudo phase model was proposed and discussed.

Nanoporous electrode with stable polydimethylsiloxane coating for direct electrochemical analysis of bisphenol A in complex wine media

Direct electrochemical analysis of bisphenol A (BPA) in alcoholic drinks without proper sample preparation is a major challenge. The current work reports a nanoporous electrode design with ultrathin polydimethylsiloxane (PDMS) coating grafted on the top of an indium tin oxide (ITO) electrode with silica nanochannels membrane and cetyltrimethylammonium bromide micelles (SNCM), using a facile contact heating step. The proposed PDMS@SNCM/ITO electrode was subjected to direct ultra-trace detection of BPA in the linear range of 1.0–100.0 µM and detection limit of 0.23 µM, under optimized pH 8 and an accumulation time of 9.0 min. The analytical utility of the proposed method was checked in real wine samples for BPA detection with successful recovery percentages in the range from 95.20 ± 8.53 to 96.22 ± 10.00. The intrinsic hydrophobic features, exceptional stability, and sensitivity of the proposed electrode show potential for food safety surveillance in complex food matrices.