Surfactant Sodium Dodecyl Sulfate Research Articles

Performance evaluation of hybrid electrochemical oxidation and ultraviolet light-based persulfate process for the abatement of sodium dodecyl sulfate from wastewater.

The application of hybrid advanced oxidation processes (AOPs) is an efficacious way to remediate emerging contaminants from wastewater. In the present research work, a hybrid electrochemical oxidation and ultraviolet light-based persulfate activation processes (EO-UV/PS) were used to efficiently degrade sodium dodecyl sulfate (SDS) surfactant from synthetic and municipal wastewater. By operating the EO-UV/PS at optimum operating conditions at pH of 7.0, NaCl of 0.02M, current density of 6.4mA/cm2, persulfate dose of 2.5mM, and operating period of 180min, about 94.5 ± 2.8% of SDS (20mg/L) removal was achieved from synthetic wastewater. The abetment of SDS in both EO and UV/PS obeyed pseudo-first-order kinetics with a rate constant of 0.012 and 0.019min-1, respectively. Moreover, the economic analysis revealed 0.23 $ m-3order-1 as the operating cost for degrading SDS in EO-UV/PS. The degradation pathway experimentation suggested the generation of lauric acid by-product during SDS abatement. Besides, nearly 89.3 ± 2.9% of SDS and 58.7 ± 2.4% of total organic carbon reduction was also achieved from real municipal wastewater. Phytotoxicity test on Vigna radiata affirms the non-toxic nature of the EO-UV/PS effluent.

Thermoascus aurantiacus harbors an esterase/lipase that is highly activated by anionic surfactant

Fungal lipolytic enzymes play crucial roles in various lipid bio-industry processes. Here, we elucidated the biochemical and structural characteristics of an unexplored fungal lipolytic enzyme (TaLip) from Thermoascus aurantiacus var. levisporus, a strain renowned for its significant industrial relevance in carbohydrate-active enzyme production. TaLip belongs to a poorly understood phylogenetic branch within the class 3 lipase family and prefers to hydrolyze mainly short-chain esters. Nonetheless, it also displays activity against natural long-chain triacylglycerols. Furthermore, our analyses revealed that the surfactant sodium dodecyl sulfate (SDS) enhances the hydrolytic activity of TaLip on pNP butyrate by up to 5.0-fold. Biophysical studies suggest that interactions with SDS may prevent TaLip aggregation, thereby preserving the integrity and stability of its monomeric form and improving its performance. These findings highlight the resilience of TaLip as a lipolytic enzyme capable of functioning in tandem with surfactants, offering an intriguing enzymatic model for further exploration of surfactant tolerance and activation in biotechnological applications.

Isothiocyanate-Based Microemulsions Loaded into Biocompatible Hydrogels as Innovative Biofumigants for Agricultural Soils.

Biofumigation was proposed as an alternative to synthetic pesticides for the disinfection of agricultural soils, in view of the biocidal effect of isothiocyanates (ITCs) released by some vegetal species, like Brassicaceae. However, biofumigation also presents limitations; thus, a novel and viable alternative could be the direct introduction of ITCs into agricultural soils as components loaded into biodegradable hydrogels. Thus, in this work, ITCs-based microemulsions were developed, which can be loaded into porous polymer-based hydrogel beads based on sodium alginate (ALG) or sodium carboxymethyl cellulose (CMC). Three ITCs (ethyl, phenyl, and allyl isothiocyanate) and three different surfactants (sodium dodecylsulfate, Brij 35, and Tween 80) were considered. The optimal system was characterized with attenuated ATR-FTIR spectroscopy and differential scanning calorimetry to study how the microemulsion/gels interaction affects the gel properties, such as the equilibrium water content or free water index. Finally, loading and release profiles were studied by means of UV-Vis spectrophotometry. It was found that CMC hydrogel beads showed a slightly more efficient profile of micelles' release in water with respect to ALG beads. For this reason, and due to the enhanced contribution of Fe(III) to their biocidal properties, CMC-based hydrogels are the most promising in view of the application on real agricultural soils.

Experimental analysis and comparison of thermophysical properties of the three different hybrid nano-catalyst blended diesel fuels

ABSTRACT In this study various hybrid nanofluids were synthesized and investigated to evaluate the different thermophysical and heat transfer properties of nanoparticle suspension-based diesel fuel (DF). The experiments were performed to measure the thermophysical properties of several hybrid nanofluids containing nanoparticles of CuO-Al2O3, Gr-Al2O3 and CuO-Gr with surfactant Sodium Dodecyl Sulphate (SDS). Five nanofluids were synthesized at 5, 44, 102, 160 and 200 mg/l with 1-3% of SDS. The experimental results indicate significant improvements in heat transfer properties with the use of CuO-Al2O3, Gr-Al2O3 and CuO-Gr based nanodiesel test fuels compared to conventional diesel fuel. The thermal conductivity improved by 16.2%-29.5% while specific heat decreased by 3.5% -5.5%. The addition of a surfactant efficiently reduces the increase in viscosity which rises with nanoparticle concentration by 10%-17.5% respectively. Increased heat transport capacities are indicated by an 7-11% rise in the Nusselt number at the different mass concentrations. CuO-Gr hybrid nano-diesel shows encouragingly better results in thermal study that had the most significant modifications. This particular combination is the most promising for heat transfer applications because the heat transfer coefficient also significantly improves by 14-18% at a Reynolds number of 5474. Prandtl number of the CuO-Gr nano-diesel interestingly drops by 5.5%.

Highly 002-Oriented Dendrite-Free Anode Achieved by Enhanced Interfacial Electrostatic Adsorption for Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (AZIBs) are gaining recognition as promising next-generation energy storage solution, due to their intrinsic safety and low cost. Nevertheless, the advancement of AZIBs is greatly limited by the abnormal growth of zinc dendrites during cycling. Electrolyte additives are effective at suppressing zinc dendrites, but there is currently no effective additive screening criterion. Herein, we propose employing the interfacial electrostatic adsorption strength of zinc ions for the initial screening of additives. Subsequently, dendrite-free plating is achieved by employing the anionic surfactant sodium dodecyl benzenesulfonate (SDBS) to enhance electrostatic adsorption. The cycled zinc anode exhibited a dense plating morphology and a high (002) orientation (I002/I101 = 22). The Zn||MnO2 full cell with SDBS exhibited a capacity retention of 85% after 1000 cycles at 1 A g-1. Furthermore, an instantaneous nucleation model and continuous nucleation model (CNM) are constructed to reveal the microscale plating/stripping dynamics under the scenarios of weak adsorption and strong adsorption. The CNM accurately explains the self-optimizing reconstruction of electrodes resulting from enhanced electrostatic adsorption. Our exploration was extended to other anionic surfactants (sodium dodecyl sulfate and disodium laureiminodipropionate), confirming the effectiveness of strong electrostatic adsorption in the screening of electrolyte additives.

Molecular interactional study of SDS and CTAB in aqueous medium of anti-HIV drugs (Emtricitabine and Lamivudine) at different temperatures: A physicochemical investigation

The present study deals with the interactions of Emtricitabine and Lamivudine (anti-HIV drugs) with anionic surfactant sodium dodecylsulphate (SDS) and cationic surfactant cetyltrimethylammonium bromide (CTAB) at (298.15–313.15) K temperature range by volumetry, compressibility and viscometric approach. The experimental values of sound velocity and density are used to compute various parameters such as apparent molar volume (φv), isentropic compressibility (κs), and apparent molar adiabatic compression (φκ) by employing cosphere overlap model. Relative viscosity parameter (ηr) evaluated from viscosity data also helps to understand various interactions prevalent in surfactant-drug-water ternary system. This attempt of extracting information about various physicochemical interactions of anti-HIV drugs with surfactants can prove beneficial to develop novel anti-HIV agents with better viral resistance activity.

Role of surfactants in the degradation and sustainable dyeing for reactive dyeing wastewater

To enhance the decolorization rate of thermally activated sodium persulfate in dye wastewater, C.I. Reactive Black 5 (RB5) was investigated in this study, which was evaluated by the decolorization of the dye solution. The effect of surfactant concentration (including anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant Tween 80 (TW-80) and amphoteric surfactant (BS-12)), SPS concentration, and reaction temperature on the degradation of RB5 was studied. Furthermore, the relationship between free radicals and RB5 degradation was investigated. The results showed that the addition of SDS and TW-80 would inhibit the decolorization of RB5. Correspondingly, the effect would enlarge as the surfactant concentration increased. Nevertheless, the addition of BS-12 wouldn’t affect the final decolorization of RB5 dye solution, despite it could increase the decolorization rate in the initial stage. After 10 min of decolorization, compared to the dye liquor without BS-12, the decolorization could increase by 9.07 % and 0.69 %, respectively, after adding 0.5 and 1.0 CMC of BS-12. Besides, when reactive dyes were degraded by thermally activated sodium persulfate, the SO4-· and ·OH would work together, and SO4-· played a major role while ·OH played an auxiliary part. When the treated wastewater was used for dyeing, the addition of BS-12 could effectively regulate the dyeing rate. The fixation and K/S value were increased by 1.1 % and 0.20, respectively. Furthermore, the dyed fabrics also exhibited improved uniformity, with negligible differences in color fastness. The effects of adding SDS were similar to BS-12, while it decreased the exhaustion and fixation rate of RB5. In addition, non-ionic TW-80 was unfavorable to dyeing. This work provides a new way for efficient treatment of dyeing wastewater as well as reuse, opening an environmentally friendly treatment concept.

Temperature dependence of the near infrared absorption spectrum of single-wall carbon nanotubes dispersed by sodium dodecyl sulfate in aqueous solution: experiments and molecular dynamics study.

Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV-Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Optical absorption measurements were carried out in the UV-Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900-1400nm (890-1380meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard-Jones 6-16 potentials) was employed.

Formation and survival of clay-mediated protocell membranes composed of single-chain amphiphiles in aqueous solutions

Protocell compartments composed of simple amphiphilic molecules could have survived on the clay mineral surfaces which can serve well as plausible sites for prebiotic chemistry on the early Earth. Herein we chose four common single-chain amphiphiles (SCAs), including the anionic surfactant sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS), the cationic surfactant dodecyltrimethylammonium bromide (DTAB) and the zwitterionic lauryl sulfobetaine (LSB)), as model constituents of early membranes to establish a tentative model for protocell compartment. Positively charged Mg2Al-/Mg2Fe-layered double hydroxides (LDHs) and FeS2 are viewed as models of clay minerals. We demonstrate by comprehensively experimental study that unconventional vesicles can be easily promoted in a SCA aqueous micellar solution in the presence of model particles. Morphology evolutions are traced by collecting samples from mixtures of LDHs and SCA aqueous solutions and then recording at different incubation times via negative-staining or cryo-transmission electron microscopy (NS-TEM or cryo-TEM) and dynamic light scattering (DLS). Additionally, the stability of SCA bilayer membranes under possible prebiotic environment are tentatively studied. This work not only offers a robust yet versatile approach for the fabrication of novel vesicles but also provides new insights into the origin of cellular life.

Thermodynamic characteristics and surface free energy analysis of bifonazole and lecithin with sodium dodecyl sulfate in hydroethanolic solvent systems

The thermodynamic investigations of the well-recognised antifungal drug bifonazole and lecithin with anionic surfactant sodium dodecyl sulphate have been established. The experiments were conducted using five distinct hydro-ethanolic concentrations, namely 0% v/v, 10% v/v, 30% v/v, 70% v/v, and 90% v/v ethanol, throughout a range of five temperatures (ranging 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃) with an increment of drug concentration. The study involved the determination of several parameters, including surface tension (σ), density (ρ), conductivity (κ), contact angle (θ) and surface free energy. Conductivity and surface tension data was used for calculating critical micelle concentration (CMC). CMC was utilised to calculate various thermodynamic properties, such as the standard entropy change (ΔS°m), standard Gibbs energy change (ΔG°m) and standard enthalpy change (ΔH°m) of micellization. This study represents a comparative analysis of the critical micelle concentration (CMC) by utilising surface tension and conductivity measurements. Contact angle is used to determine the hydrophobicity and hydrophilicity of the system. These investigations are valuable for examining the magnitude of hydrophobic interactions within the system, which might be used to ascertain an optimal concentration of bifonazole, lecithin and surfactant to prepare ethosomal formulations.

The role of the cation and anion in aqueous liquid chromatography with sodium dodecyl sulphate and imidazolium-based ionic liquids as mobile phase reagents

BackgroundIn reversed-phase liquid chromatography, solute retention is primarily influenced by interactions between a nonpolar stationary phase and a moderately polar hydro-organic mobile phase, based on the solute lipophilicity. However, challenges regarding retention and peak tailing can arise due to ionic interactions between positively charged analytes and free silanols present on silica-based stationary phases. To address these challenges, incorporating surfactants and ionic liquids (ILs) into the mobile phase offers an effective solution. These additives synergistically enhance chromatographic performance through electrostatic and lipophilic interactions, which enable fine-tuning of selectivity and improved separation efficiency. ResultsThis study explores the chromatographic behaviour of several basic compounds in aqueous mixtures containing the anionic surfactant sodium dodecyl sulphate (SDS), above its critical micellar concentration, combined with various 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) featuring chloride, tetrafluoroborate, and hexafluorophosphate anions, all without the addition of organic solvents. Specifically, this research investigates the influence of different anion types within the ILs and considers the impact of the IL cations. Analysis of solute peak profiles reveals narrow and symmetrical peaks. By introducing tetrafluoroborate and hexafluorophosphate IL anions into a mobile phase that contains an anionic surfactant, the study sheds light on the interactions occurring within the chromatographic column. This enhanced understanding of the combined effects of surfactants and ILs contributes to refining chromatographic methodologies. SignificanceThis research highlights the importance of carefully selecting the appropriate IL when incorporating it into a micellar mobile phase alongside SDS. This combination results in practical retention times that surpass the performance achieved with either the surfactant or IL alone in the mobile phase. The study particularly emphasises the impact of the IL anion, especially in the absence of SDS and organic solvents. This unveils interactions that are otherwise obscured in micellar and hydro-organic media, providing new insights into chromatographic dynamics.

Green and sensitive detection of olopatadine in aqueous humor using a signal-on fluorimetric approach: GREEnness assessment.

Olopatadine (OLP) is widely utilized as an effective antihistaminic drug for alleviating ocular itching associated with allergic conjunctivitis. With its frequent usage in pharmacies, there arises a pressing need for a cost-effective, easily implementable, environmentally sustainable detection method with high sensitivity. This study presents a novel signal-on fluorimetric method for detecting OLP in both its pure form and aqueous humor. The proposed approach depends on enhancing the weak intrinsic fluorescence emission of OLP, achieving a remarkable increase of up to 680% compared to its intrinsic fluorescence. This enhancement is achieved by forming micelles around protonated OLP using an acetate buffer (pH 3.6) and incorporating a solution of sodium dodecyl sulfate (SDS) surfactant. A strong correlation (R = 0.9996) is observed between the concentration of OLP and fluorescence intensities ranging from 1.0 to 100.0 ng mL-1 with a limit of detection of 0.22 ng mL-1. This described method is successfully employed for quantifying OLP in both its powder form and pharmaceutical eye drops. Furthermore, it demonstrates robust performance in determining OLP in artificial aqueous humor with a percentage recovery of 99.05 ± 1.51, with minimal interference from matrix interferents. Moreover, the greenness of the described method was evaluated.

Mesoporous pineapple crown-derived activated carbon modified matrix for the detection of carbendazim in the presence of anionic surfactant

Carbon paste electrodes (CPEs) are commonly employed in electroanalysis because of their chemical stability, broad electrochemical window, low capacitive current, ease of fabrication, and surface renewability. Electrocatalysts can easily be embedded into CPEs to make them suitable for a variety of applications. Poor biowaste management presents a significant challenge in the agro-industry and agriculture due to the rapid decomposition of biowaste, driven by its high water content and limited biological stability, which leads to pest attraction and greenhouse gas emissions. Consequently, this green waste can be utilized for the development of electrocatalysts. Activated carbon (AC) has been utilized in progressive electrochemical applications as it exhibits high conductivity and porosity that help to enhance electrocatalytic activity. Herein, pineapple fruit crown (PC) peel-derived AC (PCAC) is utilized as the sensing material for the determination of fungicide, carbendazim (CBM). The synthesized material was characterized using SEM, FT-IR, XRD, EDX, AFM, CV and EIS. Besides, to enhance the surface properties, Sodium dodecyl sulfate (SDS) surfactant is used as a mediator in detecting CBM. The CV and SWV approaches were employed to assess the electrochemical response of the developed electrodes for the CBM determination. Under optimum experimental conditions, the SDS/PCAC/CPE exhibits low DLim and QLim values of 32.0 nM and 128.0 nM with considerable selectivity. Furthermore, the SDS/PCAC/CPE was employed in real-time analysis of CBM in spiked environmental samples, which showed satisfying recovery results. Moreover, the electrode showed good stability over multiple measurements, and these results demonstrate that SDS/PCAC/CPE is a promising sensor for CBM detection.

Voltammetric determination of the antifungal drug posaconazole in the presence of an anionic surfactant on a boron-doped diamond electrode

This study describes a new, fast and simple procedure of electrochemical assay of posaconazole (PCZ), which is currently regarded as one of the most important antifungal agents, recommended in the treatment of systemic infections, effective even against rare and atypical kinds of fungi. PCZ is very effective and safe, displaying much lower toxicity than other traditional antifungal drugs. A new, attractive procedure of assaying the compound on boron-doped diamond (BDD) electrode after cathodic pretreatment in the presence of sodium dodecyl sulfate (SDS) is presented in the work. The anionic surfactant SDS was selected after the comparative analysis of various cationic surfactants. PCZ gave a single irreversible oxidation peak at the potential of 0.59 V. The addition of SDS resulted in an almost 5-fold growth in the value of recorded currents as compared to those observed in the absence of the surfactant. The highest peak was obtained in Britton-Robinson buffer at pH 3.78. The calibration curve of PCZ plotted using the SWV technique was linear in the concentration range from 1.34·10−8 mol/L to 1.44·10−6 mol/L. The limit of detection and limit of quantification were 3.78·10−9 mol/L and 1.14·10−8 mol/L, respectively. The value of relative standard deviation of the measurements did not exceed 4.42 %, which proves good precision of the proposed method. The proposed procedure was successfully used in assaying PCZ in simulated gastric juice.

Nitrogen-doped Graphene/Natural Rubber and Sodium Dodecyl Sulfate Modified Nanocomposites: Study on the Electrochemical Properties for the Potential Sensor Response

In this study, a piezoelectric composite was developed based on nitrogen-doped graphene/natural rubber (NGr-NR) and an anionic surfactant sodium dodecyl sulfate (SDS) through a simple sonication method. Taking advantage of the high electrical conductivity and high surface area of NGr, the hybrid network of NGr-NR-SDS nanocomposite showed excellent mechanical properties and enhanced electrochemical behavior. Here, NGr was used as functional filler materials incorporated into NR polymeric matrix. SDS was used with NGr-NR composite to reduce the aggregation and promote the interfacial interaction between NGr-NR which enhanced the stability of sensor. The surface morphology of NGr-NR-SDS was investigated by field emission scanning electron microscopy, transmission emission microscopy, and Fourier transform infrared spectroscopy. Cyclic voltammetry and electrochemical impedance spectroscopy of NGr-NR-SDS showed the highest current response of 17 μA and the lowest Rct value of 1920 Ω demonstrating the excellent electrochemical response. The significance of this result is that the developed nanocomposite shows great potential for flexible piezoelectric devices due to excellent electrochemical response and cyclic stability.

Characterization of the Solution Properties of Sodium Dodecylsulphate Containing Alkaline–Surfactant–Polymer Flooding Media

Alkaline–surfactant–polymer (ASP) flooding by means of which alkali additives, surfactant and polymer are inserted as the same slug is one of the most favourable worldwide focuses of Chemical Enhanced Oil Recovery (cEOR) research and field trials, due to the individual synergy of the three chemical components. To develop efficient oil recovery chemicals, it is essential to fully understand the mechanism behind ASP flooding. Nonetheless, there are hardly any studies reporting a systematic characterization of the ASP process. Thus, the present paper focuses on modelling this process in a laboratory by the use of an anionic surfactant—sodium dodecyl sulphate (SDS) in alkaline–polymer media—which is composed of a commercial water-soluble polymer (Flopaam AN125SH®, SNF Floerger, Andrézieux-Bouthéon, France) and alkali compounds (NaOH and Na2CO3). The samples were characterized using rheometry, dynamic light scattering (DLS), infrared spectroscopy (IR) and measurement of inferfacial tension (IFT) between the samples and rapeseed oil. In accordance with the experimental results, surprisingly lower IFT values were recorded between the alkaline–polymer solutions and rapeseed oil than the samples which contained SDS. Increasing polymer and sodium chloride concentration caused a decrease (from 0.591 mN/m to 0.0486 mN/m) in IFT between the surfactant containing samples and rapeseed oil. The IR measurements confirmed that the surfactant was not detected in the oil phase in the absence of NaOH and Na2CO3. The effects of SDS on the viscosity of the mixtures were also investigated, as viscosity is a considerably important parameter in processes using polymers.

High-efficiency triplet-triplet annihilation upconversion microemulsion with facile preparation and decent air tolerance.

Current research of triplet-triplet annihilation upconversion (TTA-UC) faces difficulty such as overuse of organic solvents and quenching of excited triplet sensitizers by molecular oxygen. Herein, we propose an efficient and facile preparation strategy of TTA-UC microemulsion to overcome these issues. With simple device and short preparation process, air-stable TTA-UC with a high upconversion efficiency of 16.52% was achieved in microemulsion coassembled from TritonX114, tetrahydrofuran and upconverting chromophores (platinum octaethyl-porphyrin and 9,10-diphenylanthracene). This is comparable to the highest UC efficiency ever reported for TTA-UC microemulsion systems. The excellent UC performance of TX114-THF could be attributed to two perspectives. Firstly, small-size micelle accommodated chromophores up to high concentrations in organic phase, which promoted efficient molecular collision. Additionally, high absorbance at 532nm ensured full use of excitation light, getting more long wavelength photons involved in the TTA-UC process. Moreover, air-stable TTA-UC also performed well in microemulsion with various surfactants, including nonionic surfactants (Tween 20, Tween 80, Triton X-110, Triton X-114), ionic surfactants (sodium dodecyl sulfate, cetyltrimethyl ammonium bromide) and block copolymers (pluronic F127, pluronic P123), through three conjectural assembly models according to the structural characteristics of surfactant molecules (concentrated, uncompacted and scattered). These discoveries could provide estimable reference for selection of surfactants in relevant fields of TTA-UC.

Surfactant Partitioning Dynamics in Freshly Generated Aerosol Droplets.

Aerosol droplets are unique microcompartments with relevance to areas as diverse as materials and chemical synthesis, atmospheric chemistry, and cloud formation. Observations of highly accelerated and unusual chemistry taking place in such droplets have challenged our understanding of chemical kinetics in these microscopic systems. Due to their large surface-area-to-volume ratios, interfacial processes can play a dominant role in governing chemical reactivity and other processes in droplets. Quantitative knowledge about droplet surface properties is required to explain reaction mechanisms and product yields. However, our understanding of the compositions and properties of these dynamic, microscopic interfaces is poor compared to our understanding of bulk processes. Here, we measure the dynamic surface tensions of 14-25 μm radius (11-65 pL) droplets containing a strong surfactant (either sodium dodecyl sulfate or octyl-β-D-thioglucopyranoside) using a stroboscopic imaging approach, enabling observation of the dynamics of surfactant partitioning to the droplet-air interface on time scales of 10s to 100s of microseconds after droplet generation. The experimental results are interpreted with a state-of-the-art kinetic model accounting for the unique high surface-area-to-volume ratio inherent to aerosol droplets, providing insights into both the surfactant diffusion and adsorption kinetics as well as the time-dependence of the interfacial surfactant concentration. This study demonstrates that microscopic droplet interfaces can take up to many milliseconds to reach equilibrium. Such time scales should be considered when attempting to explain observations of accelerated chemistry in microcompartments.

GO and surfactant assisted regulation of polyamide nanofiltration membranes for improved separation performance

Fabricating nanofiltration membranes with high water permeance and selectivity by tailoring the structure and morphology is crucial to efficient water purification. In this work, the fabrication of thin film nanocomposite (TFN) nanofiltration membranes by combining two methods, the surfactant-assembly interfacial polymerization (SARIP) and the addition of graphene oxide (GO) or ionic liquid functionalized graphene oxide (GO-IL) for the preparation of the selective PA layer on a novel porous substrate is reported. For the preparation of the porous substrate, mechanically robust, aromatic polyethers containing polar pyridine units (PDSPP) were chosen targeting to improved hydrophilicity and thus enhanced water permeability. The anionic sodium dodecyl sulfate (SDS) surfactant was used to regulate the interfacial polymerization thereby enabling the formation of dense PA layers with high cross-linking degree and consequently high salt rejections. On the other hand, the addition of GO/GO-IL nanosheets could impart hydrophilicity and antifouling properties. The novel porous PDSPP substrate was selected for the fabrication of TFN membranes due to its improved water permeability and superior salt rejection and increased hydrophilicity compared to commercial PSf substrate. The detailed study of the fabricated TFN membranes by ATR-FT-IR, SEM, AFM, XPS, contact angle measurements revealed the formation of polyamide selective layers with rougher surfaces, increased hydrophilicity and high cross-linking degrees (from 44 % to 94 %), resulted from the synergistic effect of SDS and GO incorporation. Moreover, the prepared TFN membranes exhibited high salt rejections while maintaining a moderate water permeability. In particular, the membrane containing the neat GO (TFNGO50) displayed excellent Na2SO4 and MgSO4 rejections (98.8 % and 99.5 %, respectively) while the NaCl rejection was 47.0 % and a water permeability value of 4.2 L m-2h−1 bar−1. The divalent salt rejections were among the highest values reported in the literature in comparison with commercial NF membranes and TFN membranes containing GO/functionalized GO. When GO-IL nanosheets were embedded in the PA layer, the water permeability was slightly improved while the salt rejections were significantly reduced compared to TFNGO50. Lastly, the incorporation of GO enhanced the anti-fouling properties of the prepared membranes due to increased hydrophilicity of the PA surface.

Morphological aspects and the effectiveness of photodynamic inactivation against Rhizopus oryzae in different life cycles.

Mucormycosis is an extremely aggressive fungal disease with a high mortality rate, especially in people with compromised immune systems. Most cases of mucormycosis are caused by the fungus Rhizopus oryzae. The treatments used are based on high doses of antifungals, associated with surgical resections, when it is possible. However, even with this aggressive treatment, the estimated attributable mortality rate is high. There is therefore a need to develop adjuvant treatments. Photodynamic Inactivation (PDI) may be an auxiliary therapeutic option for mucormycosis. Due to the lack of reports in the literature on the morphology and photodynamic inactivation of R. oryzae, characterization of the fungus using Confocal Microscopy and Transmission Electron Microscopy, and different protocols using Photodithazine® (PDZ), a chlorin e6 compound, as a photosensitizer, were performed. The fungus growth rate under different concentrations and incubation times of the photosensitizer and its association with the surfactant Sodium Dodecyl Sulphate (SDS) was evaluated. For the hyphae, both in the light and dark phases, in the protocols using only PDZ, no effective photodynamic response was observed. Meanwhile with the combination of SDS 0.05% and PDZ, inhibition growth rates of 98% and 72% were achieved for the white and black phase, respectively. In the conidia phase, only a 1.7 log10 reduction of the infective spores was observed. High concentration of melanin and the complex and resistant structures, especially at the black phase, results in a high limitation of the PDI inactivation response. The combined use of the SDS resulted in an improved response, when compared to the one obtained with the amphotericin B treatment.