Sodium Octyl Sulfate Research Articles

Optimization of HPLC method for metanephrine and normetanephrine detection in urine: Enhancing diagnostic precision for pheochromocytoma.

Catecholamines and their metabolites play critical physiological roles in the human body. Paragangliomas and pheochromocytomas are rare adrenal tumors that significantly alter catecholamine metabolism, particularly the concentrations of metanephrine (MN) and normetanephrine (NMN). This study presents the development and validation of a rapid and straightforward analytical method using reverse-phase high-performance liquid chromatography (RP-HPLC) coupled with a photodiode array (PDA) detector for quantifying MN and NMN in 24-h urine samples. Sample preparation involved adding 1 mL of urine to a tube containing the internal standard 3-methoxy-4-hydroxy benzylamine hydrochloride (MHBA) and a 2 g/L solution of 2-aminoethyl-diphenylborinate. After vortex mixing and centrifugation, ethyl acetate was used for extraction, and the organic layer was dried under nitrogen at 50-60 °C before reconstitution in the mobile phase. Chromatographic separation was achieved on an RP C-18 column with an isocratic flow of the mobile phase (sodium dihydrogen phosphate, citric acid monohydrate, acetonitrile, and sodium octyl sulfate). Detection was performed at 347 nm, with peak identification based on standard retention times. The method was validated for linearity (10-2000 ng/mL), recovery, sensitivity, precision, accuracy, selectivity, carryover, stability, and dilution effects. It showed a strong correlation coefficient (>0.99) and accuracy within ± 15 %. Inter- and intra-day precision confirmed the method reliability. This validated technique is suitable for clinical and research applications involving catecholamine metabolite screening.

Surface activity, aggregation behaviour and wettability of mixtures of perfluorobranched short-chain gemini quaternary ammonium surfactant and hydrocarbon anionic surfactants in dilute solution

The hydrophobic and oleophobic properties of perfluorobranched short chains are similar to those long chain fluorocarbons (fluorocarbon chain length ≥ 7), and their environmentally friendly properties make them good alternatives to traditional perfluorooctyl derivatives. For this purpose, a novel perfluorinated branched short chain quaternary ammonium gemini surfactant (PBFS) with high surface activity was synthesized, and the surface properties, aggregation behavior, wetting performance and adsorption performance of the complex system of PBFS and sodium octyl sulfate (SOS) were systematically studied. PBFS exhibited superior surface activity in aqueous solution with the critical micelle concentration (CMC) of 0.1667 mmol/L and the corresponding surface tension (γCMC) of 20.17 mN/m. Moreover, despite the fact that the mixing of PBFS and SOS was not ideal, the two still had the good synergistic effect: the CMC of the compounding solution was reduced to 0.0072 mmol/L and γCMC was 16.01 mN/m when the compounding ratio (CF: CH) was 1:8. And the composite solution could completely wet low surface energy polytetrafluoroethylene (PTFE) plates at 1 mmol/L, and could also wet PTFE plates at extremely low concentrations (0.0625 mmol/L), showing good wetting performance.

Quality assurance and quality control of atmospheric organosulfates measured using hydrophilic interaction liquid chromatography (HILIC)

Abstract. ​​​​​​​As a crucial constituent of fine particulate matter (PM2.5), secondary organic aerosols (SOAs) influence public health, regional air quality, and global climate patterns. This paper highlights the use of hydrophilic interaction liquid chromatography (HILIC) which effectively retains strongly polar analytes that might exhibit incomplete or no retention in reverse chromatography, resulting in superior separation efficiency. A HILIC column was used to analyze six standards, environmental standards (1648a and 1649b), and samples collected in urban environments in Guangzhou in the Pearl River Delta region, which serve as valuable reference points for evaluating the organic composition of the atmospheric environment. The results indicate a high degree of accuracy in the analytical method. Sodium octyl-d17 sulfate serves as the internal standard, with a linear correlation coefficient of the six standards, boasting a linear correlation coefficient r ranging from 0.993–0.9991 and a slope, k, of the linear equation from 0.966–1.882. The instrument detection limits (IDLs) are established at 0.03–0.20 µg mL−1, while the method detection limits (MDLs) fall within the range of 0.30–1.75 ng m−3, demonstrating the method's exceptional sensitivity. Since isoprene-derived organosulfates (iOSs) are highly polar due to containing a hydrophilic bond to the hydroxyl group and a hydrophobic bond to the sulfate, and as such showed strong retention using this method, this technique employs sodium ethyl sulfate and sodium octyl sulfate standards for semi-quantitative compound analysis of iOSs. The error in sample analysis (EA) ranged from 12.25 %–95.26 %, and the two standards maintained a consistent recovery rate between 116 %–131 % and 86.4 %–127 %. These findings indicate a high level of precision when semi-quantifying compounds with similar structural characteristics, affirming the analysis method's minimal relative error and underscoring its repeatability, process stability, and the reliability of its results for iOSs. To enhance the method's reliability assessment, the study analyzed polar organic components of standard particulate matter samples (1648a and 1649b), providing precise determinations of several iOSs using this method. Methyltetrol sulfate (m/z 215, C5H11SO7-) is the highest concentration in the ambient samples, up to 67.3 ng m−3 in the daytime. These results serve as valuable reference points for assessing the organic composition of the atmospheric environment.

Self-emulsifying drug delivery systems containing sulfate-based surfactants: Are they responsive to alkaline phosphatase?

This study aimed to develop self-emulsifying drug delivery systems (SEDDS) containing sulfate-based surfactants, namely, sodium dodecyl sulfate (SDS), sodium octyl sulfate (SOS) and sodium cetearyl sulfate (SCS), and to evaluate intestinal alkaline phosphatase (IAP)-triggered sulfate release from these SEDDS.Results showed a time-dependent release of para-nitrophenol from para-nitrophenyl phosphate (p-NPP) and para-nitrophenyl sulfate (p-NPS) when incubated with isolated IAP indicating that the enzyme can also cleave sulfate groups. Moreover, sulfate release from p-NPS and sulfate-based surfactants was observed. SEDDS containing sulfate-based surfactants exhibited a narrow droplet size distribution and polydispersity index (PDI). A droplet size of 35.31 ± 0.41 nm to 41.15 ± 0.98 nm, PDI of 0.17 ± 0.02 to 0.26 ± 0.02 and zeta potential of 9.59 ± 0.85 mV to −18.53 ± 2.75 mV were recorded. Droplet size and PDI showed a minor increase upon contact with isolated IAP. Incubation with isolated IAP caused a rapid sulfate release from sulfate-based surfactant-containing SEDDS (SDS-SEDDS, SOS-SEDDS and SCS-SEDDS). Furthermore, resulting SEDDS exhibited a non-toxic profile. According to these results, SEDDS containing sulfate-based surfactants can be considered as valid alternative to IAP-responsive drug delivery systems containing phosphorylated auxiliary agents.

Biotransformation of t-butyl phenols by micellar nanoreactors of peroxidase/ionic surfactants at mild conditions: nanobiocatalyst performance and kinetic analysis

Recently, some bulk reaction media were substituted by micellar systems. Micellar media can be created by different types of surfactants which generate micellar nanoreactors for diverse reactions. Ionic surfactants can be used as aqueous micellar systems, providing mild conditions for the specified reactions. Ionic surfactants: sodium dodecyl sulfate, sodium decyl sulfate (SDeS), sodium octyl sulfate (SOS), n-dodecyl trimethyl ammonium bromide, and cetyltrimethylammonium bromide were used to prepare aqueous micellar and entrapped peroxidase nanoreactors as biocatalysts. Oxidative coupling reactions were investigated for a series of phenolic hydrogen donors including 2-tert-butyl phenol, 4-tert-butyl phenol, and 2,4-tert-butyl phenol catalyzed by micellar nanoreactors of horseradish peroxidase (HRP) with hydrogen peroxide and/or tert-butyl peroxide as oxidants. Higher oxidation reaction rates were obtained for 2-tert-butylphenol and 4-tert-butylphenol with hydrogen peroxide in 90 mM SDeS (SDeS90) and 150 mM SOS (SOS150) nanoreactors, respectively. Among the micellar nanoreactors studied, the SDeS90 nanoreactor showed excellent protection of the enzyme against the peroxide inactivation effect. The long-term activity of the HRP/SDeS90 nanobiocatalyst was related to the gradual diffusion of peroxide into the nanoreactor. The biocatalytic kinetic parameters: V max, k cat, catalytic efficiency, and suicide-peroxide inactivation rate constants were determined for HRP/SDeS90. Reactions were carried out successfully under mild conditions in the micellar nanoreactors. Results confirmed that substituted functional groups on the benzene ring affect the oxidative reaction routes and products. Excellent protection of the enzyme, enhanced biocatalytic parameters, higher selectivity, and yield, in the peroxidative coupling of alkylphenols, reveal the high potential of such micellar nanoreactors for diverse organic synthesis and biotransformation.

Grazing inhibition in Daphnia and Bosmina by colony formation of Desmodesmus subspicatus triggered by sodium octyl sulfate.

There are growing concerns that several aquatic contaminants can indirectly alter biological interactions by inhibiting the adaptive phenotypic plasticity of organisms, even at nonlethal concentrations. In Scenedesmaceae, a family of green algae, many chemicals interfere with defensive colony formation against grazers (i.e., through induced or limited coloniality). Although several studies have demonstrated that the effects of coloniality can limit the feeding capacity of Daphnia spp., grazing inhibition in other zooplankton species is not well understood. In this study, we examined the influence of sodium octyl sulfate (SOS) on the growth and morphology of Desmodesmus subspicatus and on the feeding rates of three cladoceran species (Daphnia galeata, Bosmina longirostris, and Bosmina fatalis) feeding on SOS-induced colonies under factorial conditions of different food levels and grazer ages. SOS remarkably induced colony formation with no observed effect on growth in D. subspicatus. D. galeata and B. fatalis showed a remarkable reduction in feeding rates when they fed on colonial D. subspicatus, whereas no significant effect of the prey morphotype was found on the feeding rates of B. longirostris. Microscopic observations of algal morphology after being grazed showed that each species can consume colonial prey depending on food level and age. Comparisons of the inhibition ratio of feeding among the three cladocerans revealed that Daphnia was more sensitive to prey coloniality compared with Bosmina. Our findings provide specific insights into the effects of chemically interfered colony formation on population dynamics and community structures.

Improved Extended Nernst Plank nanofiltration modeling via inclusion of pore size, electrostatic interactions, and compound shape and orientation

Nanofiltration (NF) membrane rejection models are often simplified by ignoring some compound physical characteristics to ease computational complexity. Yet these simplifications can reduce model flexibility in addressing all compounds and conditions. Herein, the Extended Nernst Plank model of NF rejection is improved upon by combining compound charge, geometry, and rotation, along with pore size distribution. The NF rejection of ionic alkyl chain compounds (C2 to C14) at various pH is experimentally determined and modeled. Rejections of the ionic compounds via an NFG membrane ranged from 49.8 % to 80.6 % for benzyldimethyldodecylammonium chloride, 23.6 % to 38.6 % for 1-methyl-3-octylimidazolium chloride, 32.5 % to 37.6 % for 1-ethyl-3-methylimidazolium chloride, 52.5 % for sodium dodecyl sulfate, 34.7 % to 63.5 % for sodium octyl sulfate, and was only measurable at 28.5 % for sodium ethyl sulfate. The rejections of an additional eight membranes and 81 compounds reported in the literature were also modeled. Overall the improved model predicted rejections with lower percent differences (i.e., 0.96 % to 144 % for the model herein) compared to simplified models presented in the literature (e.g., 5.0 % to 154 %). The improved model will be useful for simulations of NF membrane rejection where pore size distributions and size and charge of compounds cannot be ignored.

Gradual transformation of anionic/zwitterionic wormlike micelles from viscous to elastic domains: Unravelling the effect of anionic surfactant chain length

HypothesisUltra-long tailed zwitterionic surfactants often form aqueous wormlike elastic micelles, whereas the shorter ones mainly exhibit spherical viscous micelles. Anionic surfactants are widely used to tune the micellar morphology from spherical into wormlike. Systematic investigations in the molecular level are insightful to understand the viscoelasticity regulative mechanism. ExperimentsAnionic/zwitterionic hybrid wormlike micelles are composed of sodium alkylsulfate (SAS) homologues and dodecyl dimethyl amidopropyl hydroxyl sulfobetaine (DHSB). The formation of wormlike micelles was studied by employing rheometer, cryogenic transmission electron microscopy (cryo-TEM) and small angle X-ray scattering (SAXS) techniques. The effects of surfactant concentration, molar ratio, anionic surfactant chain length and temperature were investigated systematically. FindingsSAS promoted the formation of SAS/DHSB hybrid wormlike micelles. The increase in both chain length and molar ratio (xSAS) of SAS are advantageous in the enhancement of viscosity. Interestingly, sodium hexadecylsulfate (SHS) endowed elastic wormlike micelles with thermally insensitive viscosity below its Krafft temperature (Tk), which was distinguished from the viscous ones formed by sodium octylsulfate (SOS). SAXS results showed that the size of SAS/DHSB wormlike micelles was primarily determinate by surfactants with longer hydrophobic tails.

Emulsion-induced polymersomes taming tetrodotoxin for prolonged duration local anesthesia.

Injectable local anesthetics that can provide a continuous nerve block approximating the duration of a pain state would be a life-changing solution for patients experiencing post-operative pain or chronic pain. Tetrodotoxin (TTX) is a site 1 sodium channel blocker that is extremely potent compared to clinically used local anesthetics. Challengingly, TTX doses are limited by its associated systemic toxicity, thus shortening the achievable duration of nerve blocks. Here, we explore emulsion-induced polymersomes (EIP) as a drug delivery system to safely use TTX for local anesthesia. By emulsifying hyperbranched polyglycerol-poly (propylene glycol)-hyperbranched polyglycerol (HPG-PPG-HPG) in TTX aqueous solution, HPG-PPG-HPG self-assembled into micrometer-sized polymersomes within seconds. The formed polymersomes have microscopically visible internal aqueous pockets that encapsulate TTX with an encapsulation efficiency of up to 94%. Moreover, the polymersomes are structurally stable, enabling sustained TTX release. In vivo, the freshly prepared EIP/TTX formulation can be directly injected and increased the tolerated dose of TTX in Sprague-Dawley rats to 11.5 μg without causing any TTX-related systemic toxicity. In the presence of the chemical penetration enhancer (CPE) sodium octyl sulfate (SOS), a single perineural injection of EIP/TTX/SOS formulation produced a reliable sciatic nerve block for 22 days with minimal local toxicity.

Affinity and putative entrance mechanisms of alkyl sulfates into the β-CD cavity

Cyclodextrins (CDs) are novel pharmaceutical excipients and are widely used in the pharmaceutical industry and drug delivery due to their ability to form host–guest complexes. There are countless structural features of guest molecules responsible for the efficiency of guest–CD interactions. Among these factors, the hydrophobic moieties of a guest and their size are commonly considered to govern its binding affinity to CD molecules. Experimentally, it is often challenging to extract structural and dynamic information at the atomic scale about CD inclusion complexes, especially in the aqueous phase. Therefore, this study consisted of experimental (isothermal titration calorimetry and conductometric titration) and in silico analysis to rigorously characterize the interactions of β -CD with three alkyl sulfates of different hydrophobic chain lengths: sodium dodecyl sulfate (S12S), sodium decyl sulfate (S10S) and sodium octyl sulfate (S8S) in aqueous solutions. We find that the hydrophobic interactions are not always a key factor leading to the formation of stable inclusion complexes. Our results demonstrate that van der Waals interactions contribute more to complexation efficiency for sulfates with a longer hydrophobic tail, whereas electrostatic interactions are more pronounced for sulfates with shorter ones. Furthermore, we propose and discuss for the first time the putative mechanisms of the guest entering the host cavity conditioned by the lengths of hydrocarbon chains of alkyl sulfates. Finally, we prove that different types of inclusion complexes can exist in a conformational equilibrium depending on the size of a guest tail.

MaAts, an Alkylsulfatase, Contributes to Fungal Tolerances against UV-B Irradiation and Heat-Shock in Metarhizium acridum

Sulfatases are commonly divided into three classes: type I, type II, and type III sulfatases. The type III sulfatase, alkylsulfatase, could hydrolyze the primary alkyl sulfates, such as sodium dodecyl sulfate (SDS) and sodium octyl sulfate. Thus, it has the potential application of SDS biodegradation. However, the roles of alkylsulfatase in biological control fungus remain unclear. In this study, an alkylsulfatase gene MaAts was identified from Metarhizium acridum. The deletion strain (ΔMaAts) and the complemented strain (CP) were constructed to reveal their functions in M. acridum. The activity of alkylsulfatase in ΔMaAts was dramatically reduced compared to the wild-type (WT) strain. The loss of MaAts delayed conidial germination, conidiation, and significantly declined the fungal tolerances to UV-B irradiation and heat-shock, while the fungal conidial yield and virulence were unaffected in M. acridum. The transcription levels of stress resistance-related genes were significantly changed after MaAts inactivation. Furthermore, digital gene expression profiling showed that 512 differential expression genes (DEGs), including 177 up-regulated genes and 335 down-regulated genes in ΔMaAts, were identified. Of these DEGs, some genes were involved in melanin synthesis, cell wall integrity, and tolerances to various stresses. These results indicate that MaAts and the DEGs involved in fungal stress tolerances may be candidate genes to be adopted to improve the stress tolerances of mycopesticides.

Simultaneous adsorption of anionic alkyl sulfate surfactants onto alpha alumina particles: Experimental consideration and modeling

Simultaneous adsorption of four anionic alkyl sulfate (AS) surfactants, including sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate and sodium tetradecyl sulfate named as C8, C10, C12 and C14, onto alpha alumina (α-Al2O3) particles were systematically investigated. Concentrations of all mixtures of anionic AS surfactants in aqueous solution were quantified by capillary electrophoresis coupled with contactless conductivity detection (CE-C4D). Adsorption isotherms of the four anionic AS surfactant homologs increased with either the decrease of pH from 6.0 to 4.0 due to enhancement of electrostatic attractions between the positively charged α-Al2O3 surface and the anionic AS surfactants or the increase of carbon chain length due to enhanced hydrophobic interactions. At different salt concentrations, a common intersection point (CIP) obtained for adsorption isotherms demonstrated that the contributions of electrostatic and hydrophobic interactions were reversed. The ionic strength effect on anionic AS surfactant adsorption isotherms onto α-Al2O3 particles was thoroughly studied. Simultaneous adsorption of the four AS surfactants onto the α-Al2O3was controlled by both electrostatic and hydrophobic interactions that were in accordance with Langmuir and two-step models.

Using surfactants as matrix for the matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) of amino acids: Sodium dodecyl sulfate (SDS) and sodium octyl sulfate (SOS)

In the present study, the applicability of two surfactants including sodium dodecyl sulfate (SDS) and sodium octyl sulfate (SOS) as the matrix for the Matrix-Assisted Laser Desorption/Ionization (MALDI) of several amino acids (phenylalanine (Phe), valine (Val), proline (Pro), alanine (Ala), and tyrosine (Tyr)) is investigated. Also, the effect of the material of the repeller plate of the ionization part of the used time of flight (TOF) mass spectrometer on the spectral patterns of the amino acids is studied. Furthermore, the recorded MALDI spectra of amino acids are compared with their corresponding direct laser desorption/ionization (direct-LDI) TOF mass spectra. It is observed that the SDS is an appropriate matrix for the Na+ transfer to the Phe and Val amino acids, especially, when the Ag metal is selected as the material of the repeller plate. In this case, the peaks of the [M + Na]+ and [M-H + 2Na]+ species are considerably more intense compared to when the NaF salt is used as a Na+ source in the LDI of these amino acids. Unlike Phe and Val, the SDS is not a good matrix for the other selected amino acids. The decrease of the carbonic chain length of the surfactant on the MALDI spectrum of Phe is investigated and it is seen that the mentioned important peaks disappeared in the presence of SOS as the matrix. The density functional theory (DFT) calculation is employed to characterize the structure of [M + Na]+ and [M-H + 2Na]+ species and determine the interaction sites of amino acids for the Na+ attachment. Also, the change in standard Gibbs free energy (∆G°) of the M + Na+ → [M + Na]+ and [M + Na]+ + Na+ → [M-H + 2Na]+ + H+ reactions are calculated. Based on the values of ∆G°, the attachment of the first Na+ to the amino acid takes place in the gas phase while the attachment of the second one to [M + Na]+ is not a favorable process in the gas phase.

Interactions of organosulfates with water vapor under sub- and supersaturated conditions

Abstract. Organosulfates (OSs) are important constituents of secondary organic aerosols, but their hygroscopic properties and cloud condensation nucleation (CCN) activities have not been well understood. In this work we employed three complementary techniques to characterize interactions of several OSs with water vapor under sub- and supersaturated conditions. A vapor sorption analyzer was used to measure mass changes in OS samples with relative humidity (RH, 0 %–90 %); among the 11 organosulfates examined, only sodium methyl sulfate (methyl-OS), sodium ethyl sulfate (ethyl-OS), sodium octyl sulfate (octyl-OS) and potassium hydroxyacetone sulfate were found to deliquesce as RH increased, and their mass growth factors at 90 % RH were determined to be 3.65 ± 0.06, 3.58 ± 0.02, 1.59 ± 0.01 and 2.20 ± 0.03. Hygroscopic growth of methyl-, ethyl- and octyl-OS aerosols was also studied using a humidity tandem differential mobility analyzer (H-TDMA); continuous hygroscopic growth was observed, and their growth factors at 90 % RH were determined to be 1.83 ± 0.03, 1.79 ± 0.02 and 1.21 ± 0.02. We further investigated CCN activities of methyl-, ethyl- and octyl-OS aerosols, and their single hygroscopicity parameters (κccn) were determined to be 0.459 ± 0.021, 0.397 ± 0.010 and 0.206 ± 0.008. For methyl- and ethyl-OS aerosols, κccn values agree reasonably well with those derived from H-TDMA measurements (κgf) with relative differences being < 25 %, whereas κccn was found to be ∼ 2.4 times larger than κgf for octyl-OS, likely due to both the solubility limit and surface tension reduction.

Heteroaggregation and Homoaggregation of Latex Particles in the Presence of Alkyl Sulfate Surfactants

Heteroaggregation and homoaggregation is investigated with time-resolved multi-angle dynamic light scattering. The aggregation rates are measured in aqueous suspensions of amidine latex (AL) and sulfate latex (SL) particles in the presence of sodium octyl sulfate (SOS) and sodium dodecyl sulfate (SDS). As revealed by electrophoresis, the surfactants adsorb to both types of particles. For the AL particles, the adsorption of surfactants induces a charge reversal and triggers fast aggregation close to the isoelectric point (IEP). The negatively charged SL particles remain negatively charged and stable in the whole concentration range investigated. The heteroaggregation rates for AL and SL particles are fast at low surfactant concentrations, where the particles are oppositely charged. At higher concentrations, the heteroaggregation slows down above the IEP of the AL particles, where the particles become like-charged. The SDS has higher affinity to the surface compared to the SOS, which induces a shift of the IEP and of the fast aggregation regime to lower surfactant concentrations.

Effect of sulfate group-containing fuels on the morphology of ZnO powders prepared by solution combustion synthesis

Zinc oxide (ZnO) powders were synthesized via solution combustion route using sodium octyl sulfate (SOS) as a sulfate group containing-anionic surfactant and sodium lauroyl sarcosinate (SLS) surfactant. Combustion behavior, phase evolution, microstructure, textural and optical properties of ZnO powders were investigated by thermal analysis, X-ray diffractometry, scanning electron microscopy, N2 adsorption–desorption isotherms, and diffuse reflectance and photoluminescence spectroscopy techniques as a function of both fuel type and fuel amount. A specific correlation between the fuel type and the morphology of ZnO powder was established on the base of the presence/absence of sulfate group in the fuel. The ZnO powders obtained by the sulfate group-containing fuel (SOS) were composed of sheet-like particles, whereas the SLS fuel led to quasi-spherical and cuboid-like particles. The sheet-like morphology was more appeared at the stoichiometric fuel amount.

The Role of Anionic Surfactant to the Particle Size Reduction of Conductive PANi

The conductive polyaniline (PANi) with fine particles of sizes from 724 nm down to 191 nm has been successfully synthesized through chemical oxidation reaction. The synthesis of PANi was carried out in acidic media under HCl 1.5 M solution using ammonium persulphate (APS) as an oxidizing agent in the presence of anionic surfactants. Two different types of surfactant respectively Sodium Octyl Sulphate (SOS) and Sodium Dodecyl Sulphate (SDS) were brought into an investigation on the effect of the surfactant chain length of C8 and C12 to the particle size formation. Such molecular chain length is responsible for the particle size growth rate. It was found that the average particle size of PANi decreased gradually by the addition of SOS and SDS surfactants with 1 % concentration each. The particle of PANi with sizes 296 nm and 191 nm was obtained as analyzed by Particle Size Analyzer (PSA). These sizes are far below 724 nm, which obtained from the same reaction but with surfactant free. Other supporting indicators showed that the pH of reaction solution was somewhat more acidic after 7 hours of reaction when the surfactant with pH value range within 0.7 – 1.4 presence. The temperature of solution increased with time following the energy released reached 30-31°C within the first 30 minutes, which was lower when compared with that of surfactant free.

Increased Electrical Conductivity of PANi: Anionic Surfactant Addition during Emulsion Polymerization

AbstractElectrically conductive polyaniline (PANi) doped with anionic surfactants is successfully synthesized and characterized. The conductive PANi is prepared by chemical oxidation polymerization reaction with the addition of two types of anionic surfactant solutions respectively 1% Sodium Octyl Sulfate (NaC8H17SO4, SOS) and Sodium Dodecyl Sulfate (NaC12H25SO4, SDS), followed by doping with a strong perchloric acid (HClO4). The addition of each surfactant solution has increased the electrical conductivity value of surfactant free PANi from 0.089 to 1.16 S cm−1 (SOS) and 1.12 S cm−1 (SDS) respectively. The viscosity value of surfactant free PANi is 1.97 mPa s which is much lower when compared with those of PANi containing surfactants in which the value is 3.58 and 4.20 mPa s for 1% of SDS added PANi each. The chain length of anionic surfactant has no major effect on the conductivity of PANi. The latter is only affected by the presence of SO3− group in hydrophobic part of surfactant.

Improved performance of thin-film nanofiltration membranes fabricated with the intervention of surfactants having different structures for water treatment

We fabricated thin-film composite nanofiltration polyamide membranes through the interfacial polymerization of two monomers: polyethyleneimine (PEI) and trimesoyl chloride (TMC). Three different types of surfactants with varied chemical structures were added to aqueous PEI solutions: sodium dodecyl sulfate (SDS), sodium octyl sulfate, and sodium dodecylbenzenesulfonate; the aim was to improve the rejection of divalent ions. Adding the surfactants led to increased isoelectric point, and, in turn, enhanced the membrane hydrophilic properties, heightened the membrane surface charge, and augmented the rejection of MgCl2. Among the three surfactants, SDS effected the most favorable conditions: the resultant composite membrane delivered the highest pure water flux (44.87 ± 3.22 L∙m−2∙h−1), and exhibited high rejections of divalent salts (RNa2SO4 = 92.26 ± 3.30%; RMgSO4 = 93.83 ± 3.22%; RMgCl2 = 94.15 ± 2.52%). SDS had long alkane chains and highly polar heads, which were conducive to bringing about an effective interaction between PEI and the polysulfone (PSf) support, thereby increasing the sorption of PEI in PSf. Accordingly, the reaction of PEI with TMC produced more amide and amine functional groups that were instrumental in raising the rejections of divalent salts and enhancing the membrane surface properties.

A Generalized Theoretical Model for the Relationship Between Critical Micelle Concentrations, Pressure, and Temperature for Surfactants

AbstractDirectional solvent extraction (DSE) has been gaining interest as a water treatment technology in recent years. DSE utilizes the process of micellization for the purposes of species separation between water and complex chemical systems. In this article, we develop a conformal geometric algebra‐based formulation that models surfactants, their solubilities, and critical micelle concentration (CMC), with relation to temperature and pressure. Molecules are represented as spatially distributed networks embedded in R4,1 space, and the mathematical characterizations of these molecules are shown to be effective in modelling CMC as a function of temperature and pressure. One of the contributions of this work is the utilization of this formulation to develop a governing expression, in the form of a three‐dimensional relationship, between CMC, pressure, and temperature for a general surfactant. In prior works, the CMC–temperature plane and CMC–pressure plane expressions have been extensively documented for sodium alkyl sulfates. In this work, we extend the formulation to model the CMC of decanoic acid, sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate, and sodium tetradecyl sulfate. Using this theoretical model, a relationship between CMC and the directional solubility of water in a surfactant is determined. Directional solubility is related to temperature and pressure, and on this basis, we devise a directional solubility–pressure–temperature expression for an arbitrary surfactant to improve the state of the art for DSE. From this expression, we propose a novel isothermal DSE process for water treatment.