Concentrations Of Anionic Surfactants Research Articles

In-syringe magnetic stirring-assisted dispersive liquid–liquid microextraction for automation and downscaling of methylene blue active substances assay

A simple and rapid method for the determination of the methylene blue active substances assay based on in-syringe automation of magnetic stirring-assisted dispersive liquid–liquid microextraction was developed. The proposed method proved to be valid for the determination of anionic surfactant in waste, pond, well, tap, and drinking water samples.Sample mixing with reagents, extraction and phase separation were performed within the syringe of an automated syringe pump containing a magnetic stirring bar for homogenization and solvent dispersion. The syringe module was used upside-down to enable the use of chloroform as an extraction solvent of higher density than water.The calibration was found to be linear up to 0.3mg/L using only 200µL of solvent and 4mL of sample. The limits of detection (3σ) and quantification (10σ) were 7.0µg/L and 22µg/L, respectively. The relative standard deviation for 10 replicate determinations of 0.1mg/L SBDS was below 3%. Concentrations of anionic surfactants in natural water samples were in the range of 0.032–0.213mg/L and no significant differences towards the standard method were found. Standard additions gave analyte recoveries between 95% and 106% proving the general applicability and adequateness of the system to MBSA index determination. Compared to the tedious standard method requiring up to 50mL of chloroform, the entire procedure took only 345s using 250-times less solvent.

Quantitative determination of anionic surfactants using optical sensors with microtiter plate reader

In this study, it is shown that anionic surfactants can be readily determined by using polymer film-based optodes containing an appropriate chromoionophore. The optodes are prepared with poly(vinyl chloride) (PVC), polyurethane (PU), bis(2-ethylhexyl) sebacate (DOS), and 2′,7′-dichlorofluorescein octadecylester (DCFOE). These optodes exhibit reproducible and sensitive absorbance changes in response to the varying titrant concentrations. Three different cationic surfactants, cetyltrimethylammonium bromide (CTAB), benzyldimethyltetradecylammonium chloride (zephiramine, Zeph), and benzyldimethylhexadecylammonium chloride (CDB), are employed as titrants to determine anionic surfactant concentrations. In addition, membrane electrodes were also employed for estimating the interactions between the cationic and anionic species. The reaction stoichiometries are compared based on the electrode measurements and Scatchard plots are prepared to estimate the strength of binding interaction of titrants with the target surfactants.

Advanced synthesis for monodisperse polymer nanoparticles in aqueous media with sub-millimolar surfactants

Highly monodisperse polystyrene nanoparticles with mean diameters of less than 100 nm are synthesized via aqueous emulsion polymerization using an amphoteric initiator (VA-057) in the presence of sub-millimolar concentrations of anionic surfactant. Since the net charge on the initiator is almost zero at neutral pH, the resultant latex particle size is mainly determined by surfactant adsorption. Polymerizations were performed in the presence of a range of anionic surfactants with differing critical micelle concentrations (CMC) by varying the concentrations of surfactant, initiator and monomer, and also the ionic strength. Sodium dodecyl benzene sulfonate (SDBS), sodium hexadecyl sulfate (SHS), and sodium octadecyl sulfate (SOS) have relatively low CMCs and so enable formation of highly monodisperse nanoparticles at relatively low (sub-millimolar) surfactant concentrations, CS (i.e. below the CMC in each case). Empirically, it was found that the particle number, Np, and coefficient of variation of the particle size, CV, were strongly dependent on the CS/CMC ratio: Np increased almost in proportion with the square of this ratio, while the CV exhibited a minimum at approximately CS/CMC = 0.20. Higher ionic strength reduced the particle size, which is consistent with the above relationship because the addition of salt lowers the CMCs of ionic surfactants. Polymer latex particles produced using such formulations form highly regular, close-packed colloidal arrays.

Detecting the micellization of anionic surfactants by a colorimetric and fluorescent probe based on electrostatic attraction

A novel fluorescent probe labeled with cation, N-n-alkyl-4-(1-methylpiperazine)-1,8-naphthalimide iodide ([C8ndi]I), has been applied as a colorimetric and fluorometric probe for detecting the micellization of anionic surfactants. The critical micellization concentration (cmc) of anionic surfactants can be conveniently determined by the change on absorption and fluorescence spectra of [C8ndi]I. The probe displays highly sensitive and selective spectroscopic responses accompanied with distinctive color change (from colorless to light green). These methods are proved to be reliable as the results are in accordance with those of the standard methods. Besides the advantage of visual detection, the multiple spectroscopic methods (absorption and fluorescence) by using [C8ndi]I as probe are also simple and convenient. One can choose any spectroscopic parameter, such as position or intensity of the absorption and emission peaks, to monitor the micelle formation process of anionic surfactants.

Quantitative Theory of Adsorptive Separation for the Electronic Sorting of Single-Walled Carbon Nanotubes

Recently, several important advances in techniques for the separation of single-walled carbon nanotubes (SWNTs) by chiral index have been developed. These new methods allow for the separation of SWNTs through selective adsorption and desorption of different (n,m) chiral indices to and from a specific hydrogel. Our group has previously developed a kinetic model for the chiral elution order of separation; however, the underlying mechanism that allows for this separation remains unknown. In this work, we develop a quantitative theory that provides the first mechanistic insights for the separation order and binding kinetics of each SWNT chirality (n,m) based on the surfactant-induced, linear charge density, which we find ranges from 0.41 e(-)/nm for (7,3) SWNTs in 17 mM sodium dodecyl sulfate (SDS) to 3.32 e(-)/nm for (6,5) SWNTs in 105 mM SDS. Adsorption onto the hydrogel support is balanced by short-distance hard-surface and long-distance electrostatic repulsive SWNT/substrate forces, the latter of which we postulate is strongly dependent on surfactant concentration and ultimately leads to gel-based single-chirality semiconducting SWNT separation. These molecular-scale properties are derived using bulk-phase, forward adsorption rate constants for each SWNT chirality in accordance with our previously published model. The theory developed here quantitatively describes the experimental elution profiles of 15 unique SWNT chiralities as a function of anionic surfactant concentration between 17 and 105 mM, as well as phenomenological observations of the impact of varying preparatory conditions such as extent of ultrasonication and ultracentrifugation. We find that SWNT elution order and separation efficiency are primarily driven by the morphological change of SDS surfactant wrapping on the surface of the nanotube, mediated by SWNT chirality and the ionic strength of the surrounding medium. This work provides a foundational understanding for high-purity, preparative-scale separation of as-produced SWNT mixtures into isolated, single-chirality fractions.

Effect of anionic surfactant concentration on the variable range hopping conduction in polypyrrole nanoparticles

The mechanism of charge transport in polypyrrole (PPy) nanoparticles prepared with different concentrations (5 to 30 mM) of anionic surfactant (sodium dodecyl sulfate) is reported. Transmission electron microscopy technique confirms the formation of PPy nanoparticles of sizes ∼52 to 28 nm under surfactant directed approach. The room temperature electrical conductivity of the prepared nanoparticles found to increase from 3 to 22 S/cm with surfactant concentration. The temperature dependent activation energy rules out the possibility of band conduction mechanism in the prepared PPy nanoparticles and thus the synthesized nanoparticles are analyzed under variable range hopping (VRH) model for conduction mechanism. The PPy nanoparticles, reduced with liquid ammonia, hold 3D VRH conduction mechanism for the charge transport. However, in the doped samples, some deviation from 3D VRH conduction behavior at higher temperatures (>150 K) has been observed. This may be attributed to the presence of anionic surfactant in these samples. The doping of anionic surfactant causes rise in conducting islands, which may lead to the change in the shape/distribution of density of states governed by Gaussian or exponential type near Fermi level.

Surfactants in Runoff Water at Different Locations in Bandar Baru Bangi, Selangor, Malaysia

A study has been conducted to determine the composition of surfactants in runoff water in the semi-urban area of Bandar Baru Bangi, Selangor, Malaysia. Runoff samples were collected from five different locations with contrasting functional activities and the colorimetric method was used to analyze the concentrations of surfactants as methylene blue active substances (MBAS) for anionic surfactants and as disulphine blue active substances (DBAS) for cationic surfactants. The results showed that the highest surfactant concentrations of MBAS and DBAS in runoff water were recorded in the samples collected at the residential area, with the concentrations of 3.192 ± 0.727 and 0.170 ± 0.028 μmol/L, respectively. Anionic surfactants as MBAS were found to dominate the concentration of surfactants in both runoff and rainwater. The concentrations of both anionic and cationic surfactants in runoff water were recorded as being higher than in rainwater.

Influence of Surfactant and Salt Concentration on the Rheological Properties of Three Different Microstructures of Associative Polyelectrolytes Obtained by Solution Polymerization

The rheological properties of three different microstructures of hydrophobically modified alkalisoluble polymers (telechelic, multisticker and combined) in the presence of various concentrations of anionic surfactant and salt (NaCl) were investigated. Associative polymers containing both ionic sites and small number of hydrophobic groups were obtained, and their thickening properties in aqueous solutions, were investigated. Solution polymerization was used for obtaining the different polymers. Relationships between hydrophobe, sodium dodecyl sulfate (SDS) and NaCl concentration are proposed. Owing to the competition between attractive hydrophobic interaction and repulsive electrostatic interactions, such hydrophobically modified polymers exhibit various rheological behaviors in aqueous solutions, depending on microstructure of polyelectrolyte, SDS and NaCl concentrations.

Influence of Surfactants on the Removal of AOX Using Micellar- Enhanced Ultrafiltration

This paper presents the development of a model for evaluating adsorbable organic halogens’(AOX) removal efficiency during wastewater treatment by using the micellar-enhanced ultrafiltration (MEUF)technique. Surfactants can form larger aggregates (micelles) were prepared into which AOXs dissolve and arethen retained by the membrane. Synthetic wastewater samples containing certain concentrations of surfactants, AOXs, and electrolytes (expressed in terms of conductivity). Regression analysis was used to examine firstly, the effect of anionic surfactants concentrations, and those of non-ionic surfactants and electrolytes on AOX removal and secondly, the effects of anionic and non-ionic surfactants removal efficiences, and electrolytes, on AOXs removal. A relationship was generated for each of the components, showing the removal of AOX as a linear functions of the concentrations of each component. The equations were validated through variance analysis. This study shows that AOXs removal efficiencies largely depend on the formation and removal of anionic surfactant micelles from the membrane. The equations obtained during this study could be used for predicting the extent to which AOXs can be removed if the input parameters are known.

Synthesis and Characteristic of Precipitated Nano-Silica

The reaction of precipitation of amorphous silicon dioxide from aqueous solution of sodium silicate and sulfuric acid has been studied. The factors affecting the precipitation process of the sodium silicate solution such as sodium silicate concentration and addition of anionic surfactant (sodium dodecyl sulfate, SDS) on particle size, size distribution and degree of agglomeration of the precipitated silica were examined. The precipitation of silica from the produced sodium silicate solution was carried out using sulfuric acid at pH 7. Scaning electron microscope (SEM), transmission electron microscope (TEM) and Dynamic light scattering (DLS) have been used for characterization of the produced nano-silica. The surface area of silica was tested by oil absorption method according to ASTM standard. Results showed that the particle size of the precipitated silica gel was decreased with increasing Na2SiO3 and SDS concentrations and Particle size of about 44nm can be achieved at 20% Na2SiO3 and 200ppm SDS. But with decreasing particle size, degree of agglomeration also increased.

Determination of Surfactants in Environmental Samples. Part II. Anionic Compounds

Abstract Surface active agents (SAA) with negative charge of polar group are named as anionic compounds. They are the main constituent of most products containing synthetic surfactants. The linear alkylbenzene sulfonates (LAS), alkyl ethoxysulfates (AES) and alkyl sulfates (AS) are typically applied from this class of compounds. Those surfactants are ingredients of household detergents and cleaners, laundry detergents, cosmetic etc. Moreover they can be applied in the paper, textile and tanning industry as optical brighteners, dispersant, wetting and suspending agents. They can be substrates in the formulation of different products like dyes, pigments, pesticides, exchange resins, plasticizers and pharmaceuticals. Anionic surfactants after use are passed into sewage-treatment plants, where they are partially degraded and adsorbed to sewage sludge (applied in agriculture fields). Finally, the anionic SAA or their degradation products are discharged into surface waters and onto bottom sediments, soils or living organisms. Therefore, it is important (widely application, bioaccumulation, toxicity for living organisms) to investigate the environmental fate of those class of compounds in more details. This research involves determination the concentration of anionic surfactants with use appropriated analytical techniques in environmental samples The official methodology for determination of anionic SAA in liquid samples is based on the ion-pair reaction of these analytes compounds with methylene blue (MB) and an extraction with toxic solvent chloroform. During isolation step of anionic compounds from solid samples are employed Soxhlet and ultrasonic-assisted extraction techniques with use of methanol or mixture of other organic solvents as extraction medium. To overcome disadvantages of those traditional techniques were applied following techniques at sample preparation step from liquid and solid matrices: solid-phase extraction (SPE) and solid-phases microextraction (SPME); accelerated solvent extraction (ASE), microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), respectively. For estimate total concentration of anionic analytes in extracts the spectrophotometric technique is used (as official regulation). For determination concentration of individual analytes were applied gas (derivatization step requires) and liquid chromatography mainly with mass spectrometry technique. The presence of anionic surface active agents was confirmed in various ecosystems (liquid and solid environmental samples).

Adsorption of CnTABr surfactants on activated carbons

Cationic surfactants of the quaternary ammonium bromide type C16TABr, C14TABr, C12TABr, and C10TABr were adsorbed from aqueous solutions onto three different types of activated carbons and compared with the adsorption of the anionic surfactant sodium dodecyl benzene sulfonate. The concentrations of both cationic and anionic surfactants in aqueous solutions were determined by UV spectroscopy. In the case of anionic surfactants, a linear dependence of UV absorbance on the surfactant concentration at 200nm can be related to the benzene fragment of the molecule. The UV sensitivity of CnTABr solutions is controlled by the hydration of bromide counterions, the electron dense nature of bromine, and a charge-transfer-to-solvent phenomenon. Changes in the textural properties of the activated carbons after adsorption of surfactants were studied by N2 adsorption and mercury intrusion porosimetry, and could be correlated to surface characteristics and adsorptive capacity. The mechanism of adsorption was found to be complex, but the porous structure of the carbon exerted a critical role and the cationic surfactants were adsorbed step-by-step. At low surfactant concentrations, adsorption occurred in micropores. We conclude that surfactants are adsorbed as individual molecules. Adsorption from more concentrated solutions occurs in meso- and macropores, and resembles surfactant adsorption on flat carbon surfaces. The carbons display somewhat different tendencies to adsorb CnTABr. Activated carbons with small pores of 0.56-0.77nm appear to be most effective for surfactant removal. A negative electrostatic potential on the interface of the carbons appears to enhance the adsorption of cationic surfactants, as would be expected. Controlling the electrostatic potential and pore size distribution of the activated carbons would be beneficial in the application of activated carbons for removal of surfactants from wastewater.

Static adsorption of anionic surfactant onto crushed Berea sandstone

Surfactant adsorption in porous media is one of the major criteria which decide the economic viability of surfactant flooding in chemical enhance oil recovery applications (CEOR). In this study, the static adsorption of a novel in-house synthesized anionic surfactant was investigated onto crushed Berea sandstone. The point of zero (PZC) charge for Berea sandstone and critical micelle concentration (CMC) of anionic surfactant are also reported in this paper. The investigated PZC for Berea core was at pH 8.0 and the maximum adsorption of anionic surfactant was 0.96 mg/g. Furthermore, the effects of alkali, salinity and temperature on static adsorption of anionic surfactant were investigated at variable conditions. It was concluded that the anionic surfactant performs better at higher pH, higher temperature and lower salt concentration. An effective control of all these parameters can lead to the situation which helps in minimizing the surfactant loss and improved economic efficiency of CEOR process.

Degradation of surface-active compounds in a constructed wetland determined using high performance liquid chromatography and extraction spectrophotometry

Degradation of anionic and nonionic surfactants in a constructed wetland with horizontal subsurface flow was studied using high performance liquid chromatography and extraction spectrophotometry. The ratio of individual homologues of linear alkylbenzene sulfonates (LAS) and the efficiency of their removal were studied. Tridecyl-, dodecyl-, undecyl-, and decylbenzene sulfonates were removed with efficiencies of 92.9%, 84.3%, 64.7%, and 41.1%, respectively. These differences are due to sequential shortening of the alkyl chain in homologues during degradation (the higher homologue can provide the lower one). The formation of sulfophenyl carboxylic acids during ω-oxidation of the alkyl chain followed by successive α- and/or β-oxidation is also a possible mechanism for removal of LAS. Solid phase extraction using Chromabond® HR-P columns was used for preconcentration of the analytes prior to their determination by HPLC. Methylene blue active compounds were determined using extraction spectrophotometry. The average efficiency of their removal was 84.9% in this case. The efficiency of nonionic surfactant removal (98.2%) was significantly higher in comparison to that for anionic surfactants. The concentration of the endocrine disruptor nonylphenol (a product of nonylphenol polyethoxylate surfactant degradation) determined in the profile of the wetland was beneath the limit of detection (0.4 μg/L). The average outflow concentrations of anionic and nonionic surfactants determined by spectrophotometry were 0.54 and 0.021 mg/L, respectively. The average outflow concentrations of decyl- and tridecylbenzene sulfonates determined by HPLC were 0.195 and 0.015 mg/L. Efficiencies of 86.4% and 92.2% were obtained for removal of organic compounds as indicated by chemical and biochemical oxygen demand (CODCr and BOD5). These results demonstrate the suitability of the constructed wetland for degrading surface-active compounds.

Composition and source apportionment of surfactants in atmospheric aerosols of urban and semi-urban areas in Malaysia

This study was conducted to determine the composition and source apportionment of surfactant in atmospheric aerosols around urban and semi-urban areas in Malaysia based on ionic compositions. Colorimetric analysis was undertaken to determine the concentrations of anionic surfactants as Methylene Blue Active Substances (MBAS) and cationic surfactants as Disulphine Blue Active Substances (DBAS) using a UV spectrophotometer. Ionic compositions were determined using ion chromatography for cations (Na+, NH4+, K+, Mg2+, Ca2+) and anions (F−, Cl−, NO3-, SO42-). Principle component analysis (PCA) combined with multiple linear regression (MLR) were used to identify the source apportionment of MBAS and DBAS. Results indicated that the concentrations of surfactants at both sampling sites were dominated by MBAS rather than DBAS especially in fine mode aerosols during the southwest monsoon. Three main sources of surfactants were identified from PCA-MLR analysis for MBAS in fine mode samples particularly in Kuala Lumpur, dominated by motor vehicles, followed by soil/road dust and sea spray. Besides, for MBAS in coarse mode, biomass burning/sea spray were the dominant source followed by motor vehicles/road dust and building material.

Correlation Between Surfactants and Heavy Metals in a Natural Lake

There is some concern that when heavy metals and surfactants exist together in the environment, the surfactants will affect the transport and fate of the heavy metals. This study was conducted to determine the presence of surfactants and heavy metals in a natural lake's surface microlayer and in rainwater from seven locations in the Lake Chini area in Malaysia. Colorimetric analysis was used to determine the concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). Inductively coupled plasma mass spectrometry was used to determine the concentration of heavy metals such as Cu, Pb, Zn, Fe, Cd, and Ni. The results indicated that the average concentrations of MBAS and DBAS in the lake's surface microlayer were higher in the dry season (0.27 ± 0.06 and 0.22 ± 0.02 μmol L−1) than in the wet season (0.22 ± 0.03 and 0.19 ± 0.02 μmol L−1). The average concentrations of MBAS and DBAS in rainwater were 0.21 ± 0.02 μmol L−1 and 0.18 ± 0.02 μmol L−1, respectively. Surfactants in the lake's surface microlayer were found to be positively correlated with Pb, Cd, Zn (p < 0.01) and with Ni (p < 0.05). These findings have implications when evaluating fate & transport of metals in the presence of surfactants that could be useful in environmental forensic investigations.

In-Sewer Aerobic and Anaerobic Laboratory-Scale Degradation Study of Organic Pollutants in Sewage

The course of the degradation of pollutants in terms of chemical oxygen demand (COD), soluble COD (SCOD), phenols, and anionic surfactants was examined both aerobically and anaerobically in sewer-like conditions. The rates of COD and SCOD degradation under aerobic condition were 0.051 and 0.052 mg/L/h, respectively. COD concentration remained unchanged during anaerobic process. However, SCOD was observed to increase with a production rate of 0.010 mg/L/h. The concentration of phenols was observed to decrease at a rate of 0.0211/h remained constant during the anaerobic process. The same profile was observed in the concentration of anionic surfactants, wherein the rate of degradation was 0.0454/h aerobically, and the concentration profile remained constant.

Improving liquid-crystal-based biosensing in aqueous phases.

Liquid crystal (LC)-based biological sensors permit the study of aqueous biological samples without the need for the labeling of biological species with fluorescent dyes (which can be laborious and change the properties of the biological sample under study). To date, studies of LC-based biosensors have explored only a narrow range of the liquid crystal/alignment layer combinations essential to their operation. Here, we report a study of the role of LC elastic constants and the surface anchoring energy in determining the sensitivity of LC-based biosensors. By investigating a mixture of rod-shape and bent-shape mesogens, and three different alignment layers, we were able to widen the useful detection range of a LC-based sensor by providing an almost-linear mapping of effective birefringence with anionic surfactant concentrations between 0.05 mM and 1 mM (model target analyte). These studies pave the way for optimization of LC-based biosensors and reveal the importance of the choice of both the LC material and the alignment layer in determining sensor properties.

A process for preparing polyethylene wax microspheres and optimization of their dissolution precipitation by response surface methodology

AbstractPolyethylene wax (PEW) microspheres were prepared by the dissolution precipitation method using a PEW byproduct as the starting material. The influence of surfactant type on the morphology and melting point of the product was investigated. The effects of each factor, including the concentration of anionic surfactants, cooling rate, and stirring rate, on the particle sizes were studied using a three‐level, three‐factor Box–Behnken design. The experimental parameters were optimized using response surface methodology. The melting point was found to increase when the blend surfactant was employed. The optimal conditions were an anionic surfactant concentration, cooling rate, and stirring rate of 1.0–3.5%, 1.00 °C/s and 1000 rpm, respectively. Under these conditions, the mean particle size was 15 μm, and the highest yield was 94.25%. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

양이온성 계면활성제 거품 지속성 증진방법 연구

This study tried to find a suitable method for enhancing the foam stability of cationic surfactants that normally generate less foam or no foam. Several trials were made to enhance the foam stability: addition of anionic surfactant, colloids and polymer. Cationic starch (CA-ST) did not form foam at all, while the foam stability of two other cationic surfactant also showed low levels; methyl triethanol ammonium methyl sulfate distearyl ester (CEQ90) for 46 sec. and Cetyl trimethyl ammonium chloride (CM29) for 31 seconds. Foam stability of cationic surfactants were significantly affected by addition of anionic surfactant, sodium dodecyl sulfate (SDS). Foam stability of CA-ST was significantly enhanced by addition of SDS, while those of CEQ90 and CM29 were decreased. Addition of colloids (SiO2, kaolin) and polyvinyl alcohol (PVA) enhanced foam stabilities of CEQ90 and CM29. However, CA-ST did not form foam even in the presence of colloids or PVA. Effect of simultaneous addition of colloids and anionic surfactant on foam stability of cationic surfactant showed that foam stability of cationic surfactant was more influenced by addition of anionic surfactant than colloids. Effect of simultaneous addition of PVA and anionic surfactant on the foam stability of cationic surfactant also showed that presence of anionic surfactant significantly affect the foam stability of cationic surfactant. Foam stability of CA-ST was greatly increased to 8,780 seconds by addition of SDS 0.14% and PVA 2.5%. The foam stability of CA-ST was 8 times higher than CEQ 90. This study suggested that cationic surfactants not forming foam can generate foam by addition of anionic surfactant and its stability can be additionally increased by addition of colloids and PVA. The study results showed that enhancement in foam stability of cationic surfactant was prominently affected by the concentration of anionic surfactant added.