Concentration Of Cationic Surfactant Research Articles

Determination of the critical micelle concentration by absorbance and fluorescence techniques using fluorescein probe

We reported a unique and sensitive probe (fluorescein) for determination the critical micelle concentration(CMC) of ionic surfactants based on both fluorescence and absorbance properties of probe in micellar solution. We found that the spectral properties (fluorescence and absorbance) of fluorescein are affected by different types of surfactants. For this purpose spectrophotometric technique using fluorescein as probe to determine the critical micelle concentration of cationic, anionic and zwitterionic surfactants. The critical micelle concentrations of surfactants were determined from the sigmoidal shaped plots or inflection points. The obtained CMC values were in good agreement with the values obtained with conductivity measurements or with literature values.

On the Head Group Effect on Critical Micelle Concentration of Cationic Surfactants Using Molecular Connectivity Indices and Atomic Partial Charges

The influence of the head group structure on the critical micelle concentration of cationic surfactants, mainly quaternary ammonium bromide salts with one alkyl tail, has been studied theoretically by QSPR using molecular connectivity indices and also the atomic partial charges. Two models obtained allow to study the effect of head group structure modification on the value of the critical micelle concentration. The model, which contains molecular connectivity indices together with the charge localized on the central nitrogen atom, has a wider descriptive capability than the model which contains topological indices only. The present semi-empirical charge investigations of different quaternary ammonium salts show that the charges of the quaternary ammonium head groups are approximately the same, but one of the obtained models shows that the significant part of that charge, which is localized on the central nitrogen atom, affects the value of the critical micelle concentration.

Optimization of Biosorption Conditions for Surfactant Induced Decolorization by Anaerobic Sludge Granules

AbstractThe sorption of Remazol Black B (RBB) by dried anaerobic sludge granules (ASG) was examined in this study. The biosorption process was monitored based on the statistical optimization data of the batch reactor studies. In the factorial tests, 36 different tests were established by considering the variables such as temperature (25°C, 50°C), pH (1, 3, 5), dye concentration (100, 150, 200 mg/L) and cationic surfactant concentration (0, 0.5 mM). Also, it was intended to investigate the effect of cationic surfactant dodecyl trimethylammonium bromide (DTAB) on decolorization of the anionic dye RBB by ASG. The sorption isotherms and kinetics were determined for RBB removal. The biosorption of RBB was fitted with Langmuir isotherm and pseudo-second-order kinetic models. The oppositely charged dye and surfactant molecules interacted electrostatically. These electrostatic interactions improved the dye biosorption properties of ASG. Our results indicate that a surfactant can be used as an inducer in the treatment of dye-contaminated water. This is the first paper combining factorial experiment design and surfactant-accelerated decolorization to achieve more effective biosorption conditions.

Effects of a cationic surfactant incorporation in phytantriol bulk cubic phases and dispersions loaded with the anticancer drug 5-fluorouracil

Ordered lyotropic liquid crystalline phases, which are particularly interesting for several biological and biomedical applications, can show the advantage of having a tunable three-dimensional nanostructure. Addition of ionic surfactants to lipid/water binary systems may influence their phase behavior and their structural properties, such as bilayer thickness, water channel diameter and interfacial curvature, resulting in specific amphiphile self-assembly materials. Understanding the effects of such additives is thus of considerable interest and, in this context, we studied the incorporation of a cationic surfactant (didodecyldimethylammonium bromide) in the phytantriol cubic phase, unloaded and loaded with the anticancer drug 5-fluorouracil. In particular, an anionic form of the drug was also used which could further influence the mesophase structure of the lipid matrix and its entrapment efficiency. The formulations, prepared as bulk and dispersed phases, were characterized by synchrotron small angle X-ray scattering, attenuated total reflection Fourier transform infrared and UV–Vis spectroscopies and dynamic light scattering. Addition of increasing amounts of the cationic surfactant resulted in phase changes following the sequence Pn3m-Im3m-Lα, which was almost unaltered when the drug in its neutral form was encapsulated in the systems. On the contrary, the presence of the anionic 5-fluorouracil stabilized the Pn3m cubic phase at all the cationic surfactant concentrations used.

Evaluation of Fabric Softener Formulations with High Concentrations of Cationic Surfactant

AbstractThe study was an attempt to develop fabric softener formulations with a markedly higher content of active substances compared to traditional products. The assumption was to design the formulations in such a manner as to eliminate problems associated with the application of cationic surfactants at high concentrations, and to obtain products exhibiting a high level of quality (products characterized by functionality and usability expected by consumers). The selection of magnesium chloride concentration in products of this type was found to be related to the desired product concentration. It was also demonstrated that by adding salt to concentrated fabric softeners, it is possible to regulate their viscosity and dissolution time in water, and also reduce the viscoelastic properties which are undesirable in the process of manufacture of such products.

Pseudomonas putida Δ9-fatty acid desaturase: Gene cloning, expression, and function in the cationic surfactants stress.

Pseudomonas putida counteract the fluidizing effect of cationic surfactants decreasing the content of membrane unsaturated fatty acid (UFA). A Δ9-fatty acid desaturase gene (desA) from P. putida was isolated, cloned, and successfully expressed in Escherichia coli, a Δ9 desaturase deficient organism. desA consists of 1185 bp and codes for 394 amino acids. The deduced amino acid sequence reveals three histidine clusters and a hydropathy profile, typical of membrane-bound desaturases. Validating desA expression in E. coli cells, the amount of palmitoleic acid increased from 2.05 to 7.36%, with the concomitant increase in membrane fluidity (fluorescence polarization value decrease from 0.13 ± 0.03 to 0.09 ± 0.02). Also, when DesA activity was assayed in vivo, the percentage of UFA obtained from exogenous palmitic acid [1-14 C] increased 10-fold. In contrast, when cells expressing desA were exposed 15 min at sublethal concentration of cationic surfactants, the amount of UFA was 82% lower than that detected in cells non-exposed. Thus, the decrease in UFA content to counteract the fluidizing effect of cationic surfactants can be correlated with reduction of DesA activity.

Simultaneous action of surfactant modified sugarcane bagasse: Adsorbent and antibacterial agent

Simultaneous action of surfactant modified sugarcane bagasse (SBH) for dye adsorption and antibacterial activity were investigated. SBH was subjected for adsorption of cationic dye, methylene blue (MB) and anionic dye, methyl orange (MO). Antibacterial activity of SBH was tested against gram negative bacterium (Escherichia coli ATCC11229) and gram positive bacteria (Enterococcus faecalis ATCC 29212 and Staphylococcus aureus ATCC6538). SBH was prepared by reacting sugarcane bagasse (SB) with different concentrations of cationic surfactant, hexadecyltrimethylammonium bromide HDTMA-Br) (0.1, 1.0 and 4.0 mM). The adsorbed amount of HDTMA-Br onto SBH was determined after modification process. SB and SBH were structurally characterized by FTIR spectroscopy. Results from simultaneous action study demonstrated that SB showed adsorption affinity towards MB and MO while the antibacterial activity of SB increased after the surfactant modification reaction. SB modified with 4.0 mM of HDTMA-Br (SBH4.0) exhibited the highest adsorption capacity and antibacterial activity. SBH demonstrated excellent antibacterial activity against gram negative in comparison to gram positive bacteria. In conclusion, the modification of SB with high concentration of HDTMA-Br enhanced the simultaneous action of cationic and anionic dye adsorption and the antibacterial activity against gram negative bacteria.

Interaction of Dyes with Cationic Surfactants in Solutions: Determination of Critical Micelle Concentration

Interactions of sulforhodamine B or ethyl eosin (as the anionic dye) with cetylpyridinium bromide (as a cationic surfactant) have been investigated by visible spectroscopy in aqueous solution. The object of research is the association between an anion of dye and of cationic surfactant in aqueous solutions and its features. Computer simulation of these interactions was carried out with the use of AM1 and PM3 semi-empirical methods. A new spectrophotometric method was developed for determination of critical micelle concentration of cationic surfactants.

Interaction of Dyes with Cationic Surfactants in Solutions: Determination of Critical Micelle Concentration

Interactions of sulforhodamine B or ethyl eosin (as the anionic dye) with cetylpyridinium bromide (as a cationic surfactant) have been investigated by visible spectroscopy in aqueous solution. The object of research is the association between an anion of dye and of cationic surfactant in aqueous solutions and its features. Computer simulation of these interactions was carried out with the use of AM1 and PM3 semi-empirical methods. A new spectrophotometric method was developed for determination of critical micelle concentration of cationic surfactants.

Catanionic and chain-packing effects on surfactant self-assembly in the ionic liquid ethylammonium nitrate

HypothesisMicelle formation, particularly the formation of compact, globular micelles in the high ionic strength environment of an ionic liquid, seems to be at odds with the principle of opposing forces and the concept of the surfactant packing parameter. Here we examine how interactions between polar head-groups, with solvent ions, and chain packing affect self-assembly structure in ionic liquids. ExperimentsThe self-assembly of pure cationic and anionic surfactants, their catanionic mixtures, and the effect of the cosurfactant tetradecanol in the ionic liquid ethylammonium nitrate (EAN) is investigated by small-angle neutron scattering (SANS). FindingsThe critical micelle concentrations of cationic surfactants are much higher and micelles much smaller in EAN than in water, whereas anionic micelles are less dramatically affected. Catanionic surfactant mixtures form small micelles in EAN at all compositions, unlike their counterparts in water which form vesicle dispersions or precipitates near 1:1 mol ratios. This contrasts with the behavior of cationic surfactants when mixed with double-chained analogs or alkanol cosurfactants, which induce micelle growth and shape transitions to rod-like and bilayer aggregates through chain packing effects similar to aqueous systems. This enables the aggregate morphology in the ionic liquid to be controlled through the composition of the surfactant mixtures.

Controlled coagulation and redispersion of thermoresponsive poly di(ethylene oxide) methyl ether methacrylate grafted cellulose nanocrystals

HypothesisCellulose nanocrystals (CNCs) undergo precipitation in the presence of high concentrations of cationic surfactants in aqueous solutions. To avoid such behavior and/or to promote redispersion of CNC/surfactant mixtures, the CNC surface was grafted with poly di(ethylene oxide) methyl ether methacrylate, P(MEO2MA). ExperimentsCNC-g-P(MEO2MA) was characterized using the following techniques 13C solid-state nuclear magnetic resonance (13C SSNMR), Fourier-transform infrared spectroscopy – attenuated total reflection spectroscopy (FTIR-ATR) and thermal gravimetric analysis (TGA). Isothermal titration calorimetry (ITC), electrophoretic mobility, light scattering and high sensitivity differential scanning calorimetry (HSDSC) were used to study the interaction between CNC-g-P(MEO2MA) and ionic surfactants, dodecyltrimethylammonium bromide (C12TAB, cationic) and sodium dodecylsulfate (SDS, anionic) at temperatures below and above the LCST. FindingsCNC-g-P(MEO2MA) underwent phase separation above its lower critical solution temperature (LCST ∼ 25 °C) and precipitated from solution as seen by HSDSC and transmittance experiments. When C12TAB was added to CNC-g-P(MEO2MA) it induced the precipitation that prevented the redispersion due to strong electrostatic interactions with the negative charges on the CNC surface. With increasing concentrations of SDS, the polymer phase transition temperature was increased, which can be used to redisperse the CNC complexes. By removing SDS from the mixture via dialysis, the CNC-g-P(MEO2MA) underwent subsequent phase transition.

Competitive Association of Antibiotics with a Clay Mineral and Organoclay Derivatives as a Control of Their Lifetimes in the Environment.

A Na-smectite clay mineral (Na-Mt) was exchanged with two concentrations of benzyldimethyltetradecyl ammonium chloride cationic surfactant up to one time the cation exchange capacity. Nonionic organoclay was prepared with polyoxyethylene (20) oleyl ether (Brij-O20) nonionic surfactant at one concentration. The resulting organoclays displayed lateral layer organization of the surfactants within their interlayer space.. The adsorption properties of these organoclays and the starting raw clay mineral were evaluated for three extensively used antibiotic pharmaceutical products: the amoxicillin (AMX), the sulfamethoxazole (SMX), and the trimethoprim (TRI), recognized as recalcitrant compounds to conventional water treatments and to display a complex behavior for different pH and temperature experimental conditions. Besides showing short half-life time with possible degradation by UV radiation, these antibiotics associated with mineral phases cause serious environmental issues of which the toxic effect can be exacerbated in the presence of other chemical compounds. From the set of data obtained by complementary techniques: UV and Fourier transform infrared spectroscopy, high-performance liquid chromatography coupled with mass spectrometry, and X-ray diffraction, it appears that the nonionic organoclay shows its versatility for the adsorption of individual molecules as well as a pool of antibiotics. The mixing of the three antibiotics showing different electric charged species (cations, anions, and zwitterions) mimics the natural context drives to a deep modification of the adsorption behavior onto the different materials that can act as possible carrier mineral phases in aquatic environment. These competition effects can be measured through the significant decrease of the KF Freundlich constants for AMX in the presence of other molecules (or electrolytes), whereas TRI and SMX, by their possible association, create a synergistic effect that favors their adsorption on the whole layered materials.

Determination of Kinetic, Isotherm, and Thermodynamic Parameters of the Methamidophos Adsorption onto Cationic Surfactant-Modified Zeolitic Materials

In the present study, a natural clinoptilolite was conditioned with NaCl solution and subsequently modified with different cationic hexadecyltrimethylammonium surfactant concentrations for methamidophos removal. The surfactant-modified zeolitic material with maximum methamidophos adsorption capacity was chosen, and the effect of several parameters such as contact time and initial pesticide concentration were performed by batch system. Other parameters such as the effect of adsorbent dosage, pH, and temperature were also evaluated. Natural, NaCl-conditioned, and the best surfactant-modified zeolitic materials were systematically characterized by several analytic techniques such as scanning electron microscopy with energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and BET-specific surface area by N2 physisorption measurements. The zero point charge was also determined in each studied zeolitic material. Derived results showed a maximum methamidophos adsorption of 1.385 mg/g onto zeolitic material surfactant-modified with 25 mmol/L at 20 °C. The experimental adsorption kinetics and isotherms data were well adjusted with pseudo-second order and Langmuir isotherm models in its not linearized form, respectively. The amount of adsorbent and pH in the surfactant-modified zeolitic material influences the pesticide adsorption capacity. Thermodynamic parameters indicated that methamidophos adsorption on surfactant-modified zeolitic material at 25 mmol/L was an exothermic in nature process, not spontaneous, and with decreased randomness. The obtained results in the present research contribute as study of methamidophos adsorption behavior with zeolitic materials application as an alternative removal method for organophosphates pesticides.

Synthesis, interfacial properties, and antimicrobial activity of a new cationic gemini surfactant

Tetramethylene-1,4-bis(N,N-dodecylammonium bromide), cationic gemini surfactant, (12-4-12) was first synthesized with an one-step and shortened procedure and its interfacial and antimicrobial properties were compared with a conventional single-chain cationic surfactant, cetyltrimethylammonium bromide (CTAB). The interfacial and thermodynamic properties of both surfactants reveal that critical micelle concentration (CMC) of this novel synthetic cationic dimeric surfactant is lower than that of cationic monomeric surfactant at almost 15 times of its magnitude, which is due to the increase in hydrophobicity of the surfactant molecules by having dual hydrocarbon chains. In comparison with CTAB, the produced compound 12-4-12 yields much better interfacial and thermodynamic properties. The antimicrobial activities of the synthesized gemini surfactant were tested against eight strains of bacteria, as well as two strains of fungi. The results showed that both 12-4-12 compound and CTAB exhibited higher inhibitory effects on the growth of Gram-positive bacteria and fungi than that of Gram-negative bacteria. The minimum inhibitory concentrations in molar of 12-4-12 against all tested Gram-negative bacteria were lower than those of CTAB, which is hypothetically due to the lower HLB together with smaller CMC values of our gemini surfactant.

Unfolding and Refolding of Protein by a Combination of Ionic and Nonionic Surfactants.

The interaction of protein and surfactant yields protein–surfactant complexes which have a wide range of applications in the cosmetics, foods, and pharmaceutical industries among others. Ionic and nonionic surfactants are known to interact differently with the protein. The interplay of electrostatic and hydrophobic interactions governs the resultant structure of protein–surfactant complexes. The present study enlightens the paramount role of the hydrophobic interaction, tuned by the hydrophobic tail length of ionic surfactants, in the unfolding of anionic bovine serum albumin (BSA) protein. The unfolding of BSA in the presence of four different tail-length cationic surfactants, that is, C10TAB, C12TAB, C14TAB, and C16TAB, has been investigated by small-angle neutron scattering and dynamic light scattering. All cationic surfactants unfold the protein at a certain concentration range. The propensity of protein unfolding increases with increasing the hydrophobic tail length. The denatured structure of BSA upon addition of cationic surfactants is characterized by the random flight model representing a beads-on-a-string chain-like complex. The unfolded protein binds the surfactant micelles in the protein–surfactant cluster. The micelles get elongated with the increasing concentration of cationic surfactants, whereas the number of micelles per cluster is decreased. In the final stage, the protein–surfactant cluster merges to one large micelle with unfolded protein wrapping the micelle surface. The pathway of protein unfolding is described in terms of the changes in the micellar size, the number of micelles formed per cluster, the separation between the micelles in the cluster, the aggregation number of micelles, and the number of proteins per cluster. The protein–surfactant interaction is further examined in the presence of a nonionic surfactant, that is, C12E10. The nonionic surfactant significantly suppresses the interaction of BSA protein with ionic surfactants by forming mixed micelles. As a result of the mixed micelles formation by ionic–nonionic surfactants, the ionic surfactant moves out from the unfolded BSA protein, and this enables the protein to refold back to its native structure. The propensity of mixed micelle-driven refolding of proteins is significantly changed with changing the tail length of the ionic surfactant.

Surfactants in the sea surface microlayer, subsurface water and fine marine aerosols in different background coastal areas

This study aims to determine the concentrations of surfactants in the surface microlayer (SML), subsurface water (SSW) and fine mode aerosol (diameter size < 1.5μm) at different coastal stations in Peninsular Malaysia. The concentrations of anionic and cationic surfactants were determined through colorimetric methods as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS), respectively. Water-soluble ions, for the determination of fine mode aerosol sources, were determined using ion chromatography (IC) for anions (SO42-, NO3-, Cl- and F-) and cations (Na+, K+, Ca2+ and Mg2+). Principal component analysis (PCA), combined with multiple linear regression (MLR), was used to identify the possible sources of surfactants in fine aerosol. The results showed the concentrations of surfactants as MBAS and DBAS in the SML ranged between 0.23 ± 0.03 and 0.35 ± 0.01μmolL-1 and between 0.21 ± 0.02 and 0.29 ± 0.01μmolL-1, respectively. The enrichment factors (Efs) ratios between MBAS and DBAS in the SML and SSW ranged between 1.04 ± 0.01 and 1.32 ± 0.04, respectively. The station that is located near to tourism and industrial activities recorded the highest concentrations of surfactants in SML and SSW. The concentrations of surfactants in fine aerosol ranged between 62.29 and 106.57pmolm-3. The three possible sources of fine aerosol during the northeast monsoon were aged sea spray/biomass burning (which accounted for 69% of the atmospheric aerosol), nitrate/mineral dust (23%) and sulphate/fresh sea salt (8%). During the southwest monsoon, the three main sources of atmospheric aerosol were biomass burning (71%), secondary inorganic aerosol (23%) and sea spray (6%). This study suggests anthropogenic sources are main contributors to the concentrations of surfactants in SML, SSW and fine aerosols.

A New Microfluidic Polymer Chip with an Embedded Cationic Surfactant Ion-selective Optode as a Detector for the Determination of Cationic Surfactants.

A new microfluidic polymer chip with an embedded cationic surfactant (CS) ion-selective optode (CS-optode) as a detector of flow-injection analysis (FIA) for the determination of CSs was developed. The optode sensing membrane is based on a poly(vinyl chloride) membrane plasticized with 2-nitrophenyl octyl ether containing tetrabromophenolphthalein ethyl ester. Under the optimal flow conditions of the FIA system, the CS-optode showed a good linear relationship between the peak heights in the absorbance, and the concentrations of CS in a concentration range from 50 to 400 μmol dm-3. The sample throughput of the present system for the determination of a CS ion (300 μmol dm-3 zephiramine) was ca. 11 samples h-1. The proposed FIA system was applied to determine the level of CS in dental rinses.

Separation of cationic biocide by means of ultrafiltration process

The usefulness of ultrafiltration process for removal of quaternary ammonium compound has been assessed. Intersep Nadir membranes with a cut-off of 5 kDa made of cellulose and polyethersulfone were tested. The concentration of cationic surfactant in the feed solutions amounted to 50–3500 mg/L. It was found that polymer type affects the removal efficiency of cationic biocide. The polyethersulfone membranes allowed to remove above 63% of BAC from the feed solution of concentration equal to 100 mg/L, while for cellulose membranes the highest retention (i.e. 27%) was obtained for process with 3500 mg/L. During the tests surfactant affected on membranes’ hydraulic properties. For experiments with polyethersulfone membranes, the relative flux obtained was in the range 80-20% (depending on pollutant concentration) of distilled water flux. Cellulose membranes were less fouling susceptible. Moreover, in experiment with surfactant concentration equal to 1000 mg/L an increase in membrane permeability (comparing to distilled water flux) was pronounced.

One-Pot Synthesis of Raspberry-Like Mesoporous Silica Nanospheres.

Mesoporous materials with hierarchical morphologies have recently gained attention due to their structural versatility for various applications including catalysis, adsorption, energy storage and nanomedicine. However, it is still desirable for facilely controllable synthesis of mesoporous particles with tunable surface properties and oriented hierarchical structures. Here, we report a one-pot synthesis method for raspberry-like mesoporous silica nanospheres with 2 nm hollow silica nanoparticles doped on the surface. We identify that the control over the concentration of cationic surfactant and silica precursor can be used to control the multiple morphological evolutions of mesoporous silica nanoparticles. This control enables the fabrication of a diverse library of multi-compartment mesoporous silicas networks consist of mesoporous silica nanospheres connecting with mesoporous silica branches. The synthesis method would enable to synthesize hierarchical mesoporous silicas with complex architecture and different pore environments for the potential application in catalysis and nanomedicine.

Formation of N-nitrosamines by micelle-catalysed nitrosation of aliphatic secondary amines.

N-Nitrosamines are an important class of potent human carcinogens and mutagens that can be present in water and wastewater. For instance, N-nitrosamines can be formed by reaction of nitrosating agents such as NO+ or N2O3 formed from nitrite under acidic conditions with secondary amine precursors by an acid-catalysed nitrosation pathway. This study investigates the catalytic effect of cationic and anionic micelles on the nitrosation of secondary aliphatic amines in the presence of nitrite at different pH values. The results of this study demonstrate that the nitrosation of hydrophobic secondary amines (e.g., dipropylamine and dibutylamine) by nitrite was significantly enhanced in the presence of micelles of the cationic surfactant cetyltrimethylammonium chloride whereas anionic micelles formed by sodium dodecylsulfate did not significantly enhance the formation of N-nitrosamines. Rate enhancements of up to 100-fold were observed for the formation of N-nitrosodibutylamine in the presence of cetyltrimethylammonium chloride. The magnitude of the catalytic effect of cationic micelles on the nitrosation reaction depended mainly of the hydrophobicity of the amine precursors (i.e., alkyl chain length), the stability and the charge of the micelles and pH. One important enhancement factor is the lowering of the pKa of the precursor alkylammonium ion due to the electrical potential at the micelle-water interface by up to ∼2.5 pH units. These results suggest that cationic micelle-forming surfactants might play a role in the formation of N-nitrosamines in wastewater, consumer products and in industrial processes using high concentrations of cationic surfactants.