High Surfactant Research Articles

Effects of linear alkylbenzene sulfonate (LAS) on the interspecific competition between Microcystis and Scenedesmus

The widespread use of detergents increases the concentration of surfactant in lakes and reservoirs. High surfactant loads produces toxicity to algae; however, the influence of the increasing surfactant on the competition between algae is not clear. In this paper, different amounts of linear alkylbenzene sulfonate (LAS) were added to test the effects of LAS on the competition between Microcystis aeruginosa and Scenedesmus obliquus under eutrophic condition. In single culture, the growth of S. obliquus was promoted under lower LAS concentrations (1 and 20mgL(-1)), but cell density of S. obliquus reduced when treated with higher LAS concentration (100mgL(-1)). The growth of M. aeruginosa was inhibited markedly with 20 and 100mgL(-1) LAS. Compared with single culture, the result was opposite in co-cultures and the cell density of S. obliquus increased significantly when treated with LAS of 1, 20, and 100mgL(-1). The specific growth rates of S. obliquus and M. aeruginosa in both cultures were 0.4-0.5day(-1) and 0.6-0.7day(-1), respectively, except that the specific growth rate of M. aeruginosa in both cultures treated with 100mgL(-1) LAS was about 0.2day(-1). M. aeruginosa dominated over S. obliquus in the co-culture without LAS, while the competition was completely opposite with the addition of 20mgL(-1) LAS. The growth of S. obliquus treated with 20mgL(-1) LAS was not affected significantly in single culture but was promoted by 75% in co-culture. Moreover, the growth of S. obliquus in co-culture treated with 100mgL(-1) LAS was promoted by more than 97%. These results suggested that the increasing LAS would overturn the competition of algae in freshwater ecosystems.

Bitumen Recovery from Carbonates by a Modified SOS-FR (Steam-Over-Solvent Injection in Fractured Reservoir) Method Using Wettability Alteration Chemicals

This study investigates the applicability of the modified version of the previously proposed SOS-FR (steam-over-solvent injection in fractured reservoir) method to recover bitumen from the Grosmont formation in Canada. Three phases were applied on a total of 13 preserved core samples. In Phase 1, the cores taken from three different parts of the Grosmont formation were soaked in a liquid solvent (heptane or distillate) at ambient conditions. The objective of the first phase was to reduce the viscosity of the bitumen in preparation for the second phase which is wettability alteration. In Phase 2, we soaked the samples in water with chemicals. Wettability modifiers tested include high pH solution, cationic surfactants, and ionic liquids because the screening process indicated they are the most useful wettability alteration chemicals for oil-wet carbonates. One of the key benefits of the ionic liquids is that they are environmentally friendly as they are chemically stable with low level of toxicity and flamm...

Identification and absolute quantification of enzymes in laundry detergents by liquid chromatography tandem mass spectrometry.

In a stricter legislative context, greener detergent formulations are developed. In this way, synthetic surfactants are frequently replaced by bio-sourced surfactants and/or used at lower concentrations in combination with enzymes. In this paper, a LC-MS/MS method was developed for the identification and quantification of enzymes in laundry detergents. Prior to the LC-MS/MS analyses, a specific sample preparation protocol was developed due to matrix complexity (high surfactant percentages). Then for each enzyme family mainly used in detergent formulations (protease, amylase, cellulase, and lipase), specific peptides were identified on a high resolution platform. A LC-MS/MS method was then developed in selected reaction monitoring (SRM) MS mode for the light and corresponding heavy peptides. The method was linear on the peptide concentration ranges 25-1000ng/mL for protease, lipase, and cellulase; 50-1000ng/mL for amylase; and 5-1000ng/mL for cellulase in both water and laundry detergent matrices. The application of the developed analytical strategy to real commercial laundry detergents enabled enzyme identification and absolute quantification. For the first time, identification and absolute quantification of enzymes in laundry detergent was realized by LC-MS/MS in a single run. Graphical Abstract Identification and quantification of enzymes by LC-MS/MS.

Equilibrium and dynamic surface tension properties of Gemini quaternary ammonium salt surfactants with hydroxyl

Abstract Five quaternary ammonium salt Gemini surfactants 2-hydroxyl-propanediyl-α,ω-bis (alkyldodecyl ammonium chloride) (n-3(OH)-n, where n represents hydrocarbon chain lengths of 10, 12, 14, 16, and 18) were synthesized and characterized by 1H NMR. Surface activity, adsorption and aggregation behaviors of these cationic Gemini surfactants were investigated by methods of measuring equilibrium surface tension, dynamic surface tension and transmission electron microscope (TEM). The critical micelle concentration (CMC) decreased with an increase in hydrophobic chain length, while the surface tension at the CMC (γCMC) showed little change. With TEM measurements, formations of vesicles in n-3(OH)-n (n = 16, 18) solutions occurred and vesicles dimensions depended on their n values. Moreover, data obtained were analyzed in accordance with Word-Tordai equation, and the diffusion coefficients for ionic liquid molecular adsorption in the initial stage and final stage under different concentration were figured out respectively. The results indicated that the adsorption process was controlled by a diffusion step at low surfactant concentration while by a mixed kinetic-diffusion adsorption mechanism at high surfactant concentration.

The Effect of Surfactants on Vertical Air/Water Flow for Prevention of Liquid Loading

Summary From field experience in the gas industry, it is known that injecting surfactants at the bottom of a gas well can prevent liquid loading. To better understand how the selection of the surfactant influences the deliquification performance, laboratory experiments of air/water flow at atmospheric conditions were performed, in which two different surfactants (a pure surfactant, sodium dodecyl sulfate, and a commercial surfactant blend) were added to the water. In the experiments, a high-speed camera was used to visualize the flow, and pressure-gradient measurements were performed. Both surfactants increase the pressure gradient at high gas-flow rates and decrease the pressure gradient at low gas-flow rates. The minimum in the pressure gradient moves to lower gas-flow rates with increasing surfactant concentration. This is related to the transition between annular flow and churn flow, which is shifted to lower gas-flow rates because of the formation of an almost stagnant foam substrate at the wall of the pipe. At high surfactant concentration, it appears that the churn flow regime is no longer present at all and that there is a direct transition from annular flow to slug flow. The results also show that the critical micelle concentration, the equilibrium surface tension, the dynamic surface tension, and the surface elasticity are poor predictors of the effect of the surfactant on the flow.

Surfactant-Assisted Electrodeposition of Mn Oxides As Promising ORR/Oer Bifunctional Non-PGM Electrocatalysts: Factorial Design Study of the Electrodeposition Parameters

Development of novel bifunctional electrocatalysts with high electrocatalytic activity and durability for both oxygen reduction and evolution reactions (ORR and OER) is of outmost importance to grasp the full potential of the regenerative H2-O2 fuel cells and metal-air batteries (e.g., Zn-air, Al-air, Mg-air, Li-air) as beneficial energy conversion and storage devices. Manganese oxides have been on the spotlight as an attractive catalyst material due to cost-competitiveness, environmentally friendliness, natural abundance as well as excellent reactivity for ORR and to some extent for OER (1, 2). The physicochemical and electrochemical properties of MnOx are highly dependent on its morphology and crystallographic nature (3). The aim of this work is to provide a systematic study on finding an active nanostructured manganese oxide for both ORR and OER via anodic electrodeposition method. A comprehensive study have been performed to investigate the main and interaction effects of key electrodeposition factors that significantly influence the electrosynthesis of manganese oxides, i.e. Mn2+ concentration (C), applied anodic potential (E), temperature (T), surfactant type and concentration (S), on the bifunctional activity of MnOx using a two-level half-fraction factorial design. Sodium dodecyl sulfate (SDS) as anioinc, hexadecyl-trimethyl-ammonium bromide (CTAB) as cataionic and Triton X-100 as non-ionic surfactants were used in this study to electro-synthesize the nanostructured MnOx. Surface characterization methods including XPS and SEM has been employed to analyze morphology and Mn valance of the synthesized electrocatalysts. Fig. 1 shows the surface plots of three different responses studied here for the electrodeposited manganese oxides in presence of Triton X-100, correlating them to the most important factors and two-factor interactions based on the Pareto plots of estimates. The highest ORR mass activity can be achieved at high surfactant concentration and low temperature (Fig. 1-A). Moreover, low applied anodic potential was found to further improve the ORR mass activity of the electrodeposited samples. The same trend was observed for highest OER mass activity as it appeared at low applied anodic potential, high surfactant concentration and low temperature (Fig. 1-B). The lowest ORR/OER potential window of below 600 mV can be obtained at high surfactant concentration, low applied anodic potential but high temperature (Fig. 1-C). The temperature seems to be a defining factor for the bifunctional characteristics of electrodeposited manganese oxides with high temperatures providing low ORR/OER potential window while low temperatures lead to high ORR/OER electrocatalytic activities.

Effect of natural and synthetic surfactants on crude oil biodegradation by indigenous strains

Hydrocarbon pollution is a worldwide problem. In this study, five surfactants containing SDS, LAS, Brij 30, Tween 80 and biosurfactant were used to evaluate their effect on crude oil biodegradation. Hydrocarbon degrading bacteria were isolated from oil production water. The biosurfactant used was a kind of cyclic lipopeptide produced by Bacillus subtilis strain WU-3. Solubilization test showed all the surfactants could apparently increase the water solubility of crude oil. The microbial adhesion to the hydrocarbon (MATH) test showed surfactants could change cell surface hydrophobicity (CSH) of microbiota, depending on their species and concentrations. Microcalorimetric experiments revealed these surfactants exhibited toxicity to microorganisms at high concentrations (above 1 CMC), except for SDS which showed low antibacterial activity. Surfactant supplementation (about 0.1 and 0.2 CMC) could improve degradation rate of crude oil slightly, while high surfactant concentration (above 1 CMC) may decrease the degradation rate from 50.5% to 28.9%. Those findings of this work could provide guidance for the application of surfactants in bioremediation of oil pollution.

Surfactant stabilisation of colloidal lignin microparticulates produced through a solvent attrition process

Abstract The stabilisation of insoluble lignin microparticulates produced through solvent attrition in aqueous media containing surfactants has been investigated. In the absence of added surfactants, addition of solvent solubilised lignin to water caused extensive precipitation and annealing of lignin, leading to the formation of large, agglomerated structures in the approximate size range of 20–200 μm. Addition of high HLB non-ionic surfactants (Polysorbate 20/sucrose ester) to the aqueous solution prior to lignin precipitation had only limited effect on the size of agglomerates produced, with a partial decrease in mean aggregate size at elevated surfactant concentrations, and no observed effect at low surfactant concentrations. In contrast, addition of either negatively (SDS) or positively (CTAB) charged ionic surfactants at concentrations Findings indicate that adsorption of charged surfactants to the surface of lignin particles during precipitation is able to provide effective electrostatic stabilisation; however, no such stabilising effect is provided by non-ionic surfactants. Furthermore, it appears that the size and stability of the particles produced is dependent on the conditions within the aqueous phase during precipitation. In this way, it may be possible to produce lignin microparticles with tailored particle distributions.

Synthesis of modified potato starches for aqueous solubilization of benzo[a]pyrene

For soil rehabilitation, the surfactant-enhanced remediation has emerged as a promising technology. For this purpose, starch derivatives were difunctionalized by 1,4-butane sultone (BS) and 2-octen-1-ylsuccinic anhydride (OSA). Eight distinct products were obtained under different synthesis conditions. The chemical structural characteristics were investigated by 1H NMR spectroscopy. The compounds were evaluated for their apparent aqueous solubility and their ability to increase the solubility of a hydrophobic pollutant such as benzo[a]pyrene (BaP), used as a polycyclic aromatic hydrocarbon model. In comparison with native starch, the best obtained compound increased starch apparent aqueous solubility by a factor of 10 (up to 3.50g/L) and also stimulated 77-fold BaP aqueous solubilization (up to 232.97μg/L) underlining its very high surfactant property. In this study, the right balance between hydrophobic character (octenyl succinate group (OS) grafted) of starch derivatives and starch apparent aqueous solubility (BS grafted) was highlighted.

Oligosaccharide-based Surfactant/Citric Acid Buffer System Stabilizes Lactate Dehydrogenase during Freeze-drying and Storage without the Addition of Natural Sugar

Experiments were conducted to assess the maintenance effects of oligosaccharide-based surfactants on the enzymatic activity of a model protein, lactate dehydrogenase (LDH), during freeze-drying and room temperature storage using the citric acid buffer system. Oligosaccharide-based surfactants, which exhibit a high glass transition temperature (Tg), promoted the eminent retention of enzymatic activity during these protocols, whereas monosaccharide-based surfactants with a low Tg displayed poor performance at high concentration, albeit much better than that of Tween 80 at middle concentration. The increase in the alkyl chain length did not exert positive effects as observed for the maintenance effect during freeze-thawing, but an amphiphilic nature and a glass forming ability were crucial for the effective stabilization at a low excipient concentration during freeze-drying. Even a low oligosaccharide-based surfactant content (0.1 mg mL(-1)) could maintain LDH activity during freeze-drying, but a high surfactant content (1.0 mg mL(-1)) was required to prevent buffer precipitation and retain high LDH activity on storage. Regarding storage, glass formation restricted molecular mobility in the lyophilized matrix, and LDH activity was effectively retained. The present results describe a strategy based on the glass-forming ability of surfactant-type excipients that affords a natural sugar-free formulation or an alternative use for polysorbate-type surfactants.

Evaluation of biosurfactant producing activity of Bacillus thuringiensis-VITNDUVNB04 isolated from oil contaminated soil by various methods

Biosurfactants are the surface active molecules that are produced by microorganisms. The present study focused on the isolation of biosurfactant producing bacteria from oil contaminated soil samples of an automobile mechanical workshop near VIT University, Vellore. A total of 5 bacterial colonies were isolated from the collected samples (DNT-1 to DNT-5). Among them the isolate DNT-2 showed maximum biosurfactant production followed by DNT-3 and DNT-5. In primary screening DNT-2 showed a good haemolytic activity with a zone of clearance of 18 mm followed by DNT-3 (12 mm) and DNT-5 (10 mm). All three isolates were positive for lipase production and capable of degrading tributyrin. In the secondary screening method, DNT-2 showed high activity with 22 mm of oil spreading activity and 20 mm of drop collapsing activity. The emulsifying capacity of DNT-3, DNT-2 and DNT-5 was evaluated using E24 emulsification index where isolates showed 52%, 86% and 43% of activity respectively. Among all the isolates DNT-2 showed high surfactant production in all screening assays. Potential isolate DNT-2 was identified as Bacillus thuringiensis using biochemical tests and molecular 16s r RNA sequencing analysis..

Synthesis of monodispersed paraffin microcapsules by polycondensation using membrane emulsification and their latent heat properties

Microencapsulation technique of phase change materials (PCMs) has been attracted as one of effective methods to store and transfer the energy. Although the size control of microcapsules as PCMs is very important, it still remains a key issue to resolve. In this study, monodispersed paraffin microcapsules with silica shell were fabricated by membrane emulsification and thermal properties were investigated for the application of energy saving wallpaper. Particle size analyzer, scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry were used for microcapsule characterization. As results, uniform size of paraffin microcapsules (mean diameter 5 µm) was obtained at high N2 pressure and low surfactant concentration using membrane emulsification and silica shell was successfully synthesized by polycondensation. Also, their latent heat properties were significantly improved compared to pure paraffin. Finally, membrane emulsification is very effective technique to fabricate paraffin microcapsules with feasible size control. Since paraffin microcapsules have high latent heat with thermal stability, those can be used for the application of functional wallpaper as well as building structure materials for saving energy.

Optimization of Nanoemulsion Fabrication Using Microfluidization: Role of Surfactant Concentration on Formation and Stability

Nanoemulsions have some important potential advantages over conventional emulsions for certain commercial applications due to their optical clarity, high physical stability, and ability to increase the bioavailability of lipophilic bioactives. In this study, the factors influencing droplet size and stability in nanoemulsions fabricated from a hydrocarbon oil and an anionic surfactant were examined. Octadecane oil-in-water nanoemulsions were produced by a high pressure homogenizer (microfluidizer) using sodium dodecyl sulfate (SDS) as a model anionic surfactant. The influence of homogenization pressure, number of passes, and surfactant concentration was examined. The droplet size decreased with increasing homogenization pressure, number of passes, and surfactant concentration. Nanoemulsions with low turbidity and small droplet diameters (≈62 nm) could be produced under optimized conditions. Interestingly, nanoemulsions containing relatively high surfactant levels were highly susceptible to creaming when they were only passed through the homogenizer a few times, which was attributed to depletion flocculation. These results show the importance of optimizing surfactant levels to produce small droplets that are also stable to creaming.

Structures of adsorption layers of surfactant mixtures on nonpolar solid surfaces

The structure of the adsorbed layer of mixtures of a low molecular mass nonionic surfactant (alkyl heptaglycolether, C12EO7) with low molecular mass anionic (sodium dodecylsulfate, SDS, and sodium dodecylbenzenesulfonate, SDBS) and high molecular mass nonionic surfactants (EO37PO56EO37) was studied by atomic force microscopy in the combination with adsorption isotherms and adsorption enthalpies by isothermal titration calorimetry. The single surfactants C12EO7 and SDS show domains of parallel stripes on the graphite lattice in the atomic force microscopy (AFM) images. These parallel stripes can be related to hemicylindrical aggregates of a width of about 5 nm repeated in a periodic order which was proposed by different authors before. These structures are backed up by the results of the adsorption isotherms and the calorimetric measurements of the adsorption enthalpies. For SDBS and the high molecular mass nonionic surfactant, no such structures are observed in the AFM images despite an adsorption of surfactants on the surface. Mixtures of C12EO7 and the anionic surfactants give similar parallel stripes as the nonionic surfactant alone even in combination with SDBS, which indicates ideal mixing behavior on the surface. The concentration ratio of the surfactants on the surface differs from that in solution. For a mixed system of C12EO7 and the high molecular mass nonionic surfactant, a demixing of the surfactants on the surface can be assumed.

Making polymer brush photosensitive with azobenzene containing surfactants

We report on rendering polyelectrolyte brushes photosensitive by loading them with azobenzene-containing cationic surfactants. Planar poly(methacrylic acid) (PMAA) brushes are synthesized using the “grafting from” free-radical polymerization scheme followed by exposure to a solution of photosensitive surfactants consisting of positively-charged head groups and hydrophobic tails into which azobenzene moieties are inserted. In this study the length of the hydrophobic methylene spacer connecting the azobenzene and the charged head group ranges from 4 to 10 CH2 groups. Under irradiation with UV light, the photo-isomerization of azobenzene integrated into a surfactant results in a change in size, geometry, dipole moment and free volume of the whole molecule. When the brush loaded with photosensitive surfactants is exposed to irradiation with UV interference patterns, the topography of the brush deforms following the distribution of the light intensity, exhibiting surface relief gratings (SRG). Since SRG formation is accompanied by a local rupturing of polymer chains in areas from which the polymer material is receding, most of the polymer material is removed from the surface during treatment with good solvent, leaving behind characteristic patterns of lines or dots. The azobenzene molecules still integrated within the polymer film can be removed by washing the brush with water. The remaining nano-structured brush can then be re-used for further functionalization. Although the opto-mechanically induced rupturing occurs for all surfactants, larger species do not penetrate deep enough into the brush such that after rupturing a leftover layer of polymer material remains on the substrate. This indicates that rupturing occurs predominantly in regions of high surfactant density.

Investigating the Degradation Resistance Improvement of Polymer Surfactant Complex Drag Reducing Agent

Polymers-Surfactant complex efficacy in reducing the drag is of an interest subject in drag reduction research. Turbulent drag reduction (DR) efficiency of Sodium Polystyrene Sulfonate (NaPSS) sodium Alkylbenzene sulfonate complex was studied in a rotating disk apparatus. The solution complex was prepared by varying the concentration of the polymer between 100 to 1200 ppm and the surfactant between 100 to 700ppm. Measurement of torque values were recorded for each sample. The NaPSS (Sodium Polystyrene Sulfante) was found to have an ability to reduce the drag in the turbulent flow. A significant improvement was recorded for the addition of tiny amount of surfactant to the polymer system compare to the pure polymer drag reduction. At high surfactant concentration, it was found that the polymer drag ability decrease. The polymer was degraded when it is subjected to a high shear stress. The degredation resistance was increased by the addation of the surfactant to the polymer solution at concentration range of 100ppm to 400ppm of surfactant.

Investigation of relationship between lipid and Monascus pigment accumulation by extractive fermentation

Fermented Monascus pigments have been utilized as traditional Chinese medicine and food colorant for thousands of years. Under the limited nitrogen concentration and/or low initial pH 2.5 conditions, it was observed that production of intracellular pigments and accumulation of microbial lipids (high content reaching to approximately 50% in dry cell weight) by edible Monascus anka exhibited a positive correlated relationship. Extractive fermentation in nonionic surfactant micelle aqueous solution selectively exported the intracellular Monascus pigments into its extracellular broth, in which the concentration of intracellular pigments was negligible while the extracellular one was enhanced. The extractive fermentation provides a novel strategy for shifting of the metabolic channeling from intracellular lipid accumulation to Monascus pigment production. High pigment concentration, i.e., approximately 40 AU of extracellular Monascus pigments, was achieved by extractive fermentation at a relatively high nonionic surfactant concentration 10g/l. This phenomenon might be attributed to the nonionic surfactant micelles acting as pigment reservoirs by biomimetic of intracellular lipids.

Mixtures of catanionic surfactants can be superspreaders: Comparison with trisiloxane superspreader

HypothesisMixed solutions of cationic and anionic surfactants show considerable synergism in their wetting behaviour, but their spreading is affected considerably by the phase separation processes. The valuable information about wetting properties of synergetic mixtures can be obtained by using mixtures in which phase separation occurs at concentrations above cmc. ExperimentsSpreading properties of mixed solutions of cationic and anionic surfactants over highly hydrophobic substrate such as polyethylene are investigated and compared with those for trisiloxane superspreader. Experiments are performed at relative humidity of 40% and 80%. Interfacial tension at water/air and water/alkane interfaces is measured to explain spreading performance. FindingsCatanionic solutions can wet hydrophobic substrates nearly as effective as solutions of trisiloxane superspreader. The spreading factor reaches 70% of that of superspreader for the most effective mixed solution. The spreading slows down earlier at high surfactant concentrations. At room humidity (40%) spread area has a maximum vs concentration. However, the maximum was not observed at higher humidity 80%. Humidity does not affect the short-time spreading rate, but it influences considerably the time when spreading slows down. The spreading rate of mixed solutions is smaller than that of superspreader despite the same spreading exponent α=0.5.

Droplets in Microchannels: Dynamical Properties of the Lubrication Film.

We study the motion of droplets in a confined, micrometric geometry, by focusing on the lubrication film between a droplet and a wall. When capillary forces dominate, the lubrication film thickness evolves nonlinearly with the capillary number due to the viscous dissipation between the meniscus and the wall. However, this film may become thin enough (tens of nanometers) that intermolecular forces come into play and affect classical scalings. Our experiments yield highly resolved topographies of the shape of the interface and allow us to bring new insights into droplet dynamics in microfluidics. We report the novel characterization of two dynamical regimes as the capillary number increases: (i)at low capillary numbers, the film thickness is constant and set by the disjoining pressure, while (ii)above a critical capillary number, the interface behavior is well described by a viscous scenario. At a high surfactant concentration, structural effects lead to the formation of patterns on the interface, which can be used to trace the interface velocity, that yield direct confirmation of the boundary condition in the viscous regime.

Surface structure of organoclays as examined by X-ray photoelectron spectroscopy and molecular dynamics simulations

AbstractOrganoclays are sorbent materials prepared from clays by exchanging inorganic with organic cations. Their properties depend on the loading and conformational structure of the organic cations, but little information is available about the surface structures of organoclays. In this work, X-ray photoelectron spectroscopy (XPS) and classical molecular dynamics (MD) simulations are combined to characterize the external interface of an organoclay prepared from hexadecylpyridinium (HDPy+) and bentonite. The XPS survey spectra show well the varying elemental composition of the surface with increasing amount of surfactant, showing a decreasing contribution of clay-derived elements with increasing organic coverage. The high-resolution C 1s XPS spectra depict sensitively the surface arrangement of the surfactant. In combination with MD simulations, the results implied a monolayer coating for low surfactant coverage and a disordered bilayer arrangement at high surfactant uptakes. Molecular dynamics simulations showed that for very high cation uptake a quasi-paraffin-like configuration is also possible. The combination of experimental and modelling methods yielded congruent information on the molecular-scale arrangement of organic cations at the organoclay surfaces and the controlling mechanisms.