Sodium Dodecyl Benzene Sulfonate Concentration Research Articles

High-Yield Preparation and Properties of Phenolic Resin-Based Carbon Microspheres.

This study aims to enhance the production efficiency of carbon microspheres (CS) and expand their potential applications. To this end, resorcinol-formaldehyde microspheres (RFS) were prepared in high yield through the modified Stöber method, utilizing resorcinol and formaldehyde as carbon sources, ammonia as a catalyst, and sodium dodecyl benzenesulfonate (SDBS) as a soft template. The resulting RFS were then carbonized to obtain high yield CS. This study examined the impact of key factors, namely, the concentration of resorcinol, ammonia, and the SDBS concentration, along with the temperature of carbonization, upon the properties of the resulting CS, which were observed with regard to microscopic morphology, average particle size, homogeneity, and yield. The findings demonstrated that the proclivity of RFS to agglomerate with one another at high carbon source concentrations was markedly diminished, while the yield of CS was notably enhanced through the introduction of the anionic surfactant SDBS. The particle size of RFS can be modified within the range 200-1000 nm by adjusting the resorcinol and ammonia concentration. The prepared RFS exhibited a regular spherical morphology and a smooth surface. Furthermore, the CS displayed a uniform spherical morphology following high-temperature carbonization, with no agglomeration or cross-linking observed between adjacent particles. It was observed that the yield of RFS reached a maximum of 93.2 g/L when the resorcinol concentration was 0.7 mol/L. Following carbonization at 800 °C, the yield of CS was found to be 41.9 g/L, with a diameter of 770 nm and good monodispersity.

New insights into the inhibition performance and mechanisms of sodium dodecyl benzene sulfonate (SDBS) on nitrogen removal in activated sludge-biofilm system

To investigate the effect of sodium dodecyl benzene sulfonate (SDBS) on nitrogen (N) removal performance and biological mechanisms, a gradient of SDBS concentrations was introduced into a set of sequencing batch biofilm reactors (SBBRs). The results indicated that a negative correlation was observed between SDBS concentration and the removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N). Compared to the control group, their removal efficiencies were the lowest (decreases of 11.83 %, 12.15 %, and 8.11 %) when SDBS concentration was 1.67 mg (g MLSS) -1 (5 mg L−1). High-throughput sequencing showed that the abundance of Proteobacteria remained stable with SDBS addition, while the abundances of Patescibacteria and Actinobacteria decreased by 0.67–0.70 % and 0.69–3.06 %, respectively. Moreover, SDBS reduced both microbial diversity and richness and hindered the interspecific relationships among microorganisms. It also inhibited N metabolic activities and led to a decrease in the expression of key functional genes involved in N transformation (nifD, nifH, nasA, norB, norC, and nosZ). Additionally, the abundances of key enzymes (EC:1.7.99.1, EC:1.7.2.4, and EC:1.1.1.42) in the N and tricarboxylic acid (TCA) cycles decreased following the addition of SDBS. This study provided insights into the effects of SDBS on N removal in activated sludge-biofilm systems and the adaptive responses of microbial communities to SDBS exposure.

Interaction of Pb(II) with microplastic-sediment complexes: Critical effect of surfactant

In this study, the impact of surfactants on the adsorption behavior of Pb(II) onto microplastics-sediment (MPs-S) complexes was investigated. Firstly, virgin polyamide (VPA) and polyethylene (VPE) were placed in Xiangjiang River sediment for six months to conduct in-situ aging. The results indicated that the biofilm-developed polyamide (BPA) and polyethylene (BPE) formed new oxygen-containing functional groups and different biofilm species. Furthermore, the adsorption capacity of Pb(II) in sediment (S) and MPs-S complexes was in the following order: S > BPA-S > VPE-S > VPA-S > BPE-S. The addition of sodium dodecyl benzenesulfonate (SDBS) promoted the adsorption of Pb(II), and the adsorption amount of Pb(II) increased with the higher concentration of SDBS, while adding cetyltrimethylammonium bromide (CTAB) showed the opposite result. The adsorption process of MPs-S complexes to Pb(II) was dominated by chemical adsorption, and the interaction between MPs-S complexes and Pb(II) was multilayer adsorption involving physical and chemical adsorption when the surfactants were added. Besides, the pH exerts a significant effect on Pb(II) adsorption in different MPs-S complexes, and the highest adsorption amount occurred at pH 6. Noteworthy, CTAB promoted the adsorption ability of Pb(II) when the exogenous FA was added. The binding characteristic of sediment endogenous DOM components and Pb(II) was influenced by the addition of MPs and surfactants. Finally, it confirmed that adsorption mechanisms mainly involve electrostatic and hydrophobic interaction. This study provides a new perspective to explore the environmental behaviors of Pb(II) by MPs and sediments with the addition of surfactants, which was conducive to evaluating the ecological risks of MPs and heavy metals in aquatic environments.

Wetting and aggregation mechanisms of coal molecules via XTG and SDBS based on molecular simulation

To study the interaction process of sodium dodecyl benzene sulfonate (SDBS) and xanthan gum (XTG) molecules in a composite dust suppressant and its influence mechanisms on the wettability and agglomeration characteristics of bituminous coal dust, Material Studio software was used to establish water–XTG binary system models, water–SDBS–XTG ternary system models, and water–SDBS–XTG–coal quaternary system models. Then, molecular dynamics simulations were performed through angular distribution, relative concentration distribution, mean squared displacement (MSD), and interaction energy to study the interaction mechanism between SDBS and XTG and the change in wettability of coal dust. Results showed that the configuration in the binary system changed after stabilization, and SDBS transformed from a disordered state into a directional arrangement with the head group oriented toward the liquid phase and the tail group oriented toward the gas phase. In the ternary system, the head group of SDBS interacted with the XTG molecules, and the XTG wound into a helical structure, reducing the viscosity of the solution. With an increase in the number of SDBS molecules, the angle of the head group of SDBS and the tail chain of SDBS increased to 113.95°. The number of H bonds in the system increased from 1676 to 1697. In the quaternary system, the rate of change of the diffusion coefficient continuously increases. The absolute value of the interaction energy increased from 5920.48 kJ/mol to 9295.35 kJ/mol. The higher the concentration of SDBS, the better the adsorption effect, and the more stable the molecular configuration. The number of H bonds and the distribution area of the overlapping region between water and coal gradually increased, indicating that the larger the area where water molecules could penetrate into the coal molecules, the better the wetting effect on coal. This study reveals the intermolecular interaction process and the mechanisms of coal dust wetting and agglomeration in a composite dust suppressant. It provides theoretical support for the application of this composite dust suppressant.

Tuning the mechanical and thermoelectric properties of self‐standing stretchable PEDOT:PSS/SDBS films

AbstractPoly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has recently attracted significant attention as a potential candidate for small‐scale thermoelectric conversion because of its ease of doping, and solution processability. This study addressed the fabrication of self‐standing PEDOT:PSS films modified with sodium dodecylbenzene sulfonate (SDBS) surfactant, presuming different annealing temperatures. According to the investigation, optimizing the annealing temperature improves crystal quality and increases the efficiency of PEDOT:PSS films. The resulting PEDOT:PSS films showed the highest electrical conductivity of about 623.68 Scm−1 and maximum power factor of 25.87 μWm−1 K−2. In addition to confirming thermoelectric properties; SDBS surfactants are being investigated to plasticize PEDOT:PSS films at different concentrations and annealing temperatures. With an optimization in annealing temperature, the elongation at break value similarly improves; and the highest elongation at break was observed at 0.94 wt% SDBS concentration, reaching 32%. To completely understand the underlying reasons for this dependence, higher‐order structures and electronic states of polymer films have been examined using electronic reflectance spectroscopy and X‐ray diffraction analysis. Overall, the outcomes of this work show how important surfactants and their annealing temperature are for improving the mechanical and thermoelectric characteristics of self‐standing PEDOT:PSS films.

Surfactant-assisted preparation of all-gel-state flexible supercapacitor with remarkable electrochemical performance based on polyaniline-polyacrylamide/sodium alginate hydrogels

The electrochemical performance of polyaniline-based all-gel-state supercapacitor (AGSSC) is significantly depended on the dispersity and mass loaded of polyaniline (PANI). In this manuscript, inspired by the properties of surfactant, sodium dodecylbenzene sulfonate (SDBS) was introduced to prepare various PANI-polyacrylamide/sodium alginate/SDBS (PANIy-PSSx) AGSSCs. With presence of SDBS, the electrochemical performance of PANIy-PSSx AGSSCs was greatly improved, displaying a trend of initial rise and then decrease with increasing concentration of SDBS from 0 to 0.75 wt%. As the content of SDBS was 0.5 wt%, the resulting PANI1.0-PSS0.5 AGSSC displayed the optimum electrochemical properties with area capacitance and energy density of 913.79 mF/cm2 and 81.23 μWh/cm2, respectively. The capacitance rate of PANI1.0-PSS0.5 AGSSC was still more than 93 % after 2000 cycles of sequential CV scans at the scan rate of 200 mV/s. These data were greatly higher than many reported PANI-based AGSSCs. Moreover, the resultant PANI1.0-PSS0.5 AGSSC could maintain high electrochemical performance even after various operations, such as compression, puncture, fluctuating temperature, bending situations and various voltage windows and series-parallel connections. The resultant PANI1.0-PSS0.5 AGSSC had the wide potentials to satisfy the real application requirements. This study offered a facile strategy for design and preparation of flexible supercapacitor with excellent electrochemical performance.

Preparation and corrosion behavior of layered double hydroxides-graphene oxide composite coatings modified by sodium dodecylbenzene sulfonate on the surface of AZ31 Mg alloy

Layered double hydroxides (LDHs) are a class of two-dimensional anionic clays with adjustable structure, which have certain corrosion resistance. However, smooth growth path of LDHs nanosheets perpendicular to the substrate limits its application in the field of corrosion. Graphene oxide (GO) possess a high specific surface area and barrier properties, which provides a promising method for further improving the corrosion resistance of LDHs. In this work, we prepared three different concentrations of sodium dodecylbenzene sulfonate (SDBS) modified GO (GO:SDBS concentration ratio = 1:1, 1:2, 1:3), and present MgAlCe-LDHs@GO-SDBS composite coatings by one-step hydrothermal method with well-zigzag morphology and good corrosion resistance. GO-SDBS was successfully incorporated in the layered double hydroxide (LDHs), the corrosion current density of the MgAlCe-LDHs@GO-S2 coatings was 1.60 × 10−8 A cm−2, which was lower than other coatings. This one-step growth of MgAlCe-LDHs@GO-S method has potential applications in manufacture of anti-corrosion protection coatings.

Influence of sodium carboxymethylcellulose on sodium dodecyl benzene sulfonate and sodium dioctyl sulfosuccinate micelles in the presence of phenol red dye

Strong dye-surfactant interactions and innovative formulations are required for dyeing, which is one of the most important operations in the pharmaceutical, food, cosmetic, and textile industries for colouring goods and other uses. The interactions of sodium dioctyl sulfosuccinate (AOT) and sodium dodecyl benzene sulfonate (SDBS) with the dye phenol red (sodium salt of PR) in the presence and absence of the polyelectrolyte sodium carboxymethylcellulose (NaCMC) were investigated using conductometric analysis. The critical micelle concentration (CMC) of SDBS and AOT was found to decrease as PR concentration increased in the water and NaCMC medium. However, in the presence of PR, the counterion binding (βc) of SDBS and AOT increased and negative (∆Gmic°) values indicated that micelle formation was energetically favourable. The results of the UV absorbance experiments indicated that the majority of the binding in the DBS¯ and DS¯ micelles was caused by the ketone proton groups (H+PR¯) of the PR. In NaCMC media, PR (H+PR¯) binding to DBS¯ and DS¯ micelles has been regulated by electrostatic interactions, which have been demonstrated by absorption data and binding constant values. According to dynamic light scattering (DLS) examinations, increasing the amount of PR increased SDBS and AOT micellar size in aqueous and NaCMC media.

Effect of sodium hydroxide, sodium dodecyl benzenesulfonate, and resin on the interfacial tension of asphaltenic synthetic oil extracted from acidic crude oil under low salinity condition

During the past years, the usage of new oil recovery methods known as enhanced oil recovery methods is increasing because of energy consumption rate enhancement and reservoir pressure depletion. Unfortunately, since most of the investigations were focused on crude oil, it is hard to find a generalized pattern of interfacial tension (IFT) and wettability change for different crude oils because of its complicated composition. So, it is necessary to examine the effect of specific fractions of crude oil especially resin and asphaltene fractions on the IFT and wettability alteration using systematic investigations. Although a limited number of investigations examined the interactions between these specific fractions and salts, there are no systematic reports respecting the possible interactions between asphaltene and resin fractions in the presence of alkaline and surfactant. So, in the first stage, the impact of dissolving asphaltene (0–9 wt%) in the toluene was investigated on the IFT reduction which revealed a decrease in IFT value from 34.8 to 23.3 mN/m as the asphaltene concentration was increased. Further experiments showed that the presence of MgCl2 and NaCl with a maximum concentration of 5000 ppm led to a reduction in IFT to a minimum value of 18.3 and 17.3 mN/m for NaCl and MgCl2, respectively, which means the higher impact of MgCl2 on the IFT reduction. After that, the selected optimum concentrations of MgCl2 and NaCl (5000 ppm) were used in the rest of the experiments in which the effect of resin fraction and other chemicals including sodium dodecyl benzenesulfonate (SDBS) and NaOH concentrations was examined on the IFT reduction and rock wettability. According to the obtained results, it was possible to reach the minimum IFT value of 0.08 mN/m, which is several orders lower than the original IFT value of the binary system without the chemicals using the optimum chemical formulation obtained by mixing proper concentrations of SDBS, NaOH, MgCl2, and NaCl. Moreover, the obtained optimum formulations were used through core flooding experiments which revealed the possibility of increasing the oil recovery to a maximum value of 10.1% based on the original oil in place.

Preparation and properties of magnesia porous ceramics by particle‐stabilized foam casting

AbstractIn this paper, magnesia porous ceramics were prepared by particle‐stabilized foams assisted foam‐gel casting. Secondly, the performance of magnesia slurry and magnesia porous ceramics was investigated. The obtained magnesia powder manifested high adsorption amount and excellent hydrophobicity, due to the strong adsorption ability of sodium dodecyl benzene sulfonate (SDBS) on magnesia particles. When the SDBS concentration is .3 wt%, the surface tension and expansion ratio of the slurry were 45 mN·m−1 and 1.68, respectively. The shape of the pore was sphere cell structure, with uniform distribution of pores in the sample, the average pore size was in the range of 58.7–73.9 μm, and the compressive strength was in the range of 25.3 MPa to 15.5 MPa when porosity varied from 56.7% to 70.2%.

Surfactant-assisted air flotation: A novel approach for the removal of microplastics from municipal solid waste incineration bottom ash

The potential for the presence of microplastics (MPs) in municipal solid waste incineration bottom ash (MSWI-BA) has not been fully explored. In this study, surfactant-assisted air flotation separation in aqueous media was used to examine the removal of MPs and other pollutants from different particle size fractions of MSWI-BA. The use of 1 mmol L−1 sodium dodecylbenzene sulfonate (SDBS), at a liquid-solid ratio of 60:1, increased by 66 % the quantity of MPs floated from the MSWI-BA 0–0.3 mm fraction, as compared to pure water. The four most common shapes of the floated MPs were pellets, fragments, films and fibers, and the major polymers were polypropylene, polyethylene, polymethyl methacrylate, and polystyrene (approximately 450 μg g−1 BA). The flotation of <10 μm MPs increased by up to 7 % using this method compared to flotation in saturated NaCl solution. Reuse of the flotation solution with the SDBS concentration maintained resulted in reduced MPs removal abundance by 22 % in the fourth use as compared to the first use. MPs removal correlated positively to SDBS concentration and negatively to turbidity. Precipitation from the fourth flotation solution was evaluated using polyacrylamide (PAM) and polyaluminium chloride (PAC) for the purpose of promoting the regeneration and recycling of the flotation solution. This treatment reduced MPs abundance, turbidity, and potential heavy metals in the recycled flotation solution. It is estimated that 3.4 kg of MPs could be removed from each ton of MSWI-BA. The findings of this study contribute to a better understanding of the redistribution of MPs during MSWI-BA pre-use treatment and provides a reference for the practical application of surfactant-assisted air flotation separation.

Preparation and Desalination of Semi-Aromatic Polyamide Reverse Osmosis Membranes (ROMs)

Reverse osmosis membrane (ROM) technology has a series of advantages, such as a simple process, no secondary pollution, high efficiency, energy saving, environmental protection, and good separation and purification effects. High-performance semi-aromatic polyamide reverse osmosis membranes (ROMs) were prepared by interfacial polymerization (IP) of novel cyclopentanecarbonyl chloride (CPTC) and m-phenylenediamine (MPD) monomers. The surface morphology, hydrophilicity and charge of the ROMs were characterized by field-emission scanning electron microscopy (SEM), a contact angle tester and a solid-surface zeta potential analyzer. The effects of CPTC concentration, MPD concentration, oil-phase solvent type, IP reaction time and additive concentration on the performance of semi-aromatic polyamide ROMs were studied. SEM morphology characterization showed that the surface of the prepared polyamide ROMs presented a multinodal structure. The performance test showed that when the concentration of MPD in the aqueous phase was 2.5 wt.%, the concentration of sodium dodecylbenzene sulfonate (SDBS) was 0.2%, the residence time in the aqueous phase was 2 min, the concentration of CPTC/cyclohexane in the oil phase was 0.13 wt.%, the IP reaction was 20 s, the NaCl rejection rate of the semi-aromatic polyamide ROM was 98.28% and the flux was 65.38 L/m2·h, showing good desalination performance. Compared with an NF 90 commercial membrane, it has a good anti-BSA pollution ability.

Construction of a recyclable chitosan-based aerogel-supported TiO2 catalyst for treating high-concentration surfactants

As high-concentration anionic surfactants easily form micelles, powdery catalysts exhibit low photocatalytic performance for treating anionic surfactants and are difficult to recycle. In this study, a recyclable chitosan-based aerogel-supported TiO2 catalyst was constructed to effectively treat high-concentration anionic surfactants using adsorption destroying micelles and in situ photocatalytic degradation of surfactants. Carboxylated carbon nanotubes/TiO2 (CCNT/TiO2) were loaded onto the skeleton of polyethyleneimine (PEI)-chitosan (CS) aerogel (PCA) by impregnation to prepare the CCNT/TiO2@PCA composite photocatalyst. CCNT/TiO2@PCA had a porous structure, and the catalyst particles were distributed on the skeleton. Sodium dodecylbenzene sulfonate (SDBS), a widely used anionic surfactant, was selected as the molecular probe. CCNT/TiO2@PCA exhibited excellent adsorption performance for SDBS (qm = 3154.5 mg g−1) and could destroy the micelles formed by a high concentration of SDBS (500 mg L−1). The SDBS removal rate by CCNT/TiO2@PCA reached 91.2% under UV light irradiation, which was 10 times faster than that of CCNT/TiO2. The excellent removal efficiency was mainly ascribed to the synergistic interaction between the electrostatic adsorption and photocatalytic degradation. The toxicity assessment indicated that the toxicity of the degradation intermediates was significantly lower than that of SDBS. After ten cycles, the removal of SDBS by CCNT/TiO2@PCA was 90.1%. Therefore, this study offers new insights into the construction of highly active photocatalysts for the treatment of high-concentration organic pollutants.

Thermal conductivity and dispersion properties of SDBS decorated ternary nanofluid: Impacts of surfactant inclusion, sonication time and ageing

Ternary nanofluids are now under the limelight of research communities due to their thermo-physical and heat transfer characteristics. In this scientific contribution, the effect of surfactant concentration, ageing, and sonication period on the thermal conductivity of ternary nanofluidis presented. A water-based Ternary nanofluid at weight concentration of (φ) of 0.06 % was prepared using SiO2, TiO2, and ZnO nanoparticles by ultrasonication. Sodium Dodecylbenzene Sulfonate (SDBS) was introduced as a surfactant. The stabilities of the samples were analysed by visual inspection, Dynamic Light Scattering (DLS), and Zeta potential analysis. The thermal conductivity of nanofluid was measured and the effects of surfactant addition, sonication time, and ageing on the stability and thermal conductivity of ternary nanofluid were examined. By increasing SDBS concentration from φ= 0–1.18 %, the thermal conduction and dispersion increased. Thermal conductivity was enhanced by surfactant addition up to 2.71 % with φ = 1.18 % at 55 °C. Surfactant concentration at φ =1.18 % showed an adverse effect on thermal conductivity enhancement. A maximum of 6.85 % enhancement in thermal conductivity can be obtained by increasing sonication duration up to 6 h at 65 °C. Old nanofluids exhibited larger thermal conductivity than newer ones. The 20 days old nanofluid showed 4.66 % enhancement with φ= 1.18 % at 35 °C. Finally, the authors recommended for an optimization study of surfactant concentration and sonication duration.

Effective treatment of high-concentration SDBS solution by developing a novel integrated technology of foam separation and photocatalysis

With the rapid increasing drainage of industrial sewage, the problems arising from sewage containing high-concentration surfactant become more urgent. In order to purify the high-concentration surfactant solution, a novel integrated technology of foam separation and TiO2 photocatalysis was developed. An anionic surfactant of sodium dodecyl benzene sulfonate (SDBS) was used as the model surfactant and its initial concentration in the simulated solution was 0.5 g/L. First, foam separation had been performed to primitively reduce SDBS concentration in the simulated solution. Based on the results of independent factor test, a five-level-three-factor central composite design (CCD) based on response surface design (RSM) was used to predict the optimal experimental conditions. Under above conditions, the enriching proportion and removing percentage of SDBS were 4.69 ± 0.14 and 84.85 ± 0.71 %, respectively. The surface tension and foam stability of the residual solution after foam separation had been measured using pulling ring method and bubbling method, respectively. The residual solution after foam separation possessed a higher surface tension and weaker foam stability compared with those of freshly prepared SDBS solution. Extrinsic fluorescence spectra using pyrene showed that interfacial adsorption had led to the generation of hydrophilic SDBS micelles. In order to perform TiO2 photocatalysis, the adsorption capacity of SDBS on TiO2 nanoparticles had been studied. The adsorption of SDBS on TiO2 nanoparticles obeyed Pseudo-second-order dynamics model and Freundlich isotherm model. Based on the unique optical property and particle entrainment capacity of foam, a coupling operation of foam separation and TiO2 photocatalysis was proposed to degrade SDBS in the residual solution. The suitable operating conditions were identified and the maximum degradation percentage of SDBS reached 94.86 ± 1.06 %. The total SDBS removing percentage of developed technology was 99.38 ± 0.10 %. Total organic carbon (TOC) concentrations of SDBS solution before and after treatment were measured using combustion oxidation coupled nondispersive infrared absorption method. Finally, the economic analysis was carried out to assess the cost effectiveness of the integrated technology of foam separation and TiO2 photocatalysis.

The effect of sand fractional wettability on SDBS-enhanced PCE immiscible mobilization in porous media.

Fractional wettability is common in the dense non-aqueous phase liquids (DNAPL) contaminated sites. However, it is still unclear how fractional wettability affects surfactant-enhanced DNAPL immiscible mobilization in saturated porous media. The macro-contact angle of the fractional wettability media was measured. The results of column experiments showed that the entrapped tetrachloroethene (PCE) saturations after sodium dodecyl benzene sulfonate (SDBS) flooding were lower in the media where NAPL-wet sand was present compared with those in water-wet media. In the media which contained 25% octadecyltrichlorosilane (OTS)-treated sand, the entrapped PCE saturations decreased to the minimum, and the decrease was much larger in fine sand media. The SDBS-enhanced PCE recoveries were jointly affected by fractional wettability, particle size, and interfacial tension (IFT). When NAPL-wet sand was present and SDBS concentration was just 0.125g⋅L-1, the SDBS-enhanced PCE recoveries increased significantly. As the SDBS concentration continues to increase to 0.5g⋅L-1, they only increased slightly. In the fine sand media, the SDBS-enhanced PCE recoveries were higher, and they increased more obviously with the increase of NAPL-wet sand fractions. The influence weight of fractional wettability on SDBS-enhanced PCE recoveries was the largest (47.09%) under the experimental conditions. These findings indicate that it is important to consider fractional wettability characteristics when establishing a DNAPL immiscible mobilization strategy, because it is not sufficient to consider only IFT reduction, especially in media with finer pore structures.

Adsorption of the Xanthan Gum Polymer and Sodium Dodecylbenzenesulfonate Surfactant in Sandstone Reservoirs: Experimental and Density Function Theory Studies.

Chemical flooding using a polymer and/or surfactant has been widely applied in oilfields worldwide for enhanced oil recovery. Chemical adsorption in reservoirs has a significant effect on the rock permeability and wettability and hence can affect the overall oil production. In this work, two chemicals, namely, the xanthan gum (XG) biopolymer and sodium dodecylbenzenesulfonate (SDBS) anionic surfactant, were used individually as displacement fluids. The amount of chemical adsorption on the rock surface and the residual resistance factor (permeability reduction) were calculated throughout the flooding experiments using an unconsolidated sandstone (SS) pack model. The effects of the injected chemicals’ concentration and reservoir salinity on adsorption capacity have been examined. Additionally, the effect of the addition of nanosilica particles (NSPs) to the injected fluid on the rock adsorption was also investigated. The results showed that the amount of XG and SDBS adsorption on the rock surface increased, albeit to a different extent, by increasing the chemical concentration at the applied salinities (0, 3.5, 5, and 10%) of the displacement fluids. Also, the permeability reduction increased with the increase in XG and SDBS concentrations; however, permeability reduction due to SDBS flooding was lower than that of XG in SS. The use of NSPs as a coinjectant to the XG and SDBS displacement fluids increased the adsorption on the SS rock. A plausible mechanism for the adsorption of the XG/NSP and SDBS/NSP blends on the SS surface was proposed. A density function theory calculation was employed to establish a relation between the adsorptivity of NSPs on SDBS and XG and the total energy and dipole moment of the molecules.

The attraction between like-charged oil-in-water emulsion droplets induced by ionic micelles

Although extensive work has been reported that micelles can induce depletion attraction between two solid spheres or a sphere and a plate, the effect of different micelles on the depletion between two soft surfaces has been rarely reported. Optical tweezers were used to measure the forces between two oil-in-water emulsions in solutions of sodium dodecylbenzenesulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), and octylphenol polyoxyethylene ether with ten oxyethylene glycol ether (OP-10) at varying concentrations. When the concentration of surfactant below their critical micelle concentration (cmc), force profiles between two emulsion droplets were purely repulsive. As the concentration of SDBS or CTAB above its cmc, the attraction between like-charged O/W emulsion droplets was dominant. The coalescence of the like-charged O/W emulsion droplets is observed. For nonionic surfactants OP-10, even if the cmc had been reached, the attractive force between O/W emulsion droplets couldn’t be measured. Results shows that attractive forces between two like-charged emulsion droplets of several microns in solution can also be induced by ionic micelles and the depletion was enhanced by counterion osmotic pressure. Our work suggests that the effect of micelle-induced depletion on the force between two solid surfaces can be used to predict forces between several micrometers of emulsion droplets.

Study on the wetting mechanism of SDBS with coals of different ranks based on surface free energy theory

Surfactants to improve the wetting ability of water sprays are considered an effective method of suppressing coal dust. Sodium dodecyl benzene sulfonate (SDBS) was used to understand the wetting mechanisms of an anionic surfactant on coals of different ranks. Atomic force microscopy (AFM) experiments and molecular dynamics simulations were used to investigate the surface free energy and hydration film. The analysis showed that the hydration film thicknesses obtained by both the experiment and simulation increase and then decrease with increasing SDBS concentration, and the high-rank coal had a thicker hydration film than the low-rank coal. The electrostatic potential distribution, hydrogen bonding, Mulliken charge, and interface formation energy were analyzed to illustrate the wetting mechanism. It was confirmed that coal's wettability is mostly determined by the electrophilicity of hydrogen atoms in oxygen-containing groups, and for high-rank coal, van der Waals forces gradually become the dominant forces in the wetting of the coal by SDBS. In conclusion, surface free energy theory by MD simulation proved to be a reasonable way to reveal the wetting mechanism of surfactants on coal, and the enhancement effect of SDBS on the wettability of high-rank coal is stronger than that of low-rank coal, which contributes to the development of surfactants for practical engineering applications.

Effect of Divalent and Monovalent Salts on Interfacial Dilational Rheology of Sodium Dodecylbenzene Sulfonate Solutions

This study presents the equilibrium surface tension (ST), critical micelle concentration (CMC) and the dilational viscoelasticity of sodium dodecylbenzene sulfonate (SDBS)-adsorbed layers in the presence of NaCl, KCl, LiCl, CaCl2 and MgCl2 at 0.001–0.1 M salt concentration. The ST and surface dilational viscoelasticity were determined using bubble-shape analysis technique. To capture the complete profile of dilational viscoelastic properties of SDBS-adsorbed layers, experiments were conducted within a wide range of SDBS concentrations at a fixed oscillating frequency of 0.01 Hz. Salts were found to lower the ST and induce micellar formation at all concentrations. However, the addition of salts increased dilational viscoelastic modulus only at a certain range of SDBS concentration (below 0.01–0.02 mM SDBS). Above this concentration range, salts decreased dilational viscoelasticity due to the domination of the induced molecular exchange dampening the ST gradient. The dilational viscoelasticity of the salts of interest were in the order CaCl2 &gt; MgCl2 &gt; KCl &gt; NaCl &gt; LiCl. The charge density of ions was found as the corresponding factor for the higher impact of divalent ions compared to monovalent ions, while the impact of monovalent ions was assigned to the degree of matching in water affinities, and thereby the tendency for ion-pairing between SDBS head groups and monovalent ions.