Sodium Dodecyl Benzene Sulfonate Solution Research Articles

Thermodynamic and surface active investigations of aqueous solution of sodium dodecylbenzene sulfonate in presence of builders: sequestration of Ca2+ ions and interaction with H2O2

Abstract The current investigation examines the micellization process of sodium dodecylbenzene sulfonate in aqueous media with builders at temperatures ranging from 298.15 K to 313.15 K. Using conductometry and tensiometry analyses, the study examines changes in micellar properties in different surfactant solutions, focusing primarily on CMC. Additionally, the variation of CMC with temperature was used to determine the thermodynamic parameters of micellization such as ∆ G m ° , Δ H m ° , ${{\increment}G}_{\mathrm{m}}^{{}^{\circ}},{\Delta }{H}_{\mathrm{m}}^{{}^{\circ}}\text{,}$ and ∆ S m ° ${{\increment}S}_{\mathrm{m}}^{{}^{\circ}}$ . This approach provides valuable insights into the behavior of the surfactant and the different intermolecular interactions involved in the system. The different surface active parameters π CMC, A min, and Γ max were elucidated using tensiometry via the Wilhelmy plate technique. Moreover, the capacity of the builder to sequester calcium ions was studied using a well-established titration method, offering valuable insights into their effectiveness. Their efficiency under oxidative conditions, particularly in preventing the interaction between copper ions and hydrogen peroxide, was evaluated. This article provides a comprehensive analysis of different builders when used with the anionic surfactant, sodium dodecylbenzene sulfonate. Their combination provides improved efficiency in protecting metals from corrosion, extracting heavy metals from polluted soils, and in personal care products such as shampoos and soaps.

Thermodynamic and surface active investigations of aqueous solution of sodium dodecylbenzene sulfonate in presence of builders: sequestration of Ca2+ ions and interaction with H2O2

Abstract The current investigation examines the micellization process of sodium dodecylbenzene sulfonate in aqueous media with builders at temperatures ranging from 298.15 K to 313.15 K. Using conductometry and tensiometry analyses, the study examines changes in micellar properties in different surfactant solutions, focusing primarily on CMC. Additionally, the variation of CMC with temperature was used to determine the thermodynamic parameters of micellization such as ∆ G m ° , Δ H m ° , ${{\increment}G}_{\mathrm{m}}^{{}^{\circ}},{\Delta }{H}_{\mathrm{m}}^{{}^{\circ}}\text{,}$ and ∆ S m ° ${{\increment}S}_{\mathrm{m}}^{{}^{\circ}}$ . This approach provides valuable insights into the behavior of the surfactant and the different intermolecular interactions involved in the system. The different surface active parameters π CMC, A min, and Γ max were elucidated using tensiometry via the Wilhelmy plate technique. Moreover, the capacity of the builder to sequester calcium ions was studied using a well-established titration method, offering valuable insights into their effectiveness. Their efficiency under oxidative conditions, particularly in preventing the interaction between copper ions and hydrogen peroxide, was evaluated. This article provides a comprehensive analysis of different builders when used with the anionic surfactant, sodium dodecylbenzene sulfonate. Their combination provides improved efficiency in protecting metals from corrosion, extracting heavy metals from polluted soils, and in personal care products such as shampoos and soaps.

Investigation of the impact of sodium dodecylbenzene sulfonate modification on the wettability of coking coal

ABSTRACT To investigate the impact of sodium dodecylbenzene sulfonate (SDBS) modification on coking coal’s wettability, our research focuses on coking coal and uses SDBS as the surfactant in the experiment. The surface tension, scanning electron microscope, FTIR, contact angle measurement, and reverse osmosis experiment are employed to measure the microscopic characteristics and wettability of raw coking coal, water-soaked coal, and coal soaked in 0.0005%, 0.005%, and 0.05% SDBS solutions. Finally, the dust reduction efficiency was determined by spray dust reduction experiments. We analyzed the effect of varying mass fractions of SDBS on coking coal’s wettability. The findings indicate that the surface of coal samples soaked in water and SDBS solution become rough. Adding clean water and SDBS solution improves the coal samples’ wettability. Among various coal samples soaked in different solutions, the one treated with 0.005% SDBS solution exhibits the smallest contact angle, significantly higher moisture absorption, and the most pronounced wetting effect. Soaking the coal samples in 0.005% SDBS solution can achieve the highest dust reduction efficiency. In summary, soaking the coal samples in no matter clean water or SDBS solution can enhance the wettability of coal dust, while soaking in 0.005% SDBS solution has a better effect.

Correlation between biological activity and physicochemical properties of sodium dodecylbenzenesulfonate in aqueous solutions

The purpose of this study was to establish a correlation between the effect of the pollutant content on the dimensional and physicochemical characteristics of the investigated solutions and its effect on aquatic organisms. To this end, the surface tension, electrical conductivity, pH, and redox potential of aqueous solutions of sodium dodecylbenzenesulfonate were measured in a wide concentration range (10–710–2 М). The change in the size and number of optical inhomogeneities was investigated using the small-angle reflection method in the micron range. In addition, the behavior of aquatic biological objects (Daphnia Magna) was studied in the investigated solutions. It was shown that the investigated concentration dependences (including the behavior of biological objects) are non-linear: they have either a stepped character or clearly expressed extremes and are well correlated with each other. A comfortable concentration range of sodium dodecylbenzenesulfonate for daphnia (all daphnia are active within 58 hours of the experiment) was established (0.018–0.037 mM). The correlation and nature of the concentration dependences indicate that at critical concentrations, structural rearrangements occur in sodium dodecylbenzenesulfonate solutions, not only the formation of micelles and pre-micelles, but also structural rearrangements of the solvent (water) itself. Thus, it has been experimentally shown that the change in the structure of water during interaction with pollutants can significantly affect both the physicochemical properties of aqueous solutions and the behavior of aquatic biological objects.

The influence of divalent cations on the dynamic surface tension of sodium dodecylbenzenesulfonate solutions

The kinetics of surfactant adsorption at interfaces is crucial in many industrial settings. Maximum bubble pressure tensiometry allows accessing the adsorption at time scales of tens of ms to uncover the initial stages of surfactant diffusion to the interface. This method was used to investigate electrolyte solutions of sodium dodecylbenzenesulfonate (SDBS), specifically targeting how the presence of small amounts of divalent cations (Mg2+, Ca2+, Sr2+ and Ba2+) influenced the adsorption kinetics and equilibrium. The dynamic surface tensions revealed that the adsorption of SDBS was strongly influenced by the presence of divalent cations due to strong interactions with the anionic surfactant. In addition, the type (i.e. size) of cations played a role. The strong divalent cation-surfactant interactions lead to distinct lowering of surfactant diffusion coefficients, calculated using the short-time approximation solution of the Ward-Tordai equation. The diffusion coefficients were slightly and similarly lowered for all types of divalent cations when the surfactant concentration was increased up to the critical micelle concentration (CMC). Above CMC, the diffusion coefficients increased steadily depending on the divalent cation. It was speculated that this could be due to differences in structure and aggregation numbers of micelles and slower disassembly of micelles to supply monomers for adsorption. Furthermore, CMC of SDBS was reduced according to the Hofmeister series in the presence of divalent cations.

Influence of Inorganic Salt Additives on the Surface Tension of Sodium Dodecylbenzene Sulfonate Solution

In order to study the effect of inorganic salt additives on the surface tension of a sodium dodecylbenzene sulfonate (SDBS) solution, the surface tension of the mixed system of six common inorganic salt additives, NaCl, CaCl2, AlCl3, Na2SO4, Na2CO3, and NaHCO3, and SDBS was measured, and the effects of the inorganic salt types, surfactant concentrations and inorganic salt concentrations on the surface tension of the SDBS solution were studied. On this basis, three inorganic salts, NaCl, CaCl2 and Na2SO4, were selected, and their effects on the critical micelle concentration (CMC) of the SDBS solution were studied. The experimental results showed that different inorganic salts had different effects on the surface tension of the SDBS solution. The order of effect of the six inorganic salts on the surface tension of the SDBS solution was CaCl2 > NaCl > Na2SO4 > NaHCO3 > Na2CO3 > AlCl3; when the mass fraction of the SDBS solution is high, the influence of the inorganic salts on the surface tension of the SDBS solution is relatively small; with an increase in the concentration of the preferred inorganic salt additives, the surface tension of the SDBS solution decreases first, then tends to be stable, and then increases; a reduction in the critical micelle concentration by the three selected inorganic salt additives shows the trend of 0.7% NaCl > 0.5% CaCl2 > 0.5% Na2SO4.

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 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.

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 > MgCl2 > KCl > NaCl > 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.

Optical fiber optofluidic laser based on surfactant solubilization of rhodamine B gain in an aqueous solution.

We report a whispering gallery mode (WGM)-based fiber optofluidic laser (FOFL), in which rhodamine B (RhB) in an aqueous surfactant solution of sodium dodecylbenzene sulfonate (SDBS) is used as the laser gain medium. Here, the role of SDBS is to scatter the RhB dye molecules to effectively prevent its self-association in the aqueous solution. Therefore, the fluorescence quantum yield of the used RhB dye is improved due to the enhanced solubilization, which results in a low lasing threshold of ∼2.2 µJ/mm2 when the concentration of SDBS aqueous solution reaches up to 20 mM, on par with or even better than most of the optofluidic dye lasers using RhB as the gain medium in an organic solution. We then establish a model of solubilization capacity of SDBS micelles, which successfully addresses the mechanisms of dye-surfactant interactions in the proposed FOFL system. We further apply this FOFL platform to the case of concentration sensing of the used SDBS, which exhibits a 2-order-of-magnitude improvement in sensitivity compared to the fluorescence measurement due to the signal amplification inherent to the lasing process. The proposed FOFL platform in combination with surfactant solubilization gain medium in an aqueous solution promises to enable chip-scale coherent light sources for various environmental and bio-chemical sensing applications.

Effect of salt and particles on the hydrodynamics of foam flows in relation to foam static characteristics

• Investigated the effect of salt and particles on dynamic behaviour of foam flow. • Characterised regimes of three-phase foam flow using signal analysis of pressure data. • Demonstrated the effect of salt and particle on the frictional pressure of foam flow. Foam flows containing particles are present in many applications including mining, wastewater treatment, environmental remediation of contaminants such as PFAS using foam fractionation, dewatering of gas wells and particle cleanout in pipelines. These applications usually involve dissolved salts and solid particulates, which may have a positive or adverse impact on the foam flow and its performance depending on the application, the system’s constituents (e.g., type and concentration of salt/particles) and the operating condition (e.g., gas and liquid flowrates). This work aims to investigate the effect of salts (primarily NaCl) up to 0.2 M salt and solid particulates (mainly clay) up to 25 g/L particles on the dynamic behaviour of 200 ppm sodium dodecylbenzene sulfonate (SDBS) foam flows, frictional and hydrostatic pressure gradient, foam holdup and flow regimes in a vertical column. Flow regimes are analysed through power spectral density (PSD) and the probability density function of differential pressure data. The results show that salt and particles affect the foaming performance of SDBS solutions, thus influencing the transition of flow regimes. Our static tests show a 1.2-to-2.2-fold increase in the effect of salts and particles on the foamability of the SDBS solutions, whereas the foam flow dynamic data show a strong dependence on the hydrodynamics of the system. For example, the pressure gradient of the foam flow experienced a 16% reduction with the addition of salt and particles at low gas superficial velocity ( V sg of 0.48–2.4 m/s and fixed V sl of 0.02 m/s) due to the domination of gravitational dP/dz while it increased up to 22% at high V sg of up to 11.2 m/s due to the domination of frictional forces. Our results demonstrate that the foam static properties such as foamability, foam stability and wetness are useful to understand the stabilising mechanisms of foams. However, they cannot represent and explain the foam behaviour in dynamic systems.

Surfactant-Modulated a Highly Sensitive Fluorescent Probe of Fully Conjugated Covalent Organic Nanosheets for Detecting Copper Ions in Aqueous Solution.

Efficient detection of aqueous copper ions is of high significance for environmental and human health, since copper is involved in potent redox activity in physiological and pathological processes. Covalent organic frameworks (COFs) have shown advantages in efficient capturing and detecting of copper ions due to their large surface area, robust chemical stability, and high sensitivity, but most of them are hydrophobic, leading to the limitation in sensing copper ions in aqueous media. Herein, the design and synthesis of an sp2 -carbon conjugated COF (sp2 -TPE-COF) are reported with surfactant-assisted water dispersion for detecting traces of copper ions based on the photo-induced electron transfer (PET) mechanism. Importantly, the olefin-linked conjugated backbone of sp2 -TPE-COF works as a signal amplified transducer for metal ion sensing. Notably, it is found that a surfactant-assisted strategy can greatly enhance COF's dispersion in aqueous solution and finely modulate their sensitivity with a significantly improved KSV to 15.15 × 104 m-1 in SDBS (sodium dodecyl benzene sulfonate) solution, the value of which is larger than that of a majority of COF/MOF based sensors for copper ions. This research demonstrates the promise of surfactant modulated fully π-conjugated COFs for sensing applications.

Sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) in single and mixed systems as corrosion inhibitors of zinc in hydrochloric acid

Abstract The influence of surfactant synergism between sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine Oxide (DDAO) on zinc corrosion in 0.05 M hydrochloric acid (HCl) solutions at 25 °C was investigated. Firstly, solutions of SDBS and DDAO with mole fractions of 0.00, 0.25, 0.50, 0.75 and 1.00 were prepared and their surface tension and critical micelle concentration (CMC) values in water and in 0.05 M HCl were measured as a function of total surfactant concentration. The SDBS/DDAO mixed system exhibited a strong synergism in 0.05 M HCl with a highly negative interaction parameter β (average β = −23.46), according to regular solution theory. Secondly, the adsorption of single surfactants SDBS and DDAO and SDBS/DDAO surfactant mixture on 2.0% zinc powder was investigated by the depletion method to find out the role of synergism in the adsorption tendency of these surfactants on the zinc surface and thus their corrosion inhibiting effect. The adsorption tendency of single surfactant and the mixed surfactant systems onto 2.0% zinc powder followed the order: SDBS > 0.75 SDBS/0.25 DDAO ≈ 0.25 SDBS/0.75 DDAO > DDAO > 0.50 SDBS/0.50 DDAO. Finally, the corrosion of zinc was investigated using the potentiodynamic polarization technique. It was found that SDBS and DDAO act as efficient corrosion inhibitors for zinc in 0.05 M HCl solution with increasing corrosion inhibition efficiency when they are mixed. Additionally, images of scanning electron microscopy were obtained for zinc sheets in solutions containing single and mixed SDBS/DDAO surfactants in the presence and absence of 0.05 M HCl. The microscopic images show an improvement in the protection of the zinc surface against acid attack in the presence of single and mixed SDBS/DDAO surfactants.

Positively charged PVC ultrafiltration membrane via micellar enhanced ultrafiltration for removing trace heavy metal cations

One of the major focuses in the field of sewage is the development of low-pressure driven and high-efficiency filtration membrane, particularly for removing extremely low-concentration heavy metals cations. A new type of polyvinyl chloride (PVC) blended ultrafiltration (UF) membrane was fabricated to reject heavy metal cations (e.g., Cd2+, Co2+, Ni2+, Cu2+, and Zn2+) from simulated waters using micellar enhanced ultrafiltration (MEUF) in this research. The positively charged PVC UF membrane was fabricated by blending PVC and amphiphilic poly (methyl methacrylate-co- dimethylaminoethyl methacrylate) (PMD) which was in-situ quaternized by methyl iodide (CH3I), then the PVC/PMD blended membrane was fabricated via nonsolvent induced phase separation (NIPS) process. The membranes' pore morphology, surface chemical compositions, surface charge, water contact angle, mechanical strength and water flux were investigated in detail. The influence of pH, transmembrane pressure, sodium dodecylbenzene sulfonate (SDBS) concentration on the filtration of pure SDBS solution was studied. SDBS was subsequently used as surfactant to remove heavy metal ions by micellar enhanced ultrafiltration (MEUF). For a molar ratio of 40:1 (SDBS: metal cation), the rejection of feed solution containing 10 ppm metal cations (e.g., Cd2+, Co2+, Ni2+, Cu2+, and Zn2+) surpassed 96% with MEUF method. The results showed that the prepared membrane had low-pressure driven and high-efficiency performance, which provided a potential solution for the high-efficiency removal of trace heavy metals cations.

Effect of Sodium Dodecylbenzene Sulfonate on the Wetting Mechanism of Tunliu Coal

AbstractCoal dust in the coal mining process may lead to a serious threat to the safety and health of miners. The addition of surfactants during coal seam water infusion can significantly improve the effect of dust suppression, so it is crucial to study the influence mechanism of surfactants on coal wettability. The variation of the hydration film thickness on the Tunliu coal surface at different concentrations of sodium dodecylbenzene sulfonate (SDBS) solution was investigated by atomic force microscopy. The experimental results indicate that the hydration film thickness increases initially and decreases afterward with the SDBS solution concentration increase, with a maximum value of 11.4 nm. The surface free energy (SFE) of coal molecules adsorbed with different numbers of SDBS molecules were calculated using two coal molecule cell models developed by Materials studio 8.0, and the simulation results display a good agreement with the experiments. The higher the SFE, the greater the hydration film thickness on the coal surface, and the stronger the enhancement effect of SDBS solution on the wettability of coal at the corresponding concentration. The interface formation energy (IFE) and cohesive energy density (CED) of coal molecules after adsorption of SDBS molecules were calculated separately. It was found that when three SDBS molecules were adsorbed, the absolute value of IFE and CED reached the maximum, and each SDBS molecule had the strongest average effect on coal molecules, the bond between them would be tighter. SFE simulations are helpful to optimize the selection of surfactants for practical engineering applications.

Dimethyl Sulfoxide-Free and Water-Soluble Fluorescent Probe for Detection of Bovine Serum Albumin Prepared by Ionic Co-assembly of Amphiphiles.

Detection of bovine serum albumin (BSA) is an important issue in the sense of medical applications and enzymatic reactions; however, the recently developed fluorescent probes require the involvement of dimethyl sulfoxide (DMSO), which may be detrimental to proteins. In this study, we demonstrated a DMSO-free and water-soluble fluorescent probe prepared by ionic co-assembly of amphiphiles. The cationic amphiphile is a newly designed molecule (denoted by DPP-12) bearing a conjugated diketopyrrolopyrrole (DPP) and two tetraphenylethylene groups. It turns out that the fluorescence emission of DPP-12 depends on the amount of anionic amphiphilic sodium dodecyl benzene sulfonate (SDBS). The fluorescence intensity first increases and then decreases with the concentration of SDBS, and each branch presents a linear relationship. BSA consumes SDBS by the formation of complexes, thus leading to an increase of fluorescence intensity of the mixed solution of DPP-12 and SDBS. Therefore, the mixed solution of DPP-12 and SDBS was applied as a fluorescent probe to detect the low concentration of BSA by back-titration. This fluorescent probe does not require DMSO and has good tolerance to metal ions in blood and good photostability. The limit of detection is as low as 940 nM, almost 3 orders of magnitude lower than the content in organisms.

Spectroscopic insight into the role of SDBS on the interface evolution of Mg in NaCl corrosive medium

To gain insights into the effect of sodium dodecylbenzene sulfonate (SDBS) on Mg corrosion in NaCl medium, in-situ Raman spectroscopy was employed to monitor the interface evolutions of Mg surface in NaCl and NaCl+SDBS solutions. Accompanied by ex-situ Raman, SEM and XPS results, the evolution models during Mg corrosion in corrosive media were established to reveal the influence of DBS−. Competitive adsorption models about the interface of Mg/NaCl+SDBS between DBS− and Cl− were also presented to explain the inhibition effect of SDBS. These models guide the optimal usage of SDBS in Mg alloy corrosion inhibition.

Role of sodium dodecyl benzene sulfonate in enhancing coal dewatering: Experiments and theoretical calculations

The surface of low-rank coal has many oxygen functionalities, which leads to poor coal slime dehydration. To improve the effect of coal slime dewatering, sodium dodecyl benzene sulfonate (SDBS) was used as accelerator in the coal slime dehydration process. In addition, the mechanism of acceleration was studied using X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations. The results of dehydration experiments showed that adding a certain amount of SDBS into the slurry water was conducive to promoting the removal of water. When the concentration of the SDBS solution was 0.06 g/L, the water content of the filter cake decreased from an initial value of 59.98% to 54.55%. XPS measurements and MD simulations show that the polar groups (sulfonic acid) of SDBS are adsorbed on the oxygen-containing functional groups on the coal surface, thus, exposing the nonpolar groups (alkyl chains) of the molecule to the solution. The calculation of the self-diffusion coefficient (D) of water molecules in the simulated system indicate that the presence of SDBS improves the mobility of water at the coal surface, which is helpful in improving the loss of water from the coal surface, thus, improving its hydrophobicity. Crucially, the results of the MD simulations are consistent with those from experiment. Highlights Addition of a certain amount of SDBS helps to remove moisture from the coal slime. Oxygen-containing functional groups on the coal surface are effectively covered by SDBS. The interaction mechanism of SDBS at coal/water interface was studied by combining experiments and theoretical calculations.

Foam fractionation for the separation of SDBS from its aqueous solution: Process optimization and property test

Foam fractionation is an adsorption bubble separation technique allowing recovery and immediate reuse of surfactants. This work was aimed at investigating the variations in recovery efficiency and physicochemical property of sodium dodecyl benzene sulfonate (SDBS) through multiple foam fractionation operation. First, a suitable SDBS concentration of 0.05 g/L was determined for preparing feeding solution. Subsequently, effects of volumetric air flow rate, height ratio of liquid phase and foam phase, and pore diameter of gas distributor on recovery efficiency of SDBS were investigated, respectively. Response surface methodology (RSM) was used to optimize the operating conditions of foam fractionation for separating SDBS. Under the conditions of volumetric air flow rate 80 mL/min, height ratio of liquid phase and foam phase 1:2, and pore diameter of gas distributor 0.180 mm, enrichment ratio and recovery percentage of SDBS were 134.83 ± 6.74 and 63.43 ± 3.17%, respectively. In repetitive separation experiments, the maximum separation number of recovered SDBS by foam fractionation was 3. Experimental results of surface activity and foam properties of recovered SDBS solution suggested that the interfacial adsorption and desorption processes had induced the structural transition and irreversible aggregation of SDBS molecules after multiple foam fractionation operation.

Formation Damage Induced by Water-Based Alumina Nanofluids during Enhanced Oil Recovery: Influence of Postflush Salinity.

Injecting nanofluids (NFs) has been proven to be a potential method to enhance oil recovery. Stranded oil is produced by wettability alteration where nanoparticles form a wedge film on pore wall surfaces, which is thought to shrink the pore space of the reservoir. Furthermore, ensuring the stability of the injected NF during the application is a major challenge. A low permeability reservoir and salinity of water make the response of NF injection to the formation damage more difficult. This article, therefore, studied the formation damage induced by the injection of alumina nanofluids (Al-NFs) in a relatively low permeability (7.1 mD) sandstone core. The salinity of the postflush water was also considered to mitigate the destructive impact. Al-NF was formulated by dispersing alumina nanoparticles (Al-NPs) in an aqueous solution of sodium dodecylbenzene sulfonate (SDBS) at its critical micelle concentration (CMC, 0.1 wt %). The formation damage, inherent to Al-NF injection, was evaluated by core-flooding tests. The assays consisted of the injection of 1 PV Al-NF (0.05 wt %) at the trail of which postflush at different salinities was flooded. The study found that the salinity of the postflush has an effect on the formation damage and oil recovery factor (RF). A chase water with a salinity concentration of 3 wt % sodium chloride (NaCl) produced an RF of 8.7% compared to a base case of water-flooding with a pressure drop of up to 13 MPa across the core (70 mm in length). These results pertained to the deposition of Al-NPs at the injection end. However, lowering the postflush salinity to 1 wt % NaCl mitigated the formation damage as evidenced by the decrease in pressure (35%) and an increase in RF to 17.2%.