Surfactant Sodium Dodecyl Sulfate Research Articles

Experimental investigation of the effects of oil asphaltene content on CO2 foam stability in the presence of nanoparticles and sodium dodecyl sulfate

Foam stability tests were performed using sodium dodecyl sulfate (SDS) surfactant and SiO2 nanoparticles as foaming system at different asphaltene concentrations, and the half-life of CO2 foam was measured. The mechanism of foam stability reduction in the presence of asphaltene was analyzed by scanning electron microscope (SEM), UV adsorption spectrophotometric concentration measurement and Zeta potential measurement. When the mass ratio of synthetic oil to foam-formation suspension was 1:9 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 751 s to 239 s, and the half-life of SDS/silica-stabilized foams decreased from 912 s to 298 s. When the mass ratio of synthetic oil to foam-formation suspension was 2:8 and the asphaltene mass fraction increased from 0 to 15%, the half-life of SDS-stabilized foams decreased from 526 s to 171 s, and the half-life of SDS/silica-stabilized foams decreased from 660 s to 205 s. In addition, due to asphaltene-SDS/silica interaction in the aqueous phase, the absolute value of Zeta potential decreases, and the surface charges of particles reduce, leading to the reduction of repulsive forces between two interfaces of thin liquid film, which in turn, damages the foam stability.

Interaction of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine drug in aqueous solution: Conductometric and molecular dynamics studies

In the present work, the interaction of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine drug in aqueous solutions was studied using conductometric measurements and molecular dynamic simulation. Conductometric data were used to determine the critical micelle concentration (CMC) values of surfactants on various amantadine aqueous solutions at T= (300.2, 310.2 and 320.2) K and 0.1 MPa. The effect of amantadine concentration (m = 0.0005, 0.0010, 0.0015 and 0.002 mol.kg−1) on CMC of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants was investigated. It was observed the CMC value of sodium dodecyl sulfate surfactant increases with increasing of amantadine concentration whereas the CMC values of cetyl trimethyl ammonium bromide surfactant decrease with increasing of amantadine concentration at the same temperature. Then, the thermodynamic properties such as standard Gibbs free energy, enthalpy, and entropy for micellization in aqueous solutions were determined. In addition, molecular dynamic simulation was carried out to understand the interaction sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine at the molecular level and microscopic interactions. The root-mean-square deviations and electrostatic, hydrogen binding and hydrophobic interactions were determined by MD simulations. It was seen, the electrostatic and hydrogen bonding interactions play a crucial role in sodium dodecyl sulfate and amantadine aqueous system. The obtained results showed the simulation and experimental data are in agreement with each other.

Sustainably sourced, water-soluble biofilms based on keratin constructed through two crosslinking modes: Turning waste into useful materials

Bio-based packaging films prepared from sustainable sources have attracted much more attention as a potential strategy to address the increasingly serious plastic pollution problems. In this paper, keratin (FK) extracted from waste chicken feathers and cellulose nanocrystals (CNCs) extracted from papers were used to construct water-soluble biofilms through physical and chemical crosslinking methods respectively, which can be adapted to different packaging scenarios. In the physical crosslinking manner, anionic surfactant sodium dodecyl sulfate (SDS) was used to protect sulfhydryl, avoiding disulfide bonding compounding, and promote the dispersion of FK molecules, ensuring the subsequent assembly of FK with CNCs and glycerol to enhance the mechanical properties and water solubility of the films. Ultrasound accelerated the construction of a three-dimensional hydrogen bonding network, the formed FK/CNCs films showed exceptional tenacity and water-solubility. In the second manner, chemical crosslinking was achieved between FK and oxidated CNCs (OCNCs) through the Schiff base reaction, by which the tensile strength and elongation at break of the films could be highly enhanced, while the films could still be dispersed in water easily. By combining the two crosslinking modes, sustainable biofilms adapted to different packaging scenarios could be prepared by changing the components and ratios. As a kind of typical biofilm, keratin-based water-soluble films have high application potential in many fields, might pave the way for the development of novel sustainable smart packaging products.

Regulation of droplet dynamic behavior after droplet impact on superhydrophobic surfaces

Controlling the impact behavior of a droplet on a superhydrophobic surface is a significant challenge for many applications. Instead of texturing the surface, this study investigated the effect of adding surfactants on the morphology of the droplet after it impacts superhydrophobic surfaces. The results showed that adding low concentrations of sodium dodecyl sulfate (SDS) surfactant prevents fragmentation and splashing. High concentrations of SDS can inhibit rebound and allow droplets to be easily deposited on surfaces after impact. When the droplet size was 3.51 mm and the SDS concentration was above the critical micelle concentration, the contact time of the solution increased by a maximum of 1.30 times compared to that of pure water. In a high-concentration SDS solution, the surfactant molecules can quickly migrate to the newly generated interface during the spreading stage, reducing the interfacial tension and causing wetting changes. The results of this study are expected to contribute toward establishing a simple method to inhibit splashing and increasing contact time on superhydrophobic surfaces.

Molecular Dynamic Simulations of Aqueous Micellar Organometallic Catalysis: Methane Functionalization as a Case Study.

Molecular Dynamics (MD) simulations constitute a powerful tool that provides a 3D perspective of the dynamical behavior of chemical systems. Herein the first MD study of the dynamics of a catalytic organometallic system, in micellar media, is presented. The challenging methane catalytic functionalization into ethyl propionate through a silver-catalyzed process has been targeted as the case study. The intimate nature of the micelles formed with the surfactants sodium dodecylsulfate (SDS) and potassium perfluorooctane sulfonate (PFOS) has been ascertained, as well as the relative distribution of the main actors in this transformation, namely methane, the diazo reagent and the silver catalyst, the latter in two different forms: the initial compound and a silver-carbene intermediate. Catalyst deactivation occurs with halide containing surfactants dodecyltrimethylammonium chloride (DTAC) and Triton X-100. Computed simulations allow explaining the experimental results, indicating that micelles behave differently regarding the degree of accumulation and the local distribution of the reactants and their effect in the molecular collisions leading to net reaction.

Molecular Dynamic Simulations of Aqueous Micellar Organometallic Catalysis: Methane Functionalization as a Case Study

AbstractMolecular Dynamics (MD) simulations constitute a powerful tool that provides a 3D perspective of the dynamical behavior of chemical systems. Herein the first MD study of the dynamics of a catalytic organometallic system, in micellar media, is presented. The challenging methane catalytic functionalization into ethyl propionate through a silver‐catalyzed process has been targeted as the case study. The intimate nature of the micelles formed with the surfactants sodium dodecylsulfate (SDS) and potassium perfluorooctane sulfonate (PFOS) has been ascertained, as well as the relative distribution of the main actors in this transformation, namely methane, the diazo reagent and the silver catalyst, the latter in two different forms: the initial compound and a silver‐carbene intermediate. Catalyst deactivation occurs with halide containing surfactants dodecyltrimethylammonium chloride (DTAC) and Triton X‐100. Computed simulations allow explaining the experimental results, indicating that micelles behave differently regarding the degree of accumulation and the local distribution of the reactants and their effect in the molecular collisions leading to net reaction.

Facile green synthesis route for new ecofriendly photo catalyst for degradation acid red 8 dye and nitrogen recovery

This study novelty is that new photo catalyst prepared from sustainability low cost precursors. Dark red color hydrogel composites have been easily prepared from gelatin biopolymer using a simple sol–gel method. Gelatin doped by cobalt chloride, and silver nanoparticles (SNPs) in the presence of traces amount of sodium dodecyl sulfate surfactant and calcium chloride. Water-insoluble Gelatin composites are thermally stable photocatalysts for the degradation of toxic anionic acid red 8 dye. Promising photodynamic activity confirmed by fluorescence emission at λmax 650 nm. Optical absorption in Vis. light enhanced photo catalytic activity. Silver nanoparticles enhanced crystallinity, and improved optical properties and porosity. Dopants by CoCl2 and silver nanoparticles increased band gap of gelatin composites from (1.82 to 1.95) indicating interfacial charge separation. Low band gaps improved photo catalytic activity. Optical band gaps (Eg) lower than 2.0 eV indicates high catalytic activity in the photo degradation acid red 8 dye using Vis. light, wavelength 650 nm. Percent removal efficiency (%Re) of the dye at 500 ppm initial concentration, pH 1, contact time 30 min., and 0.20 g L−1 dose photo catalyst reached 95%. pH not affects removal efficiency. So, gelatin composites removed AR8 dye by photodegradation mechanism rather than adsorption due to photodynamic activity. Kinetics of photodegradation followed pseudo first order kinetic with rate constant k1 5.13 × 10−2 min.−1 Good electrical conductivity and magnetic properties (effective magnetic moment (µeff 4.11 B.M) improved dye degradation into simple inorganic species. Nutrients NH4+, and NO3− degradation products recovered by using alumina silicate clay via a cation exchange mechanism.

Manipulation of the thermo-rheological properties of stable Fe3O4 nanoparticles-embedded PCM nanoemulsions

Phase Change Material (PCM) nanoemulsions offer numerous benefits as thermal energy storage systems, including high energy storage capacity, rapid thermal response, enhanced stability, and easy integration into existing thermal management systems. This study focuses on producing nanoemulsions with fine droplets of commercial paraffin RT42, stabilized with the anionic surfactant sodium dodecyl sulfate (SDS) using the sonication method. The impact of formulation of PCM nanoemulsions on its thermophysical and rheological characterization has been investigated. The results indicated that the degree of supercooling declined from 12.8 °C to 8.6 °C as the PCM volume fraction varied from 10 to 45 vol%. This decrease was attributed to the enlargement of PCM droplet size from 110 to 164 nm while maintaining a constant PCM-to-surfactant ratio of 10:1. By incorporating Fe3O4 nanoparticles as a nucleating agent at two different concentrations of 1 and 4 %, the supercooling degree decreased from 10.2 °C to 8.2 °C when 4 % Fe3O4 nanoparticles were added. The samples exhibited remarkable stability throughout a period of one year of storage and under dynamic conditions, including 50 freeze-thaw cycles. Rheological investigations and the gelation mechanism through estimation of the attractive and repulsive interaction forces among droplets revealed that nanoemulsions with volume fractions ≥30 % transformed from fluid-like states to viscoelastic gels due to the depletion attractions caused by SDS micelles in the continuous phase. These findings contribute to a better understanding of the factors influencing the formation of viscoelastic PCM nanoemulsion gels and their potential applications across various fields.

Effectively enhancing red fluorescence strategy and bioimaging applications of carbon dots

Red-emitting carbon dots have attracted much attention because of their excellent fluorescence properties. It is of great significance to synthesize red-emitting carbon dots with high fluorescence quantum yield. Herein, by using citric acid and 1,8-diaminonaphthalene as precursors in N, N-dimethylformamide, novel carbon dots (NC-CDs) exhibiting red emission at 607 nm upon excitation at 514 nm were synthesized via a solvent-thermal approach. NC-CDs aggregated in lipid droplets of cells, and hemin quenched their fluorescence. Subsequently, cationic surfactants cetyltrimethylammonium bromide, anionic surfactants sodium dodecyl sulfate and nonionic surfactants were used to functionalize the NC-CDs. The results indicated that both ionic surfactants increased the fluorescence quantum yield and solubility of NC-CDs with extended fluorescence lifetime. This approach is applicable to a class of carbon dots that possess both carboxyl and amino groups. Additionally, these functionalized NC-CDs exhibited high recognition sensitivity towards ClO− and Cu2+ respectively except for hemin. This study provides a novel approach for the synthesis of highly red-emitting carbon dots, expanding their applications in the field of biological imaging and sensing. The findings hold significant implications for the real-time monitoring of hemin in lipid droplets. Additionally, this work offers a simple method to dramatic enhance their fluorescence quantum yield.

Enhanced hydrogen sequestration through hydrogen foam generation with SDS Co-Injection in subsurface formations

Inherent obstacles of hydrogen injection encompass preferential channeling through larger pathways, hampering microscopic sweep efficiency within porous media. This work pioneers hydrogen foam generation via co-injection with aqueous sodium dodecyl sulfate (SDS) to enhance subsurface hydrogen trapping capacity. SDS addition substantially reduces hydrogen-water interfacial tension and enhances viscoelasticity. In contrast to robust hydrogen foam stability, CO2 foams display compromised integrity, stemming from surfactant aggregation and ensuing infiltration channels that permit aqueous phase CO2 dissolution. Hydrogen foams conversely sustain uniform surfactant films, forestalling hydrogen ingress into water. Synergetic microfluidic and pore-scale simulations visualise mechanisms underlying intensified hydrogen capture and mobility reduction attributed to deformation and flow resistance when traversing constricted pores. Introducing the amphiphilic SDS surfactant considerably promotes hydrogen adsorption through its hydrophobic tail. Core flooding experiments quantify over 2 times hydrogen storage ratio amplification with SDS relative to sole hydrogen injection. The framework contributes pragmatic strategies to harness high-efficiency hydrogen foam for scalable clean energy storage.

Nanoporous gold with microporous structure prepared by sodium dodecyl sulfate-mediated electrochemical dealloying

Nanoporous gold (NPG) is a promising catalytic material for the oxidation of CO and methanol applications. However, NPGs are prone to extensive macroscopic cracking that often decrease mechanic properties of NPGs and depresses their catalytic action. To produce crack-free NPG with an ultra-finer porosity in room temperature, the anionic surfactant sodium dodecyl sulfate (SDS) was added in electrochemical dealloying process. SDS has the effect of reducing the surface diffusion of gold which hinder the initial coarsening of ligaments and prevents interior silver atoms from being exposed and dissolved. As a result, the pore and ligment size are finer, but higher residual silver of NPG samples. NPG with pore size down to 2 nm and the ligament 4.0 nm was successfully fabricated with 13.32 mM SDS in perchloric acid solution. The surface diffusion coefficient of Au atoms was 1.6 × 10−24 m2·s−1, nearly 3 orders of magnitude smaller than that of Au atoms in the absence of SDS (2.8 × 10−21 m2·s−1). Nanoindentation results demonstrated that high residual silver content made NPG samples harder and stiffer，the specific surface areas of NPG with 6.66 mM SDS was 190 m2 g−1 by BET. This work provided very important clues on how to control the crack free ultrafine nanoporous structure of other materials.

Effect of surfactants on the interfacial viscoelasticity and stability of silk fibroin at different oil-water interfaces.

The biocompatible amphiphilic silk fibroin, extracted from domesticated silkworms, can adsorb at the oil-water interface and form elastic interfacial layers. In this study, three surfactants (cationic cetyltrimethylammonium bromide, the nonionic polyoxyethylene sorbitan monolaurate, and the anionic sodium dodecyl sulfate) were selected to investigate, through interfacial shear rheology, the influences of surfactants on the interfacial viscoelasticity and stability of silk fibroin at the interfaces between water and two different oils. The presence of surfactant prolongs the equilibration time and enhances the interfacial elastic modulus and toughness of the interfacial silk fibroin layers, especially at the nonpolar dodecane-water interface. However, when the surfactant exceeds a critical concentration, the shear modulus and stability of interfacial silk fibroin layers begin to decrease due to the competitive adsorption of surfactant molecules and the weakening of the protein network. Owing to electrostatic interactions, the ionic surfactants cetyltrimethylammonium bromide and sodium dodecyl sulfate can form more hydrophobic complexes with silk fibroin, which results in higher shear moduli than for silk fibroin and silk fibroin-polyoxyethylene sorbitan monolaurate mixture. Both the surfactant type and oil polarity play important roles in the adsorption, shear viscoelasticity, and stability of silk fibroin at the oil-water interface. Enhanced interactions between a silk fibroin-surfactant mixture and the oil phase delay the equilibration of the adsorption layers but strengthen the stability of interfacial layers. © 2023 Society of Chemical Industry.

Investigated the effects of surfactant concentration on cobalt ferrite nanoparticles synthesized in reverse micelles

The use of reverse micelles as nanoscale hydrophilic voids of microemulsions in the manufacture of ferrites has been recognized since the 1960s, but there has been very little attention on the structural and magnetic properties with respect to surfactant concentration. This paper investigates the influence of surfactant sodium dodecyl sulphate (SDS) concentrations on cobalt ferrite (CoFe2O4) nanoparticles prepared by reverse micelles at annealing temperatures 250°C and 500°C. Samples with varied cobalt to SDS ratios (Co: SDS = 1: 0.33, 1: 0.5, 1: 0.66) were subjected to XRD, TGA, TEM, FTIR and VSM Studies. All the samples exhibited single-phase spinel structures with crystalline diameters ranging from 10 to 18 nm. As the SDS concentration increased the crystallite size decreased. The TEM images showed the particle size in the range of 7.6 -17.7 nm. VSM investigations show the ferromagnetic behavior of the sample. The observed increase in coercivity with respect to annealing temperature for the same concentration reflects the single-domain nature of the nano particles. This underscores the crucial role of annealing conditions in customizing cobalt ferrite nanoparticles as a suitable application in longitudinal magnetic recording media.

A SANS investigation of silk-stabilized aqueous poly(3-hexylthiophene): phenyl-C61-butyric acid methyl ester nanoparticle dispersions

Regenerated silk fibroin (RSF) protein comprising both hydrophilic and hydrophobic chain segments offer great potential for interfacial interaction and stabilization of organic nanoparticles (NPs) in aqueous medium. In this work, aqueous dispersion of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) NPs of 1:1 weight ratio were prepared using RSF as surfactant for the first time via the mini-emulsion method. The size, morphology, internal structure, interface and hierarchical organization of RSF-stabilized P3HT:PCBM NPs was investigated using UV–visible spectroscopy, contrast-variation small-angle neutron scattering (CV-SANS) and ultra-small-angle neutron scattering (CV-USANS). The P3HT:PCBM NPs were established to be stabilized in the matrix of RSF colloidal microparticles in water. Unlike the commonly used surfactant sodium dodecyl sulfate which produces core–shell (PCBM–P3HT) NPs, the RSF molecules generated P3HT:PCBM NPs with internal structure that resemble phase-separated solvent-cast films. The as-prepared dispersion has good film-forming ability and has been demonstrated for fabrication of composite films comprising graphene oxide.

Quick and Green Procedure for the Quantification of Chromium in an Anionic Surfactant System

This study aims to establish a facile, user-friendly, accurate, and repeatable spectrophotometric detection method for Cr(III) ions in trace quantities. The method utilises reagent 1-nitroso-2-naphthol (NNPh) in a sodium dodecyl sulphate (SDS) 1.0 % micellar solution, replacing the old, time-consuming, and expensive solvent extraction method that employs hazardous solvents such as carbon tetrachloride and chloroform. SDS surfactant is used to solubilise indissoluble chelates, making the proposed technique easy, rapid, and environmentally friendly. The established method exhibits an improved linear calibration range, sensitivity, limit of detection, and selectivity compared to earlier spectrophotometric methods employing different complexing agents. The stoichiometric ratio between Cr and NNP was observed to be 1 : 3. The molar absorption coefficient (<i>ε</i>) was determined to be 2.05 ∙ 104 l mol<sup>–1</sup> cm<sup>–1</sup> at <i>λ</i><sub>max</sub> 579 nm. The limits of detection for Cr(III) was measured as 3.49 ng l<sup>–1</sup>. A calibration linear curve was achieved in the concentration range of 0.5–5.0 μg ml<sup>–1</sup>. Results obtained showed good comparison with the results obtained by atomic absorption spectrometry. The developed method has been adapted for the analysis of Cr(III) in various alloys, pharmaceutical, environmental, and biological samples.

Organic/inorganic heterostructures templated by interfacial instability-driven BCP colloids in deformable emulsion droplets.

Hybrid heterostructure materials have received considerable attention due to the integration of each component and abundant functional applications in micromotors, catalysis, photothermal therapy, drug delivery, and bioimaging. However, the preparation of organic/inorganic heterostructure nanoparticles (HSNPs) with high quality still remains a remarkable challenge since thermodynamically metastable structures usually coexist, resulting in a lack of organic scaffolds with extreme uniformity both in shape and size distribution. Here, we prepared polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) core-shell spherical colloids driven by interfacial instability of soft and deformable emulsion droplets. Ultra-low interfacial tension was achieved through the co-adsorption of BCP segments and sodium dodecyl sulfate (SDS) surfactant, which had a strong affinity with the P4VP segment at the interface of the emulsified droplets. The excellent and homogeneous BCP colloids were further utilized as organic scaffolds to selectively grow a functional SiO2 layer on the surface of the BCP spherical colloids, producing BCP/SiO2 HSNPs with highly uniform shape and size distribution originating from the PS-b-P4VP scaffolds, thus providing an efficient and general strategy to construct and design organic/inorganic HSNPs with diverse applications.

Effect of counterions on the structure and dynamics of water near a negatively charged surfactant: a theoretical vibrational sum frequency generation study.

Charged aqueous interfaces are of paramount importance in electrochemical, biological and environmental sciences. The properties of aqueous interfaces with ionic surfactants can be influenced by the presence of counterions. Earlier experiments involving vibrational sum frequency generation (VSFG) spectroscopy of aqueous interfaces with negatively charged sodium dodecyl sulfate (Na+DS- or SDS) surfactants revealed that the hydrogen bonding strength of the interfacial water molecules follows a certain order when salts of monovalent and divalent cations are added. It is known that cations do not directly participate in hydrogen bonding with water molecules, rather they only influence the hydrogen bonded network through their electrostatic fields. In the current work, we have simulated the aqueous interfacial systems of sodium dodecyl sulfate in the presence of chloride salts of mono and divalent countercations. The electronic polarization effects on the ions are considered at a mean-field level within the electronic continuum correction model. Our calculations of the VSFG spectra show a blue shift in the presence of added countercations whose origin is traced to different relative contributions of water molecules from the solvation shells of the surfactant headgroups and the remaining water molecules in the presence of countercations. Furthermore, the cations shield the electric fields of the surfactant headgroups, which in turn influences the contributions of water molecules to the total VSFG spectrum. This shielding effect becomes more significant when divalent countercations are present. The dynamics of water molecules is found to be slower at the interface in comparison to the bulk. The interfacial depth dependence of various dynamical quantities shows that the interface is structurally and dynamically more heterogeneous at the microscopic level.

Green Extraction of Carotenoids from Tomato By-products Using Sodium Dodecyl Sulphate

AbstractTomato peel by-products contain high levels of lycopene, which has traditionally been extracted using organic solvents. This research focuses on the optimisation of a sustainable method to obtain a lycopene-rich extract using the biodegradable anionic surfactant sodium dodecyl sulphate (SDS). A Plackett–Burman experimental design was used to investigate the effect of seven factors on the extraction of carotenoids from tomato peels using sodium dodecyl sulphate (SDS volume and concentration, homogenisation intensity and time, sonication phase, extraction time and ultracentrifugation intensity). Based on the responses of total carotenoid extraction, the SDS volume, the use of ultrasound and the extraction time significantly influenced the extraction yield and were selected for optimisation using a Box–Wilson experimental design. The final green extraction protocol (1 g sample + 11.9 ml SDS 0.3%, homogenisation at 13,500 rpm for 2 min, ultrasound phase, agitation for 8.2 h and ultracentrifugation) was selected after quantification of total carotenoids by UV–VIS and HPLC-DAD. Finally, we used nuclear magnetic resonance to demonstrate a high lycopene purity in the carotenoid extract obtained. Furthermore, using transmission electron microscopy, we observed the presence of intact chromoplasts in the extract, protecting the carotenoids from the exposure to external agents. Thus, this work reports an optimised method for the sustainable extraction of carotenoids and demonstrates the viability of the degradable solvent SDS for the extraction of liposoluble bioactive compounds, like carotenoids and mainly lycopene. The lycopene extract could be used for the technological and nutritional enrichment of new foods and/or the design of nutraceuticals.

Nano-stabilized foam for enhanced oil recovery using green nanocomposites and anionic surfactants: An experimental study

With the decline in hydrocarbon resources around the world, the use of different enhanced oil recovery (EOR) methods became more attractive. Recently, gas foams have been considered by researchers as one of the most effective ways to increase oil recovery. Despite its functions, the conventional foams have low stability. Recently, nanomaterials, as appropriate agents, are used to increase the stability of foams in enhances oil recovery. In this study, the synthesized nanocomposites (NCs), SiO2/KCl/Xanthan NCs was used to stabilize the foams obtained from sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) surfactants. Thus, the synergic effect of the surfactant and NCs was investigated along with the salinity, foam quality, alkalinity and oil properties. The experimental measurements of conductivity, pH, surface tension (ST), interfacial tension (IFT), contact angle (CA) and oil displacement were performed. The obtaining results showed that the SDS and CTAB surfactants have the critical micelle concentration (CMC) of 2000 and 300 ppm, respectively. In terms of the foam stability, both surfactants demonstrated the same behavior of equal stability, while it is improved under the influence of NaCl and NaOH at different concentrations with reducing the ST, IFT and foam generation time (tg). In addition, the optimal NCs concentrations for SDS and CTAB surfactants which improved the foam stability significantly, reduced the CA by 73.27 and improved the oil recovery by 20 % original oil in place (OOIP) were 1000 ppm and 500 ppm, respectively. This was also confirmed by macroscopic analysis of the formulated nano-surfactant systems. On the other hand, the viscosity, density and the gas rate had the inverse influence on the foam stability.

Experimental Study on the Influence of Surfactants on Ore Surface Wettability.

To reveal the evolution law of ore surface wettability under the condition of adding surfactant and chemical reaction, the test experiments of ore surface morphology, roughness, and chemical element distribution were carried out. The results show that the contour of the ore surface morphology was relatively flat in the early stage of leaching and the roughness factor increased slowly, while the contour fluctuated significantly in the late stage of leaching and the roughness factor increased sharply. With the leaching reaction, the roughness factor and spreading coefficient of the ore with a 0.008 mol/L surfactant (sodium dodecyl sulfate) concentration were always higher than those without surfactant and the surfactant enhanced the erosion effect of the solution on the ore surface. During the leaching process, the chemical elements Cu, Al, and K were dissolved on the ore surface, and the content of Cu decreased significantly from 2.01 to 0.86%; the leaching rate of copper was about 57.2%. According to the morphology characteristics of the ore surface during leaching and the distribution law of chemical elements on the ore surface before and after leaching, the leaching process was divided into four stages of "contact-penetration-reaction-disintegration". The surfactant had the most obvious effect on the ore surface morphology in the two stages of "reaction" and "disintegration".