Alcohol Polyoxyethylene Research Articles

Synergy of chelating agents and surfactants on the wettability and pore structure of coal dust: Experimental study and molecular simulation

To reduce the hazards of coal dust pollution to miner health and the environment, and to realize efficient wetting and settling of coal dust, this paper evaluates the wettability of tetrasodium glutamate diacetate (GLDA)–aliphatic alcohol polyoxyethylene ether sodium sulfate (AES), hereafter termed G–A, by selecting the surfactant through macroscopic experiments and microscopic simulations. With the help of molecular simulation to study the synergistic mechanism of the surfactants and chelating agents, the functional group changes and mesoscopic modification of coal dust particles were evaluated in combination with characterization experiments. Comprehensive analysis showed that the G-A solution had the best wettability with a low surface tension of 22.77 mN/m, the diffusion rate of the solution increased to 1.25°/s, and the contact angle with the coal dust decreased to 18° within 12 s. After infiltration, the median particle size of coal dust reached 38.140 μm, which increased by 148 %. The pores and slits on the surface of the coal dust particles are further increased, providing surfactants with more extensive adsorption sites, and the proportion of hydrophilic groups on the surface of coal increased by 8.42 %, with the consequent improvement of wettability. This study provides a theoretical basis for the research and development of more environmentally friendly and efficient dust reducing agents in the field of spray dust reduction.

Micellization and interfacial behavior of sodium fatty alcohol polyoxyethylene ether carboxylate surfactants in low-concentration aqueous hydrogen peroxide

The micellar properties of sodium fatty alcohol polyoxyethylene ether carboxylate surfactants in H2O2-free and H2O2-containing solutions, as well as their adsorption behavior at the gas–liquid interface, were investigated. The surface tension in water and a 6 wt% aqueous H2O2 solution was measured as a function of the logarithm of surfactant concentration, using glass plates rather than platinum plates, at temperatures of 283 K, 293 K, 303 K, 313 K, and 323 K. The data were used to calculate the critical micelle concentration (CMC), the surface tension at the CMC (γCMC), the maximum surface excess concentration (Γmax), and the minimum area occupied (Amin). The effects of the polyoxyethylene chain length, temperature, and H2O2 on the physical properties of surfactants were analyzed. The results indicated that the CMC values in water initially decreased with increasing polyoxyethylene chain length before rising due to competing effects of enhanced hydrophilicity and reduced electrostatic repulsion. Notably, the CMC decreased in the presence of H2O2, and the magnitude of the decrease was correlated with the hydrophilicity of the surfactant. Temperature variations further influenced CMC trends in different media (water and H2O2 solutions). Additionally, the presence of H2O2 altered the interfacial properties, leading to an increase in both γCMC and Amin.

Development and performance evaluation of a new type of temperature resistant surfactant for ultra-deep well casing flushing

During the ultra-deep well drilling process, drilling fluid tends to remain in the casing, contaminating it and affecting the progress of completion engineering. To address this issue, a screening method was employed to select nonionic surfactants, with fatty alcohol polyoxyethylene ether (AEO-7) being chosen among various types. To overcome the temperature resistance issue of AEO-7, phthalic anhydride (PA) was introduced into AEO-7, and neutralization reaction with NaHCO3 was carried out to synthesize a novel surfactant (SEO). High-temperature and high-pressure precipitation testing equipment and high-temperature cleaning equipment were set up to study the temperature-resistant cleaning performance of SEO. Results indicate that surfactant SEO maintains good solubility in high-temperature environments in the solution through ionic bonding. At 200 °C, the cleaning efficiency of SEO solution for different types of drilling fluid residues exceeds 95 %. Additionally, SEO adsorption on metal surfaces can inhibit Cl- corrosion. Combined with micro-mechanism characterization results, SEO can disperse solid particles, adsorb organic phases, reduce interfacial tension, and achieve efficient cleaning. Field experimental results show that the surface tension retention rate of well-flushing fluid after cleaning is 95.8 %, with a solid particle content of 5.4 g/L, meeting onsite requirements and broad application prospects.

Effectiveness Evaluation of Silicone Oil Emulsion In Situ Polymerization for Dehydration of Waterlogged Wooden Artifacts

Organosilicon materials have shown potential as dehydration agents for waterlogged wooden artifacts. These materials can polymerize under normal conditions to form polymers with favorable mechanical strength, antibacterial properties, and aging resistance. However, the insolubility of most organosilicon hindered their penetration into waterlogged wood, which may lead to an unwanted cracking. This study aimed to evaluate the effectiveness of polydimethylsiloxane (PDMS) and hydroxy-terminated polydimethylsiloxane (PDMS-OH) with low viscosity and moderate reactivity for dehydrating waterlogged wooden artifacts from the Nanhai No.1 shipwreck. Four surfactants ((3–aminopropyl) triethoxysilane (APTES), alkyl polyoxyethylene ether (APEO), tri-methylstearylammonium chloride (STAC), and fatty alcohol polyoxyethylene ether (AEO)) and cosurfactant were employed to transform the two kinds of water-repellent silicone oils into eight groups of highly permeable oil-in-water (O/W) emulsions. Under the catalysis of a neutral catalyst, in situ polymerization occurred within the wood cells. Group P2-2 formulated with PDMS-OH and APEO showed the best efficiency in maintaining the dimensions of the wood during dehydration. The dehydrated wood exhibited a natural color and texture with a minimal volume shrinkage rate of 1.89%. The resulting polymer adhered uniformly to the cell walls, effectively reinforcing the wood cell structure. The weight percent gain of the wood was only 218%, and the pores of the cell lumen were well maintained for future retreatment. This method effectively controlled the sol–gel reaction process of the organosilicon and prevented damage to the wooden artifact during the dehydration process. Moreover, the dehydrated wood samples only experienced a low weight gain of 17% at 95% relative humidity (RH), indicating their great environmental stability.

Study on the effect of spatial adsorption orientation on the preferential selection mechanism of dust suppression surfactants

Surfactants are widely used in the field of coal dust control. However, the dust suppression effect of different surfactants varies significantly, and the preferential selection mechanism of dust suppressants for mining is not clear. In this study, the water/surfactant/lignite system was constructed by molecular simulation to investigate the adsorption behavior of surfactants with different structures on the lignite surface at the molecular level. The reasons for the differences in the wettability adsorption of sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), fatty alcohol polyoxyethylene ether-9 (AEO-9), and alkyl polyglycoside (APG1214) on the lignite surface were also investigated based on the quantum chemical calculations and macroscopic experimental analysis. The results showed that the adsorption orientation of surfactant molecules at the solid–liquid interface exerted a pivotal influence on the surface wettability of lignite. According to molecular orbital and electrostatic potential analysis, surfactant molecules with LUMO distributed in the tail chain were more inclined to form a positive adsorption orientation than that concentrated in the polar headgroups; and the stronger the interaction between the polar headgroups and the coal surface with the like charge, the more stable the adsorption of surfactant molecules with the positive arrangement at the interface was. Furthermore, the stronger potential difference between SDS molecules and the hydroxyl-rich structure of the APG1214 molecules are conducive to the formation of hydrogen bonds with water molecules. Wettability experiments showed that the ability of surfactants to improve the wettability of coal dust was positively correlated with the adsorption orientation.

Preparation and properties of fluorinated VAc-VeoVa10 latex emulsified with allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulphate

Purpose The traditional VeoVa10-VAc copolymer latex, which prepared via the emulsion polymerization of the mixed monomers of VAc and VeoVa10, has the poor water resistance and thermal stability because of the migration of the conventional emulsifier molecules and the low bond energy of C-C bond. The purpose of this work is that the fluorinated monomer is used to modify the latex. The film of the resultant latex has the C-F bond with high bond energy and low surface energy, which can effectively improve the heat resistance and water resistance of the resultant film. In addition, the reactive emulsifier is used to replace the conventional emulsifier. The drawbacks of the conventional emulsifier molecules migrate and desorb can be avoided when the polymer latex is stored, thereby also improving the water resistance. Design/methodology/approach The modified VAc-VeoVa10 latex has been successfully synthesized via the semi-continuous seeded emulsion polymerization, which VAc and VeoVa10 is used as the main monomers and HFMA was used as the functional monomer. KPS and reactive surfactants of SE-10 were used as the initiator and emulsifier, respectively. The structure of resultant latex film was characterized by Fourier transform infrared spectroscopy (FTIR). The latex films were tested by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA). The particle size and its distribution of the latex were measured by the nano particle size analyzer. Findings The factors that had an influence on the properties of the latex and the film were investigated in detail. The stability of the resultant latex is good. The average particles of the latex and its distribution are small and uniform, respectively. In comparison with the conventional latex film, the thermal stability and hydrophobicity of the resultant latex film are improved obviously. Practical implications The resultant latex can be used in both the waterborne interior and exterior wall coatings, pickering stabilized waterborne polymer dispersions, polymer powders, environmentally friendly polymer-modified waterproof mortar and other fields, which can be satisfied with the high demand of thermal stability and hydrophobicity. Originality/value The modification of poly (VAc-VeoVa10) by reactive surfactant and fluorinated monomer is seldom reported. In this study, the fluorinated poly (VAC-VeoVa) latex is prepared via the reactive surfactants, which VAc and VeoVa10 is used as the main monomers and hexafluorobutyl methacrylate is used as the functional monomer. Potassium persulfate (KPS) and allyl nonyl phenoxy propyl alcohol polyoxyethylene ether ammonium sulfate are used as the initiator and emulsifier, respectively.

Synergistic effect of alcohol polyoxyethylene ether sodium sulphate and copper foam on methane hydrate formation

AbstractNatural gas is the cleanest fossil energy source and its consumption is increasing rapidly, so an efficient natural gas way of storing and transporting is urgently needed. Solidified natural gas (SNG) technology is gaining traction because of its higher safety, lower cost, and flexible storage and transportation modes. To improve the methane uptake rate in SNG technology, this work investigated the growth of methane hydrate in fatty alcohol polyoxyethylene ether sodium sulphate (AES) solution with the addition of three different pores per inch (PPI) of copper foam (CF). The results showed that the addition of AES caused the hydrate to grow upwards along the wall, and the methane uptake in the 300 ppm AES solution was increased by 623% compared to pure water. CF not only provided more nucleation sites for hydrate but also transferred the heat generated during hydration. Moreover, there was a synergistic effect between AES and CF and the solution could continuously transport upward along the continuous metal skeleton to increase the gas–liquid contact area. Thus, the formation rate and induction time of methane hydrate improve. Hydrate had the highest methane uptake in the 20 PPI CF system and the lower the pressure, the greater the ability of CF to promote hydrate formation. The methane uptake improved by 27.6% and the induction time was reduced by 59.7% compared to the pure AES system at 6 MPa. This work is aimed at advancing SNG technology (especially at low pressure) and informs the theoretical foundation.

Enhanced particle removal ability of two representative nonionic surfactants: A reasonable interpretation based on DFT and coarse-grained molecular dynamics methods

Cleaning of copper surfaces after chemical mechanical polishing is indispensable for removing particle residues, which is a critical step in integrated circuits manufacturing. This paper introduces two nonionic surfactants, coconut oil diethanolamine (CDEA) and fatty alcohol polyoxyethylene ether (AEO-9), into a basic alkaline cleaning solution comprising tetraethyl ammonium hydroxide and lysine to investigate their abilities to enhance particle removal performance. Cleaning performance was measured with scanning electron microscopy, which showed that the two surfactants achieved excellent particle removal efficiency (above 95 %), with CDEA performing slightly better in all tested concentrations. Concerning critical micelle concentration, surface tension tests showed that CDEA (at 1500 ppm) had superior wettability and dispersive capacity compared with AEO-9 (at 2000 ppm) and could prevent particle redeposition more effectively. Using density functional theory, CDEA was found to have more polar groups to form hydrogen bonds with the hydrophilic surface of colloidal silica particles or bond with the copper substrate, explaining CDEA’s ability to lower the surface tension of the cleaning solution and improve the zeta potential between particles and the copper substrate. Finally, based on the Martini forcefield, simulations of coarse-grained molecular dynamics provided valuable theoretical insights into the different dispersion abilities of the two nonionic surfactants that CDEA had a more significant diffusion coefficient (0.073 Å2/ps) and was able to form micelles more efficiently in solution compared with that of AEO-9 (0.066 Å2/ps).

Hydrophobically associated amphiphilic copolymer fracturing fluid with dual Functions of fracturing and flooding for enhanced oil recovery

Polymer fracturing fluids are widely used in oil and gas extraction; however, the residues left after gel breaking can easily clog fractures, leading to formation damage and a decline in economic benefits. To address this issue, this study developed a new type of hydrophobic associative amphiphilic copolymer, P(AM-AA-AAEOn), prepared through the copolymerization of fatty alcohol polyoxyethylene ether (AAEOn), acrylic acid, and acrylamide. The properties of the system, including shear resistance and thixotropy, shear recovery, viscoelasticity, salt responsiveness, and interfacial tension, were thoroughly investigated by measuring its hydrodynamic size, molecular weight, root-mean-square radius of gyration, and second virial coefficient. Experimental results demonstrated that with a monomer ratio of 300:100:1, this fracturing fluid system exhibited excellent shear resistance, viscoelasticity, effective sand carrying, and corrosion inhibition, along with good gel-breaking and compatibility properties. Further oil displacement tests revealed that P(AM-AA-AAEOn), due to its superior interfacial activity and wettability, significantly enhanced oil recovery efficiency by 25.01%. These characteristics not only resolved the issue of flowback in traditional polymer fracturing fluids but also facilitated the efficient integration of fracturing and oil displacement. The innovation of this research lies in the development of a novel, efficient, and environmentally friendly fracturing fluid, which provides significant theoretical and practical foundations for oilfield fracturing technology and holds promising industrial application prospects.

Application Properties of Gemini Quaternary Ammonium Salt with Quadra‐cationic Sites and Sodium Fatty Alcohol Polyoxyethylene Ether Carboxylate Mixed Systems

AbstractThe application properties such as foam property, electrolyte tolerance, antibacterial activity and antistatic performance of the mixed systems of a novel Gemini quaternary ammonium salt with quadra‐cationic sites (TC‐GS) and sodium fatty alcohol polyoxyethylene ether carboxylate (AE9CNa) at various molar fraction of TC‐GS (αTC‐GS), were investigated systematically. Results show that TC‐GS/AE9CNa mixed systems with different ratios form a homogeneous and transparent solution, which exhibits excellent foam stability and antibacterial activity. The foam volume of the mixed system remains nearly constant from 400 s to 1000 s, and even when TC‐GS is 10 mg/L in the mixed systems, the antibacterial rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) for 2 min. are all exceeded 99 %. The mixed systems of TC‐GS/AE9CNa at various αTC‐GS also demonstrate the superior electrolyte tolerance, their maximum tolerance of NaCl, CaCl2 and MgCl2 is severally beyond 270 g/L, 180 g/L and 180 g/L. In addition, both TC‐GS solution and the mixed systems have good antistatic properties, which can reduce the surface resistance of polyester fabric to ≤1010 Ω.

Investigation on the flotation of a mixed collector and its mechanism for enhancing low-rank coal flotation: Effect of micro adsorption and its interaction with gangue particle

The flotation effect of the association formed by dodecyl trimethyl ammonium bromide (DTAB) and dodecyl alcohol polyoxyethylene ether sodium sulfate (AES), and nonpolar kerosene mixed collectors on low-rank coal (LRC) was investigated. The results show that the combustible matter recovery was significantly improved compared with a single kerosene from 49.88% to 74.97% when the the mixed collector was used, while concentrate ash content decreased from 9.76% to 8.57% simultaneously. The utilization of the mixed collector not only enhanced the surface hydrophobicity of organic particles but also facilitated the intercoalescence among them, thereby reducing the ash content of concentrate during flotation. The molecular dynamics simulation (MDS) results show that the effect of the mixed collector on the surface of LRC is mainly the electrostatic interaction and hydrogen bonding between the collector molecules and the surface molecules of LRC, which makes the polar molecules in the collector closely adsorbed on the surface of LRC.

Mechanisms of N2 molecule adsorption and accumulation on surfactant-modified substrates: A molecular dynamics simulation

In flotation processes, gas molecules adhere to and accumulate on the target mineral surface, forming micro-nanobubbles, which can significantly enhance the efficiency of particle-bubble adhesion. Surfactants are commonly employed as auxiliary agents and play pivotal roles in flotation. However, the effect of surfactant pre-adsorption at the solid–liquid interface on the microscopic process of gas molecule adsorption and accumulation remains unclear. In this study, varying degrees of roughness surface in carbon substrates, the fatty alcohol polyoxyethylene ether (C12EO15), nitrogen molecules (N2), and water molecules (H2O) were employed to construct a gas–liquid–solid model for molecular dynamics simulations aimed at elucidating the underlying mechanisms of N2 molecule adsorption and accumulation on surfactant-modified substrates at the molecular level. The research findings revealed that N2 molecules preferred adsorption in close proximity to carbon atoms along the alkyl chain of the C12EO15 molecule. C12EO15 molecules exhibit a bending and intertwining behaviour on the hydrophobic carbon substrate surface, thereby forming a “network” adsorption layer. An increase in the quantity of surfactants provides abundant adsorption sites for N2 molecules at the solid–liquid interface, consequently augmenting the adsorption capacity of N2 molecules. Nonetheless, the presence of interstitial gaps between the surfactant-formed adsorption sites impedes the diffusion of the N2 molecules at each adsorption locus. This hindrance may obstruct the subsequent generation of micro-nano bubbles at the solid–liquid interface.

The effect of polycarboxylate superplasticizer on the strength and hydration performance of alkali slag building materials

ABSTRACT To explore the effect of polycarboxylate superplasticizers on the strength and hydration performance of alkali slag building materials, this study prepared cross-linked polycarboxylate superplasticizers with different ratios of hydrogen peroxide, methyl allyl alcohol polyoxyethylene ether, acrylic acid, polyethylene glycol diacrylate, monomer aqueous solution, reducing agent, chain transfer agent, etc. according to certain ratios, and tested their effects on the hydration performance and strength of alkali slag building materials. Through experimental analysis, it was found that the higher the proportion of cross-linked polycarboxylate based high-efficiency water-reducing agents, the lower the initial flowability of building material slurry; The addition of cross-linked polycarboxylate water-reducing agent will prolong the initial and final setting time of alkali slag building materials, delaying the hydration time of building materials; Cross linked polycarboxylate superplasticizers can reduce the electrical conductivity of alkali slag building material slurry, delaying its hydration rate; Different ratios of water-reducing agents have a significant impact on the water reduction rate of alkali slag building materials, with V2 water-reducing agent having the highest water-reduction rate of 28.6%; Cross linked polycarboxylate superplasticizers can increase the flexural and compressive strength of alkali slag building materials. Therefore, cross-linked polycarboxylate water-reducing agents have shown great potential in regulating the properties of alkali slag building materials.

Qualitative analysis of hydrophilic headgroup water molecular space dependence and wetting effects of solution systems on polluting coal dust

The hydrophilic head groups of the surfactants affect the interfacial tension of surfactant solutions and the internal micelle structure of the bulk surfactants. Because of this, investigating the effect of the hydrophilic head groups on the adsorption performance of surfactants is helpful in terms of revealing the wetting mechanism of surfactants on coal at the molecular level. In this work we combine molecular dynamics simulations and quantum chemistry calculations with a collection of experiments to analyze the interaction patterns between sodium dodecyl sulfonate (SDSO), sodium dodecyl sulfate (SDS), sodium fatty alcohol polyoxyethylene ether carboxylate (SSN), and sodium lauryl phosphate (LSN) with coal. The radial distribution results show that SDSO formed the closest first peak of the hydrated layer at 1.31 Å, with a probability peak of 3.92, which exhibited strong hydrogen bonding interactions that are consistent with the relative concentration and average azimuthal shift trends obtained from molecular trajectory simulations. The priority interaction types between four surfactants and water molecules were determined using the energy difference of molecular orbitals in quantum mechanics. The weak interaction between hydrophilic head groups and water molecules was qualitatively and quantitatively analyzed using the Independent Gradient Model (IGMH), and the fundamental reasons affecting the wetting of long flame coal were obtained.

Preparation of novel gel foam and its fire suppression performance against gasoline pool fires

The phenomenon of re-ignition after extinguishing tank fires poses a significant challenge for firefighting and rescue operations. In this study, a gel foam was prepared using linseed gum as the gelling agent and sodium tetraborate as the cross-linking agent. By analyzing the foaming performance of the gel foam, the optimal formulation for the gel foam was determined. Subsequently, microscopic structural observations and thermal stability tests were conducted on this material. A comparison of the firefighting performance between the gel foam and aqueous film-forming foam (AFFF) on extinguishing gasoline pool fires was also carried out. The results indicate when the foaming agent, consisting of coconut oil glucoside (APG0814) and fatty alcohol polyoxyethylene ether (AEO-9), is used in a 9:1 ratio with a mass fraction of 0.4 wt%. Furthermore, by introducing 0.35 wt% concentration of linseed gum and 0.02 wt% concentration of sodium tetraborate, the gel foam exhibits a foaming expansion ratio of 6.5, a half-life of 203 min, and a comprehensive value of 989.63, which represents the best performance. The gel foam and the AFFF exhibit relatively similar extinguishing effectiveness, with respective extinguishing times of 108s and 95s.Further analysis of the gel foam's resistance to re-ignition reveals that the gel foam demonstrates 25 % and 90 % ignition resistance times of 425s and 573s, respectively, representing a significant enhancement of 66.02 % and 104.64 % compared to the AFFF. These results indicate that the novel gel foam possesses excellent resistance to re-ignition, reducing the risk of fire rekindling in liquid fire scenarios. This research serves as a valuable reference for the development of environmentally friendly and re-ignition-resistant gel foam for extinguishing liquid fires.

Effects of residual foaming agent and defoamer on defoaming-flocculation-filterpress characteristics of earth pressure balance shield muck.

Foaming agents as a combination of several components are usually used as soil conditioning during earth pressure balance shield (EPBS) tunnelling. These residues in waste EPBS muck lead to a series of new challenges for in-situ recycling, i.e., foams overflow flocculation tank. This study investigates the effects of residual foaming agent components and defoamers on defoaming-flocculation-filterpress characteristics of EPBS muck using an improved flocculation and filterpress system. Residual foam height (Hf), defoaming ratio (DFR), antifoaming ratio (AFR), total suspended substance (TSS), turbidity, moisture content (MC), and zeta potential (ZP) were selected as characterization indices. The microstructure of filterpress cakes was analyzed using a scanning electron microscope. Results demonstrate that an enhancement within 0.0-1.0wt.% for sodium fatty alcohol polyoxyethylene ether sulfate (AES) and alpha olefin sulfonate (AOS) significantly reduces DFR and AFR. The MC and ZP decline, while the Hf and turbidity enhance. The combinations of nonionic surfactants alkyl polyglycoside (APG) and fatty alcohol-polyoxyethylene ether (AEO) in a concentration range of 0.0-1.0wt.% with 0.2wt.% AES causes the Hf, DFR, AFR, turbidity, and ZP to exhibit absolutely different variations. The MC with the growth in both APG and AEO presents a trend of first decreasing and then increasing. By increasing foam stabilizers sodium carboxymethyl cellulose (CMC) and guar gum (GG) within 0.02-0.10wt.%, the AFR, TSS, and ZP enhance in varying degrees, while the Hf, DFR, and MC gradually reduce. With the increase of defoamers hydroxyl silicone oil-glycerol polyoxypropylene ether (H-G) and dimethyl silicone oil-glycerol polyoxypropylene ether (D-G) within 0.002-0.010wt.%, the DFR and AFR are significantly improved, while the TSS, turbidity, MC, and ZP display varying degrees of reduction. Moreover, defoaming-flocculation-filterpress mechanisms of EPBS muck are explored to provide a useful reference for actual in-situ recycling projects.

Coal-Based Branched Vicinal Diol Ethoxylates Versus Guerbet Alcohol Ethoxylates: Role of Tertiary Hydroxyl Groups.

Branched surfactants exhibit a lower surface tension, excellent low defoaming performance, and better wetting ability compared with linear surfactants, making them promising for applications in industrial cleaning. In this study, 2-hexyl-1-decene (C8 olefin dimer), obtained from the dimerization of 1-octene, was used as the hydrophobe to synthesize branched nonionic surfactants via hydroxylation and ethoxylation. The hydroxylation of the C8 olefin dimer to synthesize 2-hexyldecane-1,2-diol (C8 BD) using H2O2 and HCOOH was investigated systematically. Under the optimal reaction conditions (H2O2/C8 olefin dimer molar ratio: 1.5, HCOOH/C8 olefin dimer molar ratio: 4.0, reaction time: 10 h, reaction temperature: 50 °C), the conversion of the C8 olefin dimer and selectivity toward C8 BD were found to reach 99.96 and 79.89%, respectively. Further, branched nonionic surfactants (C8 BDEn) were synthesized via ethoxylation of C8 BD with ethylene oxide and characterized using FTIR, LCMS, 1H NMR, and 13C NMR techniques. The presence of a tertiary hydroxyl group in C8 BD increases the reactivity of the primary hydroxyl group, leading to a narrower range of products and lower residual substrate content. The physicochemical properties and surface properties of C8 BDEn with different degrees of ethoxylation at various concentrations were investigated and compared with those of commercially available Guerbet alcohol polyoxyethylene ethers (C8 GAEO9 and C6 GAEO9). The results show that, compared with C8 GAEO9 and C6 GAEO9, C8 BDE6 displayed a higher surface activity with a lower equilibrium surface tension (27.14 mN·m-1), superior wettability with a smaller contact angle (39.2°), better emulsification performance with a longer emulsification time of 548 s, and excellent foaming properties (initial foam volume of 11.6 mL). This strategy of utilizing coal-based α-olefins for the synthesis of branched nonionic surfactants presents a route to prepare value-added fine chemicals from coal-based resources.

Preparation and Performance Evaluation of Self-Cementing Nanoscale Polymeric Microspheres with Salt and Temperature Tolerance.

Polymer microspheres with temperature and salt resistance were synthesized using the anti-suspension polymerization method, incorporating the functional monomers AMPS, AM, and AA. To enhance their self-gelling properties, the microspheres were designed with a core-shell structure. The shell is composed of a polymeric surfactant, fatty alcohol polyoxyethylene ether methacrylate (AEOMA), which serves as a thermosensitive crosslinking agent, enabling self-crosslinking upon shell decomposition, addressing compatibility with reservoir pore throat dimensions. Comprehensive characterizations including infrared spectroscopy, scanning electron microscopy, optical microscopy, and laser particle size analysis were conducted. The microspheres exhibited successful synthesis, a nanoscale size, and regular spherical morphology. They demonstrated excellent temperature and salt resistance, making them suitable for high-temperature, high-salinity reservoir profile control. With a stable three-dimensional network structure, the microspheres displayed good expansion behavior due to hydrophilic groups along the polymer chains, resulting in favorable water affinity. Even after aging, the microspheres maintained their gelling state with a distinct and stable microscopic network skeleton. They exhibited superior plugging performance in low-permeability reservoirs, while effectively improving water absorption profiles in reservoirs with permeability contrasts of 10 to 80, thereby enhancing oil recovery.

Adsorption behavior and application properties of natural alcohol polyoxyethylene polyoxypropylene ether sulfate

In recent years, the Polyoxypropylene (PO) group has been introduced between the hydrophobic group and the polyoxyethylene (EO) group of traditional surfactants to enhance interfacial properties. However, literature on surfactants introducing PO chains between EO and hydrophilic groups remains scarce. In this study, three variants of natural alcohol polyoxyethylene polyoxypropylene ether sulfate (C1214E3PnS), each with different PO addition numbers, were synthesized from natural alcohol ether through sulfation and neutralization reactions. The adsorption behavior of C1214E3PnS with different PO addition numbers was investigated and compared to AES by measuring surface tension, dynamic surface tension, and contact angle. The results indicate that as the number of PO increases, both the critical micelle concentration and maximum adsorption capacity decrease. Additionally, pC20 and the number of PO groups introduced in the surfactant show a linear negative correlation, indicating a decline in surfactant efficiency. Due to an adsorption barrier, C1214E3PnS is governed by a mixed diffusion-kinetics adsorption mechanism. According to the application performance of C1214E3PnS, as the number of PO increases, wettability and foam stability have decline, while emulsifying performance is significantly enhanced. In conclusion, surfactants such as C1214E3PnS do not favor adsorption at the solid–liquid interface, but enhance the properties at the oil–water interface.

Promoting dissolution behaviors of low-carbon alcohol polyoxyethylene polyoxypropylene ether in CO2 by molecular structure optimization and adding cosolvent

The low-carbon alcohol polyoxyethylene (EO) polyoxypropylene (PO) ether surfactants have significant application potential in CO2 flooding for enhanced oil recovery (EOR) in water-bearing oil reservoirs because of their hydrophilic, lipophilic and CO2-philic properties. The dissolution of surfactants in CO2 is the important precondition for the application of the CO2 + surfactant systems injected in oil reservoir. This work combines experiments and molecular dynamics simulations to reveal the dissolution mechanism of low-carbon alcohol polyethers in CO2 at the molecular level in order to promote the dissolution behaviors of these surfactants. The results show that the appropriate adjustment of the molecular structure can promote the dissolution of surfactants in CO2 by the interactions of dispersion forces, Lewis acid–Lewis base (LA-LB) interactions, and potential hydrogen bonding. The increase of the numbers of EO groups, PO groups, and the length of the alkyl chain all lead to the increase of the cloud point pressure due to the weaken of the dispersion forces and LA-LB interactions between the surfactants and CO2 with the increase of the molecular weight of the surfactants. Under the premise of ensuring sufficient hydrophobic, lipophilic and CO2-philic properties of the surfactant molecules, decreasing the molecular weight as much as possible can increase the dissolution properties. Moreover, the distribution adjustment of EO and PO groups in surfactants has a significant impact on the dissolution behaviors. The molecules, in which EO and PO groups cross-dispersed and the terminal hydroxyl group connected to the EO group, have a better CO2-philicity than those with long EO chains and PO chains. Furthermore, ethanol can reduce the cloud point pressure of surfactants in CO2, because that the presence of ethanol can break the stronger van der Waals forces between CO2 molecules and enhance the LA-LB interactions and hydrogen bonding between the hydroxyl groups and CO2.