Sodium Alcohol Ether Sulfate Research Articles

Impact of anionic surfactant-based foaming agents on the properties of lightweight foamed concrete

Due to its low density, high thermal insulation, and ability to contribute to energy saving, lightweight foamed concrete (LWFC) is a versatile material that finds use in a wide variety of contexts. The properties of foam are significantly influenced by the selection of surfactant and foam production parameters, which in turn impact the properties of LWFC. Therefore, the anionic foaming agent effect on the distinct properties of LWFC needs to be investigated to create a lightweight structure in modern days. This research aims to better understand the interactions between cement particles and anionic foaming agents, which produce stable and consistent aqueous foams because of their negative charge. Investigations were carried out on the effects of anionic foaming agents of LWFC features on the fresh state characteristics, mechanical behaviour, microstructure, and transport properties. In this investigation, four distinct types of anionic surfactants specifically sodium lauryl sulphate (SLS), alpha olefin sulfonate (AOS), sodium lauryl ether sulphate (SLES), and sodium alcohol ether sulphate (AES) were considered, with all mixes maintaining a consistent cement-to-sand ratio and identical amounts of foaming agents. The fresh state testing exhibits that AOS-based LWFC may be preferred when lower setting time and spreadability, as well as a higher density, are required. The AOS-based LWFC exhibits lower capillary sorption, water absorption, and gas permeability than SLES, SLS, and AES-based LWFC. At 28 days, about 91–96 % of the compressive, tensile, and flexural strength of AOS-based LWFC is obtained for SLS, SLES, and AES-based LWFC. In addition, at the same curing age, the results for modulus of elasticity were over 6 % higher in the AOS-based LWFC mixture than in the other mixes. The pore structural and microstructural behavior revealed that AOS and SLS foamed-based LWFC exhibit a considerable reduction of macropores, or long capillaries, with diameters less than 500 µm, which can be used in the lightweight structure in modern days. This research emphasizes the significance of selecting the appropriate foaming agents to optimize the mechanical and transport properties of LWFC, which provides substantial benefits for contemporary construction practices.

Static-dynamic wetting characteristics and microscopic synergistic mechanism of compound surfactant on coal dust with different metamorphic degrees

The compound surfactant has a synergistic effect on the wetting ability of coal dust. In the study, the wettability of compound surfactant on coal dust with different metamorphic degrees was studied from static wetting experiment, dynamic wetting experiment, and micro molecular simulation. The results showed that the contact angle of the anionic-nonionic compound surfactant solution on any coal sheet was significantly smaller than that of the single component, which was 14.04%～63.31% lower than that of the single component. The contact angle of the anionic-anionic compound surfactant on the six kinds of coal dust test pieces was not smaller than the contact angle of each single component, only a compromise of contact angle of single component. The dust suppression efficiency of the gas coal in 0.025 wt% fatty acid methyl esters ethoxylate sulfonate (FMES) and 0.025 wt% coconutt diethanolamide (CDEA) compound solution was the highest, which was 78.4%. Lignite coal, long flame coal, non-caking coal, coking coal, and anthracite all have the highest dust suppression efficiency when sprayed with 0.025 wt% sodium alcohol ether sulphate (AES) and 0.025 wt% CDEA, which were 91.53%, 88.24%, 85.7%, 73.25%, and 80.57%, respectively. For any metamorphic degree of coal sample dust, the anionic-nonionic compound surfactant shows obvious synergistic effect on improving the wettability of coal dust. Furthermore, when the surfactant is adsorbed on the surface of coal molecules, the concentration of water molecules on the surface of coal molecules is increased, the hydrophilicity of the solid–liquid interface is improved, and the water molecules are more intensely diffused on the surface of coal dust. And the absolute value of the adsorption energy of the surfactant on the surface of the coal dust is higher, and the more hydrogen bonds formed by the hydrophilic groups, the better the wettability of the coal dust surface.

Synergistic effect of hydrophobic modified Welan gum and sodium alcohol ether sulphate in saline solution

Surfactants are often used to change the structure of natural polysaccharide polymers and improve their properties for industrial applications. However, implementing surfactants to boost the Welan gum has yet to be studied. This study prepared the compound system HWG-A by Sodium alcohol ether sulphate (AES) with hydrophobic modified Welan gum (HWG). Compared with HWG, the critical association concentration of HWG-A they have decreased from 3.8 × 103 mg L-1 to 2.8 × 103 mg L-1. The viscosity of 2 × 103 mg L-1 HWG-A remained at 244 mPa s when the salinity was 96,670 mg L-1. The rheological test showed that HWG-A still maintained the characteristics of pseudoplastic fluid under different polysaccharide concentrations, pH and salinity. The viscoelastic test showed that the elasticity of HWG-A was interdependent with the concentration of polysaccharides. When HWG-A was higher than the critical association concentration, the elasticity dominated the whole system. The temperature resistance test showed that the viscosity of HWG-A was still much higher than that of Welan gum and HWG when the salinity was 19,334 mg L-1 at 140 ℃ and lower than the critical association concentration, and the viscosity remained above 350 mPa s. SEM showed that HWG-A presented a regular large network structure when the concentration was lower than its critical association concentration. Otherwise, HWG-A presented a gel shape. Our study promotes the industrial potential of Welan gum in such as Enhanced Oil Recovery (EOR) process. It suggests that the interaction between surfactants and natural polysaccharides is essential in determining the functional properties of the fluid system.

Experimental study on characteristics of water imbibition and ion diffusion in shale reservoirs

During the soaking process of shale gas reservoirs, due to the imbibition of fracturing fluid and the dissolution of solid substances in the reservoir, the flowback rate is low, and the salinity of the flowback fluid increases. The effects of different salt solutions, surfactants, and boundary conditions on spontaneous imbibition and ion diffusion were studied through comparative experiments. Forced imbibition experiments were conducted to investigate the effect of external pressure. The results show that the pressure applied to the fluid can increase the imbibition rate, but has little effect on ion diffusion. In the same concentration of salt solution, K+ has a stronger inhibitory effect on imbibition and ion diffusion than Na+. Both sodium alcohol ether sulfate (AES, anionic surfactant) and alcohol ethoxylate (AEO-9, non-ionic surfactant) will inhibit imbibition and ion diffusion. The controlled experiments show that AEO-9 inhibits imbibition more obviously, and the ion pair ionized by AES inhibits ion diffusion. Compared with the two-ends-closed (TEC) and two-ends-open (TEO) boundary conditions, all-faces-open (AFO) has the largest exposed areas and is the most favorable for imbibition and ion diffusion. The imbibition and the ion diffusion rates of the 15 cores are roughly linearly correlated, and the ion diffusion is a synchronous process with imbibition. Compared with previous experiments on spontaneous imbibition and ion diffusion of sandstone and hydrate sediment in distilled water, the imbibition rates of shale are the slowest, and the ion diffusion rates are between hydrate sediment and sandstone. This study is of great significance for understanding the mechanism of soaking stimulation in shale gas reservoirs.

Experimental study of microbial desulphurisation of sulphide ores combined with gel foam retardants to prevent spontaneous combustion

ABSTRACT The purpose of this study was to reduce the propensity for spontaneous combustion of sulfide ores through the combined action of microorganisms and inhibitors and to assess the flame retardant effect. The sulfide ore samples were first pretreated with biodesulphurisation. The samples were then sprayed with a foam blocker to prevent re-oxidation of the ore and further reduce the spontaneous combustion tendency of the sulfide ore. The experimental results showed that the highest desulfurization rate of 24.26% was achieved for ore samples with a particle size between 140–160 mesh. A combination of 0.05% hexadecyltrimethylammonium bromide (CTAB), 0.11% lauramidopropyl betaine (LAB-35), 0.13% sodium alcohol ether sulfate (AES), 0.11% propanetriol foam stabilizer, 7% water glass and 3% sodium bicarbonate arresting agent was the most effective. The oxidation weight gain of the desulphurised ore sprayed with the resist was only 3.16%. The oxidation weight gain of the desulphurised ore without the addition of the resist was 3.98% and the oxidation weight gain of the undesulphurised ore was 6.01%. This method is effective in reducing the tendency of spontaneous combustion of sulfide ores.

Effect of different types of surfactants adsorption characteristics on the wettability of coking coal dust

To investigate the effect of different types of surfactants adsorption characteristics on the wettability of coking coal dust, Guoyang coking coal and three different surfactants - dodecyl dimethyl benzyl ammonium chloride (DDBAC), sodium alcohol ether sulphate (AES), coconut diethanolamide (CDEA) - were used. Firstly, the amount of surfactant adsorbed on coal dust were determined using spectrophotometry. Secondly, the contact angles of surfactants on coal tablets was determined. Subsequently, the relationship between the amount of surfactant adsorbed on the coal dust surface and the contact angle was analysed. Finally, the influence mechanism of the amount of the surfactant adsorbed on the coking coal dust surface on wettability was discussed. The experimental results suggest that the adsorption isotherm of cationic surfactant DDBAC on the coal dust surface is bilayer LS-type, while the adsorption isotherm of anionic surfactant AES and non-ionic surfactant CDEA are L-type and S-type, respectively. Additionally, when the concentration of the solution was 0.05%, the amount of AES adsorbed on the coking coal dust surface was estimated to be 64.9 mgg−1, which was 4.19-fold higher than DDBAC (i.e. to 15.5 mgg−1) and 2.2-fold higher than CDEA (i.e. to 29.5 mgg−1), nearly reaching adsorption saturation. The R2 of the amount of DDBAC, AES, and CDEA adsorbed on the coal dust surface affecting the contact angle was 0.9944, 0.99238, and 0.9923, respectively. The adsorption amount of anionic surfactant AES on the coal dust surface at 0.05% is 64.9 mgg−1, and the adsorption isotherm of surfactant on the coal dust surface is L-type, which is more conducive to enhancing the wettability of coking coal dust. Thus, the amount and adsorption isotherm form of the surfactant adsorbed on the coal dust surface are critical factors affecting the coal dust wettability, which provides a theoretical basis for the reasonable selection of surfactants to improve the coal dust suppression efficiency.

Enhanced bioproduction of volatile fatty acids from excess sludge by sodium alcohol ether sulphate

The conventional approach of anaerobic fermentation of excess sludge (ES) to produce volatile fatty acids (VFA) is limited by its poor efficiency and secondary pollution. Herein, a new strategy was developed for improving VFA production from the ES by sodium alcohol ether sulphate (AES) pretreatment. A maximum VFA yield of 516 ± 6.0 mg COD/g VSS was obtained with 0.28 g AES/g SS. It was proved that AES pretreatment had a synergistic effect on the enhancement of ES flocs solubilization, as well as hydrolysis and acidification of organic compounds in the ES. Meanwhile, the hydrolytic and acid-producing bacteria (i.e., Actinobacteria and Firmicutes) were enriched, while the VFA consumers (i.e., Halobacterota) were reduced by AES pretreatment, which resulted in the improved efficiency of VFA accumulation. Thereby, the AES had a positive effect on the conversion of organic matters in the ES to VFAs. Additionally, up to 97% of added AES could be degraded naturally during the treatment process, relieving the secondary pollution to environment. The strategy of AES pretreatment proposed in this work may provide a viable approach for ES treatment and relatively low-cost recovery of waste biomass.

Tunable oxygen vacancies facilitated removal of PFOA and RhB over BiOCl prepared with alcohol ether sulphate

In this study, surfactant sodium alcohol ether sulphate (AES) was added into the solvothermal preparation system of BiOCl to decrease the surface energies of the (010) facets during the crystallization process. BiOCl samples were synthesized by controlling the amount of AES. BiOCl samples prepared with the assistance of AES have a smaller size, higher oxygen vacancies (OVs) and photogenerated electron and hole pairs (e-/h+) separation efficiency than the reference BiOCl (R-B). The content of OVs can be facilely controlled by using the different amount of AES. When the weight ratio of AES/BiOCl is 5%, the BiOCl prepared (5% AB) has suitable OVs content to hoist the separation of photoinduced charge, displaying the highest photocatalytic activity. Photocatalytic degradation ability of the 5% AB sample toward destruction of Rhodamine B (RhB) under visible light is 4.4 times of that of R-B, and the degradation rate constant and defluorination rate of perfluorooctanoic acid (PFOA) over 5% AB under UV light for 2 h is 2.9 times and 1.5 times of that over R-B, respectively. Given the experimental observations, enhancement mechanism in photocatalytic property was proposed.

Stable foam systems for improving oil recovery under high-temperature and high-salt reservoir conditions

Foams have high apparent viscosity when flowing in porous media, therefore foam flooding could significantly improve unfavorable mobility ratios, increase sweep efficiency, and enhance oil recovery. However, the applications of foam flooding in high-temperature and high-salt reservoirs are seriously restricted as foam systems often have inferior foamability and stability in these reservoirs. In this study, to improve foam flooding effectiveness in high-temperature and high-salt reservoirs, novel foam systems with excellent stability and plugging capacity are developed by combining surfactants, additives, and polymers. The performance of bulk foam, physical properties of the solutions, and properties of foam systems in core-flow experiments are investigated to determine the synergistic effects among the components of the foam systems and their foamability and plugging effect in cores. In foam systems with sodium alcohol ether sulfate (AES) and dodecylhydroxypropyl sulfobetaine (DHSB) as surfactants, and dodecanol as additive, the combination of the components makes surface tension decreased and surface dilatational modulus increased, therefore the foamability and stability of the systems are improved. The results of core-flow experiments under high-temperature and high-salt conditions show that these combined systems require low injection rate for foam generation in reservoirs, which is beneficial for foam regeneration in reservoirs. Moreover, to further improve the foam performance, a hydrophobically associating water-soluble polymer (HAWP) is employed. The interactions between HAWP and the surfactants reduce the critical association concentration of HAWP, and result in the increase of solution apparent viscosity and foam stability. The results of core-flow experiments under high-temperature and high-salt conditions show that polymer-enhanced foam systems could significantly increase the sealing pressure, widen the sealing permeability range, and deal with the gas-channeling problem of foam flooding. These foam systems could provide a potential technical pathway for improving the effectiveness of foam flooding in high-temperature and high-salt reservoirs.

Using surfactants for controlling rotifer contamination in mass cultivation of Chlorella pyrenoidosa

Frequent microzooplankton contamination such as rotifers in Chlorella mass culture often causes devastating effects on biomass production. In this study, five surfactants were used to control contamination by a rotifer, Brachionus calyciflorus, in Chlorella pyrenoidosa XQ-20044 cultures. Laboratory results showed that the minimal effective concentrations of surfactants for complete control of B. calyciflorus were 7.5, 10, 10, 10, and 15 mg L−1 for primary alcohol ethoxylate, sodium dodecylbenzene sulfonate, sodium alcohol ether sulfate, coconut diethanolamide, and sodium dodecyl sulfate, respectively. However, only 10 mg L−1 sodium dodecylbenzene sulfonate and 7.5–10 mg L−1 primary alcohol ethoxylate had no negative effects on algal growth. Moreover, in a 5 m2 open raceway pond, 10 mg L−1 sodium dodecylbenzene sulfonate ensured swift and total elimination of rotifers, while the final dry weight of the algae reached >0.74 g L−1 whereas the cost of using sodium dodecylbenzene sulfonate was only $ 0.014. The results of this study indicated that sodium dodecylbenzene sulfonate approach is fast-acting, highly effective, and a low-cost treatment. Therefore, sodium dodecylbenzene sulfonate has great potential for biological contamination control in microalgae mass culture without a negative impact on algal growth.

Study on Hydrolysis of Magnesium Hydride by Interface Control

Magnesium hydride (MgH2) is one of the competitive hydrogen storage materials on account of abundant reserves and high hydrogen content. The hydrolysis of MgH2 is an ideal and controllable chemical hydrogen generation process. However, the hydrolyzed product of MgH2 is a passivation layer on the surface of the magnesium hydride, which will make the reaction continuity worse and reduce the rate of hydrogen release. In this work, hydrogen generation is controllably achieved by regulating the change of the surface tension value in the hydrolysis, a variety of surfactants were systematically investigated for the effect of the hydrolysis of MgH2 In the meantime, the passivation layer of MgH2 was observed by scanning electron microscope (SEM), and the surface tension value of the solution with different surfactants were monitored, investing the mechanism of hydrolysis adding different surfactants. Results show that different surfactants have different effects on hydrogen generation. The hydrogen generation capacity from high to low is as follows: tetrapropylammonium bromide (TPABr), sodium dodecyl benzene sulfonate (SDBS), Ecosol 507, octadecyl trimethyl ammonium chloride (OTAC), sodium alcohol ether sulfate (AES), and fatty methyl ester sulfonate (FMES-70). When the ratio of MgH2 to TPABr was 5 : 1, the hydrogen generation was increased by 52% and 28.3%, respectively, at the time of 100 s and 300 s. When hydrolysis time exceeds 80 s, the hydrogen generation with AES and FMES-70 began to decrease; it was reduced by more than 20% at the time of 300 s. SEM reveals that surfactants can affect the crystalline arrangement of Mg(OH)2 and make the passivation layer three-dimensionally layered providing channels for H2O molecules to react with MgH2.

Development of a Gypsum Foaming Agent Based on Alkyl Polyglucosides

Abstract The formulation of gypsum foaming agents using alkyl polyglucosides (APG) as main surfactant was studied. The foaming behavior of the foam compound system and the stability of the foam were determined by experiments. The foaming property of APGs with various carbon chain lengths and of APGs in mixtures with other surfactants, such as cocoamidopropyl betaine (CAB), sodium lauryl amphoacetate (SLA) and sodium alcohol ether sulphate (AES) was investigated. The influence of some polymers used as foam stabilizers, such as hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), polyvinyl alcohol (PVA) was also examined. Foaming times, foaming stability and bleeding ratio change were tested in order to investigate the properties of foaming and foam stability. Results indicated that the best foam performance was obtained by the composition based on APGs mixed with SLA and PVA. The optimal condition was as following: m(APG0810): m(APG1214): m(SLA) = 4: 1: 2, and PVA accounted for 10% (w/w) of total. After 1 minute, the foam multiplier was 4.35. Due to the improved mix system, it remained at 3.65 even after 15 min, with a mass fraction of 0.2%, a stirring speed of 1800 rpm and a stirring time of 3 min.

Porosity, mechanical strength and structure of waste-based geopolymer foams by different stabilizing agents

Due to limited material resources and environmental concerns, novel geopolymer foams (GPFs) were synthesized using solid wastes (granulated ground blast furnace slag (GBFS) and drinking water treatment residual (DWTR)) and different stabilizing agents: sodium dodecyl sulfate (SDS), sodium alcohol ether sulphate (SAES), and disodium laureth sulfosuccinate (DLS). The effect of adding stabilizing agents and a blowing agent on the mechanical strength, pore distribution, and microstructures of the resulting GPFs were investigated, and the relationship between these properties were explored by statistical analysis. The results indicated that due to the three stabilizing agents, the mechanical strength of the GPFs followed the order of SDS-GPF (1.76–12.14 MPa) > DLS-GPF (0.91–10.91 MPa) > SAES-GPF (0.20–5.47 MPa). The total porosities followed the order of SAES-GPF (38.88–79.93 vol%) > SDS-GPF (9.94–67.89 vol%) > DLS-GPF (5.91–67.01 vol%). The statistical analysis showed that the compressive strength was positively correlated with the bulk density and the pores with specific diameter (100–200 μm). The characterization results indicate that the pore-making process mainly influences the macroscale properties of the GPFs. The increasing intensity of the crystalline peaks present after the foaming process indicates that the raw materials did not react completely during geopolymerization. Overall, the waste-based GPFs developed in this study are promising for fabricating foam materials.

Effect of foaming agent on physical and mechanical properties of alkali-activated slag foamed concrete

Alkali-activated slag cement has the characteristics of high viscosity, quick hydration, setting and hardening, and high strength, which are suitable for the preparation of foamed concrete. Three foaming agents of sodium α-olefin sulfonate (AOS), sodium dodecyl sulfate (K12) and sodium alcohol ether sulphate (AES) with the same foam stabilizer of silicone resin polyether emulsion FM-500 (MPS) were used to prepare foam. The three foam properties are similar and foam stability of AOS and K12 is better than that of AES. Effective foam ratio is put forward to express stability of foam in paste slurry. Effective foam ratio and porosity has a great effect on dry apparent density of water glass-activated slag foamed concrete. With the increase of foam content, effective foam ratio of AES decreases obviously, while that of K12 and AOS show a slight decrease. At low foam content, AES can better reduce the dry apparent density. Increase foam content of AOS and K12 appropriately may reduce dry apparent density. Rsd and compressive strength of foamed concrete with AOS foam is the highest. When porosity is similar, average pore size and pore size distribution has a great effect on thermal conductivity and mechanical properties of AAS foamed concrete. Average pore size of O3 is smaller than that of K3 and E3. O3 also shows the narrowest air-void size distribution with the majority of the voids smaller than 400 μm. Average roundness of three type foam is much the same. Foam stability is the main factor affecting pore structure of AAS foamed concrete. AOS can be preferred to prepare AAS foamed concrete.

Experimental investigation of the wetting ability of surfactants to coals dust based on physical chemistry characteristics of the different coal samples

To select suitable surfactant as water-spray additive to improve dust suppression efficiency, six types of coal sample (lignite, long flame coal, non-caking coal, gas coal, coking coal, and anthracite) were selected from some typical mining areas in China, the influence of the physical chemistry characteristics of coal samples on the wetting ability of surfactants to the coals dust was investigated. Their proximate composition, ultimate content, chemical structure, surface morphology, pore structure parameters, and contact angle were determined. Three kinds of anionic surfactants – Sodium Alcohol Ether Sulphate (AES), Sodium Alpha-Olefin Sulfonate (AOS), Fatty Acid Methyl Esters Ethoxylate Sulfonate (FMES) – and one kind of nonionic surfactant – Coco Diethanolamide (CDEA) – were selected to carry out sedimentation experiments on the coal samples dust, to explore the main factors influencing the wettability of the coal samples dust. Among these factors, pore size is the main factor determining the wettability of coal dust, the contact angle decreases linearly (R2 = 0.96) with pore size increase. The experimental results demonstrate that the following factors produce correspondingly increased wettability: higher moisture content, lower carbon content, higher oxygen content, more oxygen-containing functional groups, and increased pore size. In addition, the wettability of the six types of the coal samples dust shows a high-low-high trend with metamorphic degree increase, lignite has the strongest wettability, and the coking coal with the highest degree of metamorphism in the selected bituminous coal sample has the weakest wettability. Moreover, compared with nonionic surfactants, anionic surfactants have stronger wetting ability, but the same anionic surfactants have different wetting abilities to coal dust with different metamorphic degrees. AOS has stronger wetting ability to the dust of long flame coal, non-caking coal, and anthracite; AES has stronger wetting ability to the dust of lignite and coking coal; and FMES has stronger wetting ability to the dust of gas coal. The research results provide a theoretical basis for different coal mines to select suitable surfactants as water-spray additives to improve dust suppression efficiency.

Assessment of water-based fluids with additives in grinding disc cutting process

Application of cutting fluids in grinding disc cutting process (GDCP) plays a significant role in minimizing production cost and energy. However, GDCP is significantly different from the grinding wheel grinding process (GWGP) with its very thin disc (3.5 mm), large diameter (400 mm), large cutting depth (several and even ten of millimeters) and no cutting fluids, which lead to a lot of environmental pollution such as sparking, chips splashing, smoke, dust and so on. In this regard, atomization application of water-based cutting fluids is good choice due to less environmental threat in addition to high thermal conductivity and supreme cooling/lubricating efficiency. Besides some eco-friendly properties of additives such as surfactant and graphene, application of such additives eliminates the need for toxic additives used frequently in the industry. Hence, in this study, four types of environmentally friendly water-based cutting fluids (W, W-S, W-G, W-G-S) are prepared by ultrasonic stirring of water, surfactant (sodium alcohol ether sulfate, SAES) and graphene, then their atomization applications are assessed in GDCP of AISI 1045, as one of the most common and representative material in industry application. To optimize these cutting fluids, G-ratio, Fx-Fy and cutting tilt are compared with those of dry cutting using joint analysis of specific heat, viscosity, wettability, permeability and two-direction force. Also, agglomeration of graphene is proposed to reveal the unexpected reduction in lubrication performance and finally a cutting fluid is developed for minimizing the loss of grinding disc. The obtained results of four types of cutting fluids manifest that the proposed W-S can maximally improve G-ratio by amount of 77.6%, reduce line span by amount of 34.5% and cutting tilt by amount of 14.8% compared with conventional dry cutting.

Pore-Scale Mechanisms of the Synergistic Effects between Microbial Cultures and Chemical Surfactants on Oil Recovery

A significant synergistic effect has been reported between microbial cultures and chemical surfactants in crude oil recovery processes. A number of attempts have been made to understand the synergistic mechanism. However, the existing studies only addressed the aspects of wettability alteration and interfacial tension (IFT) reduction, although there are many more contributors to the mechanism, such as emulsification, functional microbial activities, and diverse byproducts. In addition, the previous knowledge on synergistic oil recovery was based on indirect evidence from core-scale flooding and test tube experiments. To fully exploit the synergistic effects in the future, a new experimental system must be introduced (i) to verify the existing mechanisms in situ in porous media during the flooding process and (ii) to address the other potential contributors for a more comprehensive insight into the actual major contributors. Therefore, a visual pore-scale flooding experimental system was introduced in the present study to mimic the pore networks and conditions of a reservoir (55 °C, 10 MPa). This system enabled direct observations of fluid dynamics in pores during flooding. The final oil recovery using indigenous microorganisms (8.3%) and an anionic surfactant [sodium alcohol ether sulphate (AES)] (15.5%) was considerably enhanced (22.4%) when the two solutions were equally mixed, which indicated significant synergistic effects between them, whereas no such effects were observed with a nonionic surfactant [polyoxyethylene nonylphenol ether (OP10)]. The pore-scale and macroscale analyses were combined to reveal the synergistic mechanisms between the microbial culture and AES. The results show that the IFT reduction and wettability alteration, traditionally considered to be synergistic mechanisms, contributed to the oil recovery but were not the major contributors to the synergistic effects. In this case, the synergistic mechanisms include the following aspects: the anionic surfactant promotes microbial metabolism, such as biogas production (significantly enhanced from 0.0018 mL/mL medium to 0.0196 mL/mL medium), and the microbial culture, in turn, reduces the critical micelle concentration of the surfactant and enhances the emulsion effectiveness, including reducing the oil droplet sizes (from D90 = 217 to 116 μm) and increasing the stability of the emulsion system from several minutes to a few days. The two synergistic mechanisms reflect the mutually positive effects between the chemical surfactant and the microbial system; these mutual effects are especially essential for long-term and long-distance oil migration and final recovery in a real reservoir-scale flooding process.

Effect of partially hydrolyzed polyacrylamide on the solution and foam properties of sodium alcohol ether sulfate

The solution and foam properties of systems composed of sodium alcohol ether sulfate (AES) and partially hydrolyzed polyacrylamide (HPAM) at different concentrations were investigated. The addition of HPAM could increase the surface tension of AES solutions caused by the decrease of surfactant adsorption density at the air-water surface. The viscosity of the AES/HPAM systems were determined by the HPAM concentration. With the increase in AES concentration, the foam generation time and bubble size first decreased and then reached a plateau, while the initial liquid volume of the foam increased first and then reached a plateau. The inflection occurred at an AES concentration of 0.1 wt%, which is higher than the critical micelle concentration (CMC). This is because the air-water surface area increased dramatically during foam generation, which makes surfactant surface density unsaturated at the CMC. Only a higher surfactant concentration could maintain the saturation of surface adsorption density. The addition of HPAM could improve the foamability and enlarge the bubble size at low AES concentrations, because the increased bulk viscosity and the hydrogen bonds between AES molecules and HPAM chains stabilized bubble films and reduced the breakdown of large bubbles. The increase of HPAM concentration would always improve the liquid-carrying capacity and decrease the drainage rate of the foam. These findings indicate that it is possible to use low concentrations of foaming agents and improve foam properties by adding water-soluble polymer in field applications.

Synthesis and analysis of foam drainage agent for gas well in Jilin Oilfield

The gas well in Jilin oil field has the characteristics of large temperature variation range and high condensate oil content. So the foam drainage agent of the gas well in Jilin oil field needs to have the performance of oil resistance and less effected by temperature. In this paper, a main foaming agent named lauramidopropyl betaine (LAB) and two kinds of auxiliary foaming agent named sodium alcohol ether sulphate (AES) and lauramidopropylamine oxide (LAO). Through the evaluation of the static foaming capacity and dynamic liquid carrying capacity, the AES is more suitable for LAB. The foaming agent with 70% LAB and 30% AES has 138mm foam height with ROSS-Miles equipment; stirring foam volume can reach 480mL, the half-life of foam is 520s. When the ventilation volume is 8L/min the liquid carrying capacity of 10% of the condensate oil content reached 82g. When the foaming agent concentration is 2%, the liquid carrying capacity of 10% of the condensate oil content reached 75g. When the aeration rate reaches 8-10L/min, the liquid carrying capacity of foam drainage agent can reach the best. The foam drainage agent can retain the performance after 120°C aging for 12h, these performances above can satisfy the requirements for gas well foam drainage in Jilin Oil Field.

Removal of pyridine from its wastewater by using a novel foam fractionation column

Many of pyridine compounds are considered as typical hazardous refractory organics due to their acute toxic properties and teratogenic effects. Therefore, it is great significant to develop a separation technology with the characters of low energy consumption and environmental compatibility to efficiently remove pyridine from its wastewater. In this work, foam fractionation was used to remove pyridine from its wastewater and a novel foam fractionation column was designed for enhancing interfacial adsorption by vertical sieve tray and strengthening foam drainage by floating tongue type tray, in which bubble diameter was monitored for adjusting feeding flow rate and air flow rate in the continuous foam fractionation process. By comparing the foam properties and the adsorption properties of three anionic surfactants (sodium dodecyl sulfate, sodium alcohol ether sulfate and sodium alpha-olefin sulfonate), sodium dodecyl sulfate was chosen as the optimal collector to remove pyridine at pH 4.5. Under the optimal operating conditions, the enrichment ratio and removal percentage of pyridine could reach as high as 34.5 and 90.2%, simultaneously. Above results indicated that foam fractionation was a practicable technology to efficiently remove a hazardous material from its wastewater by designing an effective foam fractionation column.