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The growing demand for sustainable and functional ingredients in the food, pharmaceutical, and cosmetic industries has heightened interest in plant proteins as foaming agents. However, a knowledge gap persists regarding how transient material properties, influenced by foaming conditions, impact foam stability. This study investigates foam formation and stability of dilute pea protein solutions (0.1–1 wt%) using a gas sparging method. We examine the impact of protein properties, including bulk viscosity, adsorption kinetics, and foaming conditions like sparging flow rate, initial liquid volume, and sparging time. By correlating foam half-life (t 1/2) with surface pressure at various time scales, we observed that transient surface pressure at residence time (π r) strongly correlated with t 1/2 (R2 = 0.94) over a wide range of foaming processing parameters (flow rate of 0.2–0.4 L/min, liquid volume of 30–150 mL, and sparging time of 5–10 s) and protein concentrations, unlike equilibrium surface pressure or surface pressure at sparging time. This highlights the significance of π r , as it directly relates to initial bubble size, in controlling foam stability for dilute protein solutions. Our results reveal key insights into how transient surface properties, influenced by foaming processing parameters, govern foam stability. These findings contribute to the broader understanding of plant protein functionality and offer potential strategies for enhancing their use in both food and non-food applications. [Display omitted] • Factors affecting foam stability of dilute pea protein solutions were studied. • Transient surface pressure at residence time (π r) notably impacts foam stability. • Strong linear correlation exists between foam half-life and π r. • Results offer insights to improve plant protein functionality in various uses. [ABSTRACT FROM AUTHOR]

The gel and functional properties of jellyfish gelatin from Stomolophus meleagris (SG) and Rhopilema esculentum kishinouye (RG) species were investigated, and commercial fish gelatin (FG) was used as a control. In comparison to FG, SG and RG had similar X-ray diffraction (XRD) and fourier transform infrared (FTIR) pattern with shorter amide A band position, representing the formation of triple helices and hydrogen bonds due to polar groups in gelatin, and indicating a more ordered structure. Moreover, FG and RG presented elastic dominance while SG exhibited viscous dominance in a dose-dependent behavior from 10% to 20%, with G′ increasing approximately 86–27038 times when comparing SG and RG at 1 Hz due to their different characteristic amino acid composition. RG showed the least water mobility and most abundant hydrogen proton density, thus supporting greater gel strength than SG. Furthermore, SG showed a sparse and loose network with large voids, while FG and RG showed dense and homogeneous gel networks with smaller holes, which was conductive to the resistance of external forces. In addition, SG showed superior foam stability (20%–200% increase) and emulsifying stability index (ESI) (12%–86% increase) than those of FG and RG in a dose-dependent manner due to larger pores and more hydrophobic amino acid contents. The comparable gelation behaviors of RG to FG and remarkable interfacial properties of SG to FG supported the possible application of SG and RG as marine-based gelling, foaming and emulsifying agents in the food sector. [Display omitted] • Various rheological behavior of RG and SG was due to different amino acid content. • More triple helix and hydrogen bonds of SG and RG than FG promoted ordered structure. • RG with less water mobility and more hydrogen proton promoted stronger gel than SG. • RG showed denser and more homogeneous gel network than SG to support gel formation. • SG had better interfacial property due to larger pores and more hydrophobic region. [ABSTRACT FROM AUTHOR]

In recent years, there has been increased interest in studies on the stabilization of liquid foams with solid particles. In such three-phase foams it is possible to completely stop the process of syneresis, reduce coalescence and diffusion of gas. The presence of particles can significantly increase the time of the foam lifetime. Such Pickering foams are also of interest as an environmentally friendly and cost-effective alternative to surfactants and high molecular weight foaming agents. This work is focused on investigating the foam stability containing SDS-PVA SDS–PVA composite foaming agents with bentonite clay particles. Foam stability was characterized via the time of foam drainage. The stability of foams of SDS-PVA SDS–PVA mixtures in absence and presence of bentonite particles was determined. The stability of foams is higher in presence of the bentonite particles.

The world is rich in heavy oil resources, however, the recovery difficulty and cost are both higher than that of conventional crude oil. To date, the most common method of recovering heavy oil is steam flooding. However, once the steam breaks through the geological formation, gas channeling readily occurs, which leads to a rapid decrease of the steam drive efficiency. To improve the swept volume of steam in the geological formation, a series of hydrophobic silica particles for stabilizing foam was synthesized. This kind of particles used hydrophilic nano silica particles as reactant. Hydrophobic groups with cationic long carbon chains were grafted onto the surface of hydrophilic silica particles by synthetic silane quaternary ammonium salt. When the quantity of silane quaternary ammonium salt used in the modification reaction is different, the product had various degrees of wettability. The hydrophobic particles with the contact angle closest to 90° had the best foam stabilization effect on the betaine zwitterionic surfactant LAB. For LAB solution with mass fraction of 0.3%, the half-life of foam was extended into 160% when the mass fraction of particles was 0.5%. The higher the gas-liquid ratio, the better the plugging effect of foam agent with hydrophobic particles presented in porous media. The adsorption test of hydrophobic particles indicated that hydrophobic particles improved the stability of foam liquid membrane by improving the adsorption capacity of surfactant molecules. The thermal stability of hydrophobic silica particles exceeded 200°C, and the good foam stability made it a potential additive for foam oil displacement in high-temperature geological formation.

• Duomeen TTM exhibited poor foam stability, which significantly improved with decreasing GLDA pH. • Armovis VES demonstrated remarkable CO 2 foam performance, with half-life times exceeding 240 min. • Reducing the GLDA pH enhanced the CO 2 -VES faomability. • Combining Duomeen TTM and Armovis VES yielded the highest foam viscosity due to a synergistic interaction between the surfactants. The injection of CO 2 foam into the carbonate reservoir for enhanced oil recovery (EOR) has attracted special interest in the last decades; nevertheless, the understanding of the effect of liquid solution chemistry on foam stability at high temperatures and salinities is limited. Hence, this paper fully investigates the effect of chelating agents L-glutamic acid-N, N-diacetic acid (GLDA) pH, and hydrochloric acid (HCl) on the stability and viscosity of generated CO 2 foam for heterogeneous carbonate formation under reservoir conditions. In this paper, Duomeen TTM and Armovis VES surfactants were utilized due to their capabilities to produce viscous CO 2 foam under harsh conditions. The foamability, foam stability, and foam structure were studied at 100 °C and 1000 psi using a high-temperature and high-pressure (HPHT) foam analyzer. The measurement of CO 2 foam viscosity was determined at 100 °C, 1000 psi, and 70 % foam quality using the HPHT foam rheometer. Rheology experiments and dynamic light scattering investigated the micelle's size or aggregation behavior of surfactants. The obtained results showed that the Duomeen TTM generated unstable foam; however, foam stability and foamability improved with the decrease in GLDA pH. Armovis VES showed excellent CO 2 foam performance, where the foam half-life time of Armovis VES systems was 240 min. The liquid drainage and bubble coarsening were delayed due to the formation of the viscoelastic liquid phase. The foamability of Armovis VES was improved as the GLDA pH decreased. Furthermore, the addition of HCl to Armovis VES solution presented the highest foamability. The outcomes of the HPHT foam analyzer and HPHT viscometer proved that as the pH of Armovis VES solution decreased, higher foamability was produced. The highest foam viscosity was obtained using the synergic effect of 0.5 wt% Duomeen TTM and 0.5 wt% Armovis VES (39 cp at 100/s). In comparison, 1 wt% Armovis VES presented the lowest foam viscosity (30 cp at 100/s). The outcomes of this research can provide insight into the effect of chemistry on CO 2 foam and extend its application in oilfield development. This work broadens the design of novel CO 2 foam formulation, leading to the improvement of sweep efficiency in CO 2 -EOR methods and enhance the gas trapping in carbon storage. [ABSTRACT FROM AUTHOR]

Protein aggregates are known to enhance foam stability by either increasing the thin film viscosity or by blocking the lamellae of a foam. In this study, we produced a mung bean protein colloids mixture (MPCM) by heating protein coacervates that were formed by liquid-liquid phase separation. The functionality of MPCM was compared to a mildly purified mung bean protein extract (MIL). The MPCM showed extraordinary foaming properties, much better than MIL, with foamability of 324 % and a half-life time of 400 min. This work focused on elucidating the exact interface and foam stabilising mechanism of the MPCM by separating the colloids (COL) from the supernatant/continuous phase of the MPCM (SUP). Their interfacial properties were studied by performing surface dilatational rheology and microstructure analysis. Finally, foaming properties, such as foamability, foam stability, and air bubble size, were studied. It was found that the highest foam capacity was observed for the SUP fraction by generating stiffer interfaces. This fraction also contributed to the high foam stability of the MPCM. The COL fraction was found to form a viscoelastic thin film between air bubbles, thereby decreasing the drainage rate of the foam. In brief, SUP and COL fractions co-operate in the formation of highly stable MPCM foam, leading to a promising plant-derived candidate for producing stable foams in food products. [Display omitted] • Protein colloid mixture had 8x higher foam stability than a protein concentrate. • The mixture was separated into non-aggregated proteins and colloids. • The non-aggregated proteins form and stabilize the air-water interface. • The colloids further increase foam stability by pinning in the thin films. • The non-aggregated proteins and colloids show synergy in foam stabilisation. [ABSTRACT FROM AUTHOR]

• The irreversible adsorption of NPs enhances foam stability. • Synergistic effect of NPs and surfactants on foam stability. • NPs-stabilized foams have good performance under harsh reservoir condition. • NPs-stabilized foams enhance CO 2 storage by blocking macroporous throats. • NPs can reduce the risk of CO 2 leakage. With the urgent need for energy and reduction of carbon emissions around the world, the use of carbon dioxide foam flooding in enhanced oil recovery and CO 2 storage in underground geological structures have received extensive attention. However, as a thermodynamically unstable system, the stability of foam restricts its application in enhancing oil and gas recovery. Nanoparticles can be used as foam stabilizers to enhance the foam stability because of its special properties, thereby improving the effect of oil displacement and storage. Therefore, the use of nanoparticles to stabilize carbon dioxide foam has become a hot topic of current research. In this paper, the mechanism of nanoparticles in enhancing foam stability is reviewed. The effects of nanoparticle type, concentration, size and surface wettability, as well as the environmental factors such as temperature and pressure on stable foams is systematically analyzed. The mechanism of nanoparticles in enhancing carbon dioxide storage is clarified. Finally, the challenges and perspective of nanoparticles to enhance the stability of carbon dioxide foam and assist carbon dioxide storage are proposed, and the future research work is made clear. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the active agent foam is too stable during the flotation process, the experiments of the surface tension, surface viscoelasticity and gas-liquid two-phase foam performance of sodium oleate were carried out under the conditions of different concentrations, pH and temperature. The aim is to explain the changes in macroscopic blistering phenomena by changes in microscopic surface properties. The results show that concentration, pH and temperature all affected the foam properties of sodium oleate. When the sodium oleate solution is 10−3 mol/L (cmc), the foam stability is the best. The foam is most stable at pH of around 8.5. Temperature has a significant effect on the foaming property of sodium oleate, the foaming ability of sodium oleate is weak at a low temperature, while sodium oleate is unstable at high or low temperature. The lower the surface tension of the sodium oleate solution, the stronger the foaming performance; and the higher the expansion modulus, the more stable the foam. This study serves as a guide to control the parameters of sodium oleate flotation system and the optimal stabilisation of foam. [Display omitted] [ABSTRACT FROM AUTHOR]

Various combinations of high hydrostatic pressure treatment (HHPT, 0.1 or 600 MPa), calcium addition (0, 0.50, or 0.75 mmol CaCl 2 /g protein), and protein content ([Prot.], 1, 5, or 10 g/L) were applied to soybean protein isolate (SPI) dispersions to analyze their effects on the formation and stability of foams. The significant interactions between these factors led to several combinations that improved foam stability via different mechanisms that involved different solubilities, aggregate sizes, and molecular structures of proteins. Thirty min after foam formation, calcium combined with HHPT improved volume of foam (VF 30) and volume of liquid retained (VLr 30), by the formation of strong interfacial films owing to the increased cross-linking ability of soluble and intermediate-sized aggregates. Calcium without HHPT had a greater effect on VLr 30 than on VF 30 , which could be owing to the insoluble and large aggregates that blocked Plateau borders. HHPT without calcium led to small denatured aggregates that were soluble and improved the VLr 30 when [Prot.] was lower. Calcium enriched plant proteins with good techno-functional properties is a prevailing need, considering the current cultural, economic and environmental changes that occur. The findings of this study could serve as an input for the incorporation of high biological value proteins and calcium into aerated foods, and would contribute to develop innovative products. Treatment with high hydrostatic pressure could be advantageous on account of modifying the protein structure and thereby improving the stability of the foams. Under certain conditions, such as those of aerosol whipping creams, high hydrostatic pressure would simultaneously improve techno-functional properties of proteins and pasteurize the dispersions, which would then have to be safely canned. • Large and non-denatured Ca-induced soy protein aggregates stabilized foams. • Insoluble soy protein stabilized foam by Pickering and/or blocking Plateau borders. • At low protein content, denatured soy protein stabilized foam without Ca addition. • Combination of Ca and high pressure improved foam stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surfactants, gases, liquids, and microbes intricately interact in foam formation. • Surfactants in foaming waterbodies are of anthropogenic and naturogenic origin. • Bacteria, enzymes, and particles add to foam stability. • Discharge treated sewage to waterbodies, to stop surface water foaming. • Foam, often non-toxic, can accumulate heavy metals/chemicals and become harmful. Foam formation in surface waters represents a multifaceted process governed by intricate interactions among surfactants, gases, liquids, and microbial entities. Despite its global prevalence, the scientific understanding of surface water foaming remains constrained, necessitating a comprehensive exploration. This comprehensive review synthesizes current knowledge and delineates prospective pathways concerning surface water foaming. Significant insights emerge surfactants, are sourced from both anthropogenic and natural origins, making it difficult to assign a relative flux. Wastewater treatment plants confront difficulties in effectively treating complex surfactants, resulting in their discharge into water bodies, exacerbating the foam occurrence. Less developed nations with limited treatment infrastructure release untreated sewage into water bodies. Further, many Natural foams, traditionally perceived as harmless, can harbor toxins under specific conditions, necessitating vigilant monitoring. The stability of foam is intricately tied to filamentous bacteria, natural enzymes, and environmental factors, with seasonality playing a pivotal role. Policy recommendations highlights the importance of parameters such as surface tension (>50 mN/m), hardness (>130 mg/l), and surfactant concentration (<1 mg/l) for formulating effective foam prevention guidelines. For rejuvenation of foaming waterbodies, desilting and pre-emptive inline treatment/treated water discharge (of dissolved oxygen 3.5 mg/l) are suggested. Future research should prioritize gathering long-term databases on foaming water bodies to predict events and developing standardized analytical techniques. These efforts are crucial for making foam prevention policies. [ABSTRACT FROM AUTHOR]

Foams are increasingly popular in the field of dermatology due to their many advantages such as easy spreading, good skin sensation, and applicability in special skin conditions. One of the critical points of foam formulation is the choice of the appropriate stabilizing ingredients. One of the stability-increasing strategies is retarding the liquid drainage of liquid films from the foam structure. Therefore, our aim was the application of different hydrogel-forming polymers in order to retain the stabilizing liquid film. Dexpanthenol and niacinamide-containing foams were formulated, where xanthan gum and hyaluronic acid were used as foam-stabilizing polymers. Amplitude (LVE range) and frequency sweep (G', G", tanδ, and frequency dependency) were applied as structure- and stability-indicating rheological parameters. The rheological data were compared with the results of the cylinder method, microscopical images, and the spreadability measurements. The application of the gel-forming polymers increased the stability of the dermal foams (increased LVE range, G' values, and decreased frequency dependency). These results were in correlation with the results of the cylinder and spreadability tests. It was concluded that in terms of both foam formation and stability, the combination of xanthan gum and dexpanthenol can be ideal. [ABSTRACT FROM AUTHOR]

Summary: The purpose of this study was to expound on the correlation between foaming properties and physicochemical characteristics of rice bran protein (RBP) samples. RBP nano‐particles (RBPNs) were prepared by acidic–thermal treatment under different RBP solution concentrations and treated times at 90 °C, and then the foaming properties were measured at pH 7.0 and pH 2.0. Compared to RBP, the foaming properties of RBPNs were increased at pH 7.0, and RBPNs could have better foam capacity but have no obvious changes in foam stability at pH 2.0. The results of Pearson correlation showed that the foaming properties were closely correlated with ζ potential, contact angle, and surface hydrophobicity for RBP and RBPNs, and a strong correlation between foaming capacity and surface hydrophobicity was shown for RBPNs. Additionally, the result of TEM images confirmed that RBPNs were inclined to form associated aggregates which may affect the physicochemical characteristics of RBPNs. [ABSTRACT FROM AUTHOR]

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Copyright of Fire Safety Science is the property of Fire Safety Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Natural gas foam can be used for mobility control and channel blocking during natural gas injection for enhanced oil recovery, in which stable foams need to be used at high reservoir temperature, high pressure and high water salinity conditions in field applications. In this study, the performance of methane (CH4) foams stabilized by different types of surfactants was tested using a high pressure and high temperature foam meter for surfactant screening and selection, including anionic surfactant (sodium dodecyl sulfate), non‐anionic surfactant (alkyl polyglycoside), zwitterionic surfactant (dodecyl dimethyl betaine) and cationic surfactant (dodecyl trimethyl ammonium chloride), and the results show that CH4‐SDS foam has much better performance than that of the other three surfactants. The influences of gas types (CH4, N2, and CO2), surfactant concentration, temperature (up to 110°C), pressure (up to 12.0 MPa), and the presence of polymers as foam stabilizer on foam performance was also evaluated using SDS surfactant. The experimental results show that the stability of CH4 foam is better than that of CO2 foam, while N2 foam is the most stable, and CO2 foam has the largest foam volume, which can be attributed to the strong interactions between CO2 molecules with H2O. The foaming ability and foam stability increase with the increase of the SDS concentration up to 1.0 wt% (0.035 mol/L), but a further increase of the surfactant concentration has a negative effect. The high temperature can greatly reduce the stability of CH4‐SDS foam, while the foaming ability and foam stability can be significantly enhanced at high pressure. The addition of a small amount of polyacrylamide as a foam stabilizer can significantly increase the viscosity of the bulk solution and improve the foam stability, and the higher the molecular weight of the polymer, the higher viscosity of the foam liquid film, the better foam performance. [ABSTRACT FROM AUTHOR]

The environmentally-friendly foam extinguishing agent was prepared by using sodium alpha-ole-fin sulfonate (AOS), phosphate betaine silicone (PPSS) and polysaccharide polymer as surfactants and foam stabilizer, respectively. The effect of polysaccharide polymers on viscosity, foaming ability and foam stability of foam was investigated. The results showed that the viscosity and the 25% drainage time of foam solutions increase with the increasing the concentration of polysaccharide polymers. Foaming ability analysis shows that both xanthan gum and sodium alginate decrease the foaming ability of foam solution while the gelatin improves the foaming ability of it. The addition of individual polysaccharide polymer cannot effectively improve the foam properties, while the combination of xanthan gum and gelatin can effectively balance the foaming ability and foam stability of foam extinguishing agents. The combination of xanthan gum and gelatin can effectively balance the foaming ability and foam stability of foam extinguishing agent, which is ascribed to the formation of hydrogen bonds that enhances the surface strength of foam liquid film and decreases the diffusion of water in the liquid film, thus effectively slowing down the drainage rate and bubbles coarsening of foam. When the concentration ratio of xanthan gum to gelatin is 1: 5, the resulting foam exhibits the optimal foam properties, corresponding to the foam height of 123. 0 mm and 25% drainage time of 128. 1 s, which is related to the fact that the xanthan gum and gelatin compound system can slow down the rate of liquid evolution and bubble coarsening. [ABSTRACT FROM AUTHOR]

Lyotropic liquid crystal prepared by triethanolamine oleate and p.xylene. The texture of liquid crystal was observed macroscopically by polarized light microscope. The viscosity of the system and the rheological behavior of the lyotropic liquid crystal were measured by steady state rheology. The foam properties of lyotropic liquid crystals were studied by the variation of gas content, half-life and foam height with time. The results show that triethanolamine oleate/p-xylene lyotropic liquid crystal exhibits the texture of lamellar liquid crystal. The lyotropic liquid crystal system behaves as a non-Newtonian fluid and has obvious yield value and shear diluency. When the mass fraction of triethanolamine oleate is 87%, the foam is the most stable, and the complete decay can reach 21 h, indicating that the lyotropic liquid crystal foam has excellent stability. [ABSTRACT FROM AUTHOR]

Water-based fracturing fluids are among the most common fluid types used in hydraulic fracturing operations. However, these fluids tend to cause damage in water-sensitive formations. Foam comprises a small amount of base fluid, and compressible gas such as carbon dioxide and nitrogen has emerged as a more ecologically friendly option to fracture such formations. Foam is an attractive option since it has a low density and high viscosity. The applicability of foamed frac fluid is characterized by foam stability and rheology, encompassing the viscosity and proppant carrying ability. The foam quality, pressure and temperature affect the foam rheology. Generally, foam viscosity and stability increase with pressure but decrease when the temperature increases. Hence, it is essential to preserve foam stability in high pressure and high temperature (HPHT) reservoir conditions. The addition of nanoparticles could increase the thermal stability of the foam. This article provides the basis of foam-based fracturing fluid characterization for an optimal application in HPHT reservoir conditions. Then, focusing on improving thermal stability, it reviews the research progress on the use of nanoparticles as foam stabilizing agent. This paper also sheds light on the literature gaps that should be addressed by future research. [ABSTRACT FROM AUTHOR]

The technique of dry hopping is used to produce many different beer styles with various alcohol contents. Information about the alcohol-dependent behaviour of hop components after dosing is crucial to control the resulting flavour and ensure consistent beer quality. This systematic pilot-scale study was therefore performed using standardised procedures by only varying the alcohol content in the beer samples in four steps from 0.5 % to 10.5 % alcohol by volume (ABV). A commercially available alcohol-free wheat beer was used as a base beer to adjust the alcohol concentrations while keeping the hop dosing rate consistent at 250 g/hl using Type 90 Pellets of the variety Solero. After a semi-static contact time of 14 days, the following attributes were analysed: hop-derived bitter and aroma compounds, polyphenol content, nitrates, foam stability and pH value. The conclusions for the non-volatile attributes are as follows: iso-alpha acids, humulinones, polyphenols and foam stability remained unchanged with varying ABV. In contrast, increasing the alcohol content improved the transfer and solubility of hydrophobic alpha and beta acids as well as xanthohumol, resulting in higher concentrations. Increasing the alcohol also caused lower quantities of nitrates to be transferred. Foam stability was negatively affected when more ethanol was added, but this drop in stability was compensated by more foam-positive alpha acids introduced. The beer pH showed very little increase and was hardly influenced by the ABV. For the hop-derived volatile substances, the conclusions are as follows: The terpene alcohols displayed very good solubility with the ABV having hardly any impact. The transfer of hop esters was only somewhat ABV-dependant and the presence of alcohol above 0.5 % further increased the solubility to finally reach a certain plateau. Ketone concentration did depend on the ABV. Mono- and sesquiterpenes are most clearly influenced by the alcohol content and the highest concentrations were reached at the highest ethanol addition. [ABSTRACT FROM AUTHOR]

Copyright of China Surfactant Detergent & Cosmetics (1001-1803) is the property of China Surfactant Detergent & Cosmetics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AlCa75 with equal Ca content was used to replace pure Ca for the preparation of AlSi12 foam in a stable pore structure after foaming for 20 min. The stability mechanism was studied based on the comparison between the macroscopic pore structure evolution and the second phase composition of AlCa75 and pure Ca aluminum foam. It was found that the porosity and average pore size of the AlSi12 foam with AlCa75 were stable without any abnormal large pores, and the foaming stage was prominent. The stability of AlSi12 foam with pure Ca is inferior. After 20 min of foaming, the foam bursts in the center. Combined with the microscopic characteristic analysis, it could see that the second phase produced by AlCa75 is mainly Al2Si2Ca, which can be uniformly dispersed in the matrix. The addition of pure Ca reduces the amount of the second phase and the main phase Al4Ca is easy to agglomerate. The stability mechanism shows that the Al2Si2Ca second phase, formed by AlCa75, demonstrates a better stabilizing effect in different foaming stages. Due to the premature agglomeration caused by Al4Ca and the low content of the second phase, the AlSi12 foam with pure Ca is challenging to long-term stability.

To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability, a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory. The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate. The foam film thickness, surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed. The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage, enhance the effect of Marangoni effect, and improve the stability of the foam liquid film. When the vibration frequency is close to the natural frequency of the foam liquid film, the vibration effect is the best, and the best vibration frequency is about 50 Hz. The higher the vibration acceleration, the faster the recovery rate of surfactant concentration in the foam liquid film is. The higher the vibration acceleration, the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is. It is not the higher the vibration acceleration, the better. The best vibration acceleration is about 0.5 times of gravity acceleration. Reasonable vibration parameters would greatly enhance the effect of Marangoni effect. The smaller the initial concentration of surfactant, the better the vibration works in enhancing Marangoni effect.

The foam performance in the presence of oil plays an essential role in foam application in enhancing oil recovery. This study systematically investigated whey protein isolate (WPI), the effectiveness of foam generation, the effect of three types of crude oil, surfactant concentration on foam performance and oil-water interfacial tension (IFT). The extraction of WPI was compared to sodium dodecyl sulfate (SDS) at the microscopic foam images to have a better understand of foaming in terms of performance. The results showed that the WPI lowers the surface tension, which also tends to disclose and stabilize the interface by forming a viscoelastic network. SDS reduced the surface tension compared to the WPI but did not produce a high modulus interface. WPI generated a more stable foam in oil than SDS foam. The WPI improved foam stability by increasing the gas-water interface dilatational viscoelasticity layers. WPI solution decreases bubble sizes and prevents oil from spreading at the foam lamellae. The WPI foam exhibits higher stability in Libya crude oil when the oil saturation is between 0–20%. WPI foam reduces fluid loss and hinders the movement of oil droplets within the lamella, the significant viscosity contrast between oil and WPI-CO2. Waxy oil is detrimental to both SDS and WPI foam, while waxy oil can harm WPI foam in some specific cases. The oil-water IFT was reduced to extremely low levels by WPI. As a result, WPI's interfacial tension values with Sharara oil were (21 mN/m) and SDS's were (44.5 mN/m).

Screening proteins for their potential use in foam applications is very laborious and time consuming. It would be beneficial if the foam properties could be predicted based on their molecular properties, but this is currently not possible. For protein-stabilized emulsions, a model was recently introduced to predict the emulsion properties from the protein molecular properties. Since the fundamental mechanisms for foam and emulsion formation are very similar, it is of interest to determine whether the link to molecular properties defined in that model is also applicable to foams. This study aims to link the exposed hydrophobicity with the foam ability and foam stability, using lysozyme variants with altered hydrophobicity, obtained from controlled heat treatment (77 °C for 0–120 min). To establish this link, the molecular characteristics, interfacial properties, and foam ability and stability (at different concentrations) were analysed. The increasing hydrophobicity resulted in an increased adsorption rate constant, and for concentrations in the protein-poor regime, the increasing hydrophobicity enhanced foam ability (i.e., interfacial area created). At higher relative exposed hydrophobicity (i.e., ~2–5 times higher than native lysozyme), the adsorption rate constant and foam ability became independent of hydrophobicity. The foam stability (i.e., foam collapse) was affected by the initial foam structure. In the protein-rich regime—with nearly identical foam structure—the hydrophobicity did not affect the foam stability. The link between exposed hydrophobicity and foam ability confirms the similarity between protein-stabilized foams and emulsions, and thereby indicates that the model proposed for emulsions can be used to predict foam properties in the future. [ABSTRACT FROM AUTHOR]

Aqueous Extract of Acanthophyllum laxiusculum root (AE) exhibited remarkable foaming profile, emulsification properties and antifungal activity due to the presence of high concentration of total saponins. Total phenolic compounds, another main component, accounted for the AE antioxidant activity. Spray drying of AE, as a thermal process, did not affect the foaming indices of A. laxiusculum Spray-dried Extract (SE) and is a recommended alternate for convenient application in food industry. Addition of SE to the malt extract at accepted levels of total saponin daily intake (below 50 mg/kg) showed positive attribution of malt and carbonation on the foaming quality of SE. Meanwhile, antioxidant activity of commercial malt beverage was enhanced by addition of phenolic compounds containing SE. The 20–60% antifungal inhibitory ratio of the SE developed here is within the applied range of total saponin that supports its application to inhibit the growth of Saccharomyces cerevisiae after malt beverage production. The bitter taste of SE was not sensed in malt beverage at 30 mg/kg total saponin content and suggested A. laxiusculum root extract as a natural additive in malt industry. [ABSTRACT FROM AUTHOR]

Etheramines are quartz collectors and also play a role as frothers in cationic reverse flotation of iron ores. While the adsorption of this surfactant on quartz surface has been widely investigated, the impact of its foam/froth properties on the selectivity in iron ore flotation has not yet been addressed in detail. The structural differences between ethermonoamine and etherdiamine result in distinct adsorption and frothing properties, offering versatility in the concentration of hematite. This study addressed the effect of the etheramine type on flotation selectivity, focused on the analysis of frothing properties. The characterization of the surfactants in the pure state and in two-phase systems (liquid/air) was conducted to investigate the behavior of etheramines concerning foam forming and stabilization. The surface tension measurements showed greater activity of etherdiamine at the liquid–air interface in comparison with ethermonoamine, which was more effective to prevent bubble coalescence and produce smaller bubbles, despite the reagent's higher critical coalescence concentration. Ethermonoamine presented faster foamability for concentrations greater than the observed critical coalescence concentration values as well as greater water recovery in foam, whereas the double CH2 group and higher molecular weight imparted strong lipophilic character to etherdiamines, producing drier, voluminous, and more stable foams, with longer lifetime. These results are fundamental for the evaluation of three-phase systems, which will be presented in a subsequent paper. [ABSTRACT FROM AUTHOR]

Froth stability is an important factor in determining flotation yield, and one of the factors affecting froth stability is dependent on the concentration and type of surfactant. Since detergents contain different types of surfactants, it is possible that they affect the froth stability (together with the frothing agent and the collector) and consequently the flotation yield. Therefore, the effect of detergents containing lauryldimethylamine oxide and sodium laureth sulphate was investigated in this study. The results showed that the addition of detergents increased the froth stability by more than 30%and 45%in terms of froth formation and froth decay, respectively. The flotation tests also showed that the addition of detergents increased the sulphur content of the concentrate by about 0.7%. [ABSTRACT FROM AUTHOR]

Abundant applications of silica nanoparticles (SiNPs) have motivated many research groups for silica nanoparticles synthesis with tuned properties. Here we show the formation of SiNPs using the top-down method in a wet attrition mill with effective use of surfactants sodium laurylsulfate (SLS) and Tween-80. The attrition milling was facilitated by using zirconium beads as milling media. The effects of surfactant concentration on particle size distribution have been studied with a particle size analyzer using the dynamic light scattering technique (DLS). The optimum conditions for wet milling with surfactant concentration were evaluated experimentally. The field emission scanning electron microscopy (FE-SEM) analysis confirmed particle size and particle shape. The energy-dispersive X-ray spectroscopy (EDX) exhibited the presence of silicon and oxygen as elemental constituents of SiNPs. The FEG - Transmission electron microscope and HR-TEM analysis identified SiNPs of spherical shape in the size range from 21 nm to 46 nm. The X-ray diffraction (XRD) peaks revealed the presence of SiNPs polycrystallite size as 35.54 nm and 40.63 nm for 5 wt % Tween-80 and 5 wt% SLS, respectively. The selected area electron diffraction (SAED) pattern analysis exhibited a polycrystalline structure of SiNPs. Fourier transform infrared spectroscopy (FTIR) peaks confirmed the purity of SiNPs and the presence of Si-O bond. The foam formation and foam stability were analyzed to explore the effects of foam formation on the wet milling process. These experimentations propose the effective use of surfactants in the milling method for the production of SiNPs. Graphical Abstract [ABSTRACT FROM AUTHOR]

In the present study, SiO2 nanoparticles were first hydrophobically modified and then added into anionic surfactant sodium dodecyl sulfate (SDS) stabilized water-based foam to improve the foam stability. The foam stability was experimentally evaluated by measuring surface tension, Zeta potential and half-life of the foam. The foam stabilizing mechanism was also studied from a micro perspective by molecular dynamics simulation through analyzing the equilibration configuration and MSD curve of both SDS surfactant and water molecules. The results show that foam exhibits an optimal stability when SiO2 concentration is 0.35 wt% under a specific surfactant concentration (0.5 wt%) in this work. The addition of SiO2 nanoparticles with suitable concentration could improve the adsorption between SDS molecules and nanoparticles, thus limiting the movement of SDS and restricting the movement of surrounding water molecules, which is beneficial to enhance the foam stability.

Purpose. To establish the relationship between the foam expansion rate and stability of low-expansion air-mechanical foam generated in deflector type sprinklers for automatic extinguishing systems. To develop a methodology and carry out field tests of foam and foam-water sprinklers. To compare the extinguishing efficiency of the tested sprinklers basing on the results of field tests. Methods. The method of regression analysis was used to establish the dependence of the foam stability on its expansion rate. The assessment of the extinguishing efficiency of the sprinklers was carried out experimentally, and the processing of the obtained experimental data was carried out using the method of estimation and expression of measurement uncertainty. Findings. A linear relationship has been established between the expansion rate K and stability C of the low-expansion air-mechanical foam: C = γ·K, where γ is an empirical coefficient depending on the physicochemical properties of the foaming agent. The empirical dependences C = f(K) were obtained for brand of the foaming agents PO-6RZ (6 %). The methodology was developed and field tests of four deflector type sprinklers (V2 sprinkler with optimized geometry on the foam expansion rate, TY 3251 (USA), DPU-15 (Russia) and DVN-11 (Belarus)) were carried out. To compare the extinguishing efficiency of the sprinklers, the extinguishing efficiency indicator Et was used. This indicator takes into account the extinguishing time of the model fire site and the discharge rate of the extinguishing agent. In the result of field tests, it was found that the V2 sprinkler has at least 2.5 times better extinguishing efficiency compared to other tested sprinklers. Application field of research. The obtained empirical dependence C = γ·K can be used to predict the stability of the foam based on its expansion rate value and vice versa. The developed methods of field testing and evaluating the extinguishing efficiency of foam and foam-water deflector type sprinklers can be implemented for the development of standards, as well as for the study of other sprinklers in conditions close to a real fire.

Introduction. Whipped dairy products can be used both as finished and semi-finished products in confectionery industry. Therefore, this sphere constantly requires new technologies. A wide range of additives, stabilizers, and structure-forming agents make it possible to get products with programmed sensory, structural, and mechanical properties. Enzymatic processing of milk base is one of the modern directions in the development of whipping process, as it requires no artificial components. Enzyme preparations of plant and microbial origin were developed to satisfy the needs of the increasing production demand and to compensate for the acute shortage of animal rennet. These enzymes have a high proteolytic activity and exhibit good technological properties in dairy industry. The research objective was to study the fermentation process with preparations of different origin and optimize the proteolysis process to obtain a milk base with a high foaming capacity and maximal stability. Study objects and methods. The research featured samples of fermented reduced skim milk. The following enzymes were selected for enzymatic hydrolysis: animal origin – rennet-beef enzyme SG-50 (Russia), chicken-beef enzyme KG-50 (Russia), pepsin (Russia); microbial nature – Fromase 750 (France), Pronase E (Russia); recombinant chymosin-preparation CHY-MAX M (Denmark). The fermented systems were tested for foaming ability, foam stability, relative content of free amino acids, and the diameter of casein micelles during hydrolysis by the ratio of the height of the foam column to the initial volume. The relative content of free amino acids was determined using the method of formal titration. The diameter of casein micelles during hydrolysis was determined by dynamic light scattering using a particle size analyzer in low-volume plastic cuvettes. These indicators were determined after inactivation of enzymes by pasteurization at 90–92°C for 3–5 sec. Results and discussion. Enzyme preparations of various natures were added to milk. The temperature and duration were measured as rational parameters of fermentation. After inactivation of the enzymes by pasteurization method, the foaming capacity, foam stability, and the relative content of free amino acids were determined every 30 minutes after application of the preparation. The greatest foaming properties (800%) were observed in the milk base fermented with the recombinant enzyme CHY-MAX M. However, the use of this preparation in commercial production was found undesirable due to the high activity of the enzyme and the resulting complexity of the control process. The lowest foaming ability was observed in the milk sample fermented with preparations of animal origin – SG-50, KG-50, and pepsin. The optimal foaming capacity and stable whipped mass were registered in the samples hydrolyzed with microbial preparations Fromase and Pronase. Under certain rational parameters, the foaming capacity of milk was 740% and 700%, respectively, while the stability was 80%. Conclusion. The research featured a comparative analysis of the foaming capacity and stability of reduced skim milk foam obtained using preparations of animal and microbial origin. The enzymes of the microbial group showed the best results for the enzymatic hydrolysis of proteins in reduced milk.

CO 2 -responsive foam (CRF) is a highly promising candidate for CO 2 -enhanced oil recovery (CO 2 -EOR) because it displays higher stability than the surfactant-stabilized foam owing to the formation of robust wormlike micelles (WLMs) upon exposure to CO 2 . In this work, the nanoparticle-enhanced CO 2 -responsive foam (NECRF) was properly prepared using lauryl ether sulfate sodium (LES)/diethylenetriamine/nano-SiO 2 , and its interfacial properties and EOR potential were experimentally and numerically assessed, aiming to explore the feasibility and effectiveness of NECRF as a novel CO 2 -EOR technique. It was found that the interfacial expansion elastic modulus increased 6-fold after CO 2 stimulation. The modulus continued to increase with the introduction of nano-SiO 2 owing to the pronounced synergistic effect of WLMs and nanoparticles. In addition to increasing the viscosity of the foaming liquid, WLMs and nano-SiO 2 enhanced the shearing resistance of the NECRF as well. Calculations demonstrated that both the coarsening rate and the size distribution uniformity coefficient of NECRF were markedly lower than that of the LES foam, which subsequently inhibited NECRF decay and greatly improved its dynamic stability. Besides, molecular dynamics simulation revealed that adding inorganic salts to NECRF could notably enhance the foaming performance due to the intensified hydration of surfactant head groups and reduced binding energy of neighboring molecules. Nuclear magnetic resonance-assisted core flooding experiments validated the exceptional capacity of NECRF to sweep the low-permeability region and improve the conformance profile. Overall, these findings may provide valuable insights into the development and application of novel materials and strategies for the CO 2 -EOR.

Understanding the fundamental aspects of foaming properties will influence its generation and stabilization at different concentrations of the critical aggregation concentration (CAC), foam volume stability, foam height, salinity influences, and crude oil CO2-foam stability. Carbon-Dioxide based enhanced oil recovery techniques are widely employed to extract additional oil from the reservoir. The adsorption of protein at the interfaces produces extremely viscoelastic layers with high viscosity. This research aims to investigate whether whey protein isolate (WPI) is a foaming agent that can be used to improve oil recovery. WPI lowers the interfaces' surface tension, which also has a propensity to disclose and stabilize the interface by forming a viscoelastic network and directing to high surface moduli. Comparatively, the surface tension is lowered by sodium dodecyl sulfate (SDS) surfactants than the WPI, but they do not produce a high modulus interface. WPI is demonstrated to be a greater foam stabilizer in oil and various salt conditions than SDS foam. Adding sodium chloride (NaCl) increased the half-life and volume of foam more on WPI foam compared to SDS foam. SDS foamability and foam consistency decreased dramatically at 2 wt% of NaCl concentration and above while WPI foam increased. The crude oil affected both foams, but WPI foam has not been affected as much as the SDS foam due to its high strength compared to traditional foams. The study shows that WPI reduced interfacial tension from 38 to 11 mN/m and reduced surface tension (72.3 to 48 mN/m). It was low enough and can be used as a substitute for a foaming agent to enhance the recovery of oil. [ABSTRACT FROM AUTHOR]

Oil-laden (OL) foams could serve an important role in various processes, particularly in enhanced oil recovery; however, OL foams are less studied than aqueous foams. In this work, the formation and stability of OL foam, by either sodium dodecyl sulphate (SDS) or Triton X-100 (TX-100) in water-pentane mixture, was evaluated. We first constructed a diagram of good and poor foaminess against pentane content in the mixture and aqueous surfactant concentration. It was shown that surfactant onset concentration for good foaming was increased with increasing pentane content. The result was fitted using a mathematical model that considers the surfactant dilution and adsorption effects by pentane. Foam height decay profiles were also monitored. Results indicated that SDS resulted in a more stable foam than TX-100 at the same critical micelle concentration (CMC). Depending on surfactant concentration, OL foams exhibited strikingly different stability behaviours. Pentane acted as an anti-foamer at surfactant concentrations at the CMC or lower. However, very high foam stability was displayed at high surfactant concentration (e.g., 3x CMC) and medium to high pentane contents; this is a result contradictory to the predication of entering, spreading, and bridging coefficients in the classic theory. The stable OL foams of this study could be attractive to potential foam applications. [ABSTRACT FROM AUTHOR]

We successfully developed new automated 'FCT (Foam Collapse Time)' system for the evaluation of visual foam stability in order to get a useful knowledge for improving practical foam stability. The FCT value is defined as the required time for a reduction of the 40 % of glass hight (32 mm) of foam layer to a single layer in a prescribed glass. The improved FCT pouring apparatus was coupled with automated turntable for 6 glasses, electronic balance, and CCD-cameras (side and upper) for measuring the foam layer (mm) and the collapse point. Based on automatically collected data, the FCT value could be statistically calculated by specialized software on the control PC. Using this system, we confirmed an importance of hop bitter acids and their derivatives, which could affect the strength of foam membrane, for visual foam stability evaluating by FCT. From comparison between FCT, Sigma, and NIBEM methods, it was suggested that detectability for foam membrane strength was more sensitive in FCT and NIBEM than Sigma, and that foam membrane strength could also affect foam lacing. [ABSTRACT FROM AUTHOR]

This investigation reveals the influence of self-assembly of surface active components of surfactants in instant coffee in rendering a stable foam, thereby providing a visual delight. Three surfactants, sucrose stearate, quillaja saponin, and Tween 80, were administered to improve the foam quality of instant coffee. The influence of the addition of these surfactants showed a reduction in surface tension of the coffee solution. Sucrose stearate showed excellent foaming properties as well as foam stability for over 1200 s. For sucrose stearate, the maximum foam height of 168.2±0.1 mm was achieved at 75.98±1.87 s that sustained for 60.27±3.59 s with a minimum coalescence rate of 0.012±0.005 μm/s, compared to other surfactants. FE-TEM results proved that closely packed patterned morphology of micelles at the air-water interface, specifically in sucrose stearate foam, could have aided in the development of the most stable foam. As deduced from the present findings, the preferred hierarchy of surfactant for a stable foam in instant coffee is sucrose stearate> quillaja saponin > Tween 80.

Controlling the stability of liquid foams is of the utmost importance for a wide range of applications. For decades, fluorocarbon vapors have been added to the gas phase of foams to ensure long‐term stability against bubble coarsening. However, it is shown here for the first time that they also have an unexpected and pronounced effect on bubble coalescence. This effect is quantified in detail for foams stabilized by the nonionic surfactant hexaethylene glycol monododecyl ether (C12E6) at controlled fluorocarbon (perfluorohexane (C6F14)) concentrations, but it is observed for all investigated surfactants. Measuring surface tensions of the foaming solution with increasing fluorocarbon concentration, a synergy between the fluorocarbon and the surfactant is found which can be explained by a) the formation of mixed layers of both species at the gas/water interface at low fluorocarbon concentrations and b) the formation of a macroscopic fluorocarbon film if the gas phase is saturated with fluorocarbon vapor. The precise mechanism responsible for reducing coalescence, that is, film rupture, remains to be elucidated. [ABSTRACT FROM AUTHOR]

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Beer is one of the oldest and most widely-consumed low-alcoholic beverage. Beer production takes an important place in food industry worldwide. There are many different types of beer depending on the fermentation technology and some visual characteristics, such as color and turbidity. Beers are differentiated commonly according to the fermentation process, which can be categorized in three categories - with upper or low fermentation and naturally fermented beer. The quality of beer is assessed by a set of sensory characteristics such as appearance, taste, aroma and texture. The appearance of the beer is related to the color, foam and clarity of the product. Changes in the volume and the height of beer foam affect one of the most important organoleptic indicators - the stability of beer foam. The aim of this paper is to study the change in the volume of beer foam over time, using techniques for computer processing of two-dimensional images and taking into account changes in the height of beer foam. Three different brands of beer are bought from the marketplace and are tested. A digital camera and an appropriate experimental setting are used for capturing videos in order to examine the changes in the volume and stability of beer foam. The videos are divided into frames at regular intervals of time. A computer program is developed for automatic determination of the change in the volume of the liquid and the volume of the foam over time. Digital image processing is applied to the obtained frames. The developed computer program is tested by processing images of beer samples and appropriate algorithms for segmentation computer vision techniques. As a result, changes in the height of the beer foam and liquid phase are observed and the volume of both is calculated. Based on the obtained results, it is concluded that the created experimental setup and computer program can be successfully used to qualify the beer by the volume and stability of beer foam. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dynamic imine bond introduced between PAH and aldehyde compounds. • Hydrophobicity of PAH controlled by dynamic covalent bonds responsive to pH. • Aggregation of amphipathic PAH-aldehyde at neutral pH stabilizes Pickering foams. • Decomposition of PAH-aldehyde at acidic condition destructs foams. • Reversible foaming and defoaming achieved by alternatively changing pH. Responsive surfactant systems based on dynamic covalent bond exhibit an unsatisfactory foamability and foam stability, despite their documented functionality in emulsions. As such we anticipate that the foaming performance should be improved by introducing Pickering effect, which is possible when the responsiveness of the dynamic covenant bonds controls not only the hydrophobicity of polymers but also their aggregation behavior (to form nanoparticles). Here we created surface active nanoparticles made from self-aggregated polymers consisting of PAH (polyallylamine hydrochloride)-BA (benzaldehyde). The covalent imine bonds between originally hydrophilic PAH and hydrophobic BA are dynamic in that their formation and breakage is a function of solution pH, confirmed by 1H NMR and dynamic interfacial tension measurement. At pH 7.4, a stable foam is achieved in the PAH-BA (amino to aldehyde ratio at 1:0.2) solution; while at pH 2.5, it defoams due to breakage of dynamic bonds corresponding to the measured diminishing surface activity. The reversibility of foaming-defoaming has been demonstrated by alternatively changing pH for multiple cycles, with the foaming performance persistent. The foam stability can be improved by more hydrophobic compounds e.g. at a lower amino to aldehyde ratio or using PAH-cinnamaldehyde (CA). The reversible and responsive foaming demonstrated in a Pickering system provides a new method to create novel foaming systems with properties desirable to many applications. [ABSTRACT FROM AUTHOR]

Most of the available commercial surfactants precipitate due to the hardness of formation water. The study of surfactant generated foam and its stability is very complex due to its multifaceted pattern and common physicochemical properties. This research involved the study of foam generation by using the blended surfactants and their evaluation in terms of enhanced oil recovery (EOR). The objective of this study is to systematic screening of surfactants based on their capability to produce stable foam in the presence of two different categories of crude oil. Surfactant types such as non-ionic, anionic and amphoteric were selected for the experimental study. The foam was generated with crude oil, and the synthetic brine water of 34,107 ppm used as formation water. Surfactant concentration with the both types of crude oil, foam decay, liquid drainage and foam longevity was investigated by measuring the generated foam volume above the liquid level. The surfactant with concentration of 0.6wt%AOSC14-16, 1.2wt%AOSC14-16, 0.6wt%AOSC14-16 + 0.6wt%TX100 and 0.6wt%AOSC14-16 + 0.6wt%LMDO resulted in the maximum foam longevity with formation water and two categories of crude oil. The 50% liquid drainage and foam decay of surfactant solutions with concentration of 0.6wt%AOSC14-16 + 0.6wt%LMDO and 0.6wt%AOSC14-16 + 0.6wt%TX100 were noted with the maximum time. The findings of this research demonstrated that the generated foam and its longevity is dependent on the type of surfactant either individual or blended with their concentration. The blend of surfactant solution combines excellent foam properties. [ABSTRACT FROM AUTHOR]

Trapped foam saturation ( S g t ), apparent viscosity ( μ app f ), and the limiting capillary pressure of foam ( P c ∗ ) are the common indices used to describe foam strength in porous media. They are linearly intercorrelated when they are obtained from a single porous medium. However, P c ∗ is inversely correlated with S g t and μ app f , when obtained from porous media with different pore structures. This paper investigates these contradictions and presents a new insight. Here, the three indices were obtained from 12 different rock samples with multiple steady-state foam injection coreflood experiments. The pore properties of the rock samples were measured with high-resolution synchrotron X-ray microtomography 3D imaging, pore network analysis, and nuclear magnetic resonance (NMR) relaxometry. Pore aspect ratio was found to offer opposing effects on P c ∗ relative to S g t and μ app f , resulting in an inverse relationship between them. Hence, S g t or μ app f may not be an absolute index of foam strength. Rather, mobile-trapped foam ratio (ranging from 0 to 1) appears to be a more appropriate index as it correlates linearly with P c ∗ . A mobile-trapped foam ratio near zero indicates a very weak foam while a ratio of unity indicates a very strong foam. The ratio also correlates strongly with NMR relaxation time, making NMR log a promising tool for predicting foam strength in reservoir rocks. The graphical interpretation technique used to obtain these ratios is presented. This technique also allowed foam stability to be evaluated based on the ability of the trapped lamellae to withstand shear force during prolonged liquid flow. Based on these, different combinations of strength and stability of foam in porous media were identified namely strong and stable; strong and unstable; weak and stable, and weak and unstable foam. [ABSTRACT FROM AUTHOR]

Generating strong and stable foam is necessary to achieve in-depth conformance control in the reservoir. Besides other parameters, the chemistry of injection water can significantly impact foam generation and stabilization. The tailored water chemistry was found to have good potential to improve foam stability. The objective of this study is to extensively evaluate the effect of different aqueous ions in the selected tailored water chemistry formulations on foam stabilization. Bulk and dynamic foam experiments were used to evaluate the impact of different tailored water chemistry aqueous ions on foam generation and stabilization. For bulk foam tests, the stability of foams generated using three surfactants and different aqueous ions was analyzed using bottle tests. For dynamic foam experiments, the tests were conducted using a microfluidic device. The results clearly demonstrated that the ionic content of aqueous solutions can significantly affect foam stabilization. The results revealed that the foam stabilization in bulk is different than that in porous media. Depending on the surfactant type, the divalent ions were found to have stronger influence on foam stabilization when compared to monovalent ions. The bulk foam results pointed out that the aqueous solutions containing calcium chloride salt (CaCl2) showed longer foam life with the anionic surfactant and very weak foam with the nonionic surfactant. The solutions with magnesium chloride (MgCl2) and CaCl2 salts displayed higher impact on foam stability in comparison with sodium chloride (NaCl) with the amphoteric alkyl amine surfactant. Less stable foams were generated with aqueous solutions comprising of both magnesium and calcium ions. In the microfluidic model, the solutions containing MgCl2 showed higher resistance to gas flow and subsequently higher mobility reduction factor for the injection gas when compared to those produced using NaCl and CaCl2 salts. This experimental study focusing about the role of different aqueous ions in the injection water on foam could help in better understanding the foam stabilization process. The new knowledge gained can also enable the selection and optimization of the right injection water chemistry and suitable chemicals for foam field applications. [ABSTRACT FROM AUTHOR]