Foam Destruction Research Articles

Pickering Foam Stabilized by Diacylglycerol-Based Solid Lipid Nanoparticles: Effect of Protein Modification.

Pickering foams have great potential for applications in aerated foods, but their foaming ability and physical stability are still far from satisfactory. Herein, solid lipid particles (SLNs) were fabricated by using diacylglycerol of varying acyl chain lengths with modification by a protein. The SLNs showed different crystal polymorphisms and air-water interfacial activity. C14-DAG SLN with a contact angle ∼ 79° formed aqueous foam with supreme stability and high plasticity. Whey protein isolate and sodium caseinate (0.1 wt %) considerably enhanced the foamability and interfacial activity of SLNs and promoted the packing of particles at the bubble surface. However, high protein concentration caused foam destruction due to the competitive adsorption effect. β-sheet increased in protein after adsorption and changed the polymorphism and thermodynamic properties of SLN. The foam collapsing behaviors varied in the presence of protein. The results gave insights into fabricating ultrastable aqueous foams by using high-melting DAG particles. The obtained foams demonstrated good temperature sensitivity and plasticity, which showed promising application prospects in the food and cosmetic fields.

Experimental and mechanism study of asphaltene on formation and stabilization of oil-based foam

Stable foam will be generated in the separation equipment after pressure reduction of crude oil, which reduce the separation efficiency and damage the power equipment. It is found that the foam formed by asphaltene-rich crude oil is particularly stable in oilfield production, and the action mechanism of asphaltene for foam remains unclear. Hence, a self-made foaming device was performed to investigate the foamability and foam stability of oil-based foam, and the impact of asphaltene concentration and oil phase composition on foam properties was elucidated from the interfacial properties, viscosity, foam structure and the microstructure of asphaltene. Results show that low asphaltene concentrations promote foaming and mitigate the foam destruction. In contrast, high asphaltene concentrations are detrimental to foaming and reduce foam stability. The changes in interfacial properties and viscosity caused by asphaltene are not the main factors affecting foam performance. Besides, we proposed that asphaltene present in the oil phase as non-adsorbed particle, and the foam stability is influenced by the shape, volume fraction and size distribution of the particles. Furthermore, the boundary conditions for the effect of asphaltene on foam performance are innovatively put forward. This work contributes to understand the mechanism by which the asphaltene enhances foam stability and provides theoretical support for defoaming techniques in crude oil foam.

The bubbly life and death of animal and plant milk foams.

Milk foams are fragile objects, readily prepared for frothy cappuccinos and lattes using bovine milk. However, evolving consumer preferences driven by health, climate change, veganism, and sustainability have created a substantial demand for creating frothy beverages using plant-based milk alternatives or plant milks. In this contribution, we characterize maximum foam volume and half-lifetime as metrics for foamability and foam stability and drainage kinetics of two animal milks (cow and goat) and compared them to those of the six most popular, commercially available plant milks: almond, oat, soy, pea, coconut, and rice. We used three set-ups: an electric frother with cold (10 °C) and hot (65 °C) settings to emulate the real-life application of creating foam for cappuccinos, a commercial device called a dynamic foam analyzer or DFA and fizzics-scope, a bespoke device we built. Fizzics-scope visualizes foam creation, evolution, and destruction using an extended prism-based imaging system facilitating the capture of spatiotemporal variation in foam microstructure over a broader range of heights and liquid fractions. Among the chosen eight milks, oat produces the longest-lasting foams, and rice has the lowest amount and stability of foam. Using the hot settings, animal milks produce more foam volume using an electric frother than the top three plant milks in terms of foamability (oat, pea, and soy). Using the cold settings, oat, soy, and almond outperform cow milk in terms of foam volume and lifetime for foams made with the frother and sparging. Most plant milks have higher viscosity due to added polysaccharide thickeners, and in some, lecithin and saponin can supplement globular proteins as emulsifiers. Our studies combining foam creation by frothing or sparging with imaging protocols to track global foam volume and local bubble size changes present opportunities for contrasting the physicochemical properties and functional attributes of animal and plant-based milk and ingredients for engineering better alternatives.

Исследование абсорбции углеводородов пеной

Purpose. To explain the behavior of air-mechanical foam in contact with hydrocarbons, there are generally accepted ideas about the thermodynamic stability of asymmetric aqueous films. These concepts cannot be considered exhaustive, since they do not explain the phenomena of foam stabilization in contact with hydrocarbons. The reason for the stabilization of foam films is the formation of stable emulsions in them caused by mass transfer. The aim of the work is to investigate the phenomenon of mass transfer between the aqueous phase and hydrocarbons on the stability of foam in contact with hydrocarbons. The following tasks are set in the work: to experimentally establish the effect of mass transfer on the contact destruction/stabilization of foam and the effect of hydrocarbon emulsification on the stability of foam from foaming agents of various nature. Methods. The experimental research method consists in measuring the rate of destruction of foam in contact with liquid and gaseous hydrocarbons, as well as with hydrocarbon vapors. Findings. The paper presents the results of experimental studies, on the basis of which it is shown that the intensification of the mass transfer process between the aqueous phase and the hydrocarbon contributes to the stabilization of foam in contact with hydrocarbons. A study of the destruction of foam in hydrocarbon vapors has shown that, regardless of the nature of foaming agents, the greatest stabilization of foam is observed in the case of compliance of the foaming agent with the optimal hydrophilic-lipophilic balance of hydrocarbon, at which its emulsification occurs. Research application field. In this paper, the effect of mass transfer between the aqueous and hydrocarbon phases on the stabilization of foam in contact with hydrocarbons is investigated. The results obtained can be used for scientific and educational purposes in the study of the physicochemical properties of air-mechanical foam. Conclusions. It has been experimentally shown that the intensification of mass transfer contributes to a more intensive formation of an emulsion, which helps to stabilize the foam. All other things being equal, a foam more stable on the surface of hydrocarbons makes it possible to obtain a foaming agent, which in this system exhibits the properties not only of a foaming agent, but also of a good emulsifier.

Toxicity of products of thermal oxidative degradation of nitrogen-containing building polymer materials

Introduction. In the event of fires in residential premises in which nitrogen-containing thermal insulation materials (foam rubber, polyisocyanurate foam) are used, the victims will be exposed to toxic thermal degradation products. Data on long-term disorders caused by intoxication by thermal degradation products of these materials could not be found in the available literature. The aim of the study was to assess the toxicity of the products of thermal oxidative degradation of nitrogen-containing thermal insulation materials, both in the early and long-term post-intoxication period. 
 Material and methods. Static inhalation intoxication of rats with products of thermooxidative destruction of polyfoam and polyisocyanurate foam (at a concentration of 0,8HLC50) was simulated. The concentration of carboxyhemoglobin in the blood of rats, indicators of vital functions were determined immediately before and on days 1, 7 and 28 after exposure. To assess learning disabilities in rats, a conditioned reflex of active avoidance by swimming was developed. To assess spatial memory in rats, the method of developing and reproducing the conditioned reflex of searching for food was used.
 Results and discussion. The intoxication of rats with products of thermooxidative destruction of the studied materials of moderate severity was simulated. Violations of the functions of the respiratory and cardiovascular system of rats in the early (7 days) and long-term (28 days) post-intoxication period were not detected. In the long-term (28 days) post-intoxication period, an increase in the duration of the latent period of active avoidance by swimming of rats was determined (compared with the control), an increase in the number of spatial memory errors in rats and the time of testing (compared with the control) was revealed.
 Limitation of the study. Limitations are due to the methodology of the research being conducted. A quantitative analysis of only some gaseous products of thermal oxidative destruction was perfomed.
 Conclusion. It was found that intoxication of rats with products of thermooxidative destruction of foam rubber and foam polyiysocyanurate (at a concentration of 0,8HLC50) led to impaired learning and spatial memory of rats in the long-term post-intoxication period.

Effect of curing agents and hollow glass microspheres on the compression properties of syntactic foams

To investigate the compression properties and failure mechanisms of syntactic foams, two different resin matrices and three types of hollow glass microspheres (HGMs) were used to prepare syntactic foams with different properties. Results showed that the compression strength of syntactic foams increases with the increase in the compression strength of HGMs or resin matrix. Low-strength HGMs will be the first to break down as a source of cracks under stress. When the stress value exceeds the compression strength of the matrix, the matrix will deform and break, leading to the overall destruction of syntactic foam. High-strength HGMs not only act as a lightweight filler but also act as a reinforcing phase to improve the strength of the syntactic foam. The matrix located at the interface will experience initial cracking when subjected to stress, becoming the origin of subsequent cracks. Consequently, the weaker part between the HGMs and the matrix will be the initial point of failure, resulting in the formation of a crack source. The failure of the matrix will ultimately result in the complete destruction of the syntactic foam.

The results of studies of the influence of temperature and density on the stability of marshmallow

Relevance. The quality of products tends to be a core indicator of any enterprise activity defining its competitiveness within market conditions to a great extent. Production of confectionery creams avoiding usage of stabilizers, preservatives and trans fats is a promising direction being demanded by consumers. Stability of the whipped mass within production and storage processes depends on the dynamics of the confectionery foam destruction, which leads to degradation of whipped products form and volume. Stability and dimensional stability of foam systems become key indicators of food products quality reflecting their major structural and mechanical properties.Methods. This article studies dependence of the stability (incl. dimensional stability) of cream marshmallow on temperature and density. Through experimental path authors show influence of molasses temperature set in line with recipe on the whipped cream density.Results. Molasses temperature determines the temperature denaturation of egg whites, their bond and forms a stable structure. The study of cream marshmallow samples obtained from molasses with a density of 1.3 g/cm3, 0.9 g/cm3 and 0.7 g/cm3 established that lower density of molasses added in line with the recipe forms a stronger and more stable structure of cream marshmallow.

FORMATION AND STABILITY OF FOAMS IN WATER CONTAINING DIESEL FUEL IN THE PRESENCE OF HYDROPHOBIZED SILICA

The formation of foams in the presence of organic liquids and the study of their properties and stability is an important scientific and practical task. The purpose of this work is to study the properties of foams that are formed in water saturated with diesel fuel (DF) in the presence of hydrophobized silica particles. Two types of silica were used as the solid phase: Aerosil-380, Ludox HS-40 and hydrophobizer-hexane-1-amine (99%) with a density of 0.766 g/cm3.Water saturated with diesel fuel was used to produce the foam. To obtain it, 50 ml of distilled water was added to 50 ml of diesel fuel (DT), stirred for 3-5 min and left in a dividing funnel at a temperature of 25 °C. After 24 h, the water was separated. Foaming was investigated when mixing a certain volume (V2) of dissolved diesel fuel and a suspension of hydrophobized solid particles with volume V1. The maximum height of the foam layer (H), which is formed in an aqueous medium containing diesel fuel in the presence of hydrophobized silica, as well as the change in its stability with an increase in the degree of hydrophobization of silica and the concentration of organic liquid, was studied. It was found that resistant to destruction foam layers (L~ 2 cm) are formed from hydrophobized Ludox HS-40 sol with a mass content of 20% and water saturated with diesel fuel, taken in equal volume ratios. When hydrophobized Ludox HS-40 was added to the suspension, dissolved diesel fuel in a larger (2-4 times) volume formed unstable foams with a higher column height H = 9-11 cm. It is shown that the foaming in the hydrophobized aerosil – dissolved diesel fuel system was insignificant (L ≤ 3 cm). The destruction of foams is due to their diffusion enlargement. The formation of a stable foam emulsion obtained from a suspension of hydrophobized aerosil and diesel fuel is possible with a volume ratio of 3:1. For citation: Vilkova N.G., Mishina S.I., Shatina E.A. Formation and stability of foams in water containing diesel fuel in the presence of hydrophobized silica. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 6. P. 54-60. DOI: 10.6060/ivkkt.20236606.6778.

Experimental Studies of Efficient Wells Completion in Depleted Gas Condensate Fields by Using Foams

Abstract The reasons for decreasing the well operating parameters of depleted gas condensate fields have been analysed. A new approach has been proposed, which involves restoring the wells productivity by creating foam by means of a device developed for removing liquid from the well bottom. The expediency of using foam has been experimentally investigated for gas condensate wells to be completed and their productivity to be recovered. Techniques for removing liquid contaminants from wells have been developed, which involve injecting non-explosive gas mixtures and foams of various volumes into wells. Computational fluid dynamics modelling of the operation of the device for the wells completion with foam was carried out. The influence of the mass flow rate of an aqueous solution at the inlet to the device on the distribution of volume fraction of the gas and liquid phases, and the quality of the foam has been investigated. The understanding of the regularities of foam destruction processes by hydrocarbon condensate was obtained, and a device design was developed for the complete foam destruction.

Modeling foam propagation in pore network with designated pressure constraints

Foam has been used for decades in petroleum industry for enhanced oil recovery (EOR) due to its mobility adjustment ability. A variety of mechanistic models have been proposed to study foam flow in porous media from multiple scales. In these models, such as population balance models, some important parameters (e.g., foam generation/coalescence rate, flowing foam fraction) are treated empirically since they cannot be obtained from conventional lab experiments. To improve the accuracy and reliability of foam description in these foam-assisted processes, pore network model interwoven with invasion percolation with memory (IPM) method has become a powerful tool in studying foam flow characteristics in porous media, which can predict relative permeability and flowing gas fraction with fully consideration of pore-scale mechanisms of foam generation, destruction, and propagation. However, the assumption of exactly sufficient incremental pressure difference used in conventional IPM-based pore-scale foam modeling is rigorous, not only making it difficult to conduct relevant experimental validations, but also creating potential algorithmic conflicts when simulates displacements in weak foam regime or displacements incorporated with foam coalescence mechanisms. In this study, a novel mixed-sorting rule, which proceeds the displacement by describing the transition between immobile foam bank and mobilized foam flow quantitively, is incorporated into IPM-based foam propagation model. In this way, the immobile foam bank is identified based on effective lamellae generation rate, whereas the mobilized foam flow is distinguished by frontal displacing velocity, respectively. Results estimated with proposed method successfully capture key properties that define pore-scale foam behavior at excessive pressure constraints from formation of immobile foam bank, foam mobilizing pressure thresholds, and fractal dimension of displacement pattern, etc.

Bubble-growth regime for confined foams: Comparison between N2–CO2/foam and CO2/foam stabilized by silica nanoparticles

The use of foam technology in Pre-Salt reservoirs is a potential solution to control gas mobility in highly heterogeneous reservoirs. However, achieving stable CO2-foams under reservoir conditions can be challenging since high solubility in water of supercritical CO2 enhances coarsening and coalescence of bubbles. Coarsening is the evolution of foam structure with time due to gas diffusion between bubbles. In this phenomenon, gas normally diffuses from smaller to larger bubbles, which for confined foam is relevant because this ends up decreasing the number of bubbles in a determined area/volume of the pore space (foam texture). When foam texture coarsens, gas mobility control is impaired, and it can also affect foam rheology. Therefore, it is important to characterize bubble growth kinetics to compare strategies to reduce coarsening and investigate their impact on gas mobility reduction due to foam injection. In a previous work, we reported the use of nanoparticles and a CO2/N2 gas mixture as strategies for improving gas mobility of CO2-foams formed with a zwitterionic surfactant in a micromodel experiment. The present study focuses on quantitatively assessing the bubble growth regime related to coarsening for these two strategies. Indeed, bubble growth is a key parameter for population balance mathematical models that simulate CO2-foams in porous media. Image analysis was used to characterize the foam texture by calculating the bubble density and bubble size distribution of the foam confined in dead-end pores areas of the micromodel. Our results showed that, the number of trapped bubbles was twice as high for the foam formed with the gas mixture compared to those containing nanoparticles, and this higher bubble density was correlated with the higher pressure drop observed for this system, indicating lower gas mobility. The coarsening rates obtained by analyzing the change in trapped bubble area with time of CO2-foam containing nanoparticles (0.25 μm2 s−1) was in the same order of magnitude compared to that obtained by a CO2/N2 gas mixture-foam (0.44 μm2 s−1), under the same high-pressure high-temperature (HPHT) conditions. These results meant that both strategies were able to stabilize the weak foam formed between zwitterionic surfactant and CO2, and that the initial foam texture determined resistance to flow. The semi-automatic algorithm successfully identified the bubbles trapped within the system during the period of analysis, which allowed us not to add dyes that could change interfacial behavior at the water-gas interface. The novel results that evaluate the coarsening rate for CO2-foam under HPHT conditions can positively impact the estimation of foam destruction parameters for population balance models for more representative reservoir conditions of trapped gas. Our findings fill part of the gap in terms of evaluation of coarsening rate under more representative reservoir conditions, improving the understanding of kinetics of foam destruction. This information is relevant for establishing a correct range of the destruction term for populational balance models. Moreover, our results reveal that the type of strategy chosen to delay coarsening can significantly impact gas mobility reduction and that using nanoparticles impacted significantly interfacial properties of the formed foam.

Modeling of kinetic characteristics of alkaline-surfactant-polymer-strengthened foams decay under ultrasonic standing wave

Foaming issues are encountered at the stages in crude oil production, transportation, processing, especially in chemical flooding enhanced oil recovery (EOR) oilfields. These accumulated foams would cause a lot of trouble for downstream operation. The destruction of foams under ultrasonic has been increasingly paying attention in the background of green oilfield development. This study focuses on the decay kinetic characteristics of alkaline-surfactant-polymer-strengthened foams under the ultrasonic standing wave. The performance of the diverse foams was characterized. A decay kinetic model incorporating the energy correlation was developed and validated. The factors that affect the decay kinetic characteristics were discussed. The results indicated that the collapse rate and the collapse volume fraction decreased when the foam size decreased, the gas-liquid ratio decreased and the surface tension increased. Ultrasonic standing wave parameters have a significant impact on the decay behavior of the foam. Both the ultrasonic frequency and ultrasonic amplitude were increased by 50%, the collapse volume fraction of foams increased by about 1.25 times in the identical irradiation time. The relative deviation between the measured results and the model prediction was less than 10%. The potential collapse mechanism was also explained using the principle of energy correlation of foam surface. This study is not only beneficial to provide a robust and rigorous way to defoam of produced liquid in the alkaline/surfactant/polymer (ASP) flooding EOR process but also meaningful to well understand the decay process of oil-based foams.

Synergism in binary surfactant mixtures containing a pH-responsive surfactant towards enhanced foam stability in brine at high pressure and high temperature conditions

The use of liquid foams in enhanced oil recovery (EOR) applications requires the formation of stable foams under harsh reservoir conditions, such as a wide pH range, brines containing divalent cations, and high temperature and pressure. In this work, mixtures of the pH-responsive surfactant bis-(2-hydroxyethyl) cocoalkylamine (C12) with nonionic (tallow fatty amine, TFA20), zwitterionic (cocamidopropyl hydroxysultaine, CAHS) and anionic (sodium olefin sulfonate, AOS) surfactants were evaluated to obtain foams with improved stability under conditions relevant to CO2-based EOR. The presence of TFA20 in the foaming formulation increased the solubility of C12 at basic pH values, but impaired foam stability. In contrast, the surfactant mixtures containing CAHS exhibited a significant synergy regarding surface tension reduction and foam stabilization. The synergy was confirmed by the negative value of the interaction parameter, indicating strong attraction, likely electrostatic, between the surfactant molecules at the interface. This effect was evidenced in the decrease in the bubble growth rate obtained with the C12:CAHS (1:2) mixture, compared to the individual components, suggesting a reduction in Ostwald ripening and coalescence mechanisms of foam destruction due to higher packing density of surfactants in the interfacial film. The presence of the zwitterionic surfactant in the foaming mixture containing C12 allowed obtaining foams with improved stability at pH 4, under high pressure (100 bar) and high temperature (65 °C) conditions. The results obtained in this study showed the potential of using synergic mixtures to tailor the solubility and foaming properties of pH-responsive surfactants for enhanced performance in foam-based EOR methods.

Modeling and monitoring of foam propagation in highly permeable porous media under lateral water flow

Foam injection is a promising option for soil remediation applications. However, predicting how it will propagate in highly permeable aquifers under groundwater flow is challenging. Here, we have studied pressure and saturation variations during foam propagation. A 2D tank packed with 1 mm glass beads was used to study foam injection in highly permeable porous media under lateral flow. Specifically, we evaluated the efficiency of pressure and time-domain reflectometer (TDR) sensors to predict foam propagation using an imaging technique. A numerical model coupling two-phase flow and surfactant transport was developed to simulate the experimental results. This model takes into account the effect of non-Newtonian behavior of foam, surfactant concentration, and critical capillary pressure through the definition of the mobility reduction factor (MRF). The experimental results show that the foam injection pressure first increases with a logarithmic law and then stabilizes. This pressure stabilization can be related to the state of pseudo-equilibrium between foam generation and destruction. We observed an asymmetrical foam propagation due to water lateral flow. Comparisons of the liquid saturation fields calculated by analysis of TDR probes and estimated by imaging show that the TDR sensors monitor foam propagation well in saturated porous media. They can predict the shape of the injected foam. Contrary to pressure sensors, it is possible to capture weak foam behavior using TDR sensors. Finally, the numerical model we have developed correctly captures the shape of foam propagation and its ability to divert water flows. This model produces the propagation of the strong foam well and predicts the saturation and pressure fields with good precision.

Доминирующая роль самоэмульгирования в процессе контактного взаимодействия пены с углеводородами

Introduction. The results of a series of experiments on the interaction of fire extinguishing foam with various hydrocarbons are described, which make it possible to understand the processes that affect the extinguishing efficiency. Goals and objectives. The purpose of this work was to explain self-emulsification during mass transfer as a possible dominant factor in the process of contact destruction of fire-extinguishing foam by hydrocarbons. For this, the following tasks were set: - to experimentally establish the possibility of self-emulsification during mass transfer in contact of foaming agent solutions with hydrocarbons; - to show the relationship between the stability of the foam and the stability of the emulsion formed in the foam films; - to establish the effect of foam parameters (multiplicity) on the possibility of stabilization (or destruction) of foams under the action of the resulting emulsion. Research methods. The main research method in this work was to observe the stability of the foam on the surface of hydrocarbons at different temperatures. Results and discussion. The paper presents the results of experimental studies showing that the contact of solutions of the investigated foaming agents with hydrocarbons leads to the spontaneous appearance of an emulsion. In the case of using aromatic hydrocarbons, this process is more intensive than for saturated ones. For solutions of a foaming agent in the form of a thin film, the process of self-emulsification during mass transfer is significantly accelerated and can take place at room temperature. A stable emulsion, introduced into the foam, stabilizes it, and an unstable one destroys it. Low expansion foam is usually stabilized in contact with hydrocarbon. Medium expansion foam is destroyed even under the condition of thermodynamic stability of foam films. Conclusion. The experimental data obtained made it possible to propose a mechanism for the contact interaction of foam with a hydrocarbon, according to which a more stable foam on the surface of a hydrocarbon can be obtained by a foaming agent, which, in addition to foaming properties, is a good emulsifier. Keywords: fire extinguishing foam, hydrocarbon, oil product, contact destruction, self-emulsification during mass transfer.

Experimental study of foam propagation and stability in highly permeable porous media under lateral water flow: Diverting groundwater for application to soil remediation

Foam propagation and stability in highly permeable porous media, encountered in soil pollution applications, are still challenging. Here, we investigated the application of foam for blocking the aquifer to divert the flow from a contaminated zone and, therefore, ease the remediation treatments. The main aim was to better understand the critical parameters when the foam is injected into a highly permeable aquifer with high groundwater flow velocity (up to 10 m/day). A decimetric-scale 2D tank experimental setup filled with 1 mm glass beads was used. The front part of the 2D tank was made of transparent glass to photograph the foam flow using the light-reflected method. The water flow was generated horizontally through injection and pumping points on the sides of the tank. The pre-generated foam was injected at the bottom center of the tank. Water streamlines (using dye tracing) and water saturation were investigated using image interpretation. Results show that 100% of the water flow was diverted during the injection of the foam. Foam stability in porous media depends significantly on the horizontal water flow rate. Recirculating water containing the surfactant increases foam stability. The main mechanism of destruction was identified as the dilution of the surfactant in water. However, the head-loss measurements showed that despite foam destruction, the relative permeability of the water phase in the media remained quite low. Injection of foam increases the radius of gas propagation, thanks to foam's high viscosity, compared to a pure gas injection case. These results are new highlights on the efficiency of foam as a blocking agent, showing that it can also serve as a means for gas transport more efficiently in porous media, especially for soil remediation applications.

Increasing the stability of the fire extinguishing foam by replenishing the liquid phase during sprinkling

Introduction. The destruction of foam films occurs when they reach critical thickness and lose the liquid phase as a result of syneresis and evaporation, which are rather difficult to slow down. We have proposed a method for increasing the stability of the fire extinguishing foam by means of replenishing the liquid phase through sprinkling.Methods. Foam stability was measured by the time of destruction of 25 % of the initial foam volume. The concentration of the foaming agent in the sprinkled solution varied from 0.5 to 6 %. Carboxymethylcellulose sodium salt (Na CMC) was used as a stabilizing additive. Field studies were carried out by feeding foam and solution from two AT-3,2-40 (43253)001-MS tank cars.Results and discussion. It has been established that the foam stability is influenced by the sprinkling intensity and the foaming agent concentration. Foam sprinkling with the solutions having low concentration of thefoaming agent leads to the washout of surfactants from the films that reduces the foam stability. The sprinkling intensity reduction boosts the foam stability due to the replenishment of the moisture lost through evaporation. The foam stability was maximal in case of sprinkling with a 2 % solution of the foaming agent, while the sprinkling intensity had no influence. An increase in the concentration of the foaming agent in the sprinkled solution led to a decrease in the foam stability. It is found that a smaller amount of the foaming agent is consumed to maintain the amount of foam through sprinkling than to replenish the destroyed amount through additional foam generation. It is shown that various stabilizing additives can be added to the foam in the process of sprinkling. If Na CMC is added to the solution exposed to sprinkling, the time of foam destruction goes up 3–5 times even in case of a non-recurrent sprinkling session. Field tests have confirmed the feasibility of adding stabilizing additives to the foam by means of sprinkling.Conclusions. The results of the research have shown the feasibility of co-feeding the foam and surfactant solutions, containing various stabilizing additives, in order to extinguish fires and generate stable foams.

Metal ion-triggered Pickering emulsions and foams for efficient metal ion extraction

Emulsions and foams were constructed by using surfactant particles as stabilizers. Bis(2-ethylhexyl) phosphate, abbreviated as HDEHP, was used as both an oil in neutral form and an anionic surfactant in deprotonated form, DEHP-. In the system of HDEHP/H2O, upon adding NaOH, a portion of HDEHP was deprotonated to form DEHP- as stabilizers of O/W emulsions. After introducing some certain metal ions, the O/W emulsions were transformed to W/O Pickering emulsions due to the generation of insoluble particles by DEHP- and metal ions. In addition, DEHP- could also combine with some metal ions to produce particles absorbed at air/water interface, forming ultrastable foams. Accompanied with the formation of Pickering emulsions and foams, the extraction of metal ions from water could be realized with high removal efficiency. The extractant, HDEHP, could be effectively recycled through convenient demulsification of Pickering emulsions or destruction of foams. This work provides new ideas for the construction of particle-stabilized dispersion systems and proposes methods with potential applications in industrial wastewater treatments.

Physio-Chemical Analysis of Amide and Amine Poly(dimethylsiloxane)-Modified Defoamer for Efficient Oil-Water Separation.

The formation of foam due to the injection of surfactant foam in FAWAG causes significant problems in the oil well production and separation facilities. The excessive foam can lead to the reduction of the separator capacity as well as its efficiency. A defoamer is needed to break and destroy the foam in the separator. There are many commercially available defoamer agents in the market, but not all defoamers are suitable for every application. For this reason, four modified silicone-based defoamers were successfully synthesized and characterized based on the data obtained from the screening process using various commercial defoamers. The performance of modified defoamers was evaluated using TECLIS FoamScan that imitate real conditions of treatment. The results show that all four of the modified silicone-based defoamers, especially amide-terminated-modified defoamers (S2) showed excellent performance as a defoaming agent to mitigate foam in specific conditions. The best-case condition for the modified defoamer to perform was at a high temperature (60 °C), gas flow rate of 1.0 L/min, and low ration concentration of the surfactant to brine (30:70). The study on the bubble count and distribution using a KRÜSS Dynamic Foam Analyzer revealed that S2 excellently contributes to the formation of unstable foam that can fasten foam destruction in the foaming system.

Bench Tests and CFD Simulations of Liquid–Gas Phase Separation Modeling with Simultaneous Liquid Transport and Mechanical Foam Destruction

This paper presents simulation and bench test results for a special type of centrifugal pump that enables the transport of dispersive foaming liquids and simultaneous separation of the liquid phase. During the design phase, CFD (Computer Fluid Dynamics) simulations were performed using Ansys Fluent. The simulations covered changing the operating parameters of the pump (mass/volume flow rate), pressure analysis for the first impeller, and structural optimization of the pump components. In the second stage of the research, the pump and a measuring station were constructed to validate the results of the numerical simulations.