Surfactant Recovery Research Articles

Optimization of surfactant-enhanced injection parameters in Lamadian oilfield

Abstract Optimizing injection fluid parameters is critical for the development of unconventional reservoirs since it is the principal strategy for increasing surfactant recovery in low-permeability reservoirs. This study used numerical simulation methods to objectively investigate the influencing variables under various injected surfactant values, based on the reservoir features of the target block. Additionally, it established the yield relationship corresponding to changes in reservoir pressure. Consequently, a correlation was established between the amount of injection, concentration of surfactant, distance between wells, extreme difference in permeability, and increase in pressure. This led to the determination of appropriate injection parameters for enhancing surfactant permeability. The study’s findings have practical implications for determining the appropriate injection scale of a reservoir surfactant system.

Chemical enhanced oil recovery under Harsh conditions: Investigation of rock permeability and insights from NMR measurements

Injecting surfactant into a hydrocarbon reservoir stands out as a highly effective method for EOR due to its ability to reduce water/oil IFT and alter rock wettability in certain cases. However, the efficiency of this process is compromised in heterogeneous reservoirs, especially carbonates, characterized by significant permeability variations. This study presents findings from three core flooding experiments on heterogeneous carbonate core samples with different permeabilities. The experiments were conducted under representative reservoir conditions of 100 °C, pressures higher than 3000 psi, and seawater salinities and formation water of 57,745 ppm and 213,768 ppm, respectively. In each experiment, seawater was continuously injected followed by continuously injecting a 2500-ppm solution of in-house synthesized Gemini surfactant. Results revealed that the recovery factor was highest in low-permeability rocks and lowest in high-permeability rocks for both seawater and surfactant floods. Surfactant floods yielded additional recoveries of 31%, 23%, and 19% for low, medium, and high-permeability samples, respectively. Nuclear magnetic resonance (NMR) analysis on short analogous core plugs at different flooding stages confirmed these results. Effluent analysis on the produced aqueous phase indicated that dynamic retention was highest (0.467 mg/gm-rock) in the lowest permeability and lowest (0.146 mg/gm-rock) in the highest permeability rock. NMR analysis suggested that the surfactant's recovery performance and dynamic retention were influenced by the larger surface area of low-permeability rocks, facilitating increased contact with the surfactant. Utilizing NMR monitoring in this work enhances EOR insights through integrated studies and coreflooding experiments and establishes a novel framework for complex reservoir conditions.

Selective removal of chlorinated organic compounds from soil flushing emulsions: Adsorbent regeneration with thermal-activated persulfate and surfactant recovery

Hydrophobic organic compounds (HOCs) released into the environment can form nonaqueous phase liquids, contaminating soil and groundwater. Surfactant-enhanced aquifer remediation, followed by extracting a highly contaminated emulsion comprising surfactants and contaminants, is a promising technology for remediating polluted sites. However, the sustainable treatment of the emulsion is crucial. This study presents a two-step method for treating emulsions containing HOCs and surfactants. Firstly, pollutants are selectively adsorbed onto granular activated carbon (GAC) in a column. Secondly, spent GAC is regenerated by oxidizing adsorbed pollutants using persulfate activated at 60 °C. The emulsion was obtained from surfactant-enhanced aquifer remediation at a polluted site with lindane production waste, consisting of E-Mulse® 3 surfactant (12 g L−1) and 28 chlorinated organic compounds (COCs) at a concentration of 9.1 gCOCs L−1. Selective adsorption of COCs was observed since the adsorption kinetic constant was much higher than the E3, being 31.60 and 1.76gGAC−W·mgj−1·h−1 respectively. The adsorption-regeneration cycle was repeated three times. It was found that the GAC adsorbed 90 mgCOCs·gGAC−1 were constant after four cycles (70 % of the COCs adsorption capacity in the first step). The surfactant adsorption decreased by approximately 80 % from 108 to 26 mgE3 gGAC−1 after the third cycle, enabling surfactant recovery from the emulsion. In addition, the remaining amount of persulfate increased from 24 to 39 %, reducing oxidant consumption. Finally, the water effluent obtained after regeneration showed reduced toxicity due to the generation of nontoxic by-products, such as short-chain acids and sulphates. The results obtained proved the GAC-based adsorption/regeneration process was effective and stable over multiple cycles.

Transport of convected soluble surfactants on and within the foam film in the context of a foam fractionation process

This study models convective transport of soluble surfactant in a foam fractionation system with reflux. Owing to reflux, initial surfactant concentration in films is lower than in Plateau borders. Marangoni flows and film drainage flows arise convecting surfactant both on the film surface and in the bulk. An interface is set up within the film bulk called a separatrix: this divides two regions of uniform surfactant concentration, one with concentration equal to that of the initial film and one with concentration equal to that in the Plateau border. The evolution of the separatrix is tracked to determine surfactant recovery and enrichment for the film. Surfactant lean films benefit most from reflux. However for films that are initially comparatively surfactant rich, recovery might actually decrease at long times owing to film drainage. Nonetheless surfactant lean films and those containing surfactant with only moderate solubility benefit from reflux even despite film drainage.

Recyclable dynamic imine‐based nonionic surfactants and potential use in postprocessing of eluted emulsions

AbstractRecovery of surfactants and retrieval of hydrocarbons from eluted emulsions in surfactant‐enhanced washing are essential to save useful resources and avoid secondary contamination. A novel nonionic surfactant of C6‐DIB‐PEG has been constructed by using a dynamic imine bond (DIB) as the linker between hexyl amine (C6‐NH2) and an aromatic aldehyde modified polyethylene glycol (PEG‐CHO). The results presented in this study reveal that an oil‐in‐water emulsion of tetradecane‐H2O stabilized by C6‐DIB‐PEG is pH‐switched. Upon reaction with HCl, C6‐DIB‐PEG readily converts to its inactive forms C6‐NH3+Cl− and PEG‐CHO when the pH is changed from 12.0 to 4.0, resulting in a complete tetradecane‐water two‐phase separation. Both C6‐NH3+Cl− and PEG‐CHO are insoluble in tetradecane but soluble in water, allowing subsequent retrieval of nearly surfactant‐free tetradecane. Recovery of C6‐DIB‐PEG was enabled by treating aqueous solutions of C6‐NH3+Cl− and PEG‐CHO with NaOH after pH was increased from 4.0 to 12.0. The pH‐switched C6‐DIB‐PEG renders a potential use for oil retrieval and surfactant recovery in the postprocessing of eluted emulsions, as demonstrated by the C6‐DIB‐PEG‐enhanced washing of tetradecane‐contaminated sand. Around 95.2% of the tetradecane and about 99.7% of the C6‐DIB‐PEG were retrieved and recycled over 10 cycles of washing. In addition, the total organic carbon (TOC) of the residual wastewater was remarkably reduced from around 7065.3 to ~54.1 mg L−1 after NaHSO3 treatment followed by ion‐exchange resin and active carbon adsorption.

Insight into the application of magnetic molecularly imprinted polymers in soil-washing effluent: Selective removal of 4,4′-dibromodiphenyl ether, high adaptivity of material and efficient recovery of eluent

Soil washing techniques can effectively remove soil polybrominated diphenyl ethers (PBDEs), but further removal of PBDEs from washing effluent is disrupted by environmental factors and coexisting organic matter. Hence, this work prepared novel magnetic molecularly imprinted polymers (MMIPs) to selectively remove PBDEs in soil washing effluent and recycling surfactants, with Fe3O4 nanoparticles as the magnetic core, methacrylic acid (MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. Later, the prepared MMIPs were applied to adsorb 4,4′-dibromodiphenyl ether (BDE-15) in Triton X-100 soil-washing effluent and characterized by scanning electron microscopy (SEM), infrared spectrometry (FT-IR), nitrogen adsorption and desorption experiments. According to our observations, BDE-15 equilibrium adsorptions on dummy-template magnetic molecularly imprinted adsorbent (D-MMIP, 4-bromo-4′-hydroxyl biphenyl as template) and part-template magnetic molecularly imprinted adsorbent (P-MMIP, toluene as template) were reached within 40 min, and their equilibrium adsorption capacities were 164.54 μmol/g and 145.55 μmol/g, respectively, with imprinted factor α > 2.03, selectivity factor β > 2.14, and selectivity S > 18.05. MMIPs exhibited good adaptability to pH, temperature, and cosolvent. Our Triton X-100 recovery rate reached as high as 99.9%, and MMIPs maintained a more than 95% adsorption capacity after being recycled five times. Our results offer a novel approach to selectively remove PBDEs in soil-washing effluent, with efficient recovery of surfactants and adsorbents in soil-washing effluent.

Ecofriendly Viscoelastic Solutions Formed from a Recyclable Rosin-Based Amine Oxide Surfactant.

Innovations in molecular structures formed using bioresources are efficient means to prepare surfactant aggregates with unique properties. Here, a rosin-based amine oxide surfactant (R-11-3-AO) containing large hydrophobic groups was synthesized from rosin derivatives, namely, dehydroabietic acid and long-chain amino acids. Cryo-transmission electron microscopy showed that R-11-3-AO molecules formed extremely long wormlike micelles with a cross-sectional diameter of 4-5 nm at a concentration of approximately 7 mmol·L-1. A gel-like system was obtained at approximately 30 mmol·L-1 due to the dense entanglement of the wormlike micelles. The solutions also exhibited unique shear thickening behavior at a shear rate of approximately 10 s-1 even at high concentrations. The large hydrophobic group contained in R-11-3-AO is the origin of the strong van der Waals interactions between the surfactant molecules, resulting in the rapid growth of wormlike micelles. This rosin-based surfactant is the first recoverable amine oxide surfactant from solutions through the salting-out effect with high recovery rates. This work demonstrates the unique capabilities of rosin-based surfactants for forming wormlike micelles and provides opportunities for the development of surfactant recovery technologies.

Surfactant recovery and efficient separation of PAHs from surfactant solutions by low-cost waste activated sludge and two-stage design optimization.

The treatment and surfactant recovery of soil washing/flushing effluent containing high levels of surfactants and organic pollutants are critical for the surfactant-assisted remediation of soils and waste management due to their complexity and high-potential risks. Combination of waste activated sludge material (WASM) and a kinetic-based two-stage system design was introduced in this study as a novel strategy for the separation of phenanthrene and pyrene from Tween 80 solutions. The results showed that WASM can effectively sorb phenanthrene and pyrene with high affinities (Kd) of 2325.5 L·kg-1 and 9911.2 L·kg-1, respectively. This allowed a high-level recovery of Tween 80 of 90.47 ± 1.86%, with selectivity of up to 69.7. In addition, a two-stage design was constructed, and the results showed an improved reaction time (approximately 5% of equilibrium time in conventional single-stage process) and increased the separation levels of phenanthrene or pyrene from Tween 80 solutions. For instance, the minimal total operating time for the sorption of 99% pyrene from 1.0g·L-1 Tween 80 was only 23.0min in the two-stage process compared to that of 480min with a 71.9% removal level in the single-stage system. Results indicated that the combination of low-cost waste WASH and two-stage design was a high-efficiency and time-saving way to recover surfactants from soil washing effluents.

Novel Amino Acid Derivatives for Efficient Methane Solidification Storage via Clathrate Hydrates without Foam Formation

Although anionic surfactants are considered the most efficient kinetic gas hydrate promoters for gas storage applications, gas recovery and reuse of surfactants are difficult due to high foam formation during hydrate melting. Additionally, most anionic surfactants are toxic, which has an intense environmental effect. In this study, novel amino acid derivatives (ACDs) were developed as the first class of superior promoters compared to surfactants without foaming during the formation and recovery of gas hydrates. The results of high-pressure autoclave experiments indicated that all ACDs significantly enhanced the kinetics of methane hydrate formation at 500 ppm. ACD5 derived from leucine showed the best promotion effect in distilled water by providing a total mole consumption of 436.1 mmol. ACD5 increased the degree of water-to-hydrate conversion from 39.6% in pure water to 94.3%, which was higher than in sodium dodecyl sulfate (SDS) solution (87.8%). Moreover, differential scanning calorimetry experiments demonstrated that ACDs could form methane hydrates at relatively lower temperatures than pure water. They increased the onset temperature of methane hydrate formation from −15 °C in pure water to −12 °C at 500 ppm. A higher promotion activity than SDS was also observed for ACDs in salt water, suggesting that seawater can be used to produce methane hydrate instead of pure water to reduce gas storage costs. Besides, visual observations revealed that no foam was formed during melting hydrates and releasing methane in the presence of ACDs. These findings show that a slight modification of amino acids makes them efficient candidates for improving gas hydrate formation for seawater desalination and gas storage applications.

Precipitation-Dissolution switchable surfactants with the potential of simultaneous retrieving of surfactants and hydrophobic organic contaminants from emulsified and micellar eluents

Simultaneous recovery of surfactants and retrieval of hydrophobic organic contaminants (HOC) from the eluent in surfactant-enhanced washing is essential for saving useful resources and avoiding secondary contamination. A pH-triggered precipitation-dissolution switchable surfactant, sodium 3-laurylaminopropanesulphonic acid (LMPS), for both emulsified and micellar eluents was reported. After tuning the pH from 12.5 to 7.5, the water-soluble LMPS is converted to its oil–water insoluble inner salt LMP; then LMP is converted back to LMPS by varying pH to 12.5, by which the LMPS-based micelles and emulsions are of reversibly switchable under pH stimuli. The removal ratio of tetradecane (15 g/30 g sand) and phenanthrene (Phe, 3.5 mg/5g sand) is no less than 99 % by washing with 150 g LMPS solution (1.0 × 10−2 mol/L) and 100 g LMPS solution (0.5 wt%), respectively. The retrieval ratio of tetradecane from the emulsified eluents was around 94 % and without obvious adverse effects over 5 cycles. The retrieval ratio of Phe from the micellar eluents via a combination of co-precipitation and Soxhelt extraction was around 98 %, which can be further simplified and increased to ∼100 % by spiking the micellar eluents with a small amount of tetradecane (1 g /100 g eluent). The recovery ratio of LMPS from micellar eluents was approximately 96 %, and in the case of emulsified eluents it remained around 99 % after 5 cycles. After a simple and conventional treatment with anion-exchange resin and active carbon (0.25 g/100 g waste water), the chemical oxygen demand (COD) of the waste water was remarkably reduced from 500 to 1700 mg O2 L−1 to less than 30 mg O2 L−1.

Potential for selective oxidation of aniline in soil washing effluent by active chlorine and testing its practicality

Recovery of surfactants in the soil washing effluent (SWE) can significantly reduce the cost of the soil washing (SW) technology. This paper consists of two parts experiments. The first part constructed a selective oxidation system of active chlorine by electrochemical technology to treat SWE. Three factors, current density, NaCl concentration and TW 80 to aniline concentration ratio (T/A), were set up for a total of nine sets of experiments after orthogonal design. The results of ANOVA analysis and visual analysis showed that the NaCl concentration greatly affected the aniline removal efficiency (ARE) and the TW 80 retention efficiency (TW 80 RE), and the effects were in opposite directions. The biotoxicity of the SWE decreased as the experiment progressed, and at the end of the experiment, 30%–45% of TW 80 was still present in each set. And the oxidation group quenching experiments determined that the degradation of aniline was mainly contributed by active chlorine. Because active chlorine slowed the loss rate of TW 80, the electrochemical treatment of SWE + soil in-situ sequential batch recirculation washing method was designed, and 50% of aniline in the soil was washed out after 125h. At the end of the experiment, the less biotoxic SWE was collected where no aniline and TW 80 were present, and only small organic acids were present after the GC-MS test. The method has a great potential to be applied as it shows good results in the treatment of soil pollution incidents.

Separate Reclamation of Oil and Surfactant from Oil-in-Water Emulsion with a CO2-Responsive Material.

Oil-in-water (O/W) emulsion is one type of oily wastewater produced by many industries. The treatment of and resource recovery from O/W emulsions are very challenging. Unlike bulk or floating oil, which can be successfully abstracted from wastewater by hydrophobic/oleophilic materials, the abstraction of emulsified oil is not easy because of its highly hydrophilic surface composed of dense surfactants. Separate reclamation of miscible oil and surfactant through a green approach is even more difficult. Here, we report that a CO2-responsive material can abstract emulsified oil and demulsify the oil droplets. Moreover, it can release the abstracted oil and surfactant separately. This material exhibited a very high adsorption capacity for emulsified oil (14 g g-1). Upon switching the surface wettability of the material under CO2 or synthetic flue gas sparging, coalesced oil was reclaimed while the surfactant was retained inside the pores. The hydrophobic character of the material was retrieved when CO2 was purged with nitrogen sparging or air heating. Then, the surfactant was reclaimed by elution with diluted alkali/ethanol. Oil and surfactant were thus separately reclaimed from the O/W emulsion. High rates of oil removal, oil recovery, and surfactant recovery were maintained during repeated adsorption/desorption operations. This work provides a potentially sustainable and green way for O/W emulsion treatment and resource recovery.

Non-Ionic Surfactant Recovery in Surfactant Enhancement Aquifer Remediation Effluent with Chlorobenzenes by Semivolatile Chlorinated Organic Compounds Volatilization.

Surfactant enhanced aquifer remediation is a common treatment to remediate polluted sites with the inconvenience that the effluent generated must be treated. In this work, a complex mixture of chlorobenzene and dichlorobenzenes in a non-ionic surfactant emulsion has been carried out by volatilization. Since this techhnique is strongly affected by the presence of the surfactant, modifying the vapour pressure, and activity coefficient, , a correlation between and surfactant concentration and temperature was proposed for each compound, employing the Surface Response Methodology (RSM). Volatilization experiments were carried out at different temperatures and gas flow rates. A good agreement between experimental and predicted remaining SVCOCs during the air stripping process was obtained, validating the thermodynamic parameters obtained with RSM. Regarding the results of volatilization, at 60 °C 80% of SVCOCs were removed after 6 h, and the surfactant capacity was almost completely recovered so the solution can be recycled in soil flushing.

Remediation and detoxification of oil contaminated marine intertidal sites through lipopeptide assisted washing strategy: An experimental and kinetic validation approach

This paper presents a tightly coupled experimental and kinetic approach for efficient remediation of oil spill from contaminated marine intertidal zone surface through a methodical strategy that deals with biosurfactant mediated washing strategy. The study deals with production, optimization and characterization of lipopeptide biosurfactant from Bacillus subtilis T1 and its application in remediation of oil contaminants from mimic model system of various marine intertidal zone i.e. woodland-Group1, saltmarsh-Group2, mangrove-Group3 and mudflats-Group4. Results demonstrates enhanced washing performance with oil desorption rate of 35 % in Group 4, 17.22 %, 15.6 % and 11 % in Group 3, 2 and 1 along with bio surfactant recovery rate of 41 %, 48.7 %, 51.71 % and 50.3 % respectively. Further, the washing strategy was efficient in soil detoxification with highest rate in Group 4. The kinetic validation depicts good match among experimental data and Lagergren pseudo second order data.

Factors influencing oil recovery by surfactant–polymer flooding in conglomerate reservoirs and its quantitative calculation method

This study aims to clarify the factors influencing oil recovery of surfactant–polymer (SP) flooding and to establish a quantitative calculation model of oil recovery during different displacement stages from water flooding to SP flooding. The conglomerate reservoir of the Badaowan Formation in the seventh block of the Karamay Oilfield is selected as the research object to reveal the start-up mechanism of residual oil and determine the controlling factors of oil recovery through SP flooding experiments of natural cores and microetching models. The experimental results are used to identify four types of residual oil after water flooding in this conglomerate reservoir with a complex pore structure: oil droplets retained in pore throats by capillary forces, oil cluster trapped at the junction of pores and throats, oil film on the rock surface, isolated oil in dead-ends of flow channel. For the four types of residual oil identified, the SP solution can enhance oil recovery by enlarging the sweep volume and improving the oil displacement efficiency. First, the viscosity-increasing effect of the polymer can effectively reduce the permeability of the displacement liquid phase, change the oil–water mobility ratio, and increase the water absorption. Furthermore, the stronger the shear drag force of the SP solution, the more the crude oil in a porous medium is displaced. Second, the surfactant can change the rock wettability and reduce the absorption capacity of residual oil by lowering interfacial tension. At the same time, the emulsification further increases the viscosity of the SP solution, and the residual oil is recovered effectively under the combined effect of the above two factors. For the four start-up mechanisms of residual oil identified after water flooding, enlarging the sweep volume and improving the oil displacement efficiency are interdependent, but their contribution to enhanced oil recovery are different. The SP flooding system primarily enlarges the sweep volume by increasing viscosity of solution to start two kinds of residual oil such as oil droplet retained in pore throats and isolated oil in dead-ends of flow channel, and primarily improves the oil displacement efficiency by lowing interfacial tension of oil phase to start two kinds of residual oil such as oil cluster trapped at the junction of pores and oil film on the rock surface. On this basis, the experimental results of the oil displacement from seven natural cores show that the pore structure of the reservoir is the main factor influencing water flooding recovery, while the physical properties and original oil saturation have relatively little influence. The main factor influencing SP flooding recovery is the physical and chemical properties of the solution itself, which primarily control the interfacial tension and solution viscosity in the reservoir. The residual oil saturation after water flooding is the material basis of SP flooding, and it is the second-most dominant factor controlling oil recovery. Combined with the analysis results of the influencing factors and reservoir parameters, the water flooding recovery index and SP flooding recovery index are defined to further establish quantitative calculation models of oil recovery under different displacement modes. The average relative errors of the two models are 4.4% and 2.5%, respectively; thus, they can accurately predict the oil recovery of different displacement stages and the ultimate reservoir oil recovery.

Removal and Recovery of an Anionic Surfactant in the Presence of Alcohol by Foam Fractionation

Removal and Recovery of an Anionic Surfactant in the Presence of Alcohol by Foam Fractionation

Recoverable Thermo-Responsive Polymeric Surfactants for the Synthesis of Bulk Plastics from Latexes

Free-radical emulsion polymerization (eFRP) is widely adopted in industries due to the great advantages that this technique offers in terms of a high polymerization rate, good heat management, and conduction in a non-toxic solvent like water. On the other hand, eFRP requires surfactants to stabilize the produced polymer nanoparticles (NPs). At the same time, the recovery of a bulk material from a NP suspension needs the addition of salts or alkali for the destabilization of the emulsion and the precipitation of the polymer. These can contaminate the final product and affect its properties. For this reason, alternative strategies able to coagulate the NP latex avoiding the addition of exogenous compounds are needed. In this work, we synthesized thermo-responsive polymeric surfactants that are able to promote the NP formation during the eFRP and to allow the recovery of the bulk polymer by simply increasing the environment temperature. Surfactants with a tunable hydrophilic–lipophilic balance were produced through reversible-addition fragmentation chain transfer (RAFT) emulsion polymerization by chain-extending a polyethylene glycol-based macromolecular chain transfer agent with butyl methacrylate, in order to obtain a series of block copolymers with high blocking efficiency, controlled molecular weight distribution, and well-defined thermo-responsive behavior. Then, the RAFT agent was removed to avoid the further extension of the block copolymers, and the surfactants were tested in the eFRP of different monomers (i.e., butyl methacrylate, methyl methacrylate, and styrene) to produce stable NP latexes. Finally, the possibility of triggering the NP aggregation and of guaranteeing the recovery of both surfactants and bulk material by simply changing the temperature of the system was assessed.

Recovery of an anionic surfactant in the presence of benzene, toluene, and hexane by foam fractionation

Recovery of an anionic surfactant in the presence of benzene, toluene, and hexane by foam fractionation

Transport of an Eco-friendly L70-c Bio-based Sucrose Ester Surfactant: Implication for Soil Remediation Purposes

Due to their biodegradability and low toxicity bio-based surfactants are very promising for use in remediation technologies, particularly for hydrocarbon contaminated soils. To enhance the application of surfactant-based technologies for remediation of organic contaminated sites, it is important to have a better understanding of the surfactant transport and retention mechanisms involved in this process, as they will impact the remediation efficiency. In this work, transport and retention mechanisms of an industrial bio-based nonionic sucrose ester surfactant were investigated through batch and column experiments, carried out on sandy porous media under saturated steady state flow conditions. Column transport experiments were conducted at surfactant concentrations ranged from 1 to 10 CMC (critical micellar concentration), for two distinct Darcy flow rates (0.35 and 0.70 cm.min-1). Surfactant transport and retention parameters were estimated by fitting a convection-diffusion transport model (implemented on HYDRUS-1D code) to the observed transport breakthrough curves, in order to provide an adequate description and understanding of the mechanisms involved in the transport and adsorption of these compounds through porous media. The results obtained from column experiments performed under high flow rate combined with high surfactant concentration provided the best conditions for high surfactant recovery in the effluent and low surfactant adsorption rate onto the sand. Numerical HYDRUS-1D simulations permitted to quantify surfactant transport behavior and provided attachment coefficients several order of magnitude greater than detachment coefficients, indicating that surfactant retention was an irreversible process.

Motor oil removal from water by continuous froth flotation: The influence of surfactant structure on interfacial adsorption and foam properties

The influence of the chemical structure of three surfactants, anionic extended surfactant Alfoterra® C145–8PO (ALF), anionic methyl ester sulfonate (MES), and cationic cetyltrimethyl ammonium bromide (CTAB), on the adsorption and foam characteristics relating to effectiveness at reduction of motor oil in a continuous froth flotation system. All surfactants were chosen based on having the similar number of carbon atoms in alkyl chain. So the effects of the different head group and the existence of a polypropylene oxide in the ALF’s structure on the surface activity and motor oil removal could be elaborated. The results demonstrated that CTAB, having strongest positively charged head group with the shortest tail length, provided the highest diffusivity, foamability, and foam stability, leading to the highest enrichment ratios of motor oil and surfactant. Conversely, ALF, having the largest molecular size and the longest tail length, gave the lowest diffusivity and foam properties. Hence, it exhibited the highest motor oil removal and surfactant recovery with the lowest enrichment ratios of both motor oil and ALF. The added packing media with 50% packing volume augmented the residence time of the rising air bubbles, enhancing the motor oil removal by about 16%, 15%, and 24% for the ALF, MES, and CTAB, respectively.