Surfactant Volume Research Articles

Techno-economic assessment of surfactant Huff-n-Puff EOR in shale plays via multi-objective optimization

Surfactant Huff-n-Puff (HnP) has proven effective for enhanced oil recovery (EOR) in unconventional petroleum reservoirs. Due to the high cost of surfactant injectants, a comprehensive techno-economic analysis is crucial for optimizing development strategies. This study focuses on the Jimusar J305 shale oil reservoir, employing a Pareto-optimal multi-objective optimization (MOO) model to identify the best injection-production strategies for surfactant HnP. Using crude oil recovery and economic performance as objectives, the model combines numerical simulations with the multi-objective particle swarm optimization (MOPSO) algorithm. A decision-making protocol based on Pareto solutions is proposed to balance objectives, alongside an EOR mechanism analysis. Results show the net present value (NPV) improved from −2.98 million to +3.48 million USD without reducing oil recovery, indicating that different surfactant HnP strategies can achieve similar recovery outcomes but vary significantly in profitability. Optimal project design involves adjusting surfactant volume to reverse rock wettability and balancing injection rates and concentrations to enhance production while controlling costs.

Nanostructured lipid carrier formulation for delivering poorly water-soluble ITF3756 HDAC inhibitor

Histone deacetylases (HDACs) are enzymes that play crucial roles in cellular processes by hydrolyzing acetyl-L-lysine side chains in core histones, thereby regulating gene expression and maintaining homeostasis. Histone deacetylase inhibitors (HDACi) have emerged as promising agents, particularly in cancer treatment, due to their ability to induce cytotoxic and pro-apoptotic effects. Selective HDAC6 inhibitors, such as ITF3756, have shown low off-target toxicity and promising pharmacological activities, but their poor water solubility limits their application in nanoparticulate drug delivery systems. Here, we optimized a nanostructured lipid carrier (NLC) formulation for delivering ITF3756 using the design of experiments (DOE) and response surface methodology (RSM). An interaction between the factor surfactant and formulation volume was observed, thus demonstrating that the surfactant concentration impacts the NLC size. It can be speculated that the higher the amount of the drug in the formulation, the lower the polydispersion index (PDI), thus resulting in more stable nanostructures. The optimized ITF3756-NLC demonstrated a size of 51.1 ± 0.3 nm, 8.85 ± 4.71 mV charge, and high entrapment efficiency (EE%), maintaining stability for 60 days. Moreover, ITF3756-NLC enhanced α-tubulin acetylation in melanoma, lung, and brain cancer cell lines, indicating retained or improved bioactivity. The ITF3756-NLC formulation offers a viable approach for enhancing the bioavailability and therapeutic efficacy of HDAC6 inhibitors, demonstrating potential for clinical applications in cancer immunotherapy.

Investigating the Feasibility of EOR While Preloading Parent Wells to Mitigate Fracture Hits: An Experimental and Modeling Study

Summary During a fracturing operation in an infill (child) well, pressure and fluid communication between this well and a nearby parent well, known as fracture hits (FHs), can impair the production performance of both wells. A cost-effective strategy to mitigate the FH is to preload the parent well with water during the fracturing of the child well. It has been hypothesized that the production performance of the parent well can be enhanced by the preloading process if proper additives are used in the injected water. We develop a laboratory protocol to physically simulate primary production and surfactant preloading stages using Montney core and fluid samples under reservoir conditions. We investigate the role of wettability alteration, interfacial tension (IFT) reduction, and surfactant’s chemical stability on the performance of enhanced oil recovery (EOR) during the preloading process. An analytical model is developed to predict the volume of leaked-off surfactant and recovered oil using measured pressure-decline data from the preloading stage. This study only focuses on the interactions of preloading fluid with the parent well’s matrix and does not consider the child-parent well interference. Our results demonstrate that 31.8% of the oil is recovered during primary production from large inorganic pores under solution-gas drive mechanism. Under countercurrent imbibition, a nonionic surfactant leaks off into the smaller organic and inorganic pores and recovers an additional 11.8% oil from a depleted core during preloading. The analytical model estimates oil recovery factors close to the experimental data determined by material balance. Core visualizations demonstrate a population of small oil droplets on the rock surface under reservoir conditions. While IFT is reduced to nearly the same extent by either surfactant, only the wettability-altering surfactant yields incremental oil recovery. Zeta-potential measurements indicate that while neither surfactant alters the rock-water surface charge, the wettability alteration is achieved by modifying the oil-water surface charge even at concentrations above the critical micelle concentration (CMC). Based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the repulsive electrostatic double-layer (EDL) forces are intensified with an increase in surfactant concentration, resulting in enhanced stability of the water film on the rock surface and increased hydrophilicity. Under elevated temperatures, we observe two phenomena, which can adversely affect the performance of a nonionic surfactant: (a) agglomeration of surfactant particles due to reduced solubility in water, reducing pore accessibility, and (b) chemical decomposition of the surfactant, affecting its ability for IFT reduction and wettability alteration.

Rapid preconcentration and determination of Co (II) ions in aqueous medium using ultrasound assisted cloud point extraction method

A flame atomic absorption spectrophotometric technique was studied for the preconcentration and determination of of Co2+ ions in trace amounts after ultrasound enhanced enrichment of its 1-(2-pyridylazo)-2-naphthol (PAN) complexes by cloud point extraction. The Co2+ ions were firstly complexed with PAN molecules at pH 4 and the complex transferred to a surfactant (Tergitol NP-7) rich phase with a very small volume under ultrasound waves. The surfactant rich phase was separated and dissolved by 1 mL, 1.0 M HNO3 in ethanol prior to determination of Co2+ concentration by flame atomic absorption spectrophotometry. The optimization steps of ultrasound interaction time, solution pH and surfactant volumes were achieved by response surface methodology (RSM) which is a combination of statistical approaches. Sample volume, PAN concentration and and possible interfering ions were optimized conventionally. The Co2+ ions were extracted only in 150 s at pH 4 quantitatively under optimum conditions (˃95%). The accuracy and validity of developed UA-CPE was granted by employing a certified reference material wastewater UME CRM 1204. The technique was applied to wastewater and natural water with satisfactory results.

Determination of Zinc and Magnesium in Food Samples via Cloud Point Extraction using Brilliant Green as a Reagent

In this article, we present a sensitive and efficient method for the separation and determination of Zinc (II) and Magnesium (II) ions using a combination of liquid ion exchange and cloud point extraction (CPE). The process includes converting these ions into metal ion complexes by using EDTA at pH 10. These complexes are then bound electrostatically with Brilliant Green (BG) to form ion pair association complexes, which are subsequently transferred into a cloud point layer. The study involved optimizing the extraction conditions, including the EDTA concentration, temperature, heating duration, and surfactant volume. The concentration of EDTA for achieving higher extraction efficiency is 1×10-4 M in the presence of 100 μg of Zn(II) and Mg(II) per 10 mL of aqueous solution using 1×10-4 M of BG. The solutions should be heated at 85°C for Zn(II) and 80°C for Mg(II) for 20 minutes. The optimal volume of surfactants is 0.5 mL of Triton X-100 for Zn(II) and 0.6 mL for Mg(II). The study also includes an analysis of the impact of electrolytes and interferences and the spectrophotometric identification of Zn(II) and Mg(II) in various samples.

The Characteristic Curvature (Cc) of Ionic Surfactants Assessed via Small-Angle X-ray Scattering.

The characteristic curvature (Cc), within the hydrophilic-lipophilic difference + net (Hn) - average (Ha) curvature (HLD-NAC) framework, is the dimensionless net curvature, -Hn·L (L is the surfactant's tail length parameter), that a surfactant acquires at the characteristic condition (T = 25 °C, no added cosurfactants, oil with an equivalent alkane carbon number (EACN) of zero and for ionic surfactants, a total salinity (S) of 1 g NaCl/100 mL). A recent article demonstrated the validity of the Cc concept, where Hn was assessed via oil and water solubilization radii. Here, we assess Hn from the characteristic length (ξ) obtained from the analysis of SAXS profiles of microemulsions produced at semicharacteristic conditions (characteristic condition but varying S). The predicted relationship, -L·Hn,semicharacteristic = Ccbi + bi·ln(S), was confirmed with the five ionic surfactants explored. The SAXS-assessed Cc (Cc = Ccbi/bi) values are consistent with those obtained from solubilization studies and phase inversion scans. The Cc-SAXS method provides a way to assess the hydrophobicity of ionic surfactants directly, avoiding the bias that could be introduced by cosurfactants in phase inversion studies and minimizing the impact of potential uncertainties in the surfactant volume to area ratio (vs/as) required to calculate the solubilization radii in the solubilization method.

Comparing polymer-surfactant complexes to polyelectrolytes

HypothesisUnderstanding the complex interactions between polymers and surfactants is required to optimise commercially relevant systems such as paint, toothpaste and detergent. Neutral polymers complex with surfactants, forming ‘pearl necklace’ structures that are often conceptualised as pseudo-polyelectrolytes. Here we pose two questions to test the limits of this analogy: Firstly, in the presence of salt, do these polymer-surfactant systems behave like polyelectrolytes? Secondly, do polymer-surfactant complexes resist geometric confinement like polyelectrolytes? ExperimentsWe test the limits of the pseudo-polyelectrolyte analogy through studying a poly(N-isopropylacrylamide) (PNIPAM) brush in the presence of sodium dodecylsulfate (SDS). Brushes are ideal for interrogating pseudo-polyelectrolytes, as neutral and polyelectrolyte brushes exhibit distinct and well understood behaviours. Spectroscopic ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), and neutron reflectometry (NR) were used to monitor the behaviour and structure of the PNIPAM-SDS system as a function of NaCl concentration. The ability of the PNIPAM-SDS complex to resist geometric confinement was probed with NR. FindingsAt a fixed SDS concentration below the zero-salt CMC, increasing NaCl concentration <100 mM promoted brush swelling due to an increase in osmotic pressure, not dissimilar to a weak polyelectrolyte. At these salt concentrations, the swelling of the brush could be described by a single parameter: the effective CMC. However, at high NaCl concentrations (e.g., 500 mM) no brush collapse was observed at all (non-zero) concentrations of SDS studied, contrary to what is seen for many polyelectrolytes. Study of the polymer-surfactant system under confinement revealed that the physical volume of surfactant dominates the structure of the strongly confined system, which further differentiates it from the polyelectrolyte case.

Microfluidic flow injection analysis system for the electrochemical detection of dopamine using diazonium-grafted copper nanoparticles on multi-walled carbon nanotube-modified surfaces

In this proof-of-concept study, a microfluidic flow injection analysis (FIA) system was developed using multi-walled carbon nanotube-modified screen-printed carbon electrodes (CNTSPEs) that were modified with copper nanoparticles (CuNPs) following the electrodeposition of the diazonium salt of 4-aminothiophenol to form 4-thiophenol-conjugated CuNPs (CuNPs-CNTSPE). Transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) were used to characterize the size of CuNPs, morphology and elemental analysis of CuNPs-CNTSPE, respectively. Using electrochemical impedance spectroscopy (EIS), the charge-transfer resistance (Rct) of CuNPs-CNTSPE was found to be 20-fold lower than that of CNTSPE. The CuNPs-CNTSPE displayed an oxidation peak for dopamine at −0.08 V which is ∼80 mV lower than the one detected using CNTSPE. The modified electrode was used in microfluidic flow injection analysis and offline systems for sensitive detection of dopamine (DA). The pH, flow rate, loop volume, concentration, and type of surfactant were all optimized for on-chip detection. Under the optimal conditions, using phosphate electrolyte solution (pH 6) containing 0.05% (w/v) Tween 20® as the carrier at a flow rate of 0.6 mL min−1 and a loop volume of 50 μL, the calibration curve was linear from 1.5 to 500 nM with a limit of detection of 0.33 nM. This technique was used for the successful detection of DA in real samples with recovery ranging from 96.5% to 103.8%. The microfluidic FIA system described here has the potential to be used as an electrochemical point-of-care device for rapid DA detection with high sensitivity and reproducibility.

Apparent molar volume, compressibility, and spectroscopic studies of ionic surfactants in aqueous solutions of antibiotic gemifloxacin

This work aims to explore the interactions between a wide-spectrum bactericidal drug, gemifloxacin (GMF), and micelles of cationic (dodecyltrimethylammonium bromide, DTAB) and anionic (sodium dodecyl sulfate, SDS) surfactants at the molecular level under physiological conditions (using a phosphate buffer, pH 7.4). Various physical parameters are calculated from volumetric and acoustic data. These include apparent molar volume ( ɸ V ), apparent molar isentropic compressibility ( ɸ K ), isentropic compressibility ( K s ), specific acoustic impedance (Z), relative association (RA), intermolecular free length (Lf ) and sound velocity number (U). The obtained quantities are interpreted regarding of solute-solute and solute-solvent interactions employing the cosphere overlap model and electrostriction effect. Further, normal and differential UV-visible spectroscopy is employed to predict GMF locus in ionic micelles and to find the binding constant (Kb ) and partition coefficient (Kc ) along with the corresponding free energy changes of GMF-ionic micelle systems. The results demonstrate that the binding and partitioning of GMF with SDS is more significant than DTAB.

An ultrasound assisted modified solid phase micro-extraction technique for enrichment of cadmium and lead in aqueous extract of coal gangue soil samples

The present study was carried out to develop a green and novel ultrasonically modified solid phase micro-extraction method (Um-SPµE) to quantify the cadmium (Cd2+) and lead (Pb2+) in acidic water extract (pH < 6.5) of coal gangue soil (CGS) samples collected from the block II of Thar coal field Sindh Pakistan. The 8-hydroxyquinoline (8-HQ) embedded benzophenone allows quantitative enrichment of the Cd2+ and Pb2+ at pH ∼ 6.0. The ultrasonic energy applied to enhance the dissolution/extraction of hydrophobic complex of Cd2+ and Pb2+ in deep eutectic solvent (DES), which synthesized by mixing of zinc chloride and acetamide at 1:2 mol ratios. The extraction capability of DES was enhanced by addition of a nonionic surfactant (Triton X-114) to improve the phase transfer ratio, to notably enhance the recovery of hydrophobic complex of Cd2+ and lead Pb2+. There were various factors (pH, concentration of ligand, adsorbent quantity, volume of DES and nonionic surfactant, and sonication time), effecting the enrichment factor, preconcentration and % recoveries of both metals; were optimized. The certified reference materials and spiking recovery test were applied to real samples in order to check precision and validity of the developed methodology. The % recoveries of both selected metals were found to be > 98% by applying developed method (p < 0.05).

Early Cpap and Large Volume Minimal Invasive Surfactant Administration (Ecalmist)

Large volume surfactant administration in premature infants less than 35 weeks using minimally invasive surfactant therapy (MIST). Background: Surfactant in small volume preparations can be successfully administered to premature infants using a narrow-bore vascular catheter inserted into the trachea under direct vision. It was not known if surfactant in large volume preparations could be administered effectively to spontaneously breathing premature infants while maintaining them on nasal continuous positive airway pressure (nCPAP). Objective: To evaluate the feasibility of administering a large volume of surfactant (5 ml/kg) in spontaneously breathing premature infants on nCPAP using a vascular catheter. Methods: Single-arm interventional trial in two level III nurseries in Canada. Spontaneously breathing premature infants between 24- and 34-weeks’ gestation, born between July 4th, 2012 and September 5th, 2012 were eligible for the trial in the first 24 hours of life. A 16-gauge vascular catheter was inserted under direct vision through the vocal cords to administer 5 ml/kg of surfactant while maintaining the infants on nCPAP. Results: Twenty-one premature infants were enrolled. The mean gestational age was 29 ± 3 (range 24 to 34 weeks) with mean birth weight of 1474 ± 575 g. Surfactant was successfully administered in 20 infants (95 %). There was a clear effect after surfactant administration with a decrease in oxygen requirement from 0.34 ± 0.111 before the procedure, to 0.26 ± 0.08 after the procedure (p = .001), and a decrease in nCPAP pressure from 7.2 ± 0.5 cm H2O before the procedure to 5.9 ± 0.5 after the procedure (p &lt; .0001). The mean duration for surfactant administration was 8.3 ± 3.4 minutes. The procedure was temporarily stopped in three cases due to bradycardia and/or apnea with desaturations that spontaneously recovered without intervention. Coughing and reflux of the surfactant were transiently observed in four cases (19 %). Conclusion: It is feasible to administer large volumes of surfactant without interrupting nCPAP via a vascular catheter, to premature infants less than 35 weeks’ gestation. Further trials are needed to confirm the safety and efficacy of this method compared to other methods of surfactant administration.

Effects of organic pollutants on struvite crystallization kinetics and the molecular mechanism of inhibition on crystal growth

The abilities of improving phosphorus (P) resources sustainability and reducing water eutrophication make struvite crystallization technology attract increasing interest in wastewater treatment, but struvite crystallization process may be affected by various impurities in wastewater. In this study, the effects of nine representative ionic surfactants including three types (anionic, cationic and zwitterionic) on crystallization kinetics and product quality of struvite were investigated, and the influencing mechanism was further probed. The results demonstrated that anionic surfactants significantly inhibit crystal growth so as to reduce crystal size especially in a-axis direction, change crystal morphology and decrease P recovery efficiency, and also lead to a slight decline in product purity. In contrast, cationic and zwitterionic surfactants have no obvious influence on the formation of struvite. A series of experimental characterizations and molecular simulations collectively revealed that the inhibition of crystal growth by anionic surfactants is attributed to the adsorption of anionic surfactant molecules on struvite crystal surface and subsequent blockage of active growth sites. The binding ability of surfactant molecules with the Mg2+ exposed on struvite crystal surface was highlighted to be the most essential factor determining the adsorption behavior and adsorption capacity. Anionic surfactants with stronger binding ability with Mg2+ have more intense inhibitory effect, but a large molecular volume of anionic surfactants will weaken the adsorption capacity on crystal surface so as to reduce the inhibitory effect. Contrastively, cationic and zwitterion surfactants without binding ability with Mg2+ have no inhibitory effect. These findings enable us to have a clearer understanding of the impact of organic pollutants on struvite crystallization and make a preliminary judgment on the organic pollutants that may have the ability to inhibit the crystal growth of struvite.

Treatment of Motor Oil-Contaminated Soil with Green Surfactant Using a Mobile Remediation System

Leak of fuels and lubricants occurring during exploration, distribution, refining and storage operations is the major cause of environmental pollution due to petroderivatives dispersion. The quick use of a series of physicochemical and biological techniques is needed to drastically reduce the magnitude of damage provoked by these pollutants. Among them, soil washing proved to be an effective alternative to the remediation of hydrocarbon-polluted sites, mainly if combined with surfactant utilization. However, the direct use of surfactants can lead to problems related to the toxicity and dispersion of the resulting by-products, as the majority of marketed surfactants are produced from oil derivatives. In this context, green surfactants appear as a promising alternative to their synthetic counterpart. In the present study, two green surfactants, i.e., a chemically synthesized biobased surfactant and a Starmerella bombicola biosurfactant, were applied in soil decontamination tests using a concrete mixer-type Mobile Soil Remediation System (MSRS). The system was designed and developed with 3D printing based on bench-scale results. A commercial biosurfactant was formulated based on the microbial surfactant, which was compared with the biobased surfactant in various experimental conditions. A set of factorial designs combined with Response Surface Methodology was used to select the optimal conditions for pollutant removal using the prototype. The following variables were tested: Surfactant type, Surfactant volume, Surfactant dilution, Contaminant concentration, Soil type, Soil mass, Washing duration, Tank tilt angle, Mixing speed, and Type of basket. Under the optimized experimental condition, the commercial biosurfactant allowed to remove 92.4% of the motor oil adsorbed in the sand. These results demonstrate the possibility of using natural surfactants and the development of novel mechanical technologies to degrade hydrocarbons with economic earnings for oil industry.

Preparation and the foaming activity of hydroxymethyl octadecyltrimethyl ammonium chloride

Abstract In this work, hydroxymethyl octadecyltrimethyl ammonium chloride (HM-OTAC) was obtained from the reaction between octadecyltrimethyl ammonium chloride (OTAC) and formaldehyde in different molar ratios. The effects of the reaction conditions (different molar ratios) on the properties of the product (surface tension, foaming, high temperature resistance, methanol resistance and salt resistance) were investigated. The results showed that the HM-OTAC produced under different molar ratios could lower the surface tension of water solutions more than the surfactant OTAC. The HM-OTAC (1:2) reduced the surface tension to 28.29 mN m−1. The HM-OTAC produced under other molar ratios gave higher interfacial tensions than HM-OTAC (1:2). With increasing surfactant concentration, the foam volume first increased and then gradually decreased. At a concentration of 0.3 wt.%, the highest foam volume (460 mL) was produced with HM-OTAC (1:3). Compared to OTAC, the foams produced by each HM-OTAC surfactant exhibited higher temperature stability. In the presence of 30 mL methanol, the initial foam volume of all HM-OTAC surfactants (0.3 wt.%) was generally higher than that of OTAC. With 300 mL HM-OTAC (1:4) solution, the highest foam volume of 20.2 mL could be produced. HM-OTAC (1:3) showed the highest salt resistance.

Aluminum Quantum Dots with Surface Controlled Blue-UV Photoluminescence

Aluminum quantum dots (AlQDs) are an emerging class of optical material due to their unique photoluminescence in the ultraviolet waveband. Herein, a strategy is presented to control their photoluminescence emission. The synthesized AlQDs displayed photoluminescence from the UV-B region (<320 nm) to the near-ultraviolet region (∼425 nm) and high quantum yields. Our investigation revealed that surfactants and phosphonic acids (PAs) were competitively bound to the surface of AlQDs, and this was affected by the space volume of surfactants and charge of head groups. The steady-state and time-resolved spectroscopic data suggested the emission properties of AlQDs mainly originated from the surface-mediated states. The red-shifting of emission peak was a result of increased amount of PAs on the surface of AlQDs, which could be related to the surface oxygen presented in both ligands and surfactants. Overall, this study indicates a method to control the photoluminescence of AlQDs by changing the surfactants and surface ligands, which is fundamental to their applications in photonics and applications to energy and environment, in addition to biomedicine.

Study of a high efficient composite foam drainage surfactant for gas production

Abstract The foam drainage technique for gas production has the disadvantage of requiring a large amount of surfactant and having low resistance to salt and oil. In this study, a new surfactant mixture (composite surfactant) of lauramidopropyl betaine (LAB-35), α-olefin sulfonate (AOST), sodium alkyl sulfonate (SASE) and cetyltrimethylammonium bromide (CTAB) was tested and its foaming properties were investigated in detail. The foaming properties were determined using high-speed measurements and the Ross-Miles method. The results show that the foaming volume of the composite surfactant can reach 563 mL, indicating that the foaming behaviour of the composite surfactant is more effective than that of the individual surfactants used for the mixture. In addition, the results show that the composite surfactant has a resistance to salt, methanol and condensate oil that most foam drainage agents do not have. However, the stability of the composite surfactant gradually decreases with increasing temperature and concentration. The surface tension was measured and the critical micelle concentration of the composite surfactant is 0.023 g/L.

Remediation of the Alluvial Aquifer of the Sardas Landfill (Sabiñánigo, Huesca) by Surfactant Application

Sardas Landfill at Sabiñánigo Huesca is polluted with Dense Non-Aqueous Liquid Phases (DNAPLs) composed of a complex mixture of chlorinated organic compounds (COCs). This DNAPL was produced as liquid waste from lindane production being dumped decades ago in the unlined landfills close to the lindane factory. This DNAPL migrated by gravity through the subsurface and accumulated in the contact between the alluvial and marls layers (about 15 m b.g.l.). Seven injections of an aqueous emulsion of a biodegradable non-ionic surfactant (E-Mulse 3®) were carried out at the most polluted areas of the Sardas alluvial. Injections were carried out between April and November 2021 using different surfactant concentrations (6.7, 20, 25 and 50 g/L), injection volumes (0.2 to 7 m3) and injection flow rates (0.08–0.85 m3/h). Injected fluids were extracted in the same well or surrounding wells, and the time elapsed between surfactant injection and extraction varied between 24 and 72 h. A total of 22 m3 were injected into the alluvial, and more than double this injected volume was extracted. Injection and extraction points were in the contact between the marls and the alluvial layer. Extracted fluid accumulated in tanks, and phases separated. DNAPL recovered here was mobilized rather than solubilized and managed as toxic waste. The aqueous supernatant was treated in a wastewater treatment plant with physicochemical treatment (including adsorption in activated carbon) before being discharged into the environment. The transport of the injected fluids was monitored by conductivity profiles using bromide (260–538 mg·L−1) as a conservative tracer. High radial dispersion of the injected fluid was found. Surfactant losses by adsorption in the alluvial and absorption in DNAPL were noticed, and both surfactant and contamination did not escape from the capture zone. Monitoring since 2018 of the COCS in groundwater and the DNAPL presence in the contact between alluvial and marls layers showed a significant reduction of COCs in the treated zone with the surfactant injections.

Eco-friendly dyeing of polyamide and polyamide-elastane knits with living bacterial cultures of two Streptomyces sp. strains.

Given the environmental burden of textile industry, especially of dyeing processes and the volume of synthetic dyes and surfactants, the intensive development of the greener approaches is under way. Herein, an environmentaly-friendly dyeing of polyamide (PA) and PA/Elastane (PA/EA) knits using live bacterial approach in water environment, completely eliminating usage of textile auxiliaries is described. A total of 12 pigment-producing Streptomyces strains were isolated and purified from soil and rizoshere or bark of smoke tree Cotinus coggygria samples. The antibacterial, antifungal and cytotoxic effects of crude bacterial extracts were tested. Antimicrobial effect was obtained by the majority of extracts but only two streptomycetes extracts, 11-5 and BPS51, showed moderate cytotoxicity against HaCaT human cell line. This was the reason to select 11-5 and BPS51 strains for the dyeing of the textile materials. Excellent properties of dyeing wool, silk and PA are achieved initially using live cultures, and the bioprocess is optimized on commercial PA and PA/EA knits used for stockings production. Satisfactory coloration of both knits is achieved with dynamic conditions (culture shaking at 180rpm over 5-14 days at 30 ºC) giving the best coloration results, except in the case of the PA sample dyed with a bacterial strain 11-5. The prolongation of dyeing time leads to higher color yields independently of fabric and bacteria strain. Although the color differences between the samples before and after washing are observed, washing fastness after three washing cycles can be considered as satisfactory.

Effect of a soluble surfactant on the linear stability of two-phase flows in a finite-length channel

We study numerically the effect of a soluble surfactant on the stability of two-phase flow in a finite-length microchannel. The two streams drag the surfactant molecules toward the downstream end of the interface against the action of the Marangoni stress. The sharp reduction of the interfacial tension at that end enhances the interface deformation and considerably destabilizes the system, translating into a sharp reduction of the critical capillary number even for very small surfactant volume concentrations.

Volumetric determination of reverse micelle structural properties and the validity of commonplace approximations

Molecular volumes within reverse micelles are important in determining many aggregate properties. Molecular volumes also depend upon differences in molecular environment and thereby might also be capable of detecting changes in molecular structure and interactions within an aggregate. However, approximations are typically used in their place along with approximations of aggregate radius, aggregation number, surfactant tail length, and reverse micelle shape particularly for Aerosol OT systems. Consequently, volumetric measurements have not been thoroughly tested as a measure of aggregate properties. Volumetric methods do not require the commonly used approximations. Therefore, comparison with previous approaches will demonstrate volumetric measurements’ utility in measuring aggregate structural properties and provide a useful assessment of the applicability of these commonplace approximations. Partial molar volumes of water and surfactant, evaporation rate, and reverse micelle radius are measured over the w0 = 0–40 range for water/Aerosol OT/isooctane solutions. These results are used to calculate how aggregation number, surfactant layer thickness, head group area, and water droplet structure change with aggregate radius. Volumetric measurements reveal a surfactant layer structural transition at w0 = 5, an aggregate shape change at w0 = 25, and reproduced the general trends in structural properties. Important variations from approximated methods are noted. Molecular volume and aggregate radius approximations were found valid in many but not all situations. However, approximations of aggregation number and tail length created important miscalculations of some properties when treating reverse micelles as spherical. It was found that consideration of an ellipsoidal reverse micelle shape for w0 < 10 could account for previously identified changes in surfactant layer thickness and head group area that were based on a spherical geometry.