Wettability alteration of outcrop obtained from Asmari formation was investigated using surfactants. Three different surfactants including a cationic surfactant: dodecyltrimethylammonium bromide (DTAB), an anionic surfactant: sodium dodecylbenzenesulfonate (SDBS) and a non-ionic surfactant that was Triton X-100 were used.
Wettability alterations in the presence of each surfactant for the three surfactant concentrations from 0.1 to 0.3 wt% in brine and at four different temperatures, from 25 to 80oC were examined. Surfactant solution droplets were placed on the rock surfaces after being saturated with brine and placed in crude oil. The potential of surfactants to alter the wettability was determined by estimating the contact angle (θ) between the surfactant droplet and the surface of the rock. The results indicated that Triton X-100 could change the wettability condition from oil-wet to water-wet more than other surfactants with the same concentrations and temperatures.

Surfactant flooding is known as an essential and important method for enhancing oil recovery from carbonate reservoirs. High amount of Adsorption of some surfactants onto carbonated surfaces makes some difficulties in accurate prediction of oil recovery efficiency in this type of injection process. In this paper, the adsorption of nonionic surfactant Triton x-100 on the surface of the carbonate rock is experimented. The carbonate rock is crushed and contacted with surfactant solution, and the amount of the surfactant adsorption on the surface of the carbonate rock is measured after arriving the equilibrium condition. It is observed that the adsorption of the surfactant is saturated at about 500 ppm. Also, the adsorption results matched well with the Langmuir model. The amount of Langmuir constant is obtained 173.34 gr sol / gr surf and the maximum adsorption is obtained 19.23 mg surf /gr rock. Comparing the adsorption data shows that the amount of surfactant adsorption and its variations especially above the critical micelle concentration in carbonate rocks is greater than sandstones. So, it is more important to consider the surfactant adsorption and its waste during surfactant injection and its simulations in carbonate reservoirs.

In this study, the effect of anionic and cationic surfactants on enhanced oil recovery was investigated by considering the wettability alteration and interfacial tension. The alpha olefin sulfonate (AOS) and cetrimonium bromide (CTAB) were considered as anionic and cationic surfactants respectively. Firstly, the stability of chemical solutions was evaluated by zeta potential test and so these solutions were used to IFT, wettability, coreflooding, and surfactant adsorption tests. Also, the surface forces were analyzed to investigate the isoelectric point and surfactant adsorption. The results show that the anionic and cationic surfactants can significantly reduce the interfacial tension. Also, the anionic surfactant alters the reservoir wettability from strongly oil wet (159o) to water wet (37o). Based on the isoelectric point, the anionic surfactant adsorption is higher than that for cationic surfactant adsorption. Consequently, the low salinity sea water which includes cationic surfactant, due to no snap-off phenomena, improved the oil recovery factor up to 19 % compared to sea water injection.

In this article, Surface Active Agents (Surfactants) and its effect on the Multiphase Flow have been studied. First, the functioning of surfactants has been explained. For this purpose, the definitions of surface tension and how it changes in the presence of surfactants have been investigated. Also, the physics of surfactant distribution in multiphase flow and its absorption and repulsion at the interface have been reported. The physical changes of the two-phase interface due to the presence of surfactants have been investigated through the balance of forces and the change in surface tension and the definition of the Marangoni effect. Types of surfactants and their properties are stated. Finally, the important applications of surfactants in industry and daily life are mentioned in detail. This review shows that surfactants as one of the effective factors on multiphase flow need to be studied more and more. A better understanding of these materials can be very useful in manipulating and optimizing multiphase flow applications. 

An effective method for the preparation of stable dispersions of graphene is the direct exfoliation of graphene from graphite flakes in the aqueous solution of surfactants. Physical adsorption of surfactants on graphene surfaces is an important step in dispersing and stabilizing exfoliated graphene sheets in the aqueous medium. Dispersion of graphene with a mixture of surfactants is an effective way to obtain stable graphene sheets. The effect of synergism on a mixture of surfactants can reduce the total concentration of surfactants required for a particular application. The present study employed molecular dynamics simulation to investigate the adsorption of mixed cationic-rich and anionic-rich surfactants onto armchair graphene. We investigated the effects of temperature, electrolyte, and alcohol in the aqueous solution of surfactants on the adsorption process to understand the adsorption and self-assembly mechanism of surfactant mixtures on the graphene surface and also to better optimize the graphene dispersion process. The simulation results suggested the improved stability of these systems by adding an electrolyte to the aqueous solution of the surfactants. The screening effect of electrolyte ions on the electrostatic repulsion between groups of charged heads of surfactants has led to a denser accumulation of surfactants on graphene and more favorable interactions between them. Increasing temperature, however, reduced the system's stability by desorbing the mixed surfactants from the graphene surface. Comparing the surfactant molecules and graphene in terms of energy levels of Lennard-Jones interactions with and without alcohol also showed increased interactions in the absence of alcohol, which helps improve the system stability.

Due to the development of various industries, surfactants are used in detergents and disinfectants, oil industries, soil washing, petrochemicals, etc., and enter the ground in different ways. Surfactants, after entering the soil composition, change the physical and mechanical properties of soils due to physical and chemical processes. In this study, the pollutant effect of anionic, cationic, and non-ionic surfactants on some properties of sandy and sand with 20% clay soil is investigated. For this purpose, compaction, direct shear, consolidation, and capillary tests were performed on the soil exposed to water with 1% of various surfactants. The results showed that surfactants have a negligible effect on the maximum dry unit weight of the granular soil. Also, Triton and HEC surfactants do not have a significant effect on the optimum moisture content, but other surfactants reduced it compared to water. In general, soil shear resistance decreases in the presence of surfactant solutions compared to clean water. Also, according to the results of consolidation tests performed on the sandy soil with 20% clay, HEC, LABSA, and CTAC surfactants increased the compression coefficient and increased the swelling coefficient compared to clean water. HEC surfactants caused a decrease and CTAC and LABSA surfactants increase the consolidation coefficient (CV) compared to water. Also, all surfactants reduced differently the capillary ascend in the soil.

We assessed amount of surfactants and their seasonal trend in eight stations in Anzali Lagoon and compared them with allowable levels in the years 2001-2002. We obtained 96 water samples and determined their surfactant content using liquid - liquid method applying methylene blue active substance (MBAS).
The concentration of surfactants in Pirbazar varied from 0.176 to 0.422 while that of the Sea station was somewhere between 0.098 to 0.049 mg/l. Seasonal concentration of surfactants varied from 0.049 to 0.422 mg/l averaging on 0.137 mg/l. A significant difference was found for surfactant concentration in different parts of the lagoon (p<0.05) with the eastern zone being the most polluted area with 0.422 g/l of the pollutants compared to 0.066 mg/l in the Sea. The highest amount of the surfactants was seen in winter in contrast to the lowest amount in spring. No statistically significant difference was found between concentrations of the surfactants in different seasons.

The solubilization of a monoazo disperse dye based on naphthalimide containing an ester group in the presence of DTAB and two gemini cationic surfactants was investigated. The results showed that the solubilization power of gemini surfactants micelles was greater than that of conventional surfactant micelles (DTAB) for this dye. The nature of the visible absorption spectra in aqueous surfactant solutions above CMC was very similar to those in the ethanol solution. The solubilization power is strongly dependent on the surfactant structure and nature of micelles. The absorption of used disperse dye intopolyester fabrics in the presence of cationic surfactants increased in the order of DTAB>12-4-12>14-414, once again confirming the higher solubilization power for gemini surfactants even at elevated temperatures. J. Color Sci. Tech. 4(2010), 55-64 © Institute for Color Science and Technology.

In this study, we aimed to compare the efficacy of laryngeal mask airway (LMA) versus endotracheal tube in the early rescue surfactant administration in premature neonates with respiratory distress syndrome (RDS). This randomized, clinical trial evaluated 60 premature neonates with RDS. Numbered envelopes randomly assigned 30 neonates to the intervention group to receive 2.5 ml/kg/dose surfactant (Curosurf) via LMA and 30 to the control group to receive 2.5 ml/kg/dose surfactant via an endotracheal tube using the INSURE technique, exclusively during the first two hours of life. There were no differences in the requirement for mechanical ventilation (23.3% vs. 20%, P=0.75), requirement for second dose surfactant (13.3% vs. 6.7%, P=0.67), bronchopulmonary dysplasia (13.3% vs. 6.7%, P=0.67), pneumothorax (6.7% vs. 0%, P=0.49), and intraventricular hemorrhage (10% vs. 10%, P=1) between neonates who received surfactant via LMA versus those who received surfactant via endotracheal tube. LMA seems to be an effective and less invasive alternative to endotracheal intubation for surfactant delivery in premature neonates with RDS.

Surfactants (adjuvants) are the substances often added to the spray tank, besides the pesticide formulation, whose role is to improve the performance of the pesticide or the physical properties of the spray mixture, or both. Adjuvants are not often used as fungicides themselves, however, it is interesting to investigate if they can improve the fungistatic activity of the system they are included in. Therefore the main aim of this work was to determine the effect of the addition of a newly obtained, never investigated before, sulfobetaine type surfactant to the fungicides on their final properties. In the in vitro experiment fungistatic activity of the surfactant and the system of surfactant with strobilurins and benzimidazole fungicides were evaluated. The tested surfactants were added to the liquid medium of Potato Dextrose Agar (PDA) at concentrations: 1, 10, 50, and 100 ppm. The organisms of Fusarium culmorum, Rhizoctonia solani, Microdochium nivale, and Alternaria brassicas were used as indicators. The experiments have shown that the addition of the new surfactant studied to the medium resulted in inhibition of mycelium growth of all the tested fungi. The system with the surfactant and the fungicide was much more effective against the tested fungi than individual fungicides.