One of the tertiary methods for enhanced oil recovery (EOR) is the injection of chemicals into oil reservoirs, and surface active agents (surfactants) are among the most used chemicals. Surfactants lead to increased oil production by decreasing interfacial tension (IFT) between oil and the injected water and to the wettability alteration of the oil reservoir rock. Since surfactants are predominantly expensive materials, it is required to consider an appropriate and high-performance plan for project economics when they are injected into oil reservoirs. One of the operational issues in surfactant flooding is the CRITICAL MICELLE CONCENTRATION (CMC), which is usually achieved by the injection of surfactant at CONCENTRATIONs higher than CMC. Therefore, the lower the CMC is, the lower the amount of the material needed to be injected into the reservoir becomes, so it will help to economize the project. The salinity of the aqueous phase is a factor affecting the CMC, and with its optimal design, it can reduce the CMC. In this study, the variations of Triton X-100 CMC’ s as a nonionic surfactant were measured by altering the CONCENTRATION of three salts with divalent ions (CaCl2, MgCl2, and Na2SO4) and a single-capacity ion salt (NaCl), as the predominant salts in the porous medium of oil reservoirs, using surface tension (ST) method at ambient temperature and pressure. Each of these salts was dissolved at three CONCENTRATIONs of 0. 1, 0. 5, and 1 wt. % in distilled water containing specific CONCENTRATIONs of surfactant, and the surfactant CMC in the presence of these salt CONCENTRATIONs was measured. The results showed that increasing the CONCENTRATION of each salt resulted in a decrease in the CMC, and, in the studied salts, NaCl produced the lowest CMC.

The interfacial tension of surfactant solutions is decreased with increasing surfactant CONCENTRATION to obtain the CRITICAL MICELLE CONCENTRATION (CMC). After that, the CMC value does not alter much. So this CONCENTRATION is a CRITICAL point during surfactant flooding that is one of the chemical EOR techniques. The reduction of the CMC value is taken into consideration, since the surfactant flooding is very expensive. The surfactant evaluated in this study is a cationic HTAB surfactant that is more appropriate for carbonated oil reservoirs. This research investigates the effect of four different salts (CaCl2, MgCl2, Na2SO4, and NaCl) at different CONCENTRATIONs (0, 0. 1, 0. 5, and 1 wt%) on the CMC value. All the experiments were conducted by surface tension technique to measure the CMC values. Also, the ionic strength was calculated for all solutions. Results imply that the addition of all of the salts reduced the CMC value and Na2SO4 had the best performance comprise the others. Increasing the salt CONCENTRATION leads to declining the CMC value for NaCl, and for other salts this behavior was continued till 0. 5 wt%. Then it is elevated. The cost consideration indicates addition of slats can reduce the amount of surfactant flooding cost over 12 times.

A simple and sensitive method is described for the pre - CONCENTRATION by cloud point extraction followed by atomic absorption spectrometric determination of copper ion in real samples. At a solution pH of 5.5, 5, 5-diphenylimidazolidine-2, 4-dione (phenytoin) (DFID) and TritonX-114 were used as hydrophobic ligand and non-ionic surfactant. The adopted CONCENTRATIONs for DFID, Triton X-114 and HNO3, bath temperature, centrifuge rate and time were optimized. Detection limits (3SDb/m) of 1.7 ng mL-1 along with enrichment factors of 35 for these ions were achieved. The proposed procedure was applied to the analysis of real samples.

Objective(s): MICELLEs have been studied as nanoparticulate drug delivery systems for improving the topical ocular delivery of hydrophobic drugs. The objective of this study was to develop and characterize dexamethasone-loaded polycaprolactone-polyethylene glycol-polycaprolactone (PCL-PEG-PCL) MICELLEs to improve patient compliance and enhance the ocular bioavailability of poorly water-soluble drugs. Materials and Methods: The PCL-PEG-PCL copolymers were synthesized via the ring opening polymerization of ε-caprolactone in the presence of PEG. The resulting purified copolymers were characterized by GPC, NMR, FTIR, XRD and DSC. The CRITICAL MICELLE CONCENTRATIONs (CMCs) of the mentioned copolymers were determined. Dexamethasone was loaded into polymeric MICELLEs by film hydration method, and dexamethasone-loaded MICELLEs were characterized by TEM and DLS. Drug release kinetics and ex vivo corneal permeability were also determined. Results: The CMC of the synthetized copolymers was approximately 0. 03 mg/ml. Aqueous solutions of the resulting copolymers (400 mg/ml) rapidly formed a gel in situ at 34° C. The TEM results exhibited the successful formation of spherical MICELLEs. The size of the prepared MICELLEs was approximately 40 nm. Formulated MICELLEs sustained the release of the incorporated dexamethasone for 5 days. Conclusion: Data from ex vivo permeability tests indicated that PCL-PEG-PCL MICELLEs can be suitable candidates for the ocular delivery of dexamethasone and, likely, other hydrophobic drugs.

In the present investigation, firstly, the surface tension measurements were conducted for aqueous solutions of cetyltrimethylammonium bromide, acetonitrile, and tetrahydrofuran by using a pendant drop apparatus at the temperature of 298. 15 K and ambient pressure. Then a thermodynamic model was used and successfully reproduced the surface tension values. The percent of the average absolute deviation for surface tension was 0. 667. The surface tensions of mixed aqueous solutions of (cetyltrimethylammonium+additives) were measured at various CONCENTRATIONs. Then, the values of CRITICAL MICELLE CONCENTRATIONs were measured based on surface tension and conductivity. The percent of the average absolute deviation of the thermodynamic model was 5. 05, proving that the model successfully predicts the surface tension for aqueous mixed solutions of (cetyltrimethylammonium+additives). The presence of additives decreases the surface coverage of cetyltrimethylammonium and increases the CRITICAL MICELLE CONCENTRATION values.

In this work, Ni nano structures with different surface morphology have been electrodeposited from the Waths bath using different techniques in the presence of three types of surfactants. CTAB, SDS, and Triton x-100 have been used as cathionic, anionic and nonionic surfactants respectively. The surfactants CONCENTRATION have been selected at below, equal to and above the corresponding CRITICAL MICELLE CONCENTRATION (CMC). The SEM analyses show that the porosity and homogeneity of the electrodeposited samples depend on the surfactant type and its CONCENTRATION. In the presence of CTAB, electrodeposition process has been certainly hindered in some region. For SDS, nano-particles with the same charges repel each other and disperse in a more uniform way. In the presence of Triton x-100, agglomeration of particles is seen and particles are not dispersed. The corrosion behavior of electrodeposited samples has also been investigated in 1 M NaOH solution using Tafel potentiodynamic polarization method as well as electrochemical impedance spectroscopy analyses. It is observed that all samples have low corrosion current density and the sample prepared above the CMC point of SDS has the lowest corrosion rate. In addition, according to our findings, the electrodeposited samples using DC method have larger particle sizes and lower corrosion rate.