Stability Of Surfactants Research Articles

Enhanced Cytotoxic Activity of 6-Mercaptopurine-Loaded Solid Lipid Nanoparticles in Hepatic Cancer Treatment.

6-Mercaptopurine (6-MCP) is an antiproliferative purine analog used in acute lymphoblastic leukemia, non-Hodgkin lymphoma, and inflammatory bowel disease (Crohn's disease, ulcerative colitis). Although 6-MCP has the great therapeutic potential for cancer and immunosuppressant-related diseases, 6-MCP is not readily soluble in water, presents a high first-pass effect, short half-life (0.5-1.5 h), and implies a low bioavailability (16%). On the contrary, solid lipid nanoparticles (SLNs) are prepared from solid lipids at room temperature and body temperature. In this study, SLNs were prepared w/o/w double emulsion-solvent evaporation method using Precirol ATO5 as matrix lipid. In the emulsion stabilization, surfactant (Tween 80) and polymeric stabilizer (polyvinyl alcohol [PVA]) were used. Two group formulations using Tween 80 and PVA were compared in terms of particle size, polydispersity index, zeta potential encapsulation efficiency%, and process yield%. Differential calorimetric analysis and release properties were examined for optimum formulation, and release kinetics were calculated. According to studies, sustained release was obtained with SLNs by the Korsmayer-Peppas kinetic model. The in vitro cytotoxicity studies were performed on the hepatocarcinoma (HEP3G) cell line. According to the results, successful SLN formulations were produced, and PVA was found best stabilizer. Optimum formulation exhibited significantly higher cytotoxic effects on HEP3G than on pure 6-MCP. These results demonstrated that solid lipid nanodrug delivery systems have great potential for formulation of 6-MCP.

Purification and Characterization of an Amylase from a Newly Isolated Geobacillus thermoleovorans TTIO4 from the Hot Spring of Tuwa‐Timba

AbstractA thermophilic amylase produced by a newly isolated Geobacillus thermoleovorans TTIO4 from a hot spring in India is investigated. The isolate TTIO4 optimally produces extracellular amylase at 55 °C, pH 7, and 24 h of growth. The amylase is purified by 42 fold with a yield of 9.7%. The enzyme has a molecular weight of 40 kDa. The purified amylase catalyzes the reaction optimally at 60 °C and pH 7. Besides, it displays maximum thermal stability at 50 °C for 18 h. While the catalyst is improved by Ca+2, it is wholly inhibited by Hg+2. Furthermore, the chelators, inhibitors and solvents adversely affect the enzyme activity. The amylase is stabilized by SDS, while other surfactants negatively affect the enzyme. Km, Vmax, Kcat, and Kcat/Km of the amylase are 0.26 mg mL−1, 192.3 µg mL−1 min−1, 1.92 s−1, and 7.383 s−1 mg−1, respectively. The deactivation constant, half‐life, and change in Gibb's free energy, enthalpy, and entropy are determined at 50–70 °C, which supports the thermal stability and substrate affinity of the amylase. The washing quality of commercial detergents is distinctly enhanced when supplemented with this enzyme. Therefore, this amylase possesses significant thermal and surfactant stability has significant commercial potential.

Supramolecular self-assembly of robust, ultra-stable, and high-temperature-resistant viscoelastic worm-like micelles

HypothesisWorm-like micelles are susceptible to heating owing to the fast dynamic exchange of molecules between micelles. Inhibition of such exchange could afford robust worm-like micelles, which is expected to largely improve rheology properties at high temperatures. ExperimentsA cationic surfactant docosyl(trimethyl)azanium chloride (DCTAC) and a strongly hydrophobic organic counterion 3-hydroxy naphthalene-2-carboxylate (SHNC) were used for the worm-like micelles fabrication. The microstructure was characterized using cryogenic transmission electron microscopy and small-angle neutron scattering, and the interactions between DCTAC and SHNC were characterized using nuclear magnetic resonance spectroscopy. Rheometer was employed to measure the rheological properties of the solution. FindingsSHNC/DCTAC at the molar ration of 1:2 forms ultra-stable worm-like micelles, whose viscosity remain stable at temperature up to 130 °C. SHNC is found to strongly adsorbs on DCTAC micelle with the orientation on the surface of micelle, keeping the naphthalene backbone entire penetration into the palisade layer while both carboxylic and hydroxyl groups protrude out of the micelle. With temperature increasing, this adsorption further strengthens, resulting in the growth contour length and accompanying the enhancement of rheological properties. One SHNC molecule and two DCTAC molecules are speculated to form a stable complex via multiple interactions including hydrophobic, cationic-π, and π-π interactions, which decreases the dynamic exchange of them between micelles. These findings are helpful to understand surfactant aggregates stability and assist the development of novel stable supramolecular nanostructures. Additionally, the excellent thermal stability of this worm-like micellar fluid makes it a potential high-temperature resistant clean fracturing fluid for deep oil reservoirs.

Preparation of superhydrophilic polyimide fibrous membranes by electrostatic spinning fabrication for the efficient separation of oil-in-water emulsions

Membrane separation is considered an effective technology for treating oily wastewater. Hydrophilic, underwater oleophobic water removal membranes prepared by electrostatic spinning have received significant attention due to their excellent antifouling properties, small pore blockage, and high permeation flux. Herein, a simple and effective method was proposed for fabricating fabrics with superhydrophilic and submerged superoleophobic properties. First, the materials were co-blended with sodium dodecyl benzene sulfonate by electrostatic spinning, and then the porous fiber membrane was obtained by a step-up temperature for thermal imidization. The obtained membranes showed superhydrophilic and underwater oleophobic properties and could separate oil–water emulsions with or without surfactant stabilization while also exhibiting certain retention of methylene blue dye. The separation efficiency was driven by gravity alone, and the oil–water separation efficiency was always above 98.5% for 10 separation cycles, with a separation flux of up to 700 L·m−2·h−1. The modified membranes were tested and evaluated for various oil–water emulsions, and the separation efficiency was found to be consistently above 98.5%. In addition, the membranes showed satisfactory mechanical strength, high-temperature resistance, and excellent contamination resistance, suggesting that these membranes could serve as promising candidates for the treatment of industrial oil-in-water emulsions.

Performance of alkyl β-D-maltosides in molecular self-assembly and formation of oil-in-water nanoemulsions as drug delivery systems

Alkyl β-D-maltosides are nonionic sugar-based surfactants that can be used as excipients in lipid-based nanoparticles because of their physiological functions and biocompatibility. The self-assembly of alkyl β-D-maltosides (C8-C12) was studied to investigate the effects of alkyl chain length in the binary and ternary systems. Surface tension measurements in the binary systems revealed a synergistic effect on the stability of mixed surfactants with Tween 80 (T80) in the critical aggregation concentration (CAC). Subsequently, formulations of 10:90 wt% oil-in-water (O/W) nanoemulsions (ternary systems) containing T80/alkyl β-D-maltosides with and without cyclosporine (CsA) as the hydrophobic model drug were characterised by particle size, polydispersity index (PDI), morphology, rheology, and physical stability. The formulations of all nanoemulsion systems were found to be stable against phase separation for 28 days at room temperature. The hydrophobic effect of n-dodecyl-β-D-maltoside (DDM, C12) was stronger by enhancing the stability of T80 nanoemulsion in molecular self-assembly compared to the shorter chains of the maltosides. The in vitro drug release study showed that T80/DDM nanoemulsion improved the cumulative release of CsA in 24 h by 98.33 ± 7.72% compared to T80 nanoemulsion at 83.75 ± 4.05%. The release of CsA has the highest fit with the Korsmeyer-Peppas kinetic model (R2 > 0.9), suggesting that CsA is released slowly from the oily core of nanoemulsions to the dissolution medium due to its hydrophobic nature. The cytotoxicity study against 3T3 cells showed that all formulations had no cytotoxicity effect (IC50) up to 500 μg/mL. The findings demonstrated that T80/DDM nanoemulsion holds great promise as a drug delivery system for the treatment of psoriasis.

Drop size distribution in batch stirred tank at high organic to aqueous phase ratios

Hydrodynamic studies were carried out at high organic to aqueous (O/A) phase ratios in a liquid-liquid batch stirred tank. Minimum mixing speed for complete dispersion, Sauter mean diameter, and drop size distribution have been measured with Rushton turbine and pitched blade turbine for three different liquid-liquid systems. Experiments have been performed at various impeller speeds and organic-to-aqueous phase ratios. Minimum mixing speed for complete dispersion (Nmin) was measured by visual observation as well as by sample withdrawal technique. Surfactant stabilization technique has been used to measure the drop size. Minimum mixing speed was found to be strongly dependent on impeller type and organic-to-aqueous phase ratios. About 10–40% decrease in minimum mixing speed was observed when organic to aqueous phase ratio was increased from 10 to 50. Sauter mean diameter was significantly affected by impeller speed, physical properties of the liquid systems, and dispersed phase holdup. Experimental drop size distributions were fitted with the log-normal distribution. Empirical correlations have been developed to predict minimum mixing speed and Sauter mean diameter at various operating conditions. Absolute Average Relative Error for the prediction of minimum mixing speed and Sauter mean diameter using developed correlations were found to be 18.45% and 11.06%, respectively.

Shape transformation of gold nanoparticles in aqueous CTAB/CTAC solution to generate high-index facets for electrocatalysis and SERS activity

Gold nanoparticles (Au NPs) have demonstrated great potential in chemical and biological sensing, catalysis, biomedicine, X-ray computed tomography, and other applications, owing to their unique properties. Au NPs with high-index facets have attracted more attention in the past decade owing to their superior electrocatalytic activity in fuel cells and enhanced performance in surface-enhanced Raman spectroscopy (SERS) applications. This review presents an overview of our achievements in the direct synthesis of Au NPs with controlled shapes in water using cationic surfactants. By deliberately adjusting the nature of the surfactant stabilizers, preformed Au NPs with simple shapes can be readily transformed into Au NPs with complicated shapes with controlled high-index facets by simple seeded growth. The high-index facets of the as-prepared Au NPs can be consistently correlated with their superior performance in the electrooxidation of methanol and ethanol and their enhanced SERS activity.

Immobilization of protease on chitosan–silica gel beads for high detergent and surfactant stability and high tolerance against metallic ions and organic solvents

Immobilization of protease on chitosan–silica gel beads for high detergent and surfactant stability and high tolerance against metallic ions and organic solvents

Foam stability of local surfactant on the presence of contaminant Cd ions, coffee, and oil in solution

The foam stability of the local product of surfactant was studied. The effect on the presence of contaminants: cadmium ions, coffee, and oil in surfactant solution were investigated. The foam of local surfactant at different concentrations in the presence of contaminant was generated by using a foam generator. After the foam capacity has reached a constant value, the foam then flows to column stability until a certain height of foam volume. The stability was then measured based on the decreasing height against the increasing time. In the presence of contaminant Cd ions in the solution, it could increase slightly the stabilization of the foam, especially at 0.5x cmc. For coffee particles and oil,it has the ability to decrease the foam stability of all surfactant variation concentrations. The stability of 2.0x cmc was slightly better than 1.0xcmc and 0.5xcmc for all contaminants. The ability of coffee colloidal particles was tending to decrease the foam stability of local surfactant then by oil and Cd ion. Coffee with colloidal particles may have stronger interaction with local surfactant and thus reduce the formation of the foam. Oil also has the ability to decrease foam stability.

Treatment of a Complex Emulsion of a Surfactant with Chlorinated Organic Compounds from Lindane Wastes under Alkaline Conditions by Air Stripping.

Surfactant-enhanced aquifer remediation is commonly applied in polluted sites with dense non-aqueous phase liquids (DNAPLs). This technique transfers the contamination from subsoil to an extracted emulsion, which requires further treatment. This work investigated the treatment of a complex emulsion composed of a nonionic surfactant and real DNAPL formed of chlorinated organic compounds (COCs) and generated as a lindane production waste by air stripping under alkaline conditions. The influence of the surfactant (1.5-15 g·L-1), COC concentrations (2.3-46.9 mmol·L-1), and temperature (30-60 °C) on the COC volatilization was studied and modeled in terms of an apparent constant of Henry at pH > 12. In addition, the surfactant stability was studied as a function of temperature (20-60 °C) and surfactant (2-10 g·L-1), COC (0-70.3 mmol·L-1), and NaOH (0-4 g·L-1) concentrations. A kinetic model was successfully proposed to explain the loss of surfactant capacity (SCL). The results showed that alkali and temperature caused the SCL by hydrolysis of the surfactant molecule. The increasing surfactant concentration decreased the COC volatility, whereas the temperature improved the COC volatilization. Finally, the volatilization of COCs in alkaline emulsions by air stripping (3 L·h-1) was performed to evaluate the treatment of an emulsion composed of the COCs (17.6 mmol·kg-1) and surfactant (3.5 and 7 g·L-1). The air stripping was successfully applied to remove COCs (>90%), reaching an SCL of 80% at 60 °C after 8 h. Volatilization can remove COCs from emulsions and break them, enhancing their further disposal.

Experimental investigation on pH and stability of distilled water ethylene glycol mixture with graphene nanoplatelets

An efficient heat transfer medium improves the overall efficiency of the equipment, and the main difficulty is with making well-dispersed nanoparticles in base fluids. The current research is focused to study the effect of different surfactants on nanoparticle dispersion and enhancement through property modifications. The stability and pH value of various surfactants with varying sonication duration were studied and compared with the graphene nanofluids. The graphene nanofluids were prepared by a two-step method by dispersing 0.1 wt% graphene nanoparticles in distilled water and ethylene glycol with a ratio of 70:30. The surfactants namely Cetyltrimethylammonium bromide (CTAB), Polyvinylpyrrolidone (PVP K-30), and Polysorbate 60 (Tween 60) of each 0.1 wt% were used for stabilizing the nanofluids. The duration of the sonication process was set as 60, 90, and 120 min respectively followed by the magnetic stirring for 60 min duration. The stability behavior of nanofluids was studied through visual inspection, UV spectrum, and zeta potential techniques, and the corresponding pH values were measured to correlate with the performance of the heat transfer equipment. The results showed that the dispersion of graphene nanofluids strongly depends on the type and amount of dispersant in the absolute value of zeta potential. Finally, the optimum conditions were found based on the enhanced stability, pH, and sonication time of graphene nanoplatelets in distilled water-ethylene glycol mixture with Polyvinylpyrrolidone (PVP K-30) as a surfactant for the battery thermal management systems (BTMS) in electric vehicles.

Non-ionic surfactant carrier/vesicle drug delivery system

Niosomes are one of the prominent Novel Drug Delivery systems. Niosomes are made up of non-ionic surfactants with or without cholesterol. Primarily niosomes are similar to liposomes in terms of physical properties but differ in chemical nature. Due to their higher chemical stability of surfactants than lipids these are unsurpassed when compared with liposomes. As niosomes are amphiphilic they can be utilized as a carrier for both lipophilic, and hydrophilic drugs. The application of niosomes is widely varied and can be used to treat several diseases like cancer, leishmaniasis, Parkinson, Psoriasis disease, etc. This review focuses on all aspects of niosomes including their historical development, structural components, types, formulation techniques, factors affecting their formation, controlling the size, separation of unentrapped materials, characterization, therapeutic potentials, and stability.

Surfactant stabilization of vanadium iron oxide derived from Prussian blue analog for lithium-ion battery electrodes

Derivatisation of iron vanadate from a Prussian blue analogue is reported, and the role of water-based surfactants in its electrochemical stability is studied. The environmental impact of the material is reduced by altering the synthesis, heat treatment and electrode preparation methods.

Comparison of Inflation and Ventilation with Hydrogen Sulfide during the Warm Ischemia Phase on Ischemia-Reperfusion Injury in a Rat Model of Non-Heart-Beating Donor Lung Transplantation.

Donor lung ventilation and inflation during the warm ischemia could attenuate ischemia-reperfusion injury (IRI) after lung transplantation. Hydrogen sulfide (H2S), as a kind of protective gas, has demonstrated the antilung IRI effect. This study is aimed at observing the different methods of administering H2S in the setting of warm ischemia, ventilation, and inflation on the lung graft from a rat non-heart-beating donor. After 1 h of cardiac arrest, donor lungs in situ were inflated with 80 ppm H2S (FS group), ventilated with 80 ppm H2S (VS group), or deflated (control group) for 2 h. Then, the lung transplantation was performed after 3 h cold ischemia. The rats without ischemia and reperfusion were in the sham group. Pulmonary surfactant in the bronchoalveolar lavage fluid was measured in donor lung. The inflammatory response, cell apoptosis, and lung graft function were assessed at 3 h after reperfusion. The lung injury was exacerbated in the control group, which was attenuated significantly after the H2S treatment. Compared with the FS group, the pulmonary surfactant in the donor was deteriorated, the lung oxygenation function was decreased, and the inflammatory response and cell apoptosis were increased in the graft in the VS group (P < 0.05). In conclusion, H2S inflation during the warm ischemia phase improved the function of lung graft via regulating pulmonary surfactant stability and decreased the lung graft IRI via decreasing the inflammatory response and cell apoptosis.

Nanoformulation of Curcuma longa Root Extract and Evaluation of Its Dissolution Potential.

Medicinal plants have been widely used for therapeutic purposes for a long time, but they have been found to have some major issues such as low water solubility and bioavailability. In the present study, the nanoformulation of Curcuma longa L. plant extract was prepared to enhance its dissolution potential and biological activities. For the formulation of the nanosuspension, an ethanolic extract of C. longa was prepared through Soxhlet extraction using the nanoformulation technique. The nanosuspensions were formulated using four different stabilizers, namely sodium lauryl sulfate (SLS), hydroxy propyl methyl cellulose (HPMC), poly(vinyl alcohol) (PVA), and polysorbate-80 (P-80). The scanning electron microscopy (SEM), polydispersity index, and ζ potential were used for characterization of the nanoformulation. Among all of these, the surfactant stabilizer SLS was found to be the best. The average particle size of the selected optimized nanosuspension was found to be 308.2 nm with a polydispersity index (PDI) value of 0.330. The ζ potential value of the optimized nanosuspension was recorded at -33.3 mV. The SEM image indicated that the particles were slightly agglomerated, which may have occurred during lyophilization of the nanosuspension. The highest dissolution rate recorded at pH = 7 was 192.32 μg/mL, which indicates pH = 7 as the most appropriate condition for the dissolution of the C. longa nanosuspension. The antioxidant, antimicrobial, and antifungal activities of the optimized nanosuspension were also determined with regard to the coarse plant extract. The study findings suggested that the nanoprecipitation approach helps in enhancing the dissolution potential and biological activities of C. longa root extract.

Thermal stability of hydroxyl sulfobetaine surfactant in high salinity brine

Hydroxyl sulfobetaine surfactant can be used as a foaming agent in high temperature and high salinity reservoirs. To find out the stability of this type of surfactant at high temperature and high salinity conditions, the solutions of four hydroxyl sulfobetaine surfactants, CH3(CH2)11N+(CH3)2CH2CH(OH)CH2SO3− (HSB1214), CH3(CH2)17N+(CH3)2CH2CH(OH)CH2SO3− (HSB1618), CH3(CH2)10CONH(CH2)3N+(CH3)2CH2CH(OH)CH2SO3−(LHSB), CH3(CH2)22CONH(CH2)3N+(CH3)2CH2CH (OH) –CH2SO3− (EHSB), were aged in 25% TDS (total dissolved solids) brine for different durations at 110–150 °C and their concentration was determined by liquid chromatography. The results showed that the thermal stability of HSB1214 and HSB1618 was significantly better than that of LHSB and EHSB, and it could be significantly improved by adding certain thiourea to the LHSB solution with high salinity. Therefore, LHSB and EHSB were recommended to be used as non-acid gas foaming agents at 110 °C, and HSB1214 and HSB1618 were recommended to be used as non-acid gas foaming agents at 130 °C and above. Given the increased thermal decomposition of hydroxyl sulfobetaine with an amide group at pH 3–4, it is recommended to select hydroxyl sulfobetaine without the amide group on the molecule, such as HSB1214 and HSB1618, as the foaming agent to control CO2 mobility for the reservoir at 110–130 °C. Liquid chromatography-mass spectrometry analysis on the heat-treated surfactant solution showed that LHSB was hydrolyzed mainly at the amide position, and HSB1214 may be broken from the connection between long alkyl chain and the quaternary nitrogen at high temperature.

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.

End-to-End Approach to Surfactant Selection, Risk Mitigation, and Control Strategies for Protein-Based Therapeutics.

A survey performed by the AAPS Drug Product Handling community revealed a general, mostly consensus, approach to the strategy for the selection of surfactant type and level for biopharmaceutical products. Discussing and building on the survey results, this article describes the common approach for surfactant selection and control strategy for protein-based therapeutics and focuses on key studies, common issues, mitigations, and rationale. Where relevant, each section is prefaced by survey responses from the 22 anonymized respondents. The article format consists of an overview of surfactant stabilization, followed by a strategy for the selection of surfactant level, and then discussions regarding risk identification, mitigation, and control strategy. Since surfactants that are commonly used in biologic formulations are known to undergo various forms of degradation, an effective control strategy for the chosen surfactant focuses on understanding and controlling the design space of the surfactant material attributes to ensure that the desired material quality is used consistently in DS/DP manufacturing. The material attributes of a surfactant added in the final DP formulation can influence DP performance (e.g., protein stability). Mitigation strategies are described that encompass risks from host cell proteins (HCP), DS/DP manufacturing processes, long-term storage, as well as during in-use conditions.

Insights into the relation of crude oil components and surfactants to the stability of oily wastewater emulsions: Influence of asphaltenes, colloids, and nonionic surfactants

Large amounts of asphaltenes, colloids, and surfactants in the oily wastewater emulsions produced during the resource utilization of oily sludge make the treatment of oily wastewater emulsions difficult. In this study, the crude oil components were separated by solvent separation method, characterized by SEM, XRD, FT-IR, and EDS for crude oil components, suspended solids, and “oil-particulate aggregates”, and compared the emulsification performance of each crude oil component according to the oil–water wetting angle. In addition, the static stability and coalescence stability of different surfactant emulsions were determined, and the kinetic parameters of emulsion decomposition and oil–water interfacial film strength parameters were calculated based on the stability model of emulsion two-phase separation. The mechanisms of active components such as asphaltenes and colloids in crude oil and surfactants on the emulsion stability of oily wastewater were analyzed. It was found that the polar components in crude oil consisted of asphaltenes and colloids, and with the increase of asphaltenes and colloids, the oil–water wetting angle decreased significantly and the emulsion stability increased, and the emulsion stability of nonionic surfactants was better than that of cationic and anionic surfactants, among which octylphenol polyoxyethylene ether (10) (OP-10) had the best emulsion stability. The results of the study provide a theoretical basis for the demulsification and oil removal of oily wastewater emulsions.

Role of ionic surfactants on the activation of K2S2O8 for the advanced oxidation processes

Effects of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate were studied to elucidate the persulfate based in-situ chemical oxidation of subsurface contamination. Advanced oxidation processes (AOP) utilizing Fenton’s like reagent was investigated for the degradation of acid orange 7 (AO7) with and without ionic surfactants. The new findings are that the CTAB and SDS retarding the S2O82− activation to some extent. The kinetics of S2O82− assisted decomposition of AO7 were performed under different reaction parameters such as [S2O82−], [Fe2+], [AO7], pH, and temperature. The rate constants (kψ) were decreased markedly in presence of both surfactants. CTAB showed the most potential deactivation than that of SDS. The stability of both surfactants were determined in presence of S2O82−, and no drastic changes was observed in the critical micellar concentration (CMC). The columbic attraction and repulsion between the reactants (S2O82−, and AO7) with ionic head groups of CTAB and SDS are responsible to deactivating the S2O82− decomposition. AO7 and S2O82−, respectively, solubilized and transferred from bulk phase to micellar surface through electrostatic interactions, which may contribute to the inhibitory role of CTAB micelles in the AOP of AO7. Finally the role of surfactants in the Fenton’s like oxidation of AO7 based on the micellar-pseudo phase model was proposed and discussed.