Commercial Nonionic Surfactants Research Articles

Synergistic solubilization of polycyclic aromatic hydrocarbons by mixed micelles composed of a photoresponsive surfactant and a conventional non-ionic surfactant

Abstract Surfactant-enhanced remediation is a powerful technology for soil clean-up. However, some drawbacks, such as its high cost and the secondary contamination caused by flushing agents, have hampered this technology and its commercial application has been largely limited to North American and European countries. The aim of this work is to introduce a novel reversible solubilization system composed of the photoresponsive surfactant 4-butylazobenzene-4′-(oxyethyl)trimethylammonium bromide (AZTMA) and the commercial non-ionic surfactant Tween80 for the solubilization of organic contaminants. The solubilization behavior of the AZTMA/Tween80 surfactant system toward polycyclic aromatic hydrocarbons (PAHs) has been studied. Critical micelle concentration (CMC) values indicate that the mixed system has a synergism in mixed micelle formation, and that the interaction parameter ( β ) is −2.85 when the mole ratio is 2:8. AZTMA is also predicted to be low biologic toxicity by the CMC and surface tension. The synergistic effect on molar solubilization ratio (MSR) and micelle-phase/aqueous-phase partition coefficient K mc values is related to the composition and concentration of the mixed system and follows the order pyrene > phenanthrene > acenaphthene, and these parameters are much higher than those for the single surfactants. After irradiation with UV light, more than 65% of the PAHs could be separated from the mixed micelles, and the cumulative release efficiencies of selected PAHs are consistent with the results of solubilization experiments. All of these features demonstrate that mixed AZTMA/Tween80 should be preferable to single surfactants for soil remediation, avoiding the issues associated with chemical flushing agents and decreasing remediation costs.

Removal of Tannic Acid From Aqueous Solution by Cloud Point Extraction and Investigation of Surfactant Regeneration by Microemulsion Extraction

AbstractThe aim of this work is the extraction of tannic acid (TA) with two commercial nonionic surfactants, separately: Lutensol ON 30 and Triton X‐114 (TX‐114).The experimental cloud point extraction results are expressed by four responses to surfactant concentration and temperature variations: extent of TA extraction (E), remaining solute (Xs,w) and surfactant (Xt,w) concentrations in dilute phase and volume fraction of coacervate (Φc) at equilibrium. An empirical smoothing method was used and the results are represented on three dimensional plots. In optimal conditions, the extraction extent of TA reaches 95 and 87 % using TX‐114 and Lutensol ON 30, respectively. Sodium sulfate, cetyltrimethylammonium bromide (CTAB) addition and pH effect are also studied. Finally, the possibility of recycling of the surfactant is proved.

Recycling of waste automotive laminated glass and valorization of polyvinyl butyral through mechanochemical separation

Due to strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility polyvinyl butyral (PVB) resin films are commonly used in the automotive and architectural application as a protective interlayer in the laminated glass. Worldwide million tons of PVB waste generated from end-of-life automotive associated with various environmental issues. Stringent environmental directive, higher land cost eliminates land filling option, needs a study, we have developed a mechanochemical separation process to separate PVB resins from glass and characterized the separated PVB through various techniques, i.e., scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR). Commercial nonionic surfactants D201 used for the mechanochemical separation purpose. Through parameter optimization following conditions are considered to be the optimum condition; 30vol% D201, stirring speed of 400rpm, 35°C temperature, operation time 1h, and dilute D201 volume to waste automotive laminated glass weight ratio of ≈25. The technology developed in our laboratory is sustainable, environmentally friendly, techno-economical feasible process, capable of mass production (recycling).

Applying Factorial Design and Response Surface Methodology to Enhance Microbial Denitrogenation by Tween 80 and Yeast Extract

In this study the effect of yeast extract as a conitrogen source and Tween 80 as a commercial and available nonionic surfactant on microbial denitrogenation MDN of carbazole by Bacillus clausii BS1 was investigated. The central composite design matrix and response surface methodology were applied in designing the batch experiments to evaluate the interactive effects of these two parameters on MDN. Quadratic model equations have been predicted finding out how significant the effects of these variables (factors) and their interactions are in practice. The validity of the predicted models was confirmed. The MDN efficiency increased from ≈88% without yeast extract or Tween 80 to ≈95% in presence of optimum concentration of 0.868 g/L yeast extract and 0.861% (v:v) Tween 80, which would represent a major economic improvement in low-margin, high-volume refining processes.

Experimental Study of Foam Flow in Sand Columns: Surfactant Choice and Resistance Factor Measurement

Contamination of soil and groundwater with nonaqueous phase liquid represents a major environmental concern because of the negative effect on human health. Traditional soil flushing techniques have been proved ineffective in heterogeneous aquifers, since liquids for remediation flow preferentially through the most permeable layers and residual oil remains trapped in the low-permeability sediments. To improve the sweep efficiency, fluids with lower mobility than resident liquids can be injected, such as polymers or in situ generated foam. In addition, foam has the potential of selectively reducing mobility in higher-permeability layers compared to lower-permeability layers. The use of foams has not been popular because foam mobility is difficult to predict. In this paper, a series of 1D column experiments were conducted to investigate the variation of the resistance factor RF as a function of the permeability. Five types of sand and calibrated glass beads were used to obtain porous media of permeabilities ranging from 250 millidarcy to 100 Darcy. Two commercial nonionic surfactants, \(\hbox {Triton}^{{\circledR }}\) X-100 (commonly used but toxic) and sucrose laurate (environmentally friendly surfactant, biodegradable), were used at a concentration equal to 10 critical micelle concentration. Columns were first saturated with water and then flushed with 1.5 PV (pore volumes) of surfactant solution in order to achieve the adsorption of molecules into the soil matrix. Then, co-injection of air and surfactant solution was performed at a constant total rate to generate in situ foam. The quality of the foam was varied from 85 to 99 % to investigate the effect of this parameter on the resistance factor. A graphic showing the dependence of RF and the permeability is presented. Results suggest that for the same total flow rate, the RF decreases as permeability increases, but for permeabilities smaller than 1 Darcy, the RF is weak, probably due to the difficulty to generate stable foam under high capillary pressures. Variations in foam quality and surfactant type do not seem to have an important effect on the results regarding RF. The presented results are assistance for predicting foam behavior in porous media of different permeabilities.

Hemolytic activity and solubilizing capacity of raffinose and melezitose fatty acid monoesters prepared by enzymatic synthesis

The hemolytic activity and solubilizing capacity of two families of non-reducing trisaccharide fatty acid monoesters have been studied to assess their usefulness as surfactants for pharmaceutical applications. The carbohydrate-based surfactants investigated included homologous series of raffinose and melezitose monoesters bearing C10 to C18 acyl chains prepared by lipase-catalyzed synthesis in organic media. The hemolytic activity was determined in vitro using a static method based on the addition of the surfactants to an erythrocyte suspension and subsequent spectrophotometric determination of the released hemoglobin. The effect of the carbohydrate head group, the acyl chain length and the regioisomeric purity was investigated. In all cases, the carbohydrate monoester surfactants decreased their hemolytic activity (with respect to their critical micelle concentration) when increasing the length of the acyl chain. A very similar behaviour was observed either the carbohydrate head-group (raffinose and melezitose) or regardless of the regioisomeric purity. Interestingly, decanoyl (C10) and lauroyl (C12) monoesters were just marginally hemolytic at their critical micelle concentrations while the longer palmitoyl (C16) and (C18) stearoyl monoesters become hemolytic at concentrations much higher than their respective cmc. The palmitoyl and stearoyl monoesters also displayed higher solubilization capacity than the shorter acyl chain monoesters in a solubilization assay of a hydrophobic dye as a model drug mimic. These results suggest that raffinose and melezitose monoesters with long-chain fatty acids (C16 to C18) are promising surfactants for pharmaceutical applications and could be an alternative to the use of current commercial nonionic polyoxyethylene-based surfactants in parenteral formulations.

Selecting enhancing solutions for electrokinetic remediation of dredged sediments polluted with fuel

In this paper a procedure for selecting the enhancing solutions in electrokinetic remediation experiments is proposed. For this purpose, dredged marine sediment was contaminated with fuel, and a total of 22 different experimental conditions were tested, analysing the influence of different enhancing solutions by using three commercial non-ionic surfactants, one bio-surfactant, one chelating agent, and one weak acid. Characterisation, microelectrophoretic and electrokinetic remediation trials were carried out. The results are explained on the basis of the interactions between the fuel, the enhancing electrolytes and the matrix. For one specific system, the electrophoretic zeta potential, (ζ), of the contaminated matrix in the solution was found to be related to the electroosmotic averaged ζ in the experiment and not to the efficiency in the extraction. This later was correlated to a parameter accounting for both contributions, the contaminant and the enhancing solution, calculated on the basis of differences in the electrophoretic ζ in different conditions which has allowed to propose a methodology for selection of enhancing solutions.

SURFACTANT-ASSISTED IMMOBILIZATION OF TiO2 ONTO GLASS SUBSTRATES FOR PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE

Titanium dioxide-based photocatalysis is a type of advanced oxidation process that can be used to completely degrade and mineralize organic pollutants. The semiconductor titanium dioxide (TiO2) is used as a photocatalyst and is activated when it absorbs photon energy equal or greater than its band gap energy. The activation of TiO2 as a photocatalyst leads to the formation of active sites on its surface that can trigger series of oxidative-reductive reactions to mineralize the pollutants. In most cases, TiO2 is commonly used in slurry form and the recovery of the catalyst after water treatment often requires another separate process. To address this concern, TiO2 photocatalyst have been immobilized on the surface of soda borosilicate glass slides with the aid of a commercial non-ionic surfactant, under the trade name Triton X-100. The TiO2 thin film was prepared using sol-gel process and immobilized on the glass surface at different number of coatings using the dip coating technique. The TiO2 thin films were characterized using FE-SEM, XRD and TGA and its photocatalytic activities were tested in the degradation of a model organic pollutant, methylene blue (MB). Characterization of the prepared samples by XRD showed that TiO2 in the form of anatase was successfully deposited on the glass slides. The addition of surfactant created thicker TiO2 thin films that showed better performance during photocatalytic activity test. The result of the activity tests showed that the TiO2 on the glass slide was able to degrade MB and the number of times that TiO2 was coated on the glass slide also affected the rate of MB degradation.

Retracted: Cloud point behaviour modelling of polyoxyethylene nonionic surfactants

The cloud point temperature, Tc, of commercial nonionic surfactants: poly(oxyethylene) alkyl ethers (case: dodecan‐1ol polyethoxylate, with the middle chemical structure n‐C12E6) was predicted by applying the Flory–Huggins theory for polymer solutions, adapted to alcohol ethoxylates aqueous solutions by Rupert and using the pseudo‐phase model original developed for micro‐emulsions diagrams composition. The variations of interaction enthalpy as a function of carbon chain length and number of ethylene oxide units are also modelled. The expression of Tc as the function of the composition was derived assuming the regular solution for mixed micelles. The experimental results of the cloud point obtained for mixtures of n‐C12E6 was better reproduced by the pseudo‐phase model, which requires more specific surfactant data (the critical micelles concentration, cmc; critical temperature TC), and a minimum of experimental data.

Toxicity of non-ionic surfactants and interactions with fungal entomopathogens toward Bemisia tabaci biotype B

Several non-ionic surfactants can be used to enhance insecticidal performance of various bio-based products and agrochemicals. In this study, we describe the toxicity of four commercial non-ionic surfactants against immature Bemisia tabaci (Gennadius) biotype B whiteflies along with their spreading ability. Results revealed that trisiloxane-based surfactants (Break-thru® and Silwet® L-77) exhibited the highest toxicity to 1st–2nd (early) and 3rd–4th (late) instar nymphs as well as the greatest wetting performance. We also investigated whether sub-lethal concentrations of Break-thru® and Silwet® L-77 improved the insecticidal efficacy of the fungal entomopathogens Beauveria bassiana (Balsamo) Vuillemin (strain CG1229) and Isaria fumosorosea Wise (strain CG1228) conidial suspensions against whiteflies. Germination of hydrophobic conidia of both isolates were unaffected by these surfactants over the range 100–1000 ppm. The combinations of both fungi with trisiloxane carriers significantly increased nymphal mortality with mostly additive and synergistic effects on early and late nymphs, respectively. In screenhouse trials, both fungi (107 conidia ml−1) mixed with 200 ppm of Silwet® L-77 significantly improved effectiveness against early nymphs (72–74 % mortality) compared with controls treated with water and Silwet® L-77 alone. In addition, reduced volume rates of I. fumosorosea in Silwet® L-77 (equivalent to 100 l ha−1) were at least as effective against late nymphs as higher volume rates (200 l ha−1) at equivalent conidial doses. Our findings underline the compatibility and enhanced activity of silicon-based surfactants with B. bassiana and I. fumosorosea for use in integrated whitefly management programs.

Unidirectional self-assembly of soft templated mesoporous carbons by zone annealing

Surfactant or block copolymer-templated mesoporous films have been extensively explored, but achieving mesostructure coherence and unidirectional orientation over macroscopic dimensions has remained quite challenging for these self-assembled systems. Here, we extend the concepts associated with zone refinement of crystalline materials to soft templated mesoporous carbon films based on the cooperative assembly of commercial non-ionic surfactants (block copolymers) and phenolic resin oligomers (resol) to provide macroscopic alignment of both cubic (FDU-16) and hexagonal (FDU-15) mesostructures. The average orientation of these mesophases is determined from rotation grazing incidence small angle X-ray scattering (GISAXS) measurements. For FDU-15 templated by Pluronic P123, the orientation factor for the zone-annealed film is 0.98 based on the average of the second Legendre polynomial, but this orientation deteriorates significantly during carbonization. Notably, a thermal stabilization step following zone annealing preserves the orientation of the mesostructure during carbonization. The orientation factor for an isotropic cubic structure (FDU-16 templated by Pluronic F127) is only 0.48 (based on the 111 reflection with incident angle 0.15°) for the same zone annealing protocol, but this illustrates the versatility of zone annealing to different mesostructures. Unexpectedly, zone annealing of FDU-15 templated by Pluronic F127 leads to stabilization of the mesostructure through carbonization, whereas this structure collapses fully during carbonization even after extended oven annealing; despite no clear macroscopic orientation of the cylindrical mesostructure from zone annealing. Thermal zone annealing provides a simple methodology to produce highly ordered and macroscopically oriented stable mesoporous carbon films, but the efficacy is strongly tied to the mobility of the template during the zone annealing.

Advanced oxidation of the commercial nonionic surfactant octylphenol polyethoxylate Triton™ X-45 by the persulfate/UV-C process: effect of operating parameters and kinetic evaluation.

This study explored the potential use of a sulfate radical (SO·−4)-based photochemical oxidation process to treat the commercial nonionic surfactant octylphenol polyethoxylate (OPPE) Triton™ X-45. For this purpose, the effect of initial S2O2−8 (0–5.0 mM) and OPPE (10–100 mg/L) concentrations on OPPE and its organic carbon content (TOC) removal were investigated at an initial reaction pH of 6.5. Results indicated that very fast OPPE degradation (100%) accompanied with high TOC abatement rates (90%) could be achieved for 10 and 20 mg/L aqueous OPPE at elevated S2O2−8 concentrations (≥2.5 mM). S2O2−8/UV-C treatment was still capable of complete OPPE removal up to an initial concentration of 40 mg/L in the presence of 2.5 mM S2O2−8. On the other hand, TOC removal efficiencies dropped down to only 40% under the same reaction conditions. S2O2−8/UV-C oxidation of OPPE was also compared with the relatively well-known and established H2O2/UV-C oxidation process. Treatment results showed that the performance of S2O2−8/UV-C was comparable to that of H2O2/UV-C oxidation for the degradation and mineralization of OPPE. In order to elucidate the relative reactivity and selectivity of SO·−4 and HO·, bimolecular reaction rate coefficients of OPPE with SO·−4 and HO· were determined by employing competition kinetics with aqueous phenol (47 μM) selected as the reference compound. The pseudo-first-order abatement rate coefficient obtained for OPPE during S2O2−8/UV-C oxidation (0.044 min−1) was found to be significantly lower than that calculated for phenol (0.397 min−1). In the case of H2O2/UV-C oxidation however, similar pseudo-first-order abatement rate coefficients were obtained for both OPPE (0.087 min−1) and phenol (0.140 min−1). From the kinetic study, second-order reaction rate coefficients for OPPE with SO·−4 and HO· were determined as 9.8 × 108 M−1 s−1 and 4.1 × 109 M−1 s−1, respectively. The kinetic study also revealed that the selectivity of SO·−4 was found to be significantly higher than that of HO·.

Towards detergency in liquid CO2 – A surfactant formulation for particle release in an apolar medium

In this paper we propose, characterize and test a surfactant formulation, consisting of a branched polyoxyethylene type commercial non-ionic surfactant (Igepal CA520), n-hexane and water, for use in CO2 dry-cleaning to enhance the removal of particulate soil. In the formulation lamellar mesophases Lα coexist in an L2 microemulsion (reverse micellar) phase. We hypothesize that enhanced soil removal would be possible due to the adsorption of lamellar liquid crystalline phases at the fabric–soil interface, the presence of water pools, the improvement of the solvent quality of liquid CO2 by the presence of n-hexane, and the enhanced viscosity due to the presence of the lamellar mesophases. We have characterized the formulation by optical microscopy with crossed polarizers, confocal microscopy, dynamic light scattering and shear viscometry to determine the phase behaviour, the size of the reverse micelles and the flow behaviour. AFM force measurements in n-hexane show that large adhesion forces between a model soil particle (silica) and fabric surface (cellulose) in water-saturated hexane can be reduced by the action of the surfactant mesophases. In the presence of the surfactant formulation the interaction forces were found to be decreased from ∼15nN to 0.5nN. The formulation, applied as a pre-treatment on standard soil test monitors and followed by washing in liquid CO2, showed a five times better soil removal ability than the control.

Characterization of the Solutol® HS15/water phase diagram and the impact of the Δ9-tetrahydrocannabinol solubilization

Here, the phase behavior of the commercial non-ionic surfactant Solutol® HS15 in water was investigated. The focus was on the evolution of the system nanostructure at low water content. Particularly, it was demonstrated that spherical micelles found in dilute surfactant solutions coalesce at a surfactant volume fraction close to 0.5. As consequence, a heterogeneous pseudo-binary mixture occurs. No liquid crystalline phases were detected even at the highest HS15 concentrations in water. Alteration of the micellar morphology induced by the addition of Δ9-tetrahydrocannabinol to the surfactant/water binary system was also investigated. It was found that the cannabinoid molecules become entrapped within the surfactant hydrophobic tails, thus increasing the surfactant effective packing parameter and inducing a radical change of the micelle shape. At sufficiently low water content (18–35wt.%), such alteration of the interfacial packing results in a lamellar organization of the surfactant molecules.

Nanoemulsions containing octyl methoxycinnamate and solid particles of TiO2: preparation, characterization and in vitro evaluation of the solar protection factor

The objective of this work was to develop and evaluate the physical–chemical properties of oil-in-water nanoemulsions for application as nanocosmetics for sun protection. Oil-in-water dispersions were processed by ultrasound (US) to obtain small emulsion droplets. These emulsions were obtained in the presence of commercial nonionic surfactants based on polyoxides and avocado oil as the oil phase. The US generated small but unstable droplets. This problem was solved by using a different surfactant, with a longer ethylene oxide chain, able to promote stabilization by steric mechanisms. The light scattering technique was used to characterize the nanoemulsions by their dispersed droplets’ size, size distribution and variation of distribution with time (stability). Chemical and physical sunscreens – octyl methoxycinnamate (OMC) and titanium dioxide (TiO2), respectively – were added to the stable system. The anti-UVB activity of the nanoemulsions and their components were evaluated by the method of Mansur et al. (1986) and spectral transmittance. The solar protection factor (SPF) was proportional to the OMC and TiO2 concentrations. The in vitro OMC release was evaluated, and the presence of TiO2 in the nanoemulsion did not affect the release profile, which showed the diffusion-dependent kinetics of the active ingredient in the formulation.

Photo-Fenton degradation of non-ionic surfactant and its mixture with cationic or anionic surfactant

The oxidative degradation of non-ionic surfactants by the photo-Fenton process has been examined. The photo-Fenton degradation kinetics of mixtures of non-ionic surfactant and other type surfactants has been also investigated since mixtures of non-ionic and ionic surfactants are commonly used to utilize their synergistic effects in many practices. Effects of operating parameters such as dosages of Fenton reagents (iron and hydrogen peroxide) and UV light intensity on the degradation of commercial non-ionic surfactant Sannonic SS-90 (polyoxyethylene alkyl ether) were studied. Although the dosages of the Fenton reagents increased the degradation rate up to the optimum dosages, further addition of the reagents could not enhance the degradation rate. Excess dosages of Fe and H2O2 caused excess OH radicals which could be a scavenger of OH radicals and as a result could not enhance the degradation of the surfactant. The increase in UV light intensity resulting in the faster photo-Fenton process or the enhancement of OH radical formation rate led to the increase in degradation rate of non-ionic surfactant. Although the existence of the anionic surfactant (sodium dodecylbenzene sulphonate) would inhibit the degradation of the non-ionic surfactant due to the formation of complex with Fe ion, the existence of cationic surfactant (dodecyltrimethyl ammonium chloride) affected insignificantly the photo-Fenton degradation process of the non-ionic surfactant.

Complex Phase Behavior in the Transition Region Between Gel (L β ) and Lamellar (L α ) Phases for a Commercial Nonionic Surfactant System, C12-14EO3

Surfactant formulators are faced with many challenges during product processing and manufacture, with increased problems from the use of commercial surfactants. Commercial surfactants have a distribution of EO sizes which can dramatically affect the product properties. The gel (L β )/lamellar (L α ) phase transition of a commercial surfactant C12-14EO2.9/water system is shown to split into two, with the sequence ↔ L α being observed, where the region occurs over a ca. 10°C temperature range. In addition, both the gel and lamellar phases can incorporate at least 2–3 times more water than the pure surfactants before the formation of a separate aqueous phase. So while commerical surfactants could pose problems for formulators, they could also offer the possibility of enhanced solubilization of actives in the lamellar regions coupled with the enhanced emulsion stabilization by the gel phase.

Adsorption of Myrj 45 on copper phthalocyanine pigment nanoparticles and effect on their dispersion stability in aqueous solution

The composition of a commercial nonionic surfactant, Myrj 45, was analyzed with mass spectrometry (MS). Six classes of components, which are polyglycols, monoesters (monostearates and monopalmitates), and diesters (distearates, dipalmitates, and mixed diesters which are the diesters with stearoyl residues at one end and palmitoyl residues at the other) were detected. Each class of components shows a wide distribution of homologues. The monoesters are the dominant components in Myrj 45. The adsorption isotherm of each class of components was obtained using HPLC with a MS detector. The adsorption densities increase with increasing concentrations of each class of components up to a plateau. The monoesters adsorb the most at the same total surfactant concentration. The diesters and polyglycols also adsorb, but to a minor extent. The overall adsorption densities of Myrj 45 by taking into account the contributions from these six classes of components, are much lower than those of Triton X-100 at the same total molar concentration. The effect of Myrj 45 on the dispersion stability of the CuPc particles in pure water was studied and compared to that of Triton X-100. Upon adsorption of Myrj 45, the CuPc particles become quite hydrophilic, dispersible, and colloidally stable. Freezing/thawing and heating/cooling cycles tests suggest that the dispersions of CuPc particles with adsorbed Myrj 45 are not as stable as those with adsorbed Triton X-100. Particle aggregation primarily occurred during the freezing/thawing process. The experimental Fuchs–Smoluchowski dispersion stability ratios W exp of CuPc particles in surfactant solutions were determined from dynamic light scattering (DLS) data, for the Rayleigh–Debye–Gans (RDG) light scattering regime. The W exp-values with Myrj 45 are found to be about one order of magnitude smaller than those with Triton X-100. The zeta potentials are substantial, in the range of −16 to −46 mV, while the resulting surface charge densities and the total particle charges are quite low. Hence, electrostatic interactions are unlikely to contribute to the dispersion stabilization mechanism, which appears to be primarily steric.

Non-ionic surfactants and membrane transport of thioridazine in goldfish

Polysorbate 80, which has been widely used in studies of the effects of surfactants on drug absorption, increases the rate of absorption of some drugs at concentrations near its critical micelle concentration (cmc). To determine whether all non-ionic surfactants were capable of inducing this effect, the effects of six commercial non-ionic surfactants on thioridazine absorption in goldfish have been compared with the effect of polysorbate 80. The reciprocal death time (T-1) determined when the fish were immersed in the solution under study was the index of absoprtion rate used. Not all surfactants tested increased T-1. Cremophor EL (polyoxyethylated castor oil), Atlas G1295 (a polyoxyethylene fatty glyceride), Atlas G1300 (a polyoxyethylene glyceride ester) had no effect below their cmc's. Those surfactants that did increase T-1 [polysorbate 80 (a polyoxyethylene lanolin derivative), G2162 (a polyoxyethylene oxypropylene monosterate) and Renex 650 (a polyoxyethylene alkyl aryl ether)] display the concentration-dependent behaviour reported previously - a decrease in absorption rate when the surfactant concentration is increased above its cmc. The factor determining whether or not the surfactant will increas absorption rate appears to be the configuration of the surfactant molecule rather than its hydrophile-lipophile balance or its surface activity.

Cloud Point Extraction of Orange II and Orange G Using Neutral and Mixed Micelles: Comparative Approach Using Experimental Design

The aim of this work was to compare two synthetic dyes, Orange G (7-Hydroxy-8-(phenylazo)-1,3-naphthalenedisulfonic acid, disodium salt) and Orange II (p-(2-Hydroxy-1-naphthylazo) benzenesulfonic acid, sodium salt), towards cloud point extraction from colored water. Three commercial non-ionic surfactants were used in this work: Oxo-C15E7, Oxo-C10E3, and Triton X-100. The experimental extraction results were expressed by the following three responses: percentage of the extracted dye (E), residual concentrations of dye in the dilute phase (Xs,w), and the volume fraction of coacervate (ϕC) at the equilibrium. The results obtained for each parameter were represented on three dimensional diagrams using an empirical smoothing method. In optimal conditions Orange II concentration in the effluent was reduced to about 227 times, whereas E did not exceed 55% using Oxo-C15E7 in the case of Orange G extraction. However, when a small amount (0.025 wt.%) of cetyltrimethylammonium bromide (CTAB) was combined with Oxo-C10E3 as a mixed micelles system, the results showed that the extraction percentage of Orange G increased from 55 to 98%. Indeed, the concentration of this dye in the effluent was reduced to about 400 times. Finally, the extraction extent of both dyes was found to be low at basic pH, which may be useful for surfactant regeneration.