Nonylphenol Ethoxylate Surfactants Research Articles

Nanoparticle catalysts for proton exchange membrane fuel cells: can surfactant effects be beneficial for electrocatalysis?

Platinum (Pt) nanoparticles were prepared in aqueous dispersion using the non-ionic surfactant nonylphenolethoxylate (NP9) and the cationic surfactant tetradecyltrimethylammonium bromide (TTAB). The surfactants were added to give colloidal stability. Such species are generally considered to block electrochemical active sites and to be undesirable for the oxygen reduction reaction (ORR). However, the procedures used to remove them are likely to cause particle aggregation. The purpose of this work was to investigate the effect of surfactants on Pt ORR performance. The nanoparticles prepared using NP9 showed good oxygen reduction performance when compared with the commercial Pt/C catalyst TKK, without removing the surfactant. In contrast, Pt nanoparticles prepared using the cationic surfactant TTAB showed very poor ORR performance, exemplifying the importance of careful surfactant selection in catalyst synthesis.

Removal of surfactants nonylphenol ethoxylates from municipal sewage-comparison of an A/O process and biological aerated filters

The concentrations of nonylphenol ethoxylates (NPnEO, n=1 to 2) and nonylphenol (NP) in water and sludge samples were measured from a full scale sewage treatment plant (STP) with an Anaerobic/Oxic (A/O) and a Biological Aerated Filter (BAF) process. The A/O process was found to exhibit improved performance in comparison to the BAF process. Mean values of NP, NP1EO and NP2EO concentrations in influents from the STP were similar, ranging from 1.8 to 2.0×103ngL−1. In the A/O process, the removal efficiency of NP, NP1EO and NP2EO from the aqueous phase was 78%, 84%, and 89%, respectively. In contrast, the removal efficiencies of NP, NP1EO, and NP2EO were relatively lower for the BAF process, at 55%, 76%, and 79%, respectively. High concentrations of NP, NP1EO and NP2EO detected in the sludge samples had a maximum value of 2.7μgg−1 dw, which indicates that improvement in the overall elimination of NP, NP1EO and NP2EO may be associated with adsorption by the sludge. To further investigate the fate of NP, NP1EO and NP2EO in the STP, our research assessed the degradation characteristics of NP by calculating its transformational loss in the STP. The results demonstrate that the quantity of NP measured in the effluent from the oxic unit increased by 32%, which indicates that NP1EO and NP2EO may undergo degradation in the oxic conditions.

Modelling the fate of nonylphenolic compounds in the Seine River — part 1: Determination of in-situ attenuation rate constants

Assessing the fate of endocrine disrupting compounds (EDCs) in the environment is currently a key issue for determining their impacts on aquatic ecosystems. The 4-nonylphenol (4-NP) is a well known EDC and results from the biodegradation of surfactant nonylphenol ethoxylates (NPnEOs). Fate mechanisms of NPnEO are well documented but their rate constants have been mainly determined through laboratory experiments.This study aims at evaluating the in-situ fate of 4-NP, nonylphenol monoethoxylate (NP1EO) and nonylphenolic acetic acid (NP1EC). Two sampling campaigns were carried out on the Seine River in July and September 2011, along a 28km-transect downstream Paris City. The field measurements are used for the calibration of a sub-model of NPnEO fate, included into a hydro-ecological model of the Seine River (ProSe). The timing of the sampling is based on the Seine River velocity in order to follow a volume of water. Based on our results, in-situ attenuation rate constants of 4-NP, NP1EO and NP1EC for both campaigns are evaluated. These rate constants vary greatly. Although the attenuation rate constants in July are especially high (higher than 1d−1), those obtained in September are lower and consistent with the literature. This is probably due to the biogeochemical conditions in the Seine River. Indeed, the July sampling campaign took place at the end of an algal bloom leading to an unusual bacterial biomass while the September campaign was carried out during common biogeochemical status. Finally, the uncertainties on measurements and on the calibration parameters are estimated through a sensitivity analysis.This study provides relevant information regarding the fate of biodegradable pollutants in an aquatic environment by coupling field measurements and a biogeochemical model. Such data may be very helpful in the future to better understand the fate of nonylphenolic compounds or any other pollutants at the basin scale.

CMC Determination and Thermodynamic Micellisation Of NPE Surfactant In Aqueous And CH3OH – H2O Solvents

The critical micelle concentration (CMC) of nonylphenolethoxylate (NPE) surfactant has been determined by measuring the surface tension as a function of the molar concentration of the surfactant in aqueous and binary mixture of water + methanol solutions at a temperature range from 20?C to 35?C. The interfacial parameters ?max, Amin, ?cmc and ?G?ads were calculated. The results indicate that the CMC increases as the temperature increases and that the addition of methanol the CMC decreases. The thermodynamic parameters such as standard Gibbs free energy (?G?), enthalpy (?H?), and entropy (?S?) of micellization were estimated using the change of CMC with temperature. The enthalpy – entropy compensation behavior of the surfactant was evaluated and a good linearity in the compensation plot has been observed.

CMC Determination and Thermodynamic Micellisation Of NPE Surfactant In Aqueous And CH3OH – H2O Solvents

The critical micelle concentration (CMC) of nonylphenolethoxylate (NPE) surfactant has been determined by measuring the surface tension as a function of the molar concentration of the surfactant in aqueous and binary mixture of water + methanol solutions at a temperature range from 20?C to 35?C. The interfacial parameters ?max, Amin, ?cmc and ?G?ads were calculated. The results indicate that the CMC increases as the temperature increases and that the addition of methanol the CMC decreases. The thermodynamic parameters such as standard Gibbs free energy (?G?), enthalpy (?H?), and entropy (?S?) of micellization were estimated using the change of CMC with temperature. The enthalpy – entropy compensation behavior of the surfactant was evaluated and a good linearity in the compensation plot has been observed.

Electronic Structure and Mesoscopic Simulations of Nonylphenol Ethoxylate Surfactants. A Combined DFT and DPD Study

The aim of this work was to gain insight into the effect of ethylene oxide (EO) chains on the properties of a series of nonylphenol ethoxylate (NPE) surfactants. We performed a theoretical study of NPE surfactants by means of density functional theory (DFT) and dissipative particle dynamics (DPD). Both approximations were used separately to obtain different properties. Four NPEs were selected for this purpose (EO = 4, 7, 11 and 15 length chains). DFT methods provided some electronic properties that are related to the EO units. One of them is the solvation Gibbs energy, which exhibited a linear trend with EO chain length. DPD calculations allow us to observe the dynamic behavior in water of the NPE surfactants. We propose a coarse-grained model which properly simulates the mesophases of each surfactant. This model can be used in other NPEs applications.

Effects of a plant extract-based nematicide (G8014S) and its components on the host finding behaviour and multiplication of Globodera pallida on glasshouse-grown potatoes

In vitro and glasshouse studies were initiated to determine the mechanisms of action of an aqueous garlic extract, salicylaldehyde, a nonylphenol ethoxylate surfactant and a formulation (G8014S) containing these substances on the potato cyst nematode Globodera pallida. The effects of these substances on host finding and migration of second-stage juveniles (J2) were assessed by investigating their ability to migrate through a sand column and towards potato roots in Pluronic F-127 gel. The garlic extract was shown to be the least disruptive to J2 host finding, reducing attraction by between 13 and 24% at concentrations of 7840 μl l−1 and 983 μl l−1, respectively. By contrast, a reduction of approximately 38% in J2 attraction to roots was achieved by treating J2 with 344 μl l−1 of G8014S. Of all the substances tested, salicylaldehyde was the least attractive to G. pallida J2 (4.1%) while the garlic extract and oxamyl treatments attracted 43.5 and 28.9% J2, respectively. In glasshouse experiments, different rates of the test substances were compared with the nematicide oxamyl for their effects on the in-soil hatch, egg viability and multiplication of G. pallida. The effect of treatment with 220.16 l ha−1 of G8014S on G. pallida multiplication in the glasshouse was comparable to that of oxamyl causing a five-fold reduction in PCN multiplication relative to the water control. These results provide evidence to support the potential of the formulation for the control of G. pallida in potatoes.

Efecto del Uso de Surfactantes Polimerizables en la Distribución de Tamaño de Partícula, pH, Viscosidad, Contenidos de Sólidos y de Monómero Residual de una Resina Estireno-Butilacrilato

Results on the emulsion polymerization of a styrenated acrylic resin using polymerizable surfactants are presented. These surfactants exhibit low foaming, high film strength upon contact with water and good stability in the polymerization. A comparison was made with results for conventional non-polymerizable alkyl aryl polyglycol ether sulphate, sodium salt and nonylphenolethoxylate surfactants. The effect of these polymerizable surfactants on the particle size distribution of the resin was evaluated; in addition to determining the final properties of the resin such as solids content, free monomer content, viscosity and pH. It is feasible to totally replace non-polymerizable surfactants by the polymerizable surfactants evaluated without affecting significantly the properties of the resin, while partial substitution of the non-polymerizable surfactants induces, in some cases, the formation of particles with larger sizes than those in the standard resin.

Ultrasound-assisted cloud point extraction for the determination of sulfonamides in honey samples by fluorescence spectrophotometry

An ultrasound-assisted cloud point extraction (UA-CPE) method using nonionic surfactant nonylphenol ethoxylate (NP-7) as the extractant was developed for determination of two sulfonamides (SAs, sulfadiazine sodium and sulfamerazine) in honey samples. The procedure was based on the derivatization SAs in honey with fluorescamine yielding fluorescent complexes, which were extracted into the surfactant-rich phase and analyzed by molecular fluorescence spectrophotometry. The polar of SAs of derivatives was reduced and strong fluorescence was produced at λex = 410 nm. Variable parameters affecting the derivatization and UA-CPE procedure were evaluated and optimized. The calibration graph was linear from 10 to 10 000 ng mL−1 with coefficient of determination more than 0.9991. The limits of detection (LOD) were 0.5 ng mL−1 for sulfadiazine sodium and 5.0 ng mL−1 for sulfamerazine with the relative standard deviations of the method ranging from 2.2% to 4.1%. Recoveries of the compounds on spiked honey samples at fortified level of 1 μg mL−1 were 92.2% for sulfadiazine sodium and 84.1% for sulfamerazine, respectively. Therefore, the developed method is practical and reliable, with potential application to determine the content of SAs in honey samples.

보조계면활성제가 노닐페놀 에톡실레이트 계면활성제, 탄화수소 오일, 물로 이루어진 삼성분계의 상평형 및 동적거동에 미치는 영향

본 연구에서는 보조계면활성제 첨가가 nonylphenol ethoxylate (NP) 계면활성제, 물, 탄화수소 오일의 3성분으로 이루어진 시스템의 평형 및 동적 거동에 미치는 영향을 살펴보았다. 실험에서 사용한 펜탄올, 옥탄올, 데칸올 등의 보조계면활성제는 모두 소수성 첨가제로 작용하였으며, 소수성 증가 효과는 알코올의 사슬 길이 증가 및 첨가량 증가에 따라 증가하였다. 계면활성제 시스템이 친수적인 조건에서는 비극성 오일의 종류에 상관없이 시간에 따라 오일의 크기가 감소하였으며, 마이셀 용액에 의한 탄화수소 오일의 가용화는 diffusion-controlled 메커니즘이 아닌, interface-controlled 메커니즘을 따름을 확인할 수 있었다. 반면에 소수성 조건에서는 과포화로 인하여 일어나는 자발적 유화 현상과 물과 계면활성제의 오일상으로의 확산으로 인한 오일의 크기 증가가 관찰되었다. 비극성 탄화수소 오일과 계면활성제 수용액 사이의 시간에 따른 계면장력 측정 결과는 동적 거동 실험결과와 일치하는 경향을 나타내었다. 한편 middle-phase 마이크로에멀젼을 포함한 3상이 형성되는 조건에서는 매우 낮은 계면장력으로 인하여 오일이 수용액 상에 빠른 속도로 가용화되었고 작은 방울 형태로 유화되었다. In this study, the effects of cosurfactant on phase equilibrium and dynamic behavior were studied in systems containing nonylphenol ethoxylate (NP) surfactant solutions and nonpolar hydrocarbon oils. All the cosurfactants used during this study such as n-pentanol, n-octanol and n-decanol acted as a hydrophobic additive and the hydrophobic effect was found to increase with both increases in chain length and amount of addition of a cosurfactant. Dynamic behavior studies under hydrophilic conditions showed that the solubilization of hydrocarbon oil by NP micellar solution is controlled by an interface-controlled mechanism rather than a diffusion-controlled mechanism. Both spontaneous emulsification of water into oil phase and expansion of oil drop were observed under lipophilic conditions because of diffusion of surfactant and water into oil phase. Under conditions of a three phase region including a middle-phase microemulsion, both rapid solubilization and emulsification of oil into aqueous solutions were found mainly due to the existence of ultralow interfacial tension.

CO2-Soluble, Nonionic, Water-Soluble Surfactants That Stabilize CO2-in-Brine Foams

Summary Several commercially available and a few experimental, nonionic surfactants were identified that are capable of dissolving in carbon dioxide (CO2) in dilute concentration at typical minimum- miscibility-pressure (MMP) conditions and, upon mixing with brine in a high-pressure windowed cell, stabilizing CO2-in-brine foams. These slightly CO2-soluble, water-soluble surfactants include branched alkylphenol ethoxylates, branched alkyl ethoxylates, a fatty-acid-based surfactant, and a predominantly linear ethoxylated alcohol. Many of the surfactants were between 0.02 to 0.06 wt% soluble in CO2 at 1,500 psia and 25°C, and most demonstrated some capacity to stabilize foam. The most- stable foams observed in a high-pressure windowed cell were attained with branched alkylphenol ethoxylates, several of which were studied in high-pressure small-angle-neutron-scattering (HP SANS) tests, transient mobility tests using Berea sandstone cores, and high-pressure computed-tomography (CT)-imaging tests using polystyrene cores. HP SANS analysis of foams residing in a small windowed cell demonstrated that the nonylphenol ethoxylate SURFONIC® N-150 [15 ethylene oxide (EO) groups] generated emulsions with a greater concentration of droplets and a broader distribution of droplet sizes than the shorter-chain analogs with 9–12 ethoxylates. The in-situ formation of weak foams was verified during transient mobility tests by measuring the pressure drop across a Berea sandstone core as a CO2/surfactant solution was injected into a Berea sandstone core initially saturated with brine; the pressure-drop values when surfactant was dissolved in the CO2 were at least twice those attained when pure CO2 was injected into the same brine-saturated core. The greatest mobility reduction was achieved when surfactant was added both to the brine initially in the core and to the injected CO2. CT imaging of CO2 invading a polystyrene core initially saturated with 5 wt% KI brine indicated that despite the oil-wet nature of this medium, a sharp foam front propagated through the core, and CO2 fingers that formed in the absence of a surfactant were completely suppressed by foams formed because of the addition of nonylphenol ethoxylate surfactant to the CO2 or the brine.

Study of the Structures of Carbon Foams Synthesized Using Non-Ionic Surfactants

Non-ionic nonylphenol ethoxylate surfactants containing 4, 6, 9 or 12 ethylene oxide residues per mole of nonylphenol were successfully used as templates for the synthesis of large-pore mesoporous carbon foams. The effects of surfactant type, foam resin precursor (phenol/formaldehyde/ethanol), temperature, thermal stability and the number of ethylene oxide residues per mole of nonylphenol on the resulting mesoporous carbon foams were studied in detail. The mesoporous carbon foams were characterized using several techniques, including scanning electron microscopy and nitrogen adsorption/desorption analysis. The present work showed that the number of ethylene oxide units on the surfactant template strongly affected the pore diameter and that the pore diameter, in turn, depended strongly on the heating time and temperature.

Nonylphenol polyethoxylate in hospital wastewater: A study of the subproducts of electrocoagulation

Chromatographic procedures such as solid phase extraction and high performance liquid chromatography coupled with a fluorescence detector (SPE-HPLC-FLD), were carried out to determine the concentrations of the surfactant nonylphenol ethoxylate (9 ethylene oxide units, NP9EO) and its biodegradation product, 4-nonylphenol (NP), in samples collected from the wastewater treatment system at the University Hospital (HUSM) of the Federal University of Santa Maria. The results showed a high concentration of NP9EO in all the collected samples (0.075 – 4.12 mg L−1) and an almost complete absence of NP. In addition, electrocoagulation (EC) of NP9EO was carried out in aqueous solution and in the HUSM effluent. A NP9EO removal rate of 95 % was achieved from the aqueous solution, following a pseudo-first-order kinetics. Through LC-MS measurements in aqueous solutions, it was possible to determine the formation of short-chain nonylphenol ethoxylate (NPEO), such as nonyl-phenoxy acetic acid (NP1EC), after 30 min of EC. In the case of the HUSM wastewater, the NP9EO removal was 89 %, and the chemical oxygen demand (COD) abatement was 26 %. A respirometric test was conducted to measure the increase of biodegradability during the EC and the aqueous samples were found to be less readily biodegradable before the 30-min period of electrocoagulation than after it had been completed.

In vitro nematicidal activity of a garlic extract and salicylaldehyde on the potato cyst nematode, Globodera pallida

AbstractThe in vitro nematicidal effects of an aqueous garlic extract, salicylaldehyde, a nonylphenol ethoxylate surfactant and a formulation containing these constituents were evaluated against the potato cyst nematode, Globodera pallida. Newly hatched, infective second-stage juveniles (J2) were placed for 24, 48 and 72 h in solutions containing concentrations of the formulation from 30.080.0 μl l–1 with 20% (v/v) potato root leachate and sterile distilled water controls. The garlic extract, salicylaldehyde and surfactant treatments were assessed at concentrations proportional to their occurrence in the formulation. Hatching assays involved a series of experiments in which G. pallida cysts were incubated for 8 weeks in potato root leachate solution containing different concentrations of the test substances. A second set of experiments involved incubating cysts in different concentrations of the test substances for 2, 4 and 8 weeks prior to hatching in potato root leachate solution to determine how prior exposure to these substances influences hatching and in-egg viability. The formulation caused 100% mortality at 75.0 μl l–1 with an LC50 of 43.6 μl l–1 after 24 h exposure. Salicylaldehyde was the most toxic constituent of the formulation with an LC50 of 6.5 μl l–1 after 24 h, while the garlic extract achieved 50% J2 mortality at 983.0 μl l–1, demonstrating that the formulation and salicylaldehyde are more toxic to G. pallida in vitro than oxamyl but less toxic when compared with aldicarb. The surfactant showed no dose-dependent toxic effects on J2 when compared with the controls. Emergence of J2 from the cysts was significantly reduced by concentrations of the formulation above 688.0 μl l–1 and its equivalent concentration of salicylaldehyde, while concentrations of the formulation above 2752.0 μl l–1 and the corresponding salicylaldehyde concentrations resulted in complete irreversible hatch inhibition. Concentrations of the garlic extract below 137.6 μl l–1 caused 26% more J2 hatch in comparison to the potato root leachate solution. This study has shown that salicylaldehyde is more toxic to nematodes than the garlic extract, and is the first report of a hatch stimulatory effect of a garlic extract on G. pallida under in vitro conditions.

Bioaccumulation and Bound-Residue Formation of a Branched 4-Nonylphenol Isomer in the Geophagous Earthworm Metaphire guillelmi in a Rice Paddy Soil

Nonylphenols (NPs) are the breakdown products of the nonionic surfactants nonylphenol ethoxylates and are toxic pollutants. Here we studied the bioaccumulation, elimination, and biotransformation of NP (12.3 mg kg(-1) soil dry weight) in a typical Chinese geophagous earthworm, Metaphire guillelmi, in a rice paddy soil, using 4-[1-ethyl-1,3-dimethylpentyl]phenol (4-NP(111)), the main constitute of technical NP, radiolabeled with (14)C. Earthworms rapidly bioaccumulated (14)C-4-NP(111) following a two-compartment first-order kinetics model. At steady state (after 20 days exposure), the normalized biota-soil accumulation factor amounted to 120, and 77% of the accumulated radioactivity were present as nonextractable bound residues. The total radioactivity was eliminated from the earthworm following an availability-adjusted decay model and controlled by the elimination rate of the bound residues (half-life = 22.6 days). The extractable residues consisted mainly of one less-polar metabolite (37%) and polar compounds (50%), including glucuronide conjugates of 4-NP(111) and the metabolite; and free 4-NP(111) accounted for only 9% of the total extractable residues. This study provides the first results of the toxicokinetics and biotransformation of 4-NP in a terrestrial organism, and underlines the significant underestimation of the bioaccumulation and risk assessment based only on free NP in earthworms.

Nonylphenol Ethoxylate Plastic Additives Inhibit Mitochondrial Respiratory Chain Complex I

The first and major entry point of electrons into the mitochondrial respiratory chain (MRC)1 occurs through NADH-coenzyme Q reductase (complex I). Decreased complex I activity is associated with a wide range of conditions, including inherited mitochondrial diseases and neurodegenerative conditions such as Parkinson disease (1)(2). More than 60 natural and commercial compounds are reported to inhibit complex I activity, among them certain pesticides, agrochemicals, and MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), a neurotoxin that induces parkinsonism in humans; thus, exposure to these compounds may be harmful(3). We report here that nonylphenol ethoxylate (NP) surfactants leach from disposable laboratory plasticware and inhibit mitochondrial complex I. During a routine diagnostic workup designed to diagnose mitochondrial diseases from patients’ muscle biopsy samples, we observed a substantial (50%–66%) decrease of mitochondrial enzymatic activities related to complex I compared with historical values determined spectrophotometrically in our laboratory. Furthermore, a 71% decrease in complex I–dependent oxygen consumption was also observed with glutamate + malate as substrates (Oxygraph, Hansatech Instruments) (2). Notably, other MRC activities, as well as citrate synthase, a mitochondrial marker enzyme, were largely unaffected. It was determined that inhibition resulted from a single brief period of contact between assay reagents and blue polypropylene 1-mL pipette …

Sonochemical synthesis of Au– [formula omitted] nanoparticles for the sonophotocatalytic degradation of organic pollutants in aqueous environment

Au– TiO 2 photocatalysts were sonochemically prepared by three different procedures and their photocatalytic and sonophotocatalytic efficiencies were evaluated by studying the degradation of a representative organic pollutant, nonylphenol ethoxylate (NPE) surfactant in aqueous solutions. In the first procedure, Au– TiO 2 nanoparticles were prepared by depositing sonochemically synthesized gold nanoparticles on Degussa P25 TiO 2 by stirring in the absence of an ultrasonic field. In the second procedure, Au nanoparticles were sonochemically synthesized and simultaneously deposited on Degussa P25 TiO 2 particles. In the third procedure, Au– TiO 2 nanoparticles were sonochemically synthesized by the simultaneous irradiation of an aqueous solution containing AuCl 4 - and titanium tetraisopropoxide. The prepared nanoparticles were characterized by UV–vis spectroscopy and transmission electron microscopy (TEM). The catalytic activities of these nanomaterials were compared for the degradation of a polydisperse nonylphenol ethoxylate, Teric GN9 by photocatalysis and sonophotocatalysis under visible light/high frequency ultrasound irradiation. The catalysts did not show a synergetic effect towards the sonophotocatalytic degradation of Teric GN9. This might be due to the interference of the degradation products generated during the simultaneous irradiation by light and ultrasound.

Formation of Single-Phase Microemulsions in Toluene/Water/Nonionic Surfactant Systems

Mixtures of toluene and water from 5 to 50% oil fraction and 5 to 25% surfactant by weight were studied. Winsor Type IV microemulsions were formed in numerous cases. Review of partial ternary phase diagrams for these systems indicated the area of single-phase microemulsion with toluene could be maximized at an hydrophilic-lipophilic balance (HLB) of approximately 14.5. Select single-phase samples were further analyzed by surface tension and dynamic light scattering techniques, which allowed a detailed characterization of the solution equilibrium thermodynamics and size stability. Particle sizes averaged approximately 5 nm and were nearly constant over a wide variety of conditions and for 6-18 months. When benzyl alcohol was used instead of toluene, the optimum HLB for the formation of single-phase systems was found to have a lower limit of 17. Particle sizes in these systems were <30 nm but showed greater variability. The decrease in particle size as surfactant concentration increased was determined to be associated with changes in ethlyene oxide chain conformation. The increase in particle size due to swelling with increased oil concentration was used to determine the surfactant surface area in the oil phase. A detailed comparison of alkylamine ethoxylate to octyl- and nonylphenol ethoxylate surfactants in terms of micelle thermodynamics, size, and stability indicate that the alkylamine-based surfactants are potential candidates for the replacement of nonylphenol-based surfactants in some systems with a more polar oil phase like benzyl alcohol.

The HLD–NAC equation of state for microemulsions formulated with nonionic alcohol ethoxylate and alkylphenol ethoxylate surfactants

The net–average curvature (NAC) model ( Langmuir, 19, 186, 2003) is a simple, yet powerful, equation of state to fit and predict the phase behavior of microemulsions (μEs) formulated with ionic surfactants. However, its use for nonionic surfactants systems has not been evaluated until now. The objective of this work is to use the NAC equation of state to model the phase behavior of μEs formulated with pure alcohol ethoxylate (CiEj) and commercial nonylphenol ethoxylate (NPEj) surfactants with a range of alkanes (Cn). The NAC model requires three basic parameters: the characteristic curvature of the nonionic surfactant (Ccn), the characteristic length ( ξ), and the scaling length parameter ( L). The first part of this contribution presents a brief review of the NAC model and other thermodynamic models of μEs. Later, five example applications of the NAC model are presented and discussed: (I) fit/prediction of phase inversion temperature (PIT) values, (II) prediction of phase transition temperatures and characteristic lengths, (III) fit/prediction of interfacial tensions, (IV) prediction of “fish” phase diagrams, and (V) prediction of the composition of bicontinuous systems. The NAC model was able to fit the phase behavior observed in all the experimental scenarios, and predict within 30% the value of phase volumes and transition temperatures for CiEj systems. The largest deviations can be attributed to a poor estimation of ξ obtained through empirical correlations. It was also noted that for commercial NPEj surfactants, the NAC model can also fit and predict the phase behavior of these systems, only that more complex empirical correlations are needed for ξ and Ccn due to the partition of different surfactant n-mers into the excess oil and aqueous phases. In all cases, a good agreement was found when the length parameter ( L) was estimated as 1.4 times the extended length of the surfactant tail.

Treatability of Nonylphenol Ethoxylate Surfactants in On‐Site Wastewater Disposal Systems

The fate of nine-mole nonylphenol ethoxylate (NPE9) discharged to an on-site wastewater disposal (septic) system was the focus of a 2-year investigation. Known amounts of NPE9-based detergent were metered daily into the plumbing at a single-family household. The ethoxylate-containing wastewater was discharged to the highly anoxic environment of a 4500-L septic tank before distribution to the oxic subsurface via 100 m of leach line. After 180 days of injecting detergent to the septic system, periodic soil pore water and/or groundwater samples were collected and analyzed for nonylphenol ethoxylates (NPEs), nonylphenol ether carboxylates, and nonylphenol. The NPE9 and degradation intermediates that were measured were reduced by 99.99% on a molar basis. An 18% reduction in molar concentration within the septic tank was observed. This was followed by a further 96.7% reduction of molar concentration within the leach lines. As the pore water migrated through the vadose zone, an additional 99.69% reduction in molar concentration was measured between the bottom of the leach lines (leach line effluent) and the lowest vadose zone monitoring location. The results obtained from these analyses indicate that degradation of the surfactant occurs within the anoxic portion of the disposal system with continued rapid biodegradation in the oxic unsaturated zone. Only trace amounts of degradation residuals were detected in soil pore water. The concentration and distribution of various degradation intermediates with respect to location, time, and ambient physical conditions were evaluated. Rapid and systematic degradation of NPE in on-site wastewater disposal systems was documented.