Search

Abstract Surfactant chemistry can affect the phenolic foam (PF) properties by controlling the collision and combination of the created bubbles during foam production. The study was accomplished using two surfactant families, nonionic: polysorbate (Tween80) and anionic: sodium and ammonium lauryl sulfates (SLS30 and ALS70) and sodium laureth sulfate (SLES270) to manufacture PF foams. Tween80 and SLS30 resulted in foams with the lowest and highest densities, 20.2 ± 0.2 and 42.72 ± 0.4 kg/m3, respectively. All the surfactants created an open-cell morphology, except Tween80 with a semi-open-cell structure consisting of large cells and thicker cell wall thickness. The anionic surfactant had better performance, the foams made by SLS30 had cells with diameters of 338.5 ± 18.5 and cell density of 2.5 cell/mm3 × 105. While the SLES270 made foam with the highest cell density and the smallest cell size that caused higher compressive strength. The SLES270 led to keeping the foam flexibility even under the fire exposition, and it increased the thermal insulation by 50% while the other samples were turned into fragile foam. A higher level of polarity in SLES270 caused better micelle production and then better bubble formation, followed by the bubble coalition.

Abstract The increasing demand for corrosion prevention strategies that are both effective and sustainable is part of the research the background. Nonionic surfactants offer a potential replacement for traditional corrosion inhibitors. These surfactants are well-known for their low toxicity and biodegradability. The research involved conducting experimental tests (such as weight loss, polarization and impedance spectroscopy) and theoretical computations to investigate the role of nonionic surfactant (polyoxyethylene (7) tribenzyl phenyl ether) (PETPE) in controlling the corrosion of mild steel in hydrochloric acid (1.0 M HCl) environment. The results of the study demonstrated that PETPE exhibited significant corrosion inhibition properties for mild steel in HCl solution. The inhibition efficiency of PETPE was found to increase with increasing PETPE concentration. PETPE is an excellent corrosion inhibitor because it significantly reduces the rate of corrosion, as seen by the notable inhibition efficiency result (95.4%) at a relatively low dose of PETPE (100 ppm). Thermodynamic studies were used to discuss the fundamental mechanisms that control PETPE-acid interactions. The adsorption process followed Langmuir adsorption isotherm, indicating a monolayer adsorption of the PETPE on the mild surface. Theoretical computations confirm the strong inhibition behavior of PETPE. The innovative feature of this research is its comprehensive strategy, which integrates experimental studies and theoretical simulations to evaluate the impact of PETPE on the corrosion control of mild steel in hydrochloric acid. The combined effort has the ability to supply valuable knowledge into the mechanisms of corrosion that will lead to the establishment of powerful corrosion control strategies.

Abstract The Museum of Sun Yat-sen University houses a collection of antique glass slides dating back to the 1940s. These historical artifacts not only serve as a record of the past but also bring history to life. During extended storage, the emulsion layer on glass slides may harden and become brittle, leading to cracking and buckling. This study suggests a method to enhance the physical property of the emulsion layer by using a combination of nonionic surfactant isomeric alcohol ethoxylates eight (TO-8) and waterborne epoxy resin (WER). We investigated the microscopic action mechanism of the two on the emulsion layer of glass slides using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), water contact angles, and other techniques. Our study revealed that TO-8 can significantly eliminate the spherulitic crystal structure of the emulsion layer, as well as improve its softness and hydrophilicity. The addition of the WER ensures that the cracking and warping of the emulsion layer film is fully corrected, resulting in a flat surface. Additionally, the size of the emulsion layer film remains stable even after wetting. The WER has minimal impact on the image information of glass slides. The emulsion layer of the glass slides, restored using the softening protection solutions developed in this study, showed almost full recovery of image information. This research holds significant theoretical and practical value for repairing cracked and warped emulsion layers on glass slides.

The polymerization of aniline hydrochloride by inverse microemulsion in a batch process and the semicontinuous process was studied as a function of the surfactant ionic and nonionic. Polymerizations were carried out at 60°C for 4 h with a yield polymer of circa 67 and 27% wt. for ionic and nonionic surfactants. The conductivity of synthesized polyaniline by the semicontinuous process is higher up to three orders of magnitude than that of the batch process for both surfactants. The calculating degree of oxidation by UV-Vis showed the relative intensities of the quinoid to benzenoid unit around one. The morphology was determined by Scanning Electron Microscopy (SEM) and observed that the formation of the different morphologies is due to the self-assembly behavior of surfactant. The diameter z-average particle size (Dz) was studied by Transmission Electron Microscopy (TEM), which determined that the diameter particle in a semicontinuous state is larger than the one produced in a batch; this is due to the control of monomer addition in the system. These findings suggest that the polymerization process and the type of surfactant influence the properties of polyaniline.

The Hetao Irrigation District, situated in the Northwest of China, serves as a significant commercial grain base. Widespread use of atrazine, an herbicide in the region, has resulted in significant environmental issues, impacting the ecosystem equilibrium and sustainable agricultural development. The co-adsorption of the globally employed atrazine herbicide along with two nonionic surfactants, Tween-80 and Brij30, onto soils treated with HCl and H2O2 was investigated. The study revealed that the adsorption isothermal curves of surfactants on soil adhered to a two-stage adsorption model. Various types of adsorption isothermal curves, such as S-type or L-type, influenced the adsorption capacity of atrazine on the soil. Observations indicated that S-type or L-type isothermal curves of surfactants interconverted with alterations in soil polarity. Moreover, it has been uncovered that the adsorption properties of Tween 80 in the soil are intricately connected to its ability to elute atrazine within the same soil. This discovery provides theoretical support for a prudent reduction in herbicide usage in the Hetao Irrigation District in the upcoming years.

The aims of this work are to study the rheological behaviors of a microemulsion of Glucopone–water–hydrocarbon systems and to use a fractional model to describe several experimental results of these systems. Four different types of hydrocarbons were considered. The frequency dependent storage, G′, and loss modulus, G″, were investigated below the critical strain. The critical strain was found to decrease as the alkane chain lengths increased, while the opposite behavior was observed for zero shear viscosity, η0. Most of the microemulsions exhibited stable elastic fluid behavior (G′ > G″) below 10 rad s−1 angular frequency. For all systems, elastic modulus values were found to be greater than loss modulus in the frequency range studied, indicating more elastic behaviors. Shear-thinning behaviors were observed, and the complex viscosity decreased with an increase in hydrocarbon chain lengths. The effects of hydrocarbon types on the rheological behaviors were more profound in the dodecane systems which showed maximum values of G′ and η0. The Friedrich–Braun model was introduced and was used to describe several experimental results on Alkyl polyglocoside solutions. Fractional rheology successfully described the viscoelastic phenomena in Glucopone surfactant solutions and the comparisons between the experimental results and the theoretical predictions were found to be satisfactory.

A simple and fast Cloud Point Extraction (CPE) preconcentration of Acid Blue 29 (AB 29) dye was developed prior to its spectrophotometric determination. The suggested procedure was successfully applied for the determination of AB 29 dye in different water samples with high recoveries. Optimization of experimental conditions such as surfactant type and volume, pH, stirring, and centrifugation conditions were studied. The effect of interfering ions was also studied. The calibration curve was in the range of 0.4-10 µgmL-1 with a limit of detection and limit of quantitation of 0.35 and 1.1 µgmL-1, respectively. Furthermore, the method is free of the interference of common ions present in water.

Abstract Al self‐corrosion in alkaline electrolytes is a critical issue that restricts the practical application of alkaline Al‐air batteries. To inhibit Al self‐corrosion, a hybrid of nonionic surfactant (branched alkyl glycoside, abbreviated as BAG) and ZnO is developed. Hydrogen evolution test, potentiodynamic polarization, and electrochemical impedance spectroscopy are performed to investigate the corrosion behavior of the Al electrode in inhibitor‐containing solutions. The findings show that the hybrid inhibitor successfully inhibits Al self‐corrosion, with an inhibition efficiency of 85.7 %. SEM and FTIR are employed to analyze the corrosion surface. It reveals the formation of the glucoside‐Al and glucoside‐Zn bonds on Al surface. As a result, the synergistic effect between BAG and ZnO is presented. The results of galvanostatic discharges demonstrate that the BAG/ZnO hybrid can improve the discharge performances of Al‐air batteries. The specific capacity at 20 mA cm−2 reaches 2396 Ah kg−1, with a high anode utilization efficiency of 80.4 %.

The aim of this research is to study the effect of hydrophilic silica nanoparticles, sizes as CO2 foam stabilizer in the presence of nonionic TX100 surfactant. Two nanosilica sizes, 15 and 70 nm, have been examined thoroughly. Physisorption of TX100 on silica nanoparticles (nanosilica) was characterized by adsorption isotherm and surface tension measurement, while CO2 foams stability was quantified based on their foamability, foam stability, particle partitioning in the foams, and bubble sizes. Results show that direct contact of TX100 with nanosilica does altered the wettability of hydrophilic nanosilica surface, enable them to lengthen CO2 foams life at certain surfactant and nanoparticles concentrations. For 15 nm nanosilica, CO2 foam stability shows excellent performance at 0.1 and 0.5 wt% TX100 concentrations. As for 70 nm nanosilica, CO2 foam demonstrates longer lifetime at much lower TX100 concentration, 0.01 wt%. Without the presence of TX100, CO2 foams exhibit undesirable lifetime performances for both nanosilica sizes. Nanosilica partitioning in CO2 foams structures demonstrate consistent relation with contact angle measurement. Estimated bubble sizes shows insignificant effect on CO2 foams life. With the assists of nanosilica and TX100, enhanced oil recovery via CO2 foam injection succeeds in increasing oil production by 13–22% of original oil-in-place (OOIP).

Abstract The development of new environmentally-friendly cutting fluids is an important technological advancement. The aim of this study was to assess the tribological behavior of microemulsions (W/O) developed with epoxidized soybean oil and nonionic surfactants with different degrees of ethoxylation (NP4EO, NP6EO and NP9.5EO). The tribological performance of the microemulsion systems was assessed in a High Frequency Reciprocating Rig (HFRR) tribometer. Microemulsions showed Newtonian fluid behavior, with viscosities compatible with conventional cutting fluids. In addition, contact angle values above 90º indicate spherical-shaped drops on the surface on which they are deposited, due to their hydrophobic nature. The microemulsions formulated using surfactants with lower ethoxylation numbers and 20% concentration exhibited greater stability, lower viscosity and better friction reduction during tribological contact between surfaces, given that the average wear scar diameter was 118 µm with smooth surfaces exhibiting slight slippage wear caused by abrasion, as identified by SEM/EDS analyses.

Objectives. This study investigated the surface properties and micelle formation of combined stabilizers, which are a mixture of ionic and nonionic surfactants or different nonionic surfactants, to establish a correlation between the composition of stabilizers and the colloidal–chemical properties of direct emulsions obtained in their presence.Methods. The surface tension at the interface between the aqueous solutions of the combined stabilizers with air and toluene was measured using a digital tensiometer. The sedimentation stability of the emulsions was assessed by the volume of the exfoliated water and oil phases for seven days. The particle sizes of the dispersed phase were determined using an Olympus CX3 bright field microscope equipped with a universal serial bus video camera connection. The rheological properties of the emulsions were evaluated using a rotary viscometer.Results. According to the isotherms of the surface tension of aqueous surfactant solutions at the interface with air and toluene at emulsion preparation temperatures of 50 °C and 65 °C, a mixture of nonionic surfactants exhibited a higher surface activity and lower critical micelle concentration at the interface with toluene. The optimal amount of stabilizers providing stability to the compositions for one month was 4 mass % for a mixture of anionic surfactants and nonionic surfactants and 7 mass % for mixtures of different nonionic surfactants. Emulsions obtained in the presence of a mixture of anionic and nonionic surfactants exhibited higher kinetic sedimentation stability values due to the formation of electrostatic and steric stabilization factors in the system. The developed compositions were microheterogeneous systems, the average droplet diameter of which varied within the range of 1.0–5.7 µm. In terms of rheological properties, emulsions were classified as liquid-like structured systems with coagulation structures; the strength of single contacts between particles of the dispersed phase was (1.6–27.0) × 10-10 N. Conclusions. A comparison of the physicochemical characteristics of the compositions obtained in the presence of organic emulsifiers showed that emulsions stabilized using a mixture of ionic and nonionic surfactants, which form mixed adsorption layers, exhibited the best set of properties.

Microemulsions are nanocolloidal systems composed of water, an oil, and a surfactant, sometimes with an additional co-surfactant, which have found a wide range of practical applications, including the extractive removal of contaminants from polluted water. In this study, microemulsion systems, including a nonionic surfactant (Brij 30), water, and esters selected from two homologous series of C1–C6 alkyl acetates and ethyl C1–C4 carboxylates, respectively, were prepared by the surfactant titration method. Phase transitions leading to the formation of Winsor II and Winsor IV microemulsions were observed and phase diagrams were constructed. The dependences of phase transitions on the salinity and pH and the addition of isopropanol as a co-surfactant were also investigated. Some physical properties, namely density, refractive index, electrical conductivity, dynamic viscosity, and particle size, were measured for a selection of Winsor IV microemulsions, providing further insight into some other phase transitions occurring in the monophasic domains of phase diagrams. Finally, Winsor II microemulsions were tested as extraction solvents for the removal of four tricyclic antidepressant drugs from aqueous media. Propyl acetate/Brij 30/H2O microemulsions provided the best extraction yields (>90%), the highest Nernst distribution coefficients (~40–88), and a large volumetric ratio of almost 3 between the recovered purified water and the resulting microemulsion extract. Increasing the ionic strength (salinity) or the pH of the aqueous antidepressant solutions led to an improvement in extraction efficiencies, approaching 100%. These results could be extrapolated to other classes of pharmaceutical contaminants and suggest ester- and nonionic surfactant-based microemulsions are a promising tool for environmental remediation.

The aim of this study was to develop a chromatographic method for 4-NP determination in anaerobic batch reactors using low amount of organic solvents and also evaluate 4-NP degradation in the presence of different co-substrates. Chromatographic parameters was improved for stationary phase (C-8 column), mobile phase (acetonitrile/water solution 90:10, v:v), column temperature (40 ºC), eluent flow (0.8 mL min-1), injection volume (100 µL) and wavelengths in fluorescence detector (FLD) (λex=225 nm and λem=305 nm). Solid phase extraction (SPE) was performed for sample purification with smaller amount of solvents (methanol - 2 mL and ethanol - 1 mL) than previously reported. Reduction in reagent consumption was about 5.5 times for HPLC and about 19 times for SPE, according to previously reported. Method was validated according to the linearity (0.9951), selectivity and limits of detection and quantification were 15.7 µg L-1 and 55.6 µg L-1, respectively. The 4-NP removal in anaerobic batch reactors was higher than 50% (4-NP initial concentration of 398 µg L-1). Fumarate was a better co-substrate to favor methanogenesis in the presence of 4-NP, which provided higher organic matter removal, higher methane production speed and shorter start-up time for methane production.

Owing to their surface active properties, surfactants have numerous applications in different fields of life. In the present research work, the solubilization of reactive red 2 (RR2) has been studied in single and mixed micellar systems (MMS) using UV-visible spectroscopy and electrical conductivity measurements. The interaction of RR2 with ionic micelles of cetylpyridinium chloride (CPC) was investigated. In order to probe the interaction of RR2 in MMS, mixtures of CPC and TX-114 (Triton X-114, a nonionic surfactant) were used. UV-visible spectroscopy has been used to obtain the degree of solubilization of RR2 in terms of the partition coefficient (Kc) and Gibbs free energy of partitioning (ΔG°p). Electrical conductivity data have been employed to detect the critical micelle concentration (CMC) of the surfactant systems in the presence of RR2 and, accordingly, to calculate the thermodynamic parameters of the micellization. From the obtained data, it is concluded that the micellization is spontaneous at all studied temperatures. Moreover, the micellization was observed to be driven by both enthalpy and entropy. The results also indicated that MMS have better solubilizing power than single micellar solutions.

Microbial fermentation with immobilized cells possesses many advantages. However, this fermentation mode is restricted to the production of extracellular products. Our previous study demonstrated that the extractive fermentation of Monascus spp. in nonionic surfactant micelle aqueous solution can export Monascus pigments that are supposed to be mainly intracellular products to extracellular culture broth and, in the meantime, extracellularly enhance the production of yellow pigments at a low pH condition; consequently, this makes the continuous production of yellow pigments with immobilized Monascus cells feasible. In this study, immobilized-cell fermentation and extractive fermentation in Triton X-100 micelle aqueous solution were successfully combined to continuously produce Monascus yellow pigments extracellularly. We examined the effects of cell immobilization and Triton X-100 on cell growth, pigment production, and pigment composition. In the repeated-batch extractive fermentation with immobilized cells, the biomass in Ca-alginate gel beads continued to grow and reached 21.2 g/L after seven batches, and dominant yellow pigments were produced extracellularly and stable for each batch. The mean productivity of the extracellular yellow pigments reached up to 22.31 AU410 nm/day within the first four batches (13 days) and 19.7 AU410 nm/day within the first seven batches (25 days). The results also provide a new strategy for producing such intracellular products continuously and extracellularly.

A polyacrylamide polysaccharide hydrogel (PASG) containing a nonionic surfactant of the polyoxyethylene nonylphenyl ethers series (NP14) has been adapted to the fabrication of a reusable cost-effective ultrasonic tissue-mimicking phantom for real-time visualization of the thermal lesions by high intensity focused ultrasound (HIFU) irradiation. The constructed NP14 (40% in w/v) PASG is optically transparent at room temperatures, and it turns out to be opaque white as heated over the clouding points of about 55 °C and returns to its original transparent state after cooling. The acoustic property of the proposed phantom is similar to those of human liver tissues, which includes the acoustic impedance of 1.68 Mrayls, the speed of sound of 1595 ± 5 m/s, the attenuation coefficient of 0.52 ± 0.05 dB cm−1 (at 1 MHz), the backscatter coefficient of 0.21 ± 0.09 × 10−3 sr−1 cm−1 (at 1 MHz), and the nonlinear parameter B/A of 6.4 ± 0.2. The NP14-PASG was tested to assess the characteristic information (sizes, shapes, and locations) of the thermal lesions visualized when exposed to typical HIFU fields (1.1 MHz, focal pressure up to 20.1 MPa, focal intensity 4075 W/cm2). The proposed NP14-PASG is expected to replace the existing costly BSA-PASG used for more effective testing of the performance of therapeutic ultrasonic devices based on thermal mechanisms.

Abstract The paper focuses on the behaviour of nonionic surfactants (NISs) for enhanced oil recovery (EOR) processes with special reference to its applicability in the reservoirs of Upper Assam. The present work specifically studies three NISs, viz. Tergitol 15-s-7(Tg7), Tergitol 15-s-9 (Tg9) and Triton X 405(TX), based on their surface tension (ST), dynamic interfacial tension, hydrophilic–lipophilic balance, emulsion stability, aqueous stability, particle size analysis and phase behaviour. Simultaneously, crude oil from an oil field of upper Assam Basin was characterized based on API gravity, kinematic and dynamic viscosities, pour point and acid number. Core flood studies were conducted in the reservoir core to determine the recovery of crude oil during secondary water flood and EOR by NISs. It was observed that Tergitol 15-S-7 when mixed with Triton X-405 (Tg7TX) had the least interfacial tension (IFT) as compared to individual NIS and their mixtures. The recovery was found to be as high as 25.67% after secondary water flood from the original oil in place when Tg7TX followed by chase water was used as an exotic fluid for EOR. This work is an attempt to identify NISs mixtures for EOR for Upper Assam Basin.

In this study, the effect of the hydrophilic–lipophilic balance (HLB) number and cloud point (CP) of a secondary-alcohol ethoxylated nonionic surfactant on degreasing efficiency was investigated. A degreasing process was conducted for steel samples with different surfactants in a degreasing solution. The HLB number and CP increased with the increasing n of the hydrophilic ethylene oxide (OCH2CH2)n group. For a constant temperature of the degreasing solution (30–80 °C), the degreasing efficiency was investigated as a function of degreasing time. The highest degreasing efficiency was observed near the cloud point of the surfactant, and the degreasing efficiency decreased significantly at temperatures lower and greater than the cloud point. A Hogaboom test was carried out to observe oil stains on the surface of samples. Additionally, the contact angle of the surface with water droplets was measured after degreasing with various surfactants.

Gas hydrate inhibitors have proven to be the most feasible approach to controlling hydrate formation in flow assurance operational facilities. Due to the unsatisfactory performance of the traditional inhibitors, novel effective inhibitors are needed to replace the existing ones for safe operations within constrained budgets. This work presents experimental and modeling studies on the effects of nonionic surfactants as kinetic hydrate inhibitors. The kinetic methane hydrate inhibition impact of Tween-20, Tween-40, Tween-80, Span-20, Span-40, and Span-80 solutions was tested in a 1:1 mixture of a water and oil multiphase system at a concentration of 1.0% (v/v) and 2.0% (v/v), using a high-pressure autoclave cell at 8.70 MPa and 274.15 K. The results showed that Tween-80 effectively delays the hydrate nucleation time at 2.5% (v/v) by 868.1% compared to the blank sample. Tween-80 is more effective than PVP (a commercial kinetic hydrate inhibitor) in delaying the hydrate nucleation time. The adopted models could predict the methane hydrate induction time and rate of hydrate formation in an acceptable range with an APE of less than 6%. The findings in this study are useful for safely transporting hydrocarbons in multiphase oil systems with fewer hydrate plug threats.

The wetting properties of the rhamnolipid and surfactin mixtures with Triton X-165 were considered based on the contact angle measurements of their aqueous solution on the polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMMA) and quartz (Q) surfaces. The obtained contact angle isotherms were described by the exponential function of the second order as well as by Szyszkowski equation in some cases. Using the contact angle isotherms of individual biosurfactants and TX165 as well as the earlier obtained isotherms of their surface tension the contact angle isotherms of the biosurfactants mixtures with TX165 were deduced. As follows the presence of the maxima on the contact angle isotherms of the biosurfactants mixtures with TX165 is justified. They do not prove negative adsorption of the biosurfactant and TX165 at the interfaces. However, the mutual exchange of the biosurfactant and TX165 molecules is observed in the layers at the interfaces. The concentration of the studied mixtures at the PTFE-solution interface was established to be close to that at the solution-air one but that at the PTFE-air is equal to zero. However, the concentration of the studied mixtures at the PMMA-solution and quartz-solution is greater than zero. The concentration at the PMMA(quartz)-air and PMMA(quartz)-solution interfaces is smaller than that at the solution-air one.

Interfacial interaction amongst the antidepressant drug-imipramine hydrochloride (IMP) and pharmaceutical excipient (triton X-100 (TX-100-nonionic surfactant)) mixed system of five various ratios in dissimilar media (H2O/50 mmol·kg−1 NaCl/250 mmol·kg−1 urea) was investigated through the surface tension method. In addition, in the aqueous solution, the 1H-NMR, as well as FT-IR studies of the studied pure and mixed system were also explored and deliberated thoroughly. In NaCl media, properties of pure/mixed interfacial surfaces enhanced as compared with the aqueous system, and consequently the synergism/attractive interaction among constituents (IMP and TX-100) grew, whereas in urea (U) media a reverse effect was detected. Surface excess concentration (Γmax), composition of surfactant at mixed monolayer (X1σ), activity coefficient (f1σ (TX-100) and f2σ (IMP)), etc. were determined and discussed thoroughly. At mixed interfacial surfaces interaction, parameter (βσ) reveals the attractive/synergism among the components. The Gibbs energy of adsorption (ΔGadso) value attained was negative throughout all employed media viewing the spontaneity of the adsorption process. The 1H NMR spectroscopy was also employed to examine the molecular interaction of IMP and TX-100 in an aqueous system. FT-IR method as well illustrated the interaction amongst the component. The findings of the current study proposed that TX-100 surfactant could act as an efficient drug delivery vehicle for an antidepressant drug. Gels can be used as drug dosage forms due to recent improvements in the design of surfactant systems. Release mechanism of drugs from surfactant/polymer gels is dependent upon the microstructures of the gels and the state of the drugs within the system.

Abstract In an aqueous buffer system, serious reverse and side reactions were found in the asymmetric reduction of 2-octanone with Saccharomyces cerevisiae. However, some nonionic surfactants added to the aqueous buffer system improved the bioreduction process by decreasing the reverse and side reaction rates in addition to effectively increasing the average positive reaction rate. Further, a shorter carbon chain length of hydrophilic or hydrophobic moieties in surfactants resulted in a higher yield of (S)-2-octanol. The alkylphenol ethoxylate surfactants had a less influence than polyoxyethylenesorbitan trialiphatic surfactants on the product e.e. It suggested that the product e.e. resulting from the change of carbon chain length of the hydrophobic moieties varied markedly compared with the change of carbon chain length of the hydrophilic moiety. Emulsifier OP-10 and Tween 20 markedly enhanced the yield and product e.e. at the concentration of 0.4 mmol L−1 with a yield of 73.3 and 93.2%, and the product e.e. of 99.2 and 99.3%, respectively, at the reaction time of 96 h.

Abstract Background Low concentrations of nonionic surfactants can change the physical properties of cell membranes, and thus and in turn increase drug permeability. Porcine circovirus 2 (PCV2) is an extremely slow-growing virus, and PCV2 infection of PK-15 cells yields very low viral titers. The present study investigates the effect of various nonionic surfactants, namely, Tween-20, Tween-28, Tween-40, Tween-80, Brij-30, Brij-35, NP-40, and Triton X-100 on PCV2 infection and yield in PK-15 cells. Result Significantly increased PCV2 infection was observed in cells treated with Tween-20 compared to those treated with Tween-28, Tween-40, Brij-30, Brij-35, NP-40, and Triton X-100 (p

Nonionic surfactants are reported as being able to enhance enzyme stability and increase the conversion of enzymatic reactions. Surfactant-assisted enzymatic hydrolysis conversion is affected by surfactant HLB values. This work investigated the influence of nonionic surfactants with different HLB values on chitosan enzymatic hydrolysis using cellulase enzyme by measuring the reducing sugars formation, viscosity, and molecular weight of hydrolyzed chitosan. A characterization analysis of hydrolyzed products was also carried out. A higher HLB value exhibits a better enzymatic chitosan hydrolysis performance, shown by the decrease in a solution’s viscosity and the increase in reducing sugar formation. Increasing the surfactant concentration will also increase the hydrolysis rate. Nonionic surfactants can protect cellulase enzyme from the denaturation of temperature and stirring influence. The higher the HLB value, the lower the molecular weight of the hydrolyzed chitosan. The result of UV–Vis demonstrated aldehyde groups formation during hydrolysis. The SEM analysis showed that the chitosan, hydrolyzed using different HLB values of surfactants, had different surface morphologies. However, it did not change the chemical structure of the hydrolysis product seen by the FTIR analysis. The XRD patterns showed that the relative crystallinity of raw chitosan decreased when hydrolyzed with surfactants.

It is a well-known fact that sirolimus (SRL) undergoes degradation process via hydrolysis in aqueous media, leading to incorrect assessment of drug amount and thus release characteristics of formulations. The main objective of the present study was to evaluate the effect of nonionic surfactants in media on in-vitro release profiles for sirolimus eluting stents (SES) coated with biodegradable polymeric matrix. Phosphate buffer and acetate buffer incorporating nonionic surfactants with varying concentrations were examined for adequate solubility and stability (by RP-HPLC). Good sink condition was achieved in phosphate buffer (at pH 4.0) with 1.0% Tween 20, 1.0% Brij 35% and 0.5% Brij 58. Hydrodynamic size (by DLS) and the micelle-water partition coefficient (P) with standard free energy of solubilization (∆Gs°) of drug were evaluated to get some understanding about the solubilization phenomena. About 80% of drug release during the period of 48 h was achieved in optimized drug release media which was 1.0% Tween 20 in phosphate buffer pH 4.0. The obtained accelerated SRL release profile in optimized medium correlated well with the real time in-vitro release in phosphate buffer (pH 7.4). Surface morphology changes (by SEM), changes in gravimetric weights and molecular weight change (by GPC) were examined before and after drug release to understand the drug release mechanism which explains that the polymer did not undergo degradation during the drug release.

This work has developed and evaluated a microemulsion-based drilling fluid formulation with characteristics to be applied in oil wells. The microemulsion was formulated with a solution of water/glycerol, pine oil, and Tween 80, a nonionic and biodegradable surfactant. The physical and chemical properties of the drilling fluid obtained in this work were investigated through rheology and filtration analysis, solids content, aging, lubricity, toxicity, and thermal degradation. A non-toxic microemulsion-based drilling fluid oil-in-water (O/W) with high lubricity (0.07638) and thermal stability was obtained with suitable viscosity, gel strength and low fluid loss (4.0 mL), low solids content (6%), stability in a wide range of salinity conditions, and the possibility of high water content (above 85% in mass fraction). The fluid presented a pseudoplastic behavior, and statistically significant Herschel–Bulkley parameters were obtained.

Surfactant-enhanced soil washing has been used for remediation of organic pollutants for an extended period, but its effectiveness and wide application was limited by the high concentration of surfactants utilized. In this work, the efficiency of conventional soil washing performance was enhanced by 12–25% through the incorporation of air bubbles into the low concentration surfactant soil washing system. Surfactant selection pre-experiment using aerated and conventional soil washing reveals Brij 35 > TX100 > Tween 80 > Saponin in diesel oil removal. Optimization of the effect of time, surfactant concentration, pH, agitation speed, and airflow rate in five levels were undertaken using Response Surface Methodology and Central composite design. The optimum degree of variables achieved was 90 min of washing time, 370 mg/l of concentration, washing pH of 10,535 rpm of agitation speed and 7.2 l/min of airflow rate with 79.5% diesel removal. The high predicted R2 value of 0.9517 showed that the model could efficiently be used to predict diesel removal efficiency. The variation in efficiency of aeration assisted and conventional soil washing was variable depending on the type of surfactant, organic matter content of the soil, particle size distribution and level of pollutant weathering. The difference in removal efficiency of the two methods increases when the level of organic matter increases and when the particle size and age of contamination decreases.

The study presents results of rheological tests and measurements of pressure drops occurring during the flow of aqueous solutions of a mixture of drag reducing surfactants: cocamidopropyl betaine (CAPB, zwitterionic surfactant) and cocamide DEA (nonionic surfactant) through straight pipes. Tests were carried out at different CAPB/DEA weight ratios and different total concentrations of surfactants in the solution. Rheological measurements demonstrate the formation of a shear-induced structure (SIS) in the temperature range below 10 °C, which provides evidence for the presence of wormlike micelles in CAPB/DEA solutions. Drag reduction was observed during the flow of CAPB/DEA solutions in the temperature range from 3 to 45 °C, however, above 25 °C the degree of drag reduction was markedly decreased. The lower temperature limit at which drag reduction occurs depends on the CAPB and DEA weight ratio in the solution. In the range of higher temperatures, during the flow of CAPB/DEA solutions (similarly to flexible-chain polymer solutions) the onset of drag reduction is noted above a certain critical value of the Rec,0 number, whose value depends on the temperature of the solution, diameter of the pipe and the weight ratio of surfactants. At the same time, the critical value of wall shear stress τw,c0 corresponding to the critical value of Rec,0 is approximately independent of pipe diameter. The critical value of the Rec,0 number has been linked to the clouding of CAPB/DEA solutions.

The aim of this study was to prepare and characterize a hybrid layered material (organoclay) with a Na-montmorillonite and the triethylene glycol mono-n-decyl ether (C10E3) nonionic surfactant which forms a lamellar phase at room temperature. The synthesized organoclay was characterized by complementary techniques (Fourier transform infrared spectroscopy and X-ray diffraction). Experiments in conjunction with electron density analysis showed that a bilayer or membrane of C10E3 was intercalated within the interlayer space of a naturally exchanged Na-montmorillonite. The intercalation of a bilayer of C10E3 in a clay mineral offers new perspectives for the manufacturing of nanomaterials. While showing a hydrophobic surface and a large interlayer space value, the resulting organoclay preserves the compensating cations within the interlayer space allowing one to perform ion exchanges, making easier the intercalation of further organic molecules of important size with functional properties or for environmental purposes.

This paper presents a nonionic surfactant in the anionic surfactant pair (ternary mixture) that influences the hydrophobicity of the alkaline–surfactant–polymer (ASP) slug within low-salinity formation water, an environment that constrains optimal designs of the salinity gradient and phase types. The hydrophobicity effectively reduced the optimum salinity, but achieving as much by mixing various surfactants has been challenging. We conducted a phase behavior test and a coreflooding test, and the results prove the effectiveness of the nonionic surfactant in enlarging the chemical applicability by making ASP flooding more hydrophobic. The proposed ASP mixture consisted of 0.2 wt% sodium carbonate, 0.25 wt% anionic surfactant pair, and 0.2 wt% nonionic surfactant, and 0.15 wt% hydrolyzed polyacrylamide. The nonionic surfactant decreased the optimum salinity to 1.1 wt% NaCl compared to the 1.7 wt% NaCl of the reference case with heavy alcohol present instead of the nonionic surfactant. The coreflooding test confirmed the field applicability of the nonionic surfactant by recovering more oil, with the proposed scheme producing up to 74% of residual oil after extensive waterflooding compared to 51% of cumulative oil recovery with the reference case. The nonionic surfactant led to a Winsor type III microemulsion with a 0.85 pore volume while the reference case had a 0.50 pore volume. The nonionic surfactant made ASP flooding more hydrophobic, maintained a separate phase of the surfactant between the oil and aqueous phases to achieve ultra-low interfacial tension, and recovered the oil effectively.

Introducing the novel technique for enhancing oil recovery from available petroleum reservoirs is one of the important issues in future energy demands. Among of all operative factors, wettability may be the foremost parameter affecting residual oil saturation in all stage of oil recovery. Although wettability alteration is one of the methods which enhance oil recovery from the petroleum reservoir. Recently, the studies which focused on this subject were more than the past and many contributions have been made on this area. The main objective of the current study is experimentally investigation of the two nonionic surfactants effects on altering wettability of reservoir rocks. Purpose of this work is to change the wettability to preferentially the water-wet condition. Also reducing the residual oil saturation (Sor) is the other purpose of this work. The wettability alteration of reservoir rock is measured by two main quantitative methods namely contact angle and the USBM methods. Results of this study showed that surfactant flooding is more effective in oil-wet rocks to change their wettability and consequently reducing Sor to a low value. Cedar (Zizyphus Spina Christi) is low priced, absolutely natural, and abundantly accessible in the Middle East and Central Asia. Based on the results, this material can be used as a chemical surfactant in field for enhancing oil recovery.

Given the water scarcity becoming endemic to a large portion of the globe, arid region irrigation has resorted to the use of treated, partially treated, or even untreated wastewaters. Such waters contain a number of pollutants, including surfactants. Applied to agricultural lands, these surfactants could affect the fate and transport of other chemicals in the soil, particularly pesticides. A field lysimeter study was undertaken to investigate the effect of nonionic surfactant, Brij35, on the in-soil fate and transport of a commonly used herbicide, metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one]. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 mg m−3. Antibiotic-free cattle manure was applied (10 mg ha−1) at the surface of the lysimeters. Metribuzin was then applied to the soil surface of all lysimeters at a rate of 1.00 kg a.i. ha−1. Each of three aqueous Brij35 solutions, 0, 0.5 and 5 mg L−1 (i.e., “good”, “poor” and “very poor” quality irrigation water) were each applied to the lysimeters in triplicate. Analysis for metribuzin residues in samples of both soil and leachate, collected over a 90-day period, showed the surfactant Brij35 to have increased the mobility of metribuzin in soil, indicating that continued use of poor quality water could influence pesticide transport in agricultural soils, and increase the risk of groundwater contamination.

A laboratory flotation column equipped with Venturi aerators and an adjustable froth removal system was used to study the effect of calcium soap and a mixture of calcium soap/alkyl phenol ethoxylate surfactant on ink and fibres transfer during flotation de-inking of a 50% old newprint (ONP) / 50% old magazines (OMG) recovered papers mixture. Mass transport phenomena determining the yield of the flotation process were interpreted using model equations describing particle removal in terms of flotation, entrainment, and drainage in the froth. A decrease in the ink and mineral fillers flotation rate constant, drainage through the froth, and in fibre entrainment was observed when increasing the surfactant concentration. These trends were consistent with the typical dispersing action of the studied nonionic surfactant. An opposite effect on ink and fillers was observed when using calcium soap alone, and the increase in the flotation rate constant and drainage through the froth were consistent with the collecting and defoaming action of the calcium soap. Moreover, fibre entrainment decreased when increasing the soap concentration. The study of the surfactant/soap mixture highlighted the absence of synergy between the calcium soap and the surfactant.

Alkyl (octyl, decyl and dodecyl; C8,C10 and C12) benzene sulphonyl chloride was used in the preparation of a novel series of nonionic surfactants (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c. The preparations were completed by reacting each alkyl (C8,C10 and C12) benzene sulphonyl chloride with ethanolamine to give (I-III) respectively. The resulting products were reacted separately with ethylene oxide in the presence of different (base KOH, Lewis acid SnCl4 and k10 clay) catalysts to produce different moles of nonionic surfactants (5, 7 and 9) in sequence corresponding to (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c respectively. The chemical structures of prepared nonionic surfactants were elucidated by IR and 1HNMR spectra. The surface activity, biodegradability and biological activities of the prepared compounds were investigated. The obtained data show that these compounds have good surface and biological activities as well as reasonable biodegradability properties.

There has been increasing concern over contamination of the environment by persistent organic pollutants (POPs) such as polychlorinated biphenyls, dioxins and hexachlorobenzene (HCB), because of their highly persistent, bioconcentrative and toxic properties. In particular, the contamination of sediments may have a significant effect on the environment, because this contamination is closely related to the contamination of POPs in aquatic organisms.In this study, the potential of sonochemistry for degrading HCB in a model sediment sample is evaluated. Further, the effects of ultrasonic irradiation and its combination with the Fenton reaction or the addition of a surfactant are examined.

In this study, the influence of NaCl on the cloud point of polyethoxylate surfactants from the family of lauryl alcohol polyethoxylates (C12EOn ) and nonylphenol polyethoxylates (NPEOn ) was investigated. Liquid-liquid equilibrium curves of the aforementioned aqueous surfactants system with the presence of NaCl were plotted and thermodynamic parameters based on the Flory-Huggins model were obtained. The visual method was used to determine the cloud point. Solutions containing surfactant concentrations between 0.5 and 20% (by weight) and NaCl between 4.9 and 12.1% (by weight) were prepared. Salt had a salting-out effect, decreasing surfactant solubility in water. Furthermore, the cloud point decreased with an increase of NaCl concentration. The Flory-Huggins model satisfactorily described the experimental data for all surfactant + NaCl aqueous mixtures studied.

In this work, the feasibility of employing micelle-mediated extraction for selective separation of homologous or isomeric organic compounds is demonstrated. Firstly, the main parameters controlling extraction performances, such as surfactant concentration and temperature were varied. A Scheffé-type experimental design was demonstrated as a novel and useful method to characterize the various experimental factors. At each point selected in the two-phase domain and for a given solute, extraction percentage (E%), concentration ratio, phase volume ratio, and equilibrium partition coefficient (K C) were determined. The values of E% and K C decrease in the following order: phenol > 1-phenylethanol ~ 2-phenylethanol > benzyl alcohol.

In this work the linear viscoelastic behaviour of micelar and liquid-crystalline phases in a polyoxy-ethylene glycol nonylphenyl ether (EOa=10)/water system was studied. A linear viscoelastic characterization using small amplitude oscillatory tests was carried out. The Maxwell and Generalized Maxwell models fit the linear viscoelastic functions of micellar and hexagonal phases respectively, fairly well. On the other hand, the lamellar phase shows a plateau region characteristic of highly structured systems. As may be deduced from the experimental results, dynamic measurements constitute an effective method to study the structural changes occurring in phase diagrams.

The magnetic aqueous micellar two-phase system (MAMTPS) has the advantages combined of magnetic solid phase extraction (MSPE) and aqueous micellar two-phase system (AMTPS). Thus, MAMTPS based on Fe3O4 magnetic nanoparticles (MNPs) and a nonionic surfactant Triton X-114 (TX-114) was developed for the extraction, enrichment and removal of three dyes (Congo red, methyl blue, and methyl violet) from aqueous solutions in this study. The MNPs Fe3O4@NH2 was screened as the optimal MNPs benefiting the extraction. Then, the influencing factors of MNPs amount, TX-114 concentration, vibration time, and extraction temperature were investigated in detail. The results showed that the extraction efficiencies of three dyes almost reached 100% using MAMTPS under the optimal conditions; MAMTPS had higher extraction ability than the individual MSPE or AMTPS. Thus, MAMTPS had the advantages of simple operation, high extraction ability, easy recycling of MNPs, and short phase-separation time, which showspotential for use in the extraction and analysis of contaminants from water samples.

Mixing an alcoholic extract of propolis with distilled water or aqueous solution, which model seawater composition, give rise to aqueous dispersions with or without emulsifier. High dispersion stability is attained at hydrophylic-lipophylic balance equaled 13.9 using sorbitan oleate and polyoxyethylene sorbitan monooleate (Polysorbate-80) as a binary emulsifier. The initial particle size of dispersions is almost identical regardless of the presence of the emulsifier or water salinity. However, in the latter case a dispersion with essentially narrow size distribution is formed and, as a result, the dispersion is more resistant to coagulation and phase separation. Apparently, the main contribution to the stability of the aqueous propolis dispersion is made by the structural-mechanical barrier, which is formed by a thick adsorption layer of the hydrated nonionic surfactant.

This study explored the potential use of a sulfate radical (SO4●-)-based photochemical oxidation process to treat the commercial nonionic surfactant octylphenol polyethoxylate (OPPE) TritonTMX-45. For this purpose, the effect of initial S2O82- (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 S2O82- concentrations (>2.5 mM). S2O82-/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 S2O82-. On the other hand, TOC removal efficiencies dropped down to only 40% under the same reaction conditions. S2O82-/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 S2O82-/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 SO4●- and HO●, bimolecular reaction rate coefficients of OPPE with SO4●- and HO● were determined by employing competition kinetics with aqueous phenol (47 M) selected as the reference compound. The first-order abatement rate coefficient obtained for OPPE during S2O82-/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 first-order abatement rate coefficients were obtained for both OPPE (0.087 min-1) and phenol (0.140 min-1). Second-order reaction rate coefficients for OPPE with SO4●- and HO● were determined as 9.8108 M-1s-1 and 4.1109 M-1s-1, respectively. The kinetic study also revealed that the selectivity of SO4●- was found to be significantly higher than that of HO●.

Surfactant is being considered as a very demandable molecule in the field of chemistry. This paper reviews most important factors especially the uses of surfactants and their effects on environment. Evaluation of surfactants are based on examining the ability of the surfactant to maintain lower interfacial tension between target contaminant and water, satisfying lower CMCs, and sustaining lower sorption and precipitation to target substrate. Surfactant mixtures of anionic and nonionic surfactant are shown to be excellent candidates for robust surfactant cleaners. Keywords: Surfactant; Interfacial tension; Critical micelle Concentration; Anionic surfactant; Nonionic surfactant DOI: 10.3126/bibechana.v7i0.4047 BIBECHANA 7 (2011) 61-64

Surfactant is being considered as a very demandable molecule in the field of chemistry. This paper reviews most important factors especially the uses of surfactants and their effects on environment. Evaluation of surfactants are based on examining the ability of the surfactant to maintain lower interfacial tension between target contaminant and water, satisfying lower CMCs, and sustaining lower sorption and precipitation to target substrate. Surfactant mixtures of anionic and nonionic surfactant are shown to be excellent candidates for robust surfactant cleaners. Keywords: Surfactant; Interfacial tension; Critical micelle Concentration; Anionic surfactant; Nonionic surfactant DOI: 10.3126/bibechana.v7i0.4047 BIBECHANA 7 (2011) 61-64

Ion exchange resins, which are widely used for the removal of copper (II) ions from effluents, can also sorb nonionic surfactants entering into the wastewater with copper (II) ions simultaneously after various industrial processes. The study of equilibrium sorption of copper (II) and nonionic surfactant Lutensol AO‐10 under laboratory conditions by different types of ion exchangers and activated carbon has shown that the Purolite S950 chelating ion exchanger has the highest sorption capacity for copper (II) ions. Ion exchangers with carboxylic functional groups demonstrate the highest affinity for nonionic surfactant. Purolite C107E weak acid cation exchanger could be suitable for the cosorption of copper (II) ions and nonionic surfactant Lutensol AO‐10. Kinetic study of this ion exchange resin leads to a conclusion that the sorption of copper (II) ions was a fast process, and after 30 min the equilibrium was attained. When the concentration of copper (II) solution decreases, difference between the sorption capacity of various ion exchangers decrease. The influence of nonionic surfactant on the sorption of copper (II) is insignificant. Cu (II) jonų ir nejoninių paviršinio aktyvumo medžiagų (PAM) sorbcija jonitais ir aktyvintąja anglimi Santrauka Jonitai, plačiai naudojami vario (II) jonams iš nuotekų šalinti, gali sorbuoti ir nejonines paviršinio aktyvumo medžiagas (NPAM), kurios neretai patenka į nuotekas po įvairių gamybinių procesų kartu su vario jonais. Laboratorinėmis sąlygomis tiriant pusiausvirąją vario jonų ir NPAM Lutensol AO-10 sorbciją įvairių tipų jonitais ir aktyvintąja anglimi buvo nustatyta, kad didžiausia geba sulaikyti vario jonus būdinga chelatiniam jonitui Purolite S950. Didžiausias giminingumas nejoninei PAM būdingas karboksiliniams katijonitams. Bendrai vario (II) jonų ir NPAM sorbcijai geriausiai tiktų silpnai rūgštinis katijonitas Purolite C107E. Kinetiniai šio jonito tyrimai leidžia daryti išvadą, kad vario jonų sorbcija vyksta greitai, ir pusiausvyra nusistovi per 30 min. Mažėjant vario jonų koncentracijai tirpale skirtumai tarp įvairių jonitų sorbcinės gebos mažėja. Nejoninės PAM Lutensol AO-10 įtaka vario jonų sorbcijai yra nežymi. Reikšminiai žodžiai: jonitas, aktyvintoji anglis, sorbcija, varis, nejoninė paviršinio aktyvumo medžiaga (NPAM), išvalymo laipsnis. Сорбция меди (ii) и неионных поверхностно-активных веществ с помощью ионитов и активированного угля Резюме Иониты, широко используемые для устранения ионов меди (II) из сточных вод, способны сорбировать и неионные поверхностно-активные вещества (НПАВ), которые после многих производственных процессов переходят в сточные воды совместно с ионами меди (II). Исследования равновесной сорбции меди (II) и НПАВ с помощью разных типов ионитов и активированного угля в лабораторных условиях показали, что наивысшей сорбционной емкостью отличается хелатный ионит Purolite S950. Наивысшим сродством к НПАВ отличаются карбоксильные катиониты. Наиболее приемлемым ионитом для совместной сорбции меди (II) и НПАВ можно считать слабокислотный катионит Purolite C107E. Исследование кинетики сорбции меди (II) этим катионитом показало, что сорбция меди (II) отличается быстротой, и равновесие достигается в течение 30 минут. При снижении концентрации меди (II) в растворе различия между сорбционной емкостью разных ионитов снижаются. Установлено, что влияние НПАВ на сорбцию меди (II) незначительно. Ключевые слова: ионит, активированный уголь, сорбция, неионное поверхностно-активное вещество, медь, степень очистки. Firstd Published Online: 14 Oct 2010

The concentration of salivary secretory immunoglobulin A (sIgA) is a well-known stress marker for humans. The concentration of salivary sIgA in dogs has also been reported as a useful stress marker. In addition, salivary sIgA in dogs has been used to determine the adaptive ability of dogs for further training. There are conventional procedures based on enzyme-linked immunosorbent assay (ELISA) for measuring salivary sIgA in dogs. However, ELISA requires long assay time, complicated operations and is costly. In the present study, we developed an immunochromatographic assay for measuring salivary sIgA in dogs using a dilution buffer containing a non-ionic surfactant. We determined 2500-fold dilution as the optimum condition for dog saliva using a phosphate buffer (50 mM, pH 7.2) containing non-ionic surfactant (3 wt% Tween 20). The results obtained from the saliva samples of three dogs using immunochromatographic assay were compared with those obtained from ELISA. It was found that the immunochromatographic assay is applicable to judge the change in salivary sIgA in each dog. The immunochromatographic assay for salivary sIgA in dogs is a promising tool, which should soon become commercially available for predicting a dog's psychological condition and estimating adaptive ability for training as guide or police dogs.

Abstract The use of nonionic surfactants to modify the surface of bentonite is still quite restricted, although many advantages of that method can be found in the literature, like superior stability and low toxicity. On the other hand, problems involving the fluidity and viscosity of dispersions used in organic drilling fluids have become more and more challenging to colloid science. Therefore, the present study had the purpose of assessing the thixotropic behavior of dispersions of Brazilian bentonite organophilizated with nonionic surfactants for use in organic drilling fluids. Bentonite samples were organophilizated by a combination of two nonionic surfactants, being the process evaluated by X-ray diffraction and thermogravimetric analysis, in which the amount of nonionic surfactants incorporated was quantified. Fluid evaluation followed current standards. The flow curves of the organophilic clays revealed pseudoplastic behavior and the presence of hysteresis, which suggested thixotropy, with a relation between the thixotropy and the apparent viscosity of the final dispersions. Most of the process parameters evaluated showed significant effects on the value of d001 and the overall performance. Factors like clay type and organophilization method also directly affect the thixotropic behavior of dispersions. One of the samples can be considered promising for use in organic drilling fluids.