Concentration Of Surface-active Agent Research Articles

Encapsulation of essential oil to prepare environment friendly nanobio-fungicide against Fusarium oxysporum f.sp. lycopersici: An experimental and molecular dynamics approach

This study aims to develop a nano-biofungicide comprising of volatile essential oil molecules to enhance its efficacy in the field of agriculture through easily scalable green synthesis technique. It was prepared through one pot hot melt ultrasonication technique with easy water dispersability and long term stability. The effective surface-active agent concentration which controls the size and stability of nano bio-fungicide was studied. The small particle size (158 nm) and narrow particle distribution (0.36) were obtained for the nano bio-fungicide at 20 mg of lecithin and 100 mg of surfactant concentration. The physico-chemical analysis revealed that, nano bio-fungicides were amorphous sphere-shaped nanoparticles with low melting point. The greater molecular level affinity of essential oil towards lipids and their interfacial interaction towards essential oil to achieve stabilised dispersion in aqueous environment were deciphered through molecular dynamics simulation. The unique preferential binding of eugenol, bornanone and cinnamaldehyde with the hydrocarbon chain of glycerol monostearate and phospholipid enhanced their biological stability in aqueous environment by preventing its autoxidation. It was further confirmed through accelarated ageing studies. The major components of essential oil like alpha-terpineol, linalool, thymol and cinamaldehyde had an encapsulation efficiency of 29 %, 65 %, 21 % and 50 % respectively. Subsequently, all these bioactives of essential oil follows Higuchi model of release kinetics. Besides, the essential oil loaded nanostructured lipid carrier had significantly higher mycelial growth inhibition than pure essential oil at the same concentration. Thus, our results suggest that essential oil compactly packed at the intramolecular spaces of lipids and surfactants were having enhanced bio-efficacy with long term storage potential. Hence, the present nano-biofungicide could be a good alternative to the harsh pesticidal chemicals with easy and simple large scale production protocol for the eco- friendly management of wilt disease caused by Fuarium oxysporum.

Mass transfer behaviour and energy utilization efficiency of gas sparged rotating cylinder reactor and possible applications

This work aims to investigate the mass transfer behaviour of a gas sparged rotating cylinder electrochemical reactor suitable for conducting diffusion-controlled liquid-solid and gas-liquid-solid reactions. Variables studied were: cylinder rotation speed, N2 superficial velocity and the effect of sodium lauryl sulphate surface-active agent concentration. Gas sparging enhanced the rate of mass transfer by a factor ranging from 1.1 to 2.67. Addition of sodium lauryl sulphate reduced the rate of mass transfer by an amount ranging from 2.7 to 27%. The effect of specific power consumption (∈) on the mass transfer coefficient of un-sparged rotating cylinder was found to agree fairly with the well-known Calderbank – Moo-Young equation. The performance of the gas sparged rotating cylinder was expressed in terms of the criterion kA∈. The value of kA∈ was found to increase with decreasing gas superficial velocity and cylinder rotation speed. Possible applications of the present study for designing electrochemical reactors suitable for conducting diffusion limited reactions such as production of H2O2, flue gas desulphurization and air pollution control were highlighted. The possible use of the present reactor as a catalytic reactor for conducting diffusion controlled biochemical reactions catalyzed by immobilized enzyme or cell was noted.

Enhanced stability of free viscous films due to surface viscosity

The stability of a thin liquid film bounded by two free surfaces is examined in the presence of insoluble surface-active agents. This study is broadly aimed at understanding enhanced stability of emulsions with the increasing surface concentration of surface-active agents. Surface-active agents not only cause gradients in surface tension but could also render surface viscosity to be significant, which could vary with surface concentration. We employ two phenomenological models for surface viscosity, a linear viscosity model and a nonlinear viscosity model. In the latter, surface viscosity diverges at a critical concentration, which is termed the “jamming” limit. We show that rupture can be significantly delayed with high surface viscosity. An analysis of the “jamming” limit reveals that Γi(nl)>3D/M provides a simple criterion for enhanced stability, where Γi(nl), D, and M are the normalized initial surfactant concentration, disjoining pressure number, and Marangoni number, respectively. Nonlinear simulations suggest that high surface viscosity renders free films remarkably stable in the jamming limit, and their free surfaces behave like immobile interfaces consistent with experimental observations. Furthermore, it is shown that rupture times can be arbitrarily increased by tuning the initial surfactant concentration, offering a fluid dynamical route to stabilization of thin films.

Using response surface methodology and Box-Behnken design in the study of affecting factors on the dairy wastewater treatment by MEUF

Micelle-Enhanced Ultrafiltration (MEUF) is a membrane separation processes that improving ultrafiltration process with the formation of micelles of the surface active agents. Surface active agents are widely used to improve membrane processes due to the ability to trap organic compounds and metals in the treatment of industrial waste water. In this study, surface active agents are used to improve micelle-enhanced ultrafiltration (MEUF) to reduce chemical oxygen demand (COD), total dissolved solid (TDS), turbidity and clogging the membrane in dairy wastewater treatment. Three important operational factors (anionic surface active agent concentration, pressure and pH) and these interactions were investigated by using response surface methodology (RSM) and Box-Behnken design. Results show that due to the concentration polarization layer and increase the number of Micelles; the anionic surface active agent concentration has a negative effect on the flux and has a positive effect on the elimination of contamination indices. pH, and the pressure have the greatest effect on flux. On the other hand, it could be stated that these percentages of separation are in the percentages range of Nano-filtration (NF). While MEUF process has higher flux than NF process. The results have been achieved at lower pressure while NF process needs high pressure, thus making MEUF is the replacement for the NF process.

Removal of Zinc from an Aqueous Solution Using Micellar-Enhanced Ultrafiltration (MEUF) with Surfactants

In the present study, the optimum conditions have been investigated for the separation of Zn2+ ions from aqueous media by micellar enhanced ultrafiltration (MEUF). For this purpose, optimum conditions for the concentration of surface active agent in the feed solution (sodium dodecyl sulfate, SDS), cetyltrimethyl ammonium bromide (CTAB), triton-X-100 (TX100)), filtering pressure, stirring rate and for the membrane porosity have been determined. It is shown that the filtering pressure has a significant effect on the permeate flux but a relatively insignificant impact on rejection of Zn2+. Permeate flux increased linearly with increasing pressure, ranging from 0.32 mLmin-1m-2 at 3 bar to 0.72 mLmin-1m-2 at 4 bar. The results showed that by adding SDS anionic surfactant, the permeate flux and the removal efficiency of zinc increased. Best results in terms of zinc rejection coefficient is 97.5 % at 5.0 x 10-4 M zinc concentration, 1.0 x 10-2 M SDS concentration (~x 8 cmc), stirring rate 500 rpm and transmembrane pressure 4 bar.

Surfactants: a real threat to the aquatic geoecosystems of lobelia lakes

Abstract Lobelia lakes are valuable elements of the natural environment. They are characterised by low trophy, mainly in-forest location and a high transparency of water. However, similarly to other surface waters, they are subjected to increasing anthropogenic pressures, a good indicator of which is the level of surfactants, also called surface-active agents (SAAs). The aim of the study was to evaluate the intensity of anthropogenic pressures in 13 selected lobelia lakes and 14 streams in the catchments of these lakes in Northern Poland, based on SAA concentrations in the waters of these water bodies. We collected one water sample from each of these water bodies and determined the concentrations of cationic, anionic and non-ionic SAAs. We then compared the results with data concerning the ways in which these catchments and water bodies are used. While ionic (cationic and anionic) SAAs were found to be present in all the 27 samples (with concentrations ranging from 0.05 to 0.51 mg dm−3), non-ionic SAAs were identified in 17 of 27 samples (from 0.00 to 2.43 mg dm−3) with three samples largely exceeding the maximum concentration values reported by other authors. We concluded that SAAs are a real threat to the aquatic geoecosystems of lobelia lakes and that the pressures of tourism and leisure have the greatest impact.

Evaluation of Foaming Performance of Bitumen Modified with the Addition of Surface Active Agent

The article presents the analysis of the performance of foamed bitumen modified using surface active agents. Although, bitumen foaming permits production of asphalt concrete and other asphalt mix types without using chemical additives in significantly reduced temperatures, the decrease in processing temperatures still impacts the adhesion performance and bitumen coating of aggregates in final mixes. Therefore, in some cases it may be feasible to incorporate adhesion promoters and surface active agents into warm and half-warm mixes with foamed bitumen to increase their service life and resilience. Because of the various nature of the available surface active agents, varying bitumen compatibility and their possible impact on the rheological properties of bitumen, the introduction of surface active agents may significantly alter the bitumen foaming performance. The tests included basic performance tests of bitumen before and after foaming. The two tested bitumen were designated as 35/50 and 50/70 penetration grade binders, which were modified with a surface active agent widely used for improving mixture workability, compactibility and adhesion in a wide range of asphalt mixes and techniques, specifically Warm Mix Asphalt. Alongside to the reference unmodified bitumen, binders with 0.2%, 0.4% and 0.6% surface active agent concentration were tested. The analysis has shown a positive influence of the modifier on the foaming performance of both of the base bitumen increasing their maximum expansion ratio and bitumen foam halflife. In the investigations, it was found that the improvement was dependent on the bitumen type and modifier content. The improved expansion ratio and foam half-life has a positive impact on the aggregate coating and adhesion, which together with the adhesion promoting action of the modifier will have a combined positive effect on the quality of produced final asphalt mixes.

Effects of surface active agents on DNAPL migration and distribution in saturated porous media

Dissolved surface active agents such as surfactant and natural organic matter can affect the distribution and fate of dense nonaqueous liquids (DNAPLs) in soil and groundwater systems. This work investigated how two common groundwater surface active agents, humic acid (HA) and Tween 80, affected tetrachloroethylene (PCE) migration and source zone architecture in saturated porous media under environmentally relevant conditions. Batch experiments were first conducted to measure the contact angles and interfacial tensions (IFT) between PCE and quartz surface in water containing different amount of surface active agents. Results showed that the contact angle increased and IFT decreased with concentration of surface active agent increasing, and Tween 80 was much more effective than HA. Five 2-D flow cell experiments were then conducted. Correspondingly, Tween 80 showed strong effects on the migration and distribution of PCE in the porous media due to its ability to change the medium wettability from water-wet into intermediate/NAPL-wet. The downward migration velocities of the PCE in three Tween 80 cells were slower than those in the other two cells. In addition, the final saturation of the PCE in the cells containing surface active agents was higher than that in the water-only cell. Results from this work indicate that the presence of surface active agents in groundwater may strongly affect the fate and distribution of DNAPL through altering porous medium wettability.

Research on Influence Factors of ASP Flooding and Prediction of Water Containing PatternResearch on Influence Factors of ASP Flooding and Prediction of Water Containing Pattern

ASP flooding is one of main ways for oilfields to enhance oil recovery, but it needs to further research which slug parameters of ASP flooding are important factors influencing oil recovery. Taking a pilot zone as example, by designing scheme with orthogonal design method to conduct numerical analog calculation, analyzing data with grey correlation and multiple regression, it concluded that dosage of main slug, concentration of polymer, concentration of surface active agent and auxiliary slug are main factors influencing oil recovery; combining these factors to predict water containing rule can obtain water containing rule prediction formula with higher accuracy to meet requirements on site.

Synthesis of iron oxyhydroxide nanoparticles and its application for fluoride removal from water

Iron oxyhydroxide nanoparticles were synthesized from natural clay to remove fluoride from aqueous medium. Natural clay was leached in acid solution to obtain iron precursor consist of ferrous and ferric ions to prepare the iron oxyhydroxide nanoparticles. The various process parameters like pH, iron concentration in the precursor, surfactant co-surfactant ratio and critical micelle concentration of surface active agent were optimized to obtain smaller sizes nanoparticles. The synthesized nanoparticles were characterized using, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and BET surface area analyzer. Nanoparticles of average diameters of 6–20nm were revealed through TEM analyses. The specific surface area and total pore volume of the nanoparticles sample obtained under optimized process conditions were 312m2/g and 0.2mL/g, respectively. Experimental data were fitted the Freundlich adsorption isotherm more satisfactorily compared to the Langmuir isotherm. The pseudo second order kinetic model was shown better fit to the experimental data compared to first order kinetic model. Thus, the rate controlling factors involved in the adsorption process may be both fluoride concentration and adsorbent’s active sites concentration. Batch adsorption isotherm study reveals that with an initial fluoride concentration of 100mg/L and adsorbent dosing 0.2g/L, the adsorption of fluoride was observed 111.1±4.32mg/g within the 45min of agitation time at pH ∼7.5.

Understanding Selectivity on Germanium/SiO2 Chemical Mechanical Planarization Through Design of Experiments

ABSTRACTThe continuous trend of achieving more complex microelectronics with smaller nodes yet larger wafer sizes in microelectronics manufacturing lead to aggressive development requirements for chemical mechanical planarization (CMP) process. Particularly, beyond the 14 nm technology the development needs made it a must to introduce high mobility channel materials such as Ge. CMP is an enabler for integration of these new materials into future devices. In this study, we implemented a design of experiment (DOE) methodology in order to understand the optimized CMP slurry parameters such as optimal concentration of surface active agent (sodium dodecyl sulfate-SDS), concentration of abrasive particles and pH from the viewpoint of high removal rate and selectivity while maintaining a defect free surface finish. The responses examined were particle size distribution (slurry stability), zeta potential, material removal rate (MRR) and the surface defectivity as a function of the selected design variables. The impact of fumed silica particle loadings, oxidizer (H2O2) concentration, SDS surfactant concentration and pH were analyzed on Ge/silica selectivity through material removal rate (MRR) surface roughness and defectivity analyses.

Determination of quality of wastewater containing surfactants

The article presents the results of public service enterprises wastewater biotesting, which contain surfactants and model solutions in comparison with the colloidal-chemical properties. It is established that the maximum allowable concentration of surface active agents coincides with the concentration of saturation of the adsorption layers, which is determined by the isotherm of surface tension. This allows you to replace the tedious and less accurate biotesting measurement to the surface tension of surface active agents solutions to normalize indicators of wastewater.

Some physicochemical remarks on spontaneous emulsification of vitreal tamponades.

The importance of gravitational instability in determining the emulsification of vitreal tamponades is discussed. Theoretical results and numerical simulations indicate that the spontaneous formation of water-silicon oil is a rare event and that the very low concentration of surface active agents cannot justify the systematic formation of emulsions. The gravitational instabilities seem to play the main role. Our theoretical results seem in agreement with the experimental evidences; furthermore they indicate a future research line for the improvement of endotamponades. Indeed, the use of biodegradable antifoam may avoid the formation of bubbles and delay the formation of emulsions.

Al(III) and Cu(II) simultaneous foam separation: Physicochemical problems

AbstractIn the paper, simultaneous removal of Al(III) and Cu(II) from dilute aqueous solutions by ion and precipitate flotation methods is investigated. Influence of the pH of the initial solution, the surface active collector concentration and the gas flow rate on the final removal ratio and the course of ion and precipitate flotations is presented. The results show that simultaneous flotations of Al(OH)3 and Cu(OH)2 insoluble species occur allowing to achieve their almost complete removal in the pH range between 7 and 9. An increase of the surface active agent concentration causes a decrease of the final removal ratio as well as of the flotation rate constant. An increase of the gas flow rate results in an increase of ion and precipitate flotation rates.

Ultra-Fine Characteristics of Starch Nanoparticles Prepared Using Native Starch With and Without Surfactant

Starch nanoparticles (St-NPs) were synthesized using native maize starch (NS). The synthesis was carried out as per the Solvent displacement method after being modified. Modification involved the use of aqueous alkaline medium as the solvent and ethanol as the organic non-solvent. This was done with a view to assure easier and more reproducible St-NPs preparation without consuming more solvent. The modified method for preparation of St-NPs was evaluated; investigation into factors affecting it were made in order to discover the optimum conditions for such preparation. Factors studied included concentration of starch as well as concentration of surface-active agent, namely, Tween® 80, which was added before precipitation. World-class facilities was used for evaluation of the obtained St-NPs such as transmission electron microscopy, particle size analyzer, polydispersity index (PdI), Fourier transform infrared (FT-IR) spectroscopy and, X-ray diffraction. The results indicate that there are no changes of the chemical structure of St-NPs as indicated by FT-IR and the crystallinity pattern is converted from A-type to amorphous (V-type). The data obtained indicate also that the smallest, highly distributed particles size with good PdI of St-NPs are obtained in the presence of 20 % Tween® 80 (based on weight of NS).

The oxidation of solubilised and emulsified oils. Part III. The oxidation of methyl linoleate in potassium laurate and cetomacrogol dispersions.

Abstract Oxidation rates of aqueous dispersions of methyl linoleate emulsified and solubilised by potassium laurate and cetomacrogol, have been measured manometrically at 40°. Emulsions of methyl linoleate oxidised at a greater rate than solutions. The relation between concentration of surface-active agent and oxidation rate of emulsions is complex, and appears to depend on the relative amounts of emulsified and solubilised oil present. Poor agreement was obtained between oxidation rates calculated from peroxide values, chemical and polarographic, and those calculated from oxygen uptake. The results are discussed. An increase in light absorption at 234 mμ in the early stages of oxidation was observed. An uptake of 2.5 mol. oxygen per mol. of methyl linoleate was estimated to occur during the primary oxidation reaction in the presence of cetomacrogol, and 1.5 mol. oxygen per mol. of methyl linoleate in potassium laurate dispersions. The possible mechanism of the reaction and the nature of the oxidation by-products are discussed.

THE HYDROLYSIS OF PROPYL BENZOATE IN AQUEOUS SOLUTIONS OF SURFACE-ACTIVE AGENTS.

Abstract The effect of cetrimide and sodium lauryl sulphate on the alkaline hydrolysis of emulsions and solutions of n-propyl benzoate has been investigated and compared with results obtained previously in cetomacrogol solutions. Evidence is presented to show that the rate of reaction depends on the degree of saturation of the dispersion expressed as a “Saturation Ratio”, which is the ratio of ester concentration to its solubility in a given concentration of surface-active agent. The hydrolysis rate of solubilised ester decreases with increase in surface-active agent concentration while the effect of such an increase in concentration on the hydrolysis rate of emulsified ester depends on the nature of the surface-active agent. The initial rate in sodium lauryl sulphate and cetomacrogol is independent of concentration, but in cetrimide the rate increases with cetrimide concentration until sufficient is present to solubilise the ester.

The oxidation of solubilised and emulsified oils. I. Oxidation of benzaldehyde in potassium laurate and cetomacrogol dispersions.

Abstract The solubility of benzaldehyde in solutions of potassium laurate and cetomacrogol, has been measured at 20°. Oxidation rates of emulsified and solubilised benzaldehyde have been observed manometrically at 25°. The effect of concentration of surface-active agent on the oxidation rate of benzaldehyde has been studied. Emulsified benzaldehyde oxidised at a greater rate than solubilised benzaldehyde. Emulsified benzaldehyde was more susceptible to the action of copper catalysts than was solubilised benzaldehyde. Possible reaction mechanisms and loci of reaction are discussed.

The relationship between the adhesion work, the wettability and composition of the surface layer in the systems polymer/aqueous solution of anionic surfactants and alcohol mixtures

Measurements of advancing contact angle ( θ) were carried out on polytetrafluoroethylene (PTFE) and polymethylmethacrylate (PMMA) for aqueous solution of sodium dodecyl sulfate (SDDS) mixtures with methanol, ethanol and propanol in the range of SDDS concentration from 10 −5 to 10 −2 M, and for sodium hexadecyl sulfonate (SHS) with the same alcohols at the SHS concentration ranging from 10 −5 to 8 × 10 −4 M at 293 K. The concentration of methanol, ethanol and propanol used for measurements varied from 0 to 21.1, 11.97 and 6.67 M, respectively. On the basis of the contact angles the critical surface tension of PTFE and PMMA wetting was determined by using for this purpose the relationship between the adhesion and the surface tension and cos θ and surface tension both at constant alcohol and surfactant concentration, respectively. The obtained contact angles were also used in the Young Dupre’ equation for calculations of the adhesion work of aqueous solution of mixtures of anionic surfactants and short chain alcohols to PTFE and PMMA surface. The adhesion work calculated in this way was compared to that of the particular components of aqueous solution to these surfaces determined on the basis of the surface tension components and parameters of the surface tension of the surface active agents, water, PTFE and PMMA from van Oss et al. equation. The calculated adhesion work was discussed in the light of the concentration of surface active agents at polymer–water and water–air interface determined from Lucassen-Reynders, Gibbs and Guggenheim-Adam equations.

The effect of different concentrations of surface active agent on the absorption of sulphamethoxazole and trimethoprim from rabbit ileum

A combination of sulphamethoxazol SMX and trimethoprim TMP is widly used in the treatment of various systemic infections . This investigation was carried out to see the effect of increasing concentration of surface active agents ( SAA ) used in suspensions on the absorption of both drugs from isolated rabbit ileum . The study was carried out at PH 7.4 and at 37°C . The SAA chosen were tween 80, sodium laurylsulphate ( SLS ), polyethylene glycole ( PEG400 ), and PEG4000 at a concentrations of 0.1%w/v , 1%w/v, 2%w/v and 15% w/v (Note : 15% was chosen for the purpose of the investigation not as a concentration for formulation ). It was found that the absorption of both drugs decreased as a function of increasing the concentration of the different SAA.