Addition Of Surface Active Agents Research Articles

Impact of Additives on the Foamability of a Road Paving Bitumen

Because of the needs for the increased efficiency and environmental concerns that now emerge environmentally friendly techniques are more sought for and more commonly utilized in the road paving industry. Typical asphalt mixes are produced in temperatures exceeding 150˚C depending on the type of asphalt binder used, but new techniques are being developed, permitting decreased production and paving temperatures. One of the most effective techniques that are being studied are the Warm Mix Asphalt and Half Warm Mix Asphalt methods utilizing water based bitumen foaming that allow production of asphalt mixes at temperatures as low as 100˚C. Due to the extremely low processing temperatures, it is often difficult to obtain satisfactory results regarding the physical and mechanical properties of the resulting mixes, specifically the resistance to moisture the damage and resistance to the permanent deformation being in concern. As these issues were found to be originating in the inadequate coating of aggregates, a surface active agent in amounts of 0, 2% - 0, 6% and synthetic wax in amounts of 1, 0% - 2, 5% were added to 50/70 paving bitumen to improve its foamability and coating potential. Foaming characteristics were established in terms of bitumen foam expansion ratio ER and its half-life HL as a function of foaming water content ranging from 1, 5% to 4, 0%. It was found that the addition of surface active agent in the amount of 0, 6% resulted in the most favourable foaming performance at 2, 5% foaming water content, resulting in a doubling in expansion ratio and more than a 2, 5 times increase in half-life compared to the base bitumen. It is believed that the improved foaming characteristics of the bitumen would significantly benefit the performance of a subsequent warm or half-warm asphalt mix.

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.

Crosslinking of floating colloidal monolayers

Crosslinked colloidal monolayers are promising as templates, lithographic masks, filtration membranes, or membranes for controlled release rates in drug delivery. We demonstrate assembly of monodisperse micron-sized polystyrene (PS) beads at an air/water interface, which are transformed into crystalline monolayers using addition of surface-active agents. Vapor annealing methods with solvents (toluene and xylene) and crosslinking agents (divinylbenzene) were investigated regarding their ability to crosslink these floating monolayers directly at the interface, generating crosslinked membranes with crystal size up to 44 cm2, domain size up to 1.9 mm2, and nano-sized pores (100–300 nm). The demonstrated fabrication method emphasizes short fabrication time using a simple setup.Graphical abstract

新しい尿中たんぱく定量法の検討(その 2) : トリクロール酢酸-ポンソー S 改良法(界面活性剤の添加)

新しい尿中たんぱく定量法の検討(その 2) : トリクロール酢酸-ポンソー S 改良法(界面活性剤の添加)

Studying bubble–particle interactions by zeta potential distribution analysis

Over a decade ago, Xu and Masliyah pioneered an approach to characterize the interactions between particles in dynamic environments of multicomponent systems by measuring zeta potential distributions of individual components and their mixtures. Using a Zetaphoremeter, the measured zeta potential distributions of individual components and their mixtures were used to determine the conditions of preferential attachment in multicomponent particle suspensions. The technique has been applied to study the attachment of nano-sized silica and alumina particles to sub-micron size bubbles in solutions with and without the addition of surface active agents (SDS, DAH and DF250). The degree of attachment between gas bubbles and particles is shown to be a function of the interaction energy governed by the dispersion, electrostatic double layer and hydrophobic forces. Under certain chemical conditions, the attachment of nano-particles to sub-micron size bubbles is shown to be enhanced by in-situ gas nucleation induced by hydrodynamic cavitation for the weakly interacting systems, where mixing of the two individual components results in negligible attachment. Preferential interaction in complex tertiary particle systems demonstrated strong attachment between micron-sized alumina and gas bubbles, with little attachment between micron-sized alumina and silica, possibly due to instability of the aggregates in the shear flow environment.

Photo-initiated chemical vapor deposition as a scalable particle functionalization technology (a practical review)

Chemical vapor deposition (CVD), and its variants, is a more viable technology than the addition of surface active agents to modify nanoparticle surfaces. While thermally-activated CVD simply works by initiating the monomers using heat, some other techniques are more powerful and versatile. Indeed, higher energy CVD methods open up possibilities to a wider range of monomers. Unfortunately, different terminologies and classifications due to parallel work have led to confusion. This paper presents and explains the different techniques as well as their equivalent terminologies to clarify the big picture. While the demand for functionalized nanoparticles grows rapidly, current functionalization methods are still too expensive for most applications. This paper is intended to be a practical review of the gas phase methods available in order to identify a potential candidate for large scale functionalization of nanoparticles. This study identifies photo-initiated CVD (PICVD) as an ideal solution for scalable particle functionalization technology. This paper is intended to be a practical review of the gas phase methods available in order to identify a potential candidate for large-scale functionalization of nanoparticles. The focus is put on photo-initiated CVD (PICVD) as an ideal solution for scalable particle functionalization technology. ► Review of gas-phase nanoparticle surface treatment technologies ► Ranking based on technique scalability and versatility ► Equivalence between existing terminologies and proposal of a common terminology ► Identification of avenues of research for one promising technique: PICVD

The effect of surface tension reduction on the clinical performance of sodium hypochlorite in endodontics

Sodium hypochlorite (NaOCl) is recommended as an endodontic irrigant in view of its broad antimicrobial and tissue dissolution capacities. To enhance its penetration into inaccessible areas of root canals and to improve its overall effect, the addition of surface-active agents has been suggested. The aim of this investigation was to review the effect of the reduction of the surface tension on the performance of NaOCl in endodontics. A search was performed in the Medline electronic database (articles published up to 28 July 2012, in English) with the search terms and combinations as follows: 'sodium hypochlorite AND surface tension or interfacial force or interfacial tension or surface-active agent or amphiphilic agent or surface active agent or surfactant or tenside or detergent'. The purpose of this search was to identify publications that compared NaOCl alone and NaOCl modified with the addition of a surface-active agent in endodontics. A hand search of articles published online ('in-press' and 'early view'), and appearing in the reference list of the articles included, was further performed, using the same search criteria as the electronic search. The search identified 302 publications, of which 11 fulfilled the inclusion/exclusion criteria of the review. The evidence available suggests that surface-active agents improve the penetration of NaOCl in the main canal and have no effect on its pulp tissue dissolution ability. There are, however, insufficient data to enable a sound conclusion to be drawn regarding the effect of modifying NaOCl's surface tension on lubrication, antimicrobial and smear layer or debris removal abilities.

Sulfur removal in coal tar pitch by oxidation with hydrogen peroxide catalyzed by trichloroacetic acid and ultrasonic waves

A procedure for the desulfurization of coal tar pitch (CTP) by oxidation with hydrogen peroxide (H2O2) was developed, in which trichloroacetic acid (TCA) was used as a catalyst combined with ultrasonic waves. For comparison, the effects of H2O2 combined with different catalysts on sulfur removal were also investigated. The oxidative system composed of H2O2 and TCA is highly effective for sulfur removal from CTP. The reaction conditions such as type of solvent used, temperature, and CTP-to-TCA ratio considerably influence sulfur removal when the same oxidant is used. The desulfurization efficiency for CTP with 0.9wt.% sulfur content reaches 91.1wt.% at a xylene-to-CTP volume ratio of 2.5, a CTP-to-TCA mass ratio of 0.5, an ultrasonic treatment duration of 60min, a reaction temperature of 70°C, and with an extraction liquid containing methanol and sodium hydroxyl. The experiment confirms that the addition of surface active agent has no beneficial effect on sulfur removal.

Study of copper electrodeposition from acidic sulfate and perchlorate electrolytes using faradaic impedance spectroscopy and quartz microbalance methods

Copper electrodeposition from acidic sulfate and perchlorate electrolytes is studied. Some measurements are performed with addition of gelatine as a surface active agent. In the course of microgravimetric studies, decrease of the derivative of the electrode mass variation by the consumed charge is found, as compared to the value corresponding to the current efficiency of 100%. The latter is in part related to the effect of the double layer structure on the rate of the consecutive stages of copper recharge (Cu2+ + e → Cu+) and deposition (Cu+ + e → Cu). This effect is most pronounced in the case of solutions containing surface active agents that cause hyperpolarization and extension of the monovalent copper stability range as a result of their adsorption on the electrode surface. The faradaic impedance spectra obtained in sulfate and perchlorate electrolytes evidence at least the difference in the rate constants of recharge and copper deposition in these electrolytes. In both cases, the recharge rate constant is considerably lower than the deposition rate constant. The difference between these constants decreases noticeably at the addition of surface active agents.

Fluid flow and heat transfer on a falling liquid film with surfactant from a heated vertical surface

The addition of surface active agent to a falling liquid film affects the flow characteristics of the falling film. In this study, the flow and heat transfer characteristics for a falling liquid film have been investigated by addition of the surfactant. The falling liquid film was formed on a vertical flat plate. Contact angle of a liquid droplet above a plate surface can be substantially reduced with an increase in the surfactant concentration. The results obtained indicate that not only the wetted area of falling liquid film is increased but also the film thickness is decreased as the surfactant concentration is increased. It is also found that heat transfer rate is significantly increased while the heat transfer coefficient is almost constant value with an increase in the surfactant concentration at a given mass flow rate.

RETRACTED: Effect of Fe/Ba mole ratios and surface-active agents on the formation and magnetic properties of co-precipitated barium hexaferrite

Nanocrystalline barium hexaferrite (BaFe 12O 19) powders have been synthesized through the co-precipitation route. The produced ferrite precursors were obtained from aqueous mixtures of barium and ferric chlorides by co-precipitation of barium and iron ions using 5 M sodium hydroxide solution at pH 10 in room temperature. These precursors were calcined at temperatures of 800–1200 °C for constant 2 h in a static air atmosphere. The effect of Fe 3+/Ba 2+ mole ratio and addition of surface-active agents during co-precipitation step on the crystal structure, morphology and magnetic properties of produced ferrite powders were studied. The results obtained showed that the single phase BaFe 12O 19 powders was achieved by decreasing the Fe 3+/Ba 2+ molar ratio from the stoichiometric value 12 to 8 and increasing the calcination temperature ≥1000 °C. In addition, the Fe 3+/Ba 2+ mole ratio of 8 and presence of surface-active agents promoted the formation of homogeneous nanopowders (ca. 113 nm) of BaFe 12O 19 at a low temperature of 800 °C with good saturation magnetization (50.02 emu/g) and wide coercivities (642.4–4580 Oe).

Synthesis and characterization of barium hexaferrite nanoparticles

This investigation dealt with the synthesis of nanocrystalline barium hexaferrite (BaFe 12O 19) powders through the co-precipitation–calcination route. The ferrite precursors were obtained from aqueous mixtures of barium and ferric chlorides by co-precipitation of barium and iron ions using 5 M sodium hydroxide solution at pH 10 in room temperature. These precursors were calcined at temperatures of 800–1200 °C for constant 2 h in a static air atmosphere. The effect of Fe 3+/Ba 2+ mole ratio and addition of surface active agents during co-precipitation step on the structural and magnetic properties of produced ferrite powders were studied. It is found that the formation of single phase BaFe 12O 19 powders was achieved by decreasing the Fe 3+/Ba 2+ molar ratio from the stoichiometric value 12–8 and increasing the calcination temperature ≥1000 °C. In addition, the Fe 3+/Ba 2+ mole ratio of 8 the surface active agents promoted the formation of homogeneous nanopowders (ca. 113 nm) of BaFe 12O 19 at a low-temperature of 800 °C with resultant good magnetic saturations (50.02 emu/g) and wide intrinsic coercivities (642.4–4580 Oe).

A circular dichroism study of the interaction between n-decanoyl-N-methylglucamide and surface active agents in mixed micelles

The interaction between MEGA-10 and surface active agents was studied by means of circular dichroism. The molecular ellipticity of MEGA-10 varied with the addition of surface active agents, but its peak wavelength did not. The carbonyl group of MEGA-10 did not interact with the nonionic surface active agents nor the catanionic surfactant (of which the anionic and cationic portions were decanesulfonate and decyltrimethylammonium, respectively). It did, however, interact with the ionic surfactants, and also strongly with the ammonium group and the benzene ring. The interaction between MEGA-10 and ionic surfactant charges did not differ according to the sign of the charge. Circular dichroism spectra are a useful tool for performing research into the interaction between an optically active carbonyl group and an additive.

Some factors affecting spherical oil agglomeration performance of coal fines

Spherical oil agglomeration of bituminous coal fines was carried out using diesel oil as a bridging liquid. The effects of parameters, such as the dosage of bridging liquid, the solid content of slurry, the agitation time and rate, the pH and surface active agent on the agglomeration performance, were investigated. When the bridging oil loading increased from 5 to 30 wt.%, the values of grade and recovery increased gradually. The grade increased from 0.62 to 0.79 and the recovery increased from 0.91 to 0.98. Under the test conditions reported, agitation time and rate did not significantly affect the grade and recovery values. When the solid content in the slurry increased from 5 to 25, the grade values decreased from 0.75 to 0.6 and the recovery increased from 0.95 to 0.99. Laser particle size analyses of the agglomerate and tailing fractions showed that the agglomerates and tailings contained coarser and finer particles than the particles of the corresponding feed. However, the amounts of particles under 0.8 μm in the agglomerate fractions were higher than that of the tailing fractions. Variation of the pH of the slurry changed the agglomeration performance. The grade values were 0.78 and 0.72 for the pHs of 3.1 and 11 respectively. The addition of surface active agent (Triton X-100) caused a decrease in the recovery. However, the Triton X-100 in the slurry did not significantly change the grade of the final product.

Effect of surface active agents on the production of biopesticides using wastewater sludge as a raw material

Effect of surface active agents on the production of Bacillus thuringiensis based biopesticides using secondary wastewater sludge as a raw material was studied. The experiments were conducted in a shake flask and nine different commercial surface active agents were used at a concentration of 0.2% (v/v). The sludge samples after addition of surface active agents were sterilised at 121 degrees C for 30 min. The progress of biopesticide production was monitored by measuring viable cells and viable spores counts. The entomotoxicity was determined through bioassay against 3rd instar larvae of spruce budworm. ATPLUS 522, Tween 80 and Tween 85 increased the entomotoxicity potential in comparison to the control. The highest increase of 24% in entomotoxicity was observed when sludge was fortified with Tween 80.

00/01246 Effect of addition of surface active agent on the viscosity of a high concentration slurry of a low-rank British coal in water

00/01246 Effect of addition of surface active agent on the viscosity of a high concentration slurry of a low-rank British coal in water

ELECTROSTATIC CHARGE ON SPRAY DROPLETS OF AQUEOUS SURFACTANT SOLUTIONS

Electrostatic charges on individual spray droplets were measured using a refined form of the Millikan oil drop method. The measurement system consisted of three main sections; a droplet generation cell, a settling column and a charge measurement chamber. The trajectories required for calculation of charge were determined using a high-speed motion analyzer coupled to a long-focal-length microscope. Charges on droplets were manipulated by the addition of surface-active agents into the spray solution. Droplet charge was a function of the type and concentration of the surfactant added. For ionic surfactants, it showed a maximum at low surfactant concentrations, decreased with further surfactant addition and was constant after the CMC. The charge on cationic surfactants was always more than that observed with the anionic surfactants. Nonionic surfactants displayed a steady increase in droplet charge with increasing concentration. The charges were lower compared to the ionic surfactants.

Effect of addition of surface active agent on the viscosity of a high concentration slurry of a low-rank British coal in water

Coal–water mixtures (CWM) are concentrated suspensions of coal particles in water. The rheological properties of CWM depend on a number of factors such as the type of coal, the solid content and its size distribution, the temperature, the pH and the presence of electrolytes and chemical additives. The slurry viscosity was influenced significantly by initial surfactant loading, the particle size distribution and the ash content of the feeds. CWS of up to 60% prepared from Bickershaw coal samples with low ash contents (4.0% and 6.86%) could be produced at acceptable viscosities in the presence of a non-ionic surfactant, Triton X-405. To produce pumpable slurries with more than 60% solid, it will be necessary first to achieve a significant level of demineralisation, and to use high levels of reagent addition. The viscosities of the slurries with low ash content were significantly reduced by the surfactant addition which also altered the rheological characters of these slurries from non-Newtonian towards Newtonian fluids. However, sample containing very fine particles with a high ash content (24.5%) showed non-Newtonian behaviour even in the presence of reagent.

湿式球形造粒における平衡造粒粒子径の検討

Equilibrium agglomerate diameter in wet spherical agglomeration was investigated at various concentrations of added surface active agent and the addition ratios of bridging liquid. Spherical polyethylene particles, castor oil and sodium oleate were used respectively as the raw particles, the bridging liquid and the surface active agent. The addition of surface active agent to disperse medium modified both the interfacial tension between bridging liquid and disperse medium and the contact angle of bridging liquid on raw particles, and therefore affected the agglomeration phenomena. The relationship between the equilibrium agglomerate diameter and the factors affecting wet spherical agglomeration was well explained by the theoretical model, which takes into account the balance between the cohesive force by capillary suction potential and the destructive force by agitation.

Centrifugal float–sink separation of fine Turkish coals in dense media

Zonguldak bituminous coal, Tunçbilek and Soma–Merkez lignites were each separated into two sub-fractions, coal rich and mineral matter rich, using a centrifugal float–sink separation technique in heavy media. An isopropyl alcohol (IPA)–carbon tetrachloride (CCl 4) mixture and a zinc chloride (ZnCl 2) solution, with a specific gravity of 1.40 g cm −3 at 25°C were used as dense medium liquids. The addition of surface active agents (Triton X-100 and Brij-35) to the zinc chloride solution improved the removal of minerals. The recovery and purity of the final product (float) obtained from the heavy media separation depend on such parameters as the density of the medium, rotor speed and centrifugation time. The separation efficiency of each coal differed significantly. Particle size distributions of the coals and their float and sink fractions were analysed using a Laser Particle Size Analyser. A Scanning Electron Microscope (SEM) was used to interpret the liberation of minerals from the coal particles.