Volume 56, Issue 4

The increasing use of silicone polymers has attracted the interest of many researchers and manufacturers for the past three decades. The silicone surfactants have excellent surface properties, of which the wetting and spreading ability is particularly noteworthy. So silicone surfactants are used in various fields, starting with textiles to agriculture. Because of this particular wetting and spreading property, silicone surfactants will be used together with conventional surfactants to achieve the desired throughput. In this paper we describe in detail the origin of silicone surfactants and various silicone surfactant compounds, as well as their physicochemical properties. We also handle various applications of silicone surfactants in agriculture, textile manufacturing, personal care and cosmetics, polyurethane foam, metal extraction, foam floatation and other industrial applications. However, the main focus is on the latest syntheses, developments and applications of newly developed tailor-made molecules.

The effect of ethoxylated rapeseed oil fatty acid methyl esters (ROFAME) on the viscosity, functional properties and skin compatibility of hand dishwashing liquids was analyzed. It was found that, over the test range, both the degree of ethoxylation and concentration in the formulation were essential for the properties of the evaluated products. Among others, this was due to the fact that ROFAME had the favorable effect of modifying the viscosity of these formulations to an acceptable range. The relationship between the concentration and degree of polyaddition of ROFAME on the detergent and foaming properties of the complete formulation was presented, showing their increase in comparison to the reference dishwashing liquid without ROFAME. With respect to the parameters relating to the skin irritant, the degree of skin dryness after dishwashing with the auxiliary surfactants was lower.

This study evaluated the bactericidal activity of the cationic surface active compound didecyldimethylammonium chloride in 2-propanol against the two reference strains Pseudomonas aeruginosa and Pseudomonas aeruginosa (tetracycline-resistant) as well as their isolates adapted to this active substance. Individual phases and stages of European Standards which are intended to determine the bactericidal activity of disinfectants in medical areas were used. Disinfection parameters of the tested substance as determined by suspension methods were not sufficient to achieve the required bactericidal reduction in the carrier method for Pseudomonas aeruginosa and all its adapted isolates. Pseudomonas aeruginosa (tetracycline-resistant) and its adapted isolates were more sensitive to the tested active substance when the contact time was extended from 5 to 10/15 min. Adaptive resistance of Pseudomonas aeruginosa strains can be abolished by using increased concentrations of the tested substance and/or extended contact time.

The objective of the present study was to analyze different sources of carbon (diesel oil, soybean oil and frying oil) to optimize the production of bioemulsifier by a yeast isolated from soil contaminated with diesel oil. A total of 45 autochthonous yeast were isolated from soil contaminated with diesel oil. Cell growth was achieved in soybean oil and frying oil at 30°C and agitation of 200 rpm. Growth in diesel oil was significantly lower, with a mean of 2.99 g/L. Detection of bioemulsifiers was performed with the emulsification index (E 24 ), the drop-collapse test, the flowability of oil and measurement of surface tension. The mean emulsification indices obtained were between 29.27 % and 43 %, with greater production in the cultivation with diesel oil. This study showed that a stronger emulsifying activity is achieved with yeast growing in a medium with diesel oil, and thus that carbon source should be used for bioemulsifier production.

The aggregation behaviour of the cationic surfactant carbethopendecinium bromide (Septonex) and cetyltrimethylammonium bromide (CTAB) in aqueous solution was investigated by steady-state and time-resolved fluorescence experiments. Values of critical micelle concentration were obtained from the pyrene emission polarity index. The micellar aggregation numbers for four different concentrations of both surfactants were determined by steady-state and time-resolved fluorescence quenching methods, using pyrene as a probe and cetylpyridinium chloride as a quencher. The results obtained for Septonex were compared with the aggregation parameters of CTAB. Generally, Septonex micelles were formed by a smaller number of surfactant monomers than in the case of CTAB and the critical micelle concentration of Septonex is lower than that of CTAB. Also, the concentration dependence of the micelle aggregation number was found.

The wettability of phosphonium benzene sulfonate on parafilm has been investigated by means of dynamic contact angle measurement. Based on the surface tension data, the spreading coefficient, adhesion tension (γ lg cosθ), and adhesion work (W A ) were further analyzed. It was revealed that the surface tension and contact angle decreased with the increase in concentration, and remained constant when the concentration was higher than the critical micelle concentration (CMC). Furthermore, the spreading coefficient increased with increase in concentration then stays unchanged. In the studied concentration range, the value of spreading coefficient is negative, indicating that it cannot rapidly spread the surfactant on the parafilm surface to an uniform film. The measurements show a linear relationship between the adhesion tension γ lg cosθ and the surface tension in the concentration range of 2 × 10 −6 mol L −1 to 1 × 10 −4 mol L −1 . The adsorbed amount of surfactant molecules at the parafilm-solution interface is lower than that at the gas-liquid interface. The value of W A was initially decreased then increased as the concentration was increasing and reaches a minimum value at the concentration near the CMC.

Studies of the interaction between the zinc-peptide complex ([Zn(II)-Gly-Gly] + ) and ninhydrin in aqueous and CTAB surfactant media were executed by the means of UV-visible spectrophotometry. The reaction rates ( k obs and k ψ ) were determined in both media by varying different parameters such as pH, temperature and the concentration of the reactants and CTAB. The micellar binding constants and activation parameters were also calculated. The catalytic activity in the CTAB medium was found to be better than in the aqueous medium on the title reaction. The catalysis by CTAB is treated quantitatively by applying the model of the kinetic pseudo-phase of the micelle. Variation of the rate constant with the change of the CTAB concentration was used for the calculation of several kinetic parameters such as the binding constants ( K B and K Nin ) and the micellar rate constant k m . On basis of the experimental results, a probable mechanism is proposed.

Four cationic Gemini surfactants with different length of the hydrophobic chain (abbreviated as C 12 -CGB, C 14 -CGB, C 16 -CGB and C 18 -CGB) have been synthesized. The structures were confirmed by MS and 1 H NMR. Their basic surface chemical properties and antistatic properties were investigated. The result indicated that upon increasing the number of carbon, the critical micelle concentration ( CMC ) and the equilibrium surface tension ( γ CMC ) decreased initially and then increased. The products' Krafft points were all below 0°C except that of C 18 -CGB, it was 16.5°C. Emulsifying properties were determined by the water separation time method. The data show that the emulsifying capability increased gradually with the increase of concentration and then stabilized. In addition, the static voltage and static half period values of the calicoes treated with the four products were measured. These products exhibited excellent antistatic properties.

In this paper, the physicochemical properties and application properties of two isomers, one with a branched structure (9,10-dihydroxystearic acid ethoxylate) and the another with a linear structure (stearic acid ethoxylates) were systematically studied. It has been found that: (1) The DHSAE-15 (9,10-dihydroxystearic acid ethoxylated with 15 mean EO units) with a branched structure has better wettability and higher efficiency in reducing surface tension than the corresponding linear product SAE-15 (stearic acid ethoxylated with a 15 mean EO units); (2) SAE-15 has better detergency than DHASE-15; (3) the spatial configuration plays a limiting role on the size of the aggregate.

In recent years, long-chain amidosulfobetaine surfactants are interesting additives in the acidification process. However, there is a strong interaction between them and Fe(III) ions, which has a negative effect on viscoelastic behavior. In this work, the rheological behavior of a spent solution of amidosulfobetaine and iron ions as an impurity in the acidification process was investigated. The results showed that by increasing the iron ion concentration, the viscosity of the solution increased slightly, followed by a significant decrease and subsequent precipitation of the viscoelastic surfactant. By increasing the temperature, the iron tolerance decreases noticeably.

Advances in science and technology are promoting eco-friendly synthesis routes, green chemicals, and non-hazardous solvents. A suitable method for the synthesis of 2-(prop-2-ynyloxy) benzaldehyde was developed using three different aqueous micellar media. The targeted product ether is completely immiscible in water, but in combination with interface active surfactants it has been possible to produce the hydrophobic organic compound in water. Micelles function as a pseudocellular organic environment to isolate species from the main solvent and favor compartmentalization of reagents. There is an increase in the local concentration and consequently the reactivity increases. The use of such unique chemo-, regio-, and stereoselectivity renders this reaction new. Organic species added to a micellar media are distributed between water and micelles depending on polarity, charge, and size. In the experiments it was observed that salicylaldehyde and propargyl bromide interacted best in CTAB media and the yield of the formed product was 96 %.

Three reactive amphoteric surfactants (M10, M12 and M14) with different alkyl chain lengths have been synthesized using N , N '-dimethyl-1,3-propyldiamine, maleic anhydride and alkyl bromide as raw materials. The compounds had been characterized by mass spectrometry and 1 H-NMR. The critical micelle concentration (CMC) and the corresponding surface tension (γ CMC ) of M10, M12 and M14 were measured at temperatures from 298 K to 313 K. The results showed that the CMC of M10, M12 and M14 are 5,89 × 10 −4 mol L −1 , 2,63 × 10 −4 mol L −1 and 1,35 × 10 −4 mol L −1 . The γ CMC of M10, M12 and M14 are 31.26 mN m −1 , 28.79 mN m −1 , and 26.87 mN m −1 at 298 K respectively. As the temperature rises, the CMC and the minimum molecule area (A min ) increased gradually, but the γ CMC and the maximum surface adsorption capacity (Γ max ) decreased moderately. The micelle aggregation number (N m ) was determined and changed slightly in the temperature range of 298 K–313 K, which showed that the micelle aggregation number was insensitive to the temperature change.