Volume 50, Issue 4

The surface tension of the unsaturated octadecyl carboxybetaine aqueous solution, and the interfacial tension between crude oil and surfactant solutions prepared by formation water were measured. Meanwhile, solutions of the corresponding saturated octadecyl carboxybetaine were prepared and determined for comparison. The effect of surfactant concentration, Na + concentration, and Ca 2+ concentration on the interfacial behavior of crude oil-water were investigated in detail. The results showed that the critical micelle concentration of unsaturated octadecyl carboxybetaine was higher but the surface tension at critical micelle concentration was lower than the corresponding saturated octadecyl carboxybetaine. Compared to the saturated betaine, the interfacial tension of unsaturated octadecyl carboxy betaine could reach to ultralow values (10 –3 mN · m –1 ) at lower surfactant concentration and at higher Na + concentration and Ca 2+ concentration.

Nonionic organosilicone surfactant trisiloxane-modified oligo (propylene oxide-block-ethylene oxide) was selected as the typical modifying agent in the synthesis of thermoresponsive SiO 2 composite. Absolute ethanol was used as the reaction medium. The properties of the prepared composite were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement instrument and dynamic light scatter (DLS). The results showed that the low critical solution temperature (LCST) of the composite is consistent with the cloud point of trisiloxane-modified oligo (propylene oxide-block-ethylene oxide).

Chromic acid oxidation of D-mannitol to mannose has been studied in aqueous media. The effect of promoter (PA, phen and bpy), micellar catalyst (SDS, TX-100 and CPC) and their combination is studied. All the reactions were performed under the condition [D-mannitol] T ≫ [Cr(VI)] T . All the promoters accelerate the reaction rate and the rate is highest in presence of phen. In absence of a promoter the anionic surfactant SDS increases the rate followed by Triton TX-100. The cationic surfactant CPC retards the reaction in comparison to the reaction in aqueous media. Although phen is the best promoter in absence of any surfactant the catalyst combination of bpy and SDS produce a maximum rate enhancement.

In domestic laundry, the question how to achieve a sufficient germ reduction gains importance since the trend towards lower washing temperatures and the incremental use of bleach-free liquid detergents does not ensure a sufficient hygiene by the means of temperature and bleach any longer. Hygiene rinsers as products being added to the rinse cycle offer further antimicrobial efficacy and seem to provide an adequate solution for this challenge. However, their regular application is debated due to the used ingredients and it is still unclear whether they are able to exhibit an additional antimicrobial efficacy. This study investigates the germ reduction by a supplementary use of hygiene rinsers under conditions that are close to the parameters found in the household to evaluate the benefit of these products for the hygienic reconditioning of laundry.

Laundry washing consumes resources. It is therefore a clear task for everyone, especially the industry and the consumer, to try to reduce the amount of resources needed as much as possible. Many possibilities and alternatives to the classical cleaning process using a washing machine and a readily formulated detergent are in discussion and are offered to the consumer. Task of this study is to investigate the effectiveness of some of these alternative methods to see whether the task to save resources can be accomplished by them. This is done by carrying out washing performance tests in a common household washing machine using stain monitors and stain strips as indicators for the washing effect in a 30°C and 60°C cotton program and comparing those alternatives (soap nuts, soapwort, two kind of wash-balls) with the use of regular detergent and washing with pure water. As result it is shown, that none of the investigated alternative cleaning methods does deliver any washing effect better than the result achieved with pure water, besides for soapwort that also included other surfactants. Interesting to note that on most stains the use of just 50% of the detergent delivers already a cleaning performance not much lower as 100% of detergent does provide.

A foamable dialdehyde starch-aniline Schiff-base (DAS-AN) was synthesized by the reaction of dialdehyde starch (DAS) and oil-soluble aniline in a homogeneous dimethyl sulfoxide system under N 2 atmosphere. The DAS-ANs were characterized by gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FT-IR) and NMR spectroscopy. Their foaming behavior and surface tension were investigated. Foaming power and stability tests were performed for solutions of DAS-ANs with different degrees of substitutions with aniline ( DS AN ) and concentrations. The maximum foaming power was 2.6 times the initial solution volume of the foam test in 450 mg · L –1 CaCO 3 aqueous solution. The most stable foams only decreased by 6% in volume in deionized water after 20 min.

A homologous series of cationic gemini diphenyl methane quaternary ammonium salts have been synthesized via chloromethylation of diphenyl methane followed by quaternization using tertiary amines with different chain length. The chemical structures of the prepared surfactants were confirmed using different spectroscopic techniques including, FTIR and 1 H-NMR spectra. Surface activity of these compounds have been thoroughly studied and their surface properties including surface and interfacial tension, emulsification power, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area were determined. The new synthesized surfactants were screened as antimicrobial agents against different strains of bacteria, yeast and fungi.

Curcumin, the most active polyphenolic constituent of turmeric cucuminoids obtained from rhizome Curcuma longa, holds a high place in ayurvedic medicine but its role in conventional disease management is also established. Unfortunately, the compound has poor aqueous solubility, which results in poor bioavailability following high doses by oral administration. In order to enhance its effectiveness and improve bioavailability, surfactant assemblies as the colloidal drug carriers with desired properties have been largely utilized. The interaction of curcumin with cetyltrimethylammonium bromide (CTAB) surfactant has been investigated by absorption spectroscopy as a function of surfactant concentration in pre-micellar and micellar range at acidic pH of 6.4. The pre-micellar and micellar region of pure CTAB surfactant at acidic pH of 6.4 is examined through tensiometry and conductometry techniques. Spectral data shows that in presence of curcumin at lower C CTAB , the change in absorbance and peak form initially was assigned to attraction of positive head group of CTAB towards the β-diketone group of drug. In micellar region including CMC, the type of interaction corresponds to the attachment of C 16 chains of CTAB to nonpolar aryl groups of drug and simultaneously displacement of polar head group from β-diketone group of the drug. Finally at post micellar C CTAB , the encapsulation of the curcumin into micelles, predominantly in intact monomeric form is observed with the sharp peak at λ max = 423 nm.

Hydrotropes (amphiphiles) start to aggregate at a certain minimum concentration known as the minimum hydrotrope concentration (MHC), above which an appreciable solubilization of insoluble compounds in aqueous solution is observed. However, the MHC values are very high, thus, limiting the applications of hydrotropes. The salts are found to increase the association tendency of hydrotropes and reduction in the MHC. The present study discusses the effect of various electrolytes (Na + , Mg 2+ and K + series) on the behavior of sodium salicylate at different temperatures. Design of experiment was employed to optimize the process parameters. Furthermore, thermodynamic parameters were investigated to observe the stability of the aggregates at higher temperatures.

The effect of cationic surfactant on the oxidation of galactose by N-bromophthalimide in the presence of acidic medium at 308 K has been studied. The order of reaction with respect to [Gal], [oxidant], and [H + ] were found to be fractional, first, and negative fractional order, respectively. The effects of KCl, KBr, phthalimide and mercuric acetate have also been studied and summarized. The rate of reaction decreased with an increase in dielectric constant of the medium. The effect of cationic surfactant cetylpyridinium chloride (CPC) has been studied. CPC retards the rate of reaction. Thermodynamic and activation parameters have been evaluated.