Band 53, Heft 4

A trimeric sulfate-type surfactant was synthesized and the surface chemical properties and micellar behavior of this surfactant were investigated by surface tension and fluorescence measurements. The critical micelle concentration (CMC) and the surface tension at CMC both decreased with the increase of NaCl concentration. The thermodynamic parameters indicate that the micelle formation is entropy-driven. The micelle aggregation number was determined and changed little between 303 K and 313 K. All the experimental results show that the surface-active properties of the surfactant are insensitive to the temperature compared with conventional surfactants.

A series of saturated cardanol polyoxyethylene ether carboxylates was synthesized using renewable saturated cardanol originating from Cashew Nut Shell Liquid as raw material. The structures were characterized by hydrogen nuclear magnetic resonance spectroscopy. The studies of their surface activity and interface activity were carried out to analyze the influence of the chemical structures of the series of cardanol surfactants on the adsorption and micellization. Results showed that saturated cardanol polyoxyethylene ether carboxylates had a good surface activity and interface activity, and the interface activities of the Gemini cardanol surfactants were better than those of the corresponding monomer cardanol surfactants. The critical micelle concentrations (CMC) of all investigated cardanol surfactants, obtained from surface tension measurements, were low in the order of 10 −5 mol/L. The CMCs decreased and the oil-water interface tension for the same cardanol surfactants increased with the increase of the oxyethylene number. The process of micellization became easier with increasing the oxyethylene number. The Δ G θ m values of the Gemini cardanol surfactants were more negative than those of the corresponding monomer cardanol surfactants. The micellization for all cardanol surfactants was a spontaneous process and exhibited enthalpy-entropy compensation. The micellization of all the cardanol surfactants was entropy-driven.

The surfactants dioctyl diphenyl ether disulfonate gemini (C 8 -DADS) and monohexadecyl diphenyl ether disulfonate (C 16 -MADS) were synthesized by Friedel-Crafts alkylation, followed by sulfonation and neutralization. Sulfated zirconia was prepared by the impregnation method and used to catalyze the alkylation reaction. Equilibrium surface tension measurements show that C 8 -DADS has a lower critical micelle concentration (CMC), surface tension at CMC (γ cmc ) and minimum area per molecule (A min ), higher efficiency of adsorption at the surface (pC 20 ) than C 16 -MADS, implying that C 8 -DADS has a higher surface activity. The emulsifying ability of C 8 -DADS is better than that of C 16 -MADS. The salinity and hardness tolerance property of C 16 -MADS is superior to that of C 8 -DADS.

A series of N-alkyl pyridinium aldoxime surfactants was synthesized by the reaction of pyridinium aldoxime with long chain alkyl halides (decyl, dodecyl, tetradecyl and hexadecyl bromide). The chemical structure of the synthesized compounds was confirmed by elemental analysis and FTIR spectra. Surface tension was measured in aqueous solutions for different concentrations at 25 °C. Various surface properties of the synthesized surfactants were evaluated, particularly the critical micelle concentration (CMC), effectiveness (π CMC ), efficiency (P C20 ) as well as the maximum surface excess (Γ max ) and minimum surface area (A min ). Also, the micellization and adsorption at liquid/air interfaces were investigated. The synthesized cationic surfactants were evaluated for their biocidal activity. Good antibacterial and antifungal activities were recorded against Gram-positive bacteria ( Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 25922), followed by Gram-negative bacteria ( Escherichia coli ATCC 23282, Pseudomonas aeruginosa ATCC 10145), yeast ( Candida albicans IMRU 3669) and filamentous fungus ( Aspergillus niger ATCC 16404).

In the present study, an aqueous root-extract of Acanthophyllum laxiusculum (AREAL) was evaluated for phenanthrene removal from two samples of contaminated soil. AREAL showed a linear solubilization enhancement for phenanthrene with a weight solubilization ratio of 0.05. Batch soil washing experiments caused the removal of phenanthrene with efficiencies of 96.7 % and 78 % from soils with 0.78 % and 2.73 % organic carbon, respectively. Desorption kinetics of phenanthrene exhibited a two-phase pattern, namely, a rapid release as the initial phase and a slower removal as a subsequent phase. A two-compartment exponential model could adequately represent the two phases of the kinetic pattern of phenanthrene desorption. The rise of pH from acidic to basic levels, decreased phenanthrene removal due to changes in the micelle number of the surfactant phase. Maximum achievable yield of removal was 82 % phenanthrene in a column experiment at defined operational conditions. High removal efficiencies show the potential application of AREAL for improving the bioremediation of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils.

Kinetics of permanganate oxidation of D-mannitol have been investigated spectrophotometrically under pseudo-first-order conditions in aqueous acidic media at 30 °C. The spectral analysis of hydrazone derivative of the product indicates the product to be an aldehyde. The observed rate constant value was found to be relatively slow in the uncatalyzed path, which increases by the presence of four isomeric promoters: 2-picolinic acid (2-PA), 4-picolinic acid (4-PA), 2,3-dipicolinic acid (2,3-diPA) and 2,6-dipicolinic acid (2,6-diPA). The catalytic effect of sodium dodecylbenzene sulfonate (SDBS) surfactant on the permanganate oxidation of D-mannitol has been also studied in the presence of the promoters. The critical micelle concentration (CMC) of SDBS alone and in presence of D-mannitol was determined by conductometry and spectrophotometry. The aggregation and morphological changes during reaction were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The variation of the reaction rates for the different promoters in the presence and absence of SDBS micellar catalyst is discussed qualitatively in the terms of partitioning nature of substrate, charge of surfactant and reactants. 2,3-diPA in association with SDBS as micellar catalyst accelerated the reaction velocity compared to the uncatalyzed path.

The catalytic effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the MnO 2 -paracetamol (PCM) redox reaction has been examined spectrophotometrically in acidic medium at 298 K. The reaction demonstrates that the stoichiometric ratio of MnO 2 and PCM is 1 : 1. The reaction exhibited first order kinetics with respect to [MnO 2 ] and [PCM] but a negative fractional order was observed with respect to [H 2 SO 4 ]. Various effects such as ionic strength, dielectric constant, [Mn(II)], [salts] and temperature have been studied. The catalytic effect of CTAB has been treated quantitatively by the well known Menger Portnoy and Piszkiewicz model. The values of binding constant ( K s ), rate constant in the micellar phase ( k m ), cooperativity index (n) and dissociation constant ( K D ) have also been calculated. From the several observations, a reaction mechanism has been proposed and the rate law has been derived. Applying the Arrhenius equation, various thermodynamic activation parameters have also been evaluated.

The adsorption and corrosion inhibition behaviour of zwitterionic gemini surfactant, 2-decyl phosphate-1-(N,N-dimethyl,N-tetradecylammonium) ethane on mild steel in 0.5 M HCl in the temperature range of 25–65°C has been investigated. The zwitterionic gemini surfactant was synthesized, purified and characterized using nuclear magnetic resonance (NMR) spectroscopy. Surface tension measurements were carried out to evaluate the surface and thermodynamic properties of the surfactant in 0.5 M HCl. Weight loss measurements, potentiodynamic polarization measurements, electrochemical impedance (EIS) measurements and thermodynamic/kinetic parameters were applied to elaborate the adsorption and corrosion inhibition mechanism of the surfactant. Surface morphology of the mild steel specimen corroded in unihibited and inhibited acid was also evaluated using scanning electron microscopy (SEM). The zwitterionic gemini surfactant acts as an excellent inhibitor for mild steel corrosion in 0.5 M HCl; the inhibition efficiency (IE) of inhibitor is concentration and temperature dependent. The evaluated gemini surfactant performed as a mixed-type corrosion inhibitor. The adsorption of surfactant on mild steel surface obeyed Langmuir's adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitor and the mild steel surface.

The study discusses the technology of preparation, and antibacterial, physicochemical and functional properties of advanced eco-friendly products for maintaining hygiene in toilets. The active substance with antibacterial properties which was added to the formulations for the purpose of the study was Humulus lupulus (hop cone) extract obtained under supercritical carbon dioxide conditions. The assumption was that the extract would improve the antibacterial activity of the products without adversely affecting their functional properties. The addition of hop cone extract at the concentration of 0.1% to the tested formulations was found to produce an antibacterial effect against S. aureus bacteria, however, no such activity was demonstrated against E. coli bacteria. Moreover, an increase in the content of the extract was shown to enhance product viscosity, at the same time extending the time of dissolution in water and improving the adhesive power to solid surfaces. The properties are highly desirable for the functionality of products of this type.

To identify key features in the perception of consumer satisfaction of washing performance, a survey among detergent users from five European countries was run. Respondents from each country were volunteers recruited through the Internet without previous selection criteria. The size of the sample (over 4,000 participants) and the wide geographical distribution of the respondents delivered a large set of data. According to the collected answers, respondents show a significant degree of satisfaction with the detergents they use, regardless of type and country. They were only dissatisfied by tough stains and exceptional problems with their wash loads. Detergent additives are widely used but the use and type of laundry additive showed significant differences from country to country. Respondents understood the usefulness of stain removers and showed a high degree of satisfaction using them. Damages to textiles, when it occurs, are not usually associated with the quality of the detergent used but with other factors in the washing process.

The objective of this paper is to measure the deposition of solid impurity on finished cotton fabric treated with DMDHEU resin during washing cycles of cotton fabric treated with different softeners. Fabrics will be softened with the conventional esterquat and with aminosilicone products having different molecular weights and mixtures of both. The anionic surfactant sodium dodecyl benzene sulphonate and non-ionic surfactant ethoxylated fatty alcohol were used. Both separately and in different proportions during the deposition trials were used. In general, the deposition values decrease on increasing the quantity of non-ionic surfactant in the mixture and with the finished cotton fabric increase this one after the application of the softeners tested alone and with their mixtures.