Band 52, Heft 1

How to calculate the amount of colored oily soil adhered to fabric by measuring the reflectance was studied. Fatty acid, triacylglycerol and hydrocarbon were selected as typical oily soil and mixed with Sudan IV. Removal of fatty acid was greatly affected by alkaline property of washing liquid, and those of triacylglycerol and hydrocarbon were largely affected by interfacial activity of washing liquid. The detergency of Japanese artificial soiled fabric was largely affected by the fatty acid composition.

The aim of this work is to determine the influence of certain clay micro particles added to detergent formulation to act as builders in removal of impurities (detersive power) during the washing of a standard cotton fabric (EMPA), and also to determine the whiteness of the fabric and its softness after washing. Sepiolite was used separately and together with bentonite, in the form of micro particles. Bentonite is held to have a softening effect on cotton. A whitener was added to the detergent formulations to compensate for a possible effect of diminished whiteness in the washed fabric. Scanning electron microscope images of the fibres were taken to show deposition of the builders on the fabric. A non-toxic microemulsified solvent, dimethylsulfoxide (DMS), suitably microdispersed with use of an amphoteric surfactant as emulsifier, was added to improve the performance of the detergent formulations used, notably enhancing the detergency obtained in the presence of the clay microparticles tested.

Tartaric acid-based symmetric and hybrid gemini surfactants having dodecyloxy (C 12 H 25 O-) and tridecafluoro nonyloxy groups (C 6 F 13 (CH 2 ) 3 O-) as hydrophobic groups were synthesized, and their surface properties were studied by surface tension (γ)-concentration and surface pressure-area (π- A ) measurements. All geminis showed superior surfactant properties to 1+1 type surfactant. Especially, hybrid gemini showed high efficiency of lowering the surface tension comparable to that of bis(C 6 F 13 (CH 2 ) 3 O) gemini. Further, hybrid gemini showed an unusual existence of two breakpoints at γ = ∼25 and 18 mN m −1 . In the π- A measurements, regardless of symmetric or hybrid structures, geminis having fluoroalkyl group formed only liquid condensed monolayers while the bis(dodecyloxy) gemini formed solid monolayer. Molecular occupied areas of hybrid gemini were subequal to the mean of those of symmetric geminis.

Surfactant flooding aims at lowering the interfacial tensions between the oil and water phases to improve the displacement efficiency during oil recovery. However, ionic surfactants will lose their property in high temperature and high salt reservoirs. This investigation considers the cardanolbetaine surfactants as candidates for enhanced oil recovery (EOR) application in high temperature and high salt reservoirs. According to the experimental results, these surfactants can be effective in lowering interfacial tension (IFT) at dilute concentration, without requiring an alkaline or co-surfactants. In addition, these surfactants exhibit a low IFT at high salinity, high temperature and high concentration of divalent condition, the best surfactant concentration is 0.3 g L −1 . The temperature resistance results show that it also has an excellent interfacial property at a wide range temperature from 35.0°C to 85.0°C, and remains its ultralow IFT (≤ 10 −3 mN m −1 ) during 60 days at 85.0°C. The optimal concentration of salt tolerance is 50 g L −1 to 100 g L −1 of NaCl, 100 mg L −1 to 300 mg L −1 of Ca 2+ respectively.

Oxidation kinetics of 1-butanol by permanganate have been carried out in the presence of surfactant in aqueous acidic medium to observe the micellar effect on rate. The oxidation kinetics were studied by UV–VIS spectrophotometry. The presence of cationic N -cetylpyridinium chloride (CPC) micelles was found to accelerate the reaction rate and this effect has been explained by the partitioning of the reactants in micelle and also by considering the hydrophobic and electrostatic interactions between the surfactant and reactants. The alcohol was quantitatively oxidized to the carbonyl compound, which was identified by the preparation of 2,4-DNP derivatives. The probable mechanism is proposed and pseudo-first-order rate constants are calculated. The cationic surfactant (CPC) accelerates the reaction. The critical micelle concentration (CMC) value of the CPC micelle has been determined from the plot of rate constant values at different CPC concentration.

In aqueous solution the adsorption of Cr(VI) was examined onto plant based biosorbents viz. Kekar sawdust ( Acacia nelotica ) and rice husk ( Oryza sativa ) and their non-ionic surfactant (Tween-20) modified forms. The parameters studied in this work include: contact time, adsorbent dosage, pH and metal concentration. The adsorption capacities of the biosorbents were dependent on the pH of the Cr(VI) solution, and were found to be 96.1 mg/g, 147.1 mg/g, 35.7 mg/g and 37.2 mg/g for raw Acacia nelotica , surfactant modified Acacia nelotica , raw Oryza sativa and surfactant modified Oryza sativa, respectively at optimum pH = 2. The studies revealed that the modification of biomass with Tween-20 enhanced the biosorption capacity of raw Acacia nelotica by 53%. The adsorption process was tested for Langmuir and Freundlich isotherm models. Langmuir isotherm model fitted the data best. Desorption studies were also carried out and revealed the possibility of recycling the adsorbent and adsorbate.

The densities, ρ and viscosities, η of glycine (Gly), L-alanine (Ala), L-phenylalanine (Phe) and glycylglycine (Gly-Gly) in aqueous Triton X-100 (TX-100) solutions have been measured as a function of amino acid/peptide concentration at 298.15, 303.15, 308.15 and 313.15 K. The experimental data have been utilized to evaluate various thermodynamic parameters, viz., apparent molar volumes, V 2 , partial molar volumes at infinite dilution, V 0 2 , partial molar isobaric expansibilities, ϕ 0 2 , partial molar volumes of transfer, Δ tr V 0 2 and A and B -coefficients of viscosity, respectively. The hydration numbers have also been calculated. The results have been discussed in terms of interactions taking place in the present systems. The structure-making/-breaking ability of the solute (amino acid/peptide) in the presence of surfactant, Triton X-100 has also been considered.

The cloud point (CP) of Triton-X-100 have been studied at various concentration of surfactant in pure and mixed system with water soluble polymers polyacrylic acid (PAA) and polyacrylamide (PAM). The CP of Triton-X-100 was found to be increases with increasing surfactant concentration. The CP of Triton-X-100 has found to decrease with increase of mass of the additives PAA and PAM. The same trend was observed for all surfactant concentrations in presence of PAA and PAM. Considering CP as a threshold temperature of the solubility, the thermodynamic parameters of the clouding process (ΔG 0 cl , ΔH 0 cl and ΔS 0 cl ) have been evaluated using “Phase Separation Model”. The results indicate that the clouding phenomenon of Triton-X-100 is exothermic and in presence of polymer additives the process is endothermic and non-spontaneous.

Knowledge of the release kinetics together with its (mathematical) model is inevitable for prediction of properties and optimization of dosage forms. The ability to optimize the release kinetics is a key factor in the endeavour of increasing pharmaceutical availability. The optimization may be done by a suitable choice of the dosage form or by clever distribution of the drug in the auxiliary substances or even by using an automatically working drug delivery device. This paper describes a model-based analysis and preparation of hydrogels. The following composition was used in the experiment: Chitosan – the gel creating basis; polymer, chlorhexidine – the drug; dodecyltrimethylammonium bromide – the auxiliary substance and surfactant. The release kinetics were studied at three temperatures and were evaluated by using several models (zero order, pseudo-first order, first order, Higuchi, Hixon Crowell, Weibul distribution and Korsmeyer-Peppas). It was found that the best fitting model of the drug release was the Higuchi model. So as to predict character of the release process (exothermic and spontaneous), the activation energy, activation enthalpy, entropy and Gibbs free energy were evaluated.

The present study involves the micellization of novel biodegradable gemini surfactants (1,2-diyl-bis(N,N-dimethyl-N-alkyl-ammoniumacetoxy) dichlorides, m-E2-m; m = 12,14,16 is the number of carbon atoms in the tail and E2 represents the diester-group-containing spacer) in presence of sodium alkanoates (sodium propionate, sodium hexanoate, sodium decanoate). The techniques of tensiometry and spectrofluorimetry were utilized to probe the changes in various physicochemical parameters, viz. critical micellar concentration (CMC), surface excess concentration (Γ max ), minimum area per head group (A min ), Gibbs free energy of micellization (ΔG ° mic ), Gibbs free energy of adsorption (ΔG ° ads ), aggregation number (N agg ) and local polarity index (I 1 /I 3) . Results depict that the alkanoates are effective in bringing significant changes in the physicochemical parameters of the m-E2-m geminis; the order being followed is NaDec > NaHx > NaPr. Both hydrophobic and electrostatic factors were found to be contributive. This study can be helpful to understand tuning and evolution of biodegradable microstructures in amphiphilic salt environments, which may have implications in biomedical research (gene transfection and drug delivery).

This paper focuses on the synthesis of new demulsifiers based on oleic acid monoamide to treat gas condensate-in-water emulsions. The chemical structure of the prepared ethoxylated demulsifier was confirmed by FT-IR and 1 H NMR spectroscopy. The treatment of gas condensate-in-water emulsions was investigated by means of dissolved-air flotation jar-tests. The effect of several parameters on the flotation efficiency for separation of the emulsified oil was investigated such as: effect of pH value, demulsifiers concentration, feed rate (L/min) and saturator working pressure (psi). Also, the surface and interfacial tensions, and the thermodynamic properties of the prepared surfactants have been studied. The results show that the optimum oil removal (99.9%) was obtained for OT3 at the concentration of 150 ppm, pH = 2, feed rate = 0.1 L/min and the saturation pressure 10 psi.