Band 47, Heft 6

Microemulsions are preferred over conventionally used pesticide systems for their long term thermodynamic stability, low viscosity, cost economy and aesthetic appeal. Such systems provide a method for preparing an isotropic mixture of oil and water. Neem and Karanjia isolates have proven activities. Therefore, uses of these oils provide a biologically and environmentally acceptable pesticide formulation. The present investigation deals with the systematic study to arrive at the economical composition for formulating microemulsion systems using these oils. These microemulsions, when diluted with water, formed macroemulsions which were stable over an extended period of time.

An environmentally benign aqueous alkylation protocol for the regioselective synthesis of thioalkylated imidazoles using cationic, anionic and neutral surfactants has been achieved. The efficiency of the coupling reaction depends strongly on the nature and the concentration of the surfactant. The highest yield (up to 94%) was obtained in the presence of an anionic surfactant, while neutral or cationic surfactants gave poorer results with no change in regioselectivity.

Cationic lignin amine flocculants were obtained by the Mannich reaction of Kraft lignin with formaldehyde and polyamines. The cationic reaction products were tested as a flocculating agent by flocculation of reactive brilliant blue KN-R and linear alkylbenzene sulphonates in an aqueous system. The effects of flocculant dosage and pH on the flocculation performance are discussed in detail. The results indicate that under optimum conditions, the rate of eliminating reactive brilliant blue KN-R and linear alkylbenzene sulphonates from the water exceed 99% and 96% respectively, which illustrated that the cationic reaction products are extremely effective as flocculants for reactive brilliant blue KN-R and linear alkylbenzene sulphonates.

The phase behavior of microemulsions containing composite surfactants of non-ionic alkyl polyglucoside and anionic sodium dodecyl sulfate was studied by the ∊-β fishlike phase diagram method. In microemulsion systems APG(SDS)/alcohol/alkane/water, there exists an obvious synergistic effect in terms of the composition of the interfacial layer and the solubilization ability. In the interfacial layer the number of surfactant and alcohol molecules notably decrease, resulting in a significant improvement in the solubilization ability of the system. The effects of alcohols, alkanes and salinity on the ∊-β fishlike phase diagrams of APG/SDS/alcohol/alkane/brine microemulsion systems were also discussed.

Important physicochemical characteristics for drugs, namely micellar properties and experimental partition coefficient of the series of five acyl stobadine derivatives in aqueous solutions were studied. The aim was to find out whether the studied compounds prepared as oxalates form associates. For measurements conductometry was used. The critical micelle concentrations (CMC) and thermodynamic parameters of micellization (standard molar Gibbs energy, enthalpy and entropy of micellization) were calculated from conductivity curves within the temperature range 25°C–50°C. The spectrophotometrically determined partition coefficients in the system octyl alcohol-water increased in parallel with increasing molar mass of studied substances. The dependences between values of common logarithm of CMC and partition coefficients of studied compounds were compared.

Clomipramine hydrochloride (CLP, an amphiphilic drug) solutions, prepared in sodium phosphate buffer, show temperature dependent phase separation (commonly known as Cloud Point, CP). CP can be varied with the help of additives. Hence, in this paper we are reporting the effect of various additives on the CP of CLP. Alcohols affect in two ways: CP either remains constant (or increases slightly) or decreases. Short chain alcohols remain soluble in aqueous phase and CP remains nearly constant in their presence as alcohol-water mixed system proves better solvent for the drug. Long chain alcohols, due to their hydrophobic nature, partition into the drug micelles and cause micellar growth which, in turn, decreases the CP. Sugars enhance the hydrophobic forces and decrease the CP. CP with amino acids is found to be nature dependent: acidic amino acids and hydrochloride salts of basic amino acids increase the CP (due to the interaction of their negatively charged side chains with the drug molecules). Basic amino acids decrease the CP. With polar and uncharged polar amino acids, CP remains constant. This last class of amino acids either remains in the bulk phase or solubilizes inside the micelle, and in either case, the hydration of micelles, and the CP, remain unaffected.

Two structural studies of the following two liquid crystals systems: [(C 12 EO 4 + 1% SDS)/H 2 O, ca. 25–85 wt.% surfactant] and [(C 12 EO 8 + 1% SDS)/H 2 O, ca. 40–71 wt.% surfactant] have been investigated. Both previous systems contain similar amount of Sodium Dodecyl Sulphate, SDS. It has been found that there are two mesophases at 25°C: the lamellar L α and the hexagonal H 1 . Their structural parameters were determined using small angle X-ray scattering (SAXS) patterns. The mesophases study of the L α and H 1 regions allows the evolution description of the surfactant chains conformation. The geometrical parameters of the L α and H 1 mesophases such as the thickness of hydrocarbon core of the lamellar mesophase and the diameter of rods forming the hexagonal structure were calculated. In the lamellar, L α and the hexagonal, H 1 mesophases, the surface area per molecule and the thickness of the hydrocarbon core exhibited a little sensitivity change toward concentration. The thickness of the ethoxy groups was estimated in L α and H 1 mesophases as a function of surfactant concentration in (C 12 EO 4 + 1% SDS)/H 2 O and (C 12 EO 8 + 1% SDS)/H 2 O systems at 25°C, respectively.

In this study, an attempt has been made to synthesize esterquat by esterification of stearic acid and 3-dimethylamino-1,2-propanediol (DMAPD) followed by quaternization with dimethyl sulfate, resulted in new quaternary useful as biodegradable fabric softener (2,3-bis(stearoloxy)-propyltrimethylamine [DMAPDEQDMS]). The softening property, biodegradation of DMAPDEQDMS were investigated, and compared with distearyl dimethylammonium chloride (D1821) and other ester quaternary. The results showed that DMAPDEQDMS's biodegradation was better than that of D1821, and its softening property was comparable with D1821. It is a new style softener with excellent properties, which can replace D1821.

Lowering the washing temperature of laundry has environmental benefits, but consumers are reluctant to decrease the temperature in fear of not getting clean textiles. The objective of this study was to test eight leading laundry detergents for low temperature washing at 30°C and at 40°C. The cleaning effect was tested by measuring the reflection values of pre-soiled swatches after wash based on standard EN 60456. The results show that the difference in reflection value was on average only 1.9% higher at 40°C than at 30°C, indicating very small difference in cleaning effect. Most differences between temperatures could be seen in liquid detergents for white textiles, and least in powder detergents for coloured textiles. This confirms that modern detergents are suitable for wash at 30°C, and the soil removal will in most cases be satisfactory for household use instead of the more common wash at 40°C.