Volume 57, Issue 6

The paper studies the influences of two cationic surfactants - cetylpyridinium chloride (CPCl) and cetylpyridinium bromide (CPBr) - at concentrations 10-times below and 10-times above the CMC - at 258C-408C on the release of ibuprofen from hydrogels, rheological properties and pH. The association of surfactants in the water solutions was studied by conductometry. It was found that the temperature dependences of the surfactants’ CMCs are not linear and the CMCs of CPCl are higher than that of CPBr. The concentrations of the polymer (chitosan) and the drug were kept constant. Amounts of the released drug increased with the increasing temperature. From the hydrogels with CPBr and CPCl, whose surfactant concentration was below the respective CMC, higher amounts of the active ingredient were released than from the hydrogels with surfactant concentrations above the respective CMC. It is shown that for increasing temperature the hydrogels exhibit gradual transition for pseudo plastic to thixotropic system, what is advantageous for their practical application. The hydrogels’ pH values were in the interval 5.10-5.46, which is ideal for their application on the skin and for the chitosan swelling. The presented topic is a precondition of synthesis of the on-line and off-line control algorithms of an optimal release kinetics, elaborated by the authors.

Hemp seed oil has good sun protection, repair, anti-allergy and anti-aging effects, and is a high quality raw material for the production of skincare products. However, the influence of surfactants and co-surfactants on the emulsification of hemp seed oil in aqueous solution has been rarely investigated. In this investigation, the surfactants and co-surfactants which were suitable for hemp seed oil emulsion were optimized, and the factors which influence the particle size and the stability of the emulsion were studied. Moreover, the application of hemp seed emulsion in different cosmetics was also further investigated. It was found that sorbitan monooleate/polysorbate-80 and glyceryl stearate were the most effective surfactant and co-surfactant in the emulsification of hemp seed oil. After three months the hemp seed oil emulsion had no layered separation and remained homogeneous at -48C, 258C and 408C. The water-resistant sunscreens and the hemp seed oil sunscreens were homogeneous pastes, had a soft texture and were stable at higher temperatures. No microorganisms were detected in these cosmetic creams. Therefore, hemp seed oil is suitable for sunscreen cosmetic materials.

The surface tension, pH and contact angle of the wetting liquid as well as the complex composition of the leaf surface are important parameters to describe the spreading, wettability and absorption of agrochemicals on the leaf surfaces. The contact angle of aqueous solutions of agrochemicals (multi-micronutrient fertilizers, growth regulator and insecticides) with/without Leaf guard, bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) and Sapindus mukorrossi (Ritha) were measured over the surface of mango leaves. The order of contact angle (mean) values was found to be AOT < Ritha < Leaf guard, which implies that AOT is a better wetting agent, but Ritha has a higher range of adhesion work because of its acidic nature (low pH). The wetting free energy was found to be more negative in the presence of Leaf guard, Ritha and AOT than in water, which indicates that wetting is more spontaneous in the presence of surfactants. The adaxial surface of mango leaves had a higher surface free energy than the abaxial part and hence showed higher wettability than the abaxial part.

The effect of oxyethylene groups on the adsorption properties of fatty alcohol polyoxyethylene ether sodium sulfate with narrow ethylene oxide distribution (AEmS, m = 3, 5, 7, 9) was characterized by means of the equilibrium surface tension, the dynamic surface tension and the contact angle. The results show that at a concentration lower than the critical micelle concentration (CMC) the oxyethylene groups act like hydrophobic groups to change the absorption properties. If the concentration is higher than the critical micelle concentration, the oxyethylene groups act as hydrophilic groups to change the absorption properties. The long polyoxyethylene chain of AE9S is very curly, which means that AE9S does not strictly follow the rule derived from AEmS (m = 3, 5, 7). The adsorption process of AEmS is a mixed diffusion-kinetic adsorption mechanism.

The 'Recommendations for the Quality Assessment of the Cleaning Performance of Dishwasher Detergents" provide detailed procedures to assess the performance of a household dishwasher detergent using a standard test programme of a standard dishwasher. As such, they are a de facto standard for a whole industry. Consequently, it is relevant to ensure that the conditions under which the tests are carried out represent the relevant market: the automatic dishwashing machines installed and used in households in Europe. But no data are available by now describing the situation in the households. The task here is to model the distribution of total energy, water consumption and programme duration of the automatic dishwashing machines installed and used in private households in Europe when used by the consumer. Those data are then compared to the data of the reference dishwasher and, thus, the relevance of the reference system to the dishwashers installed in private households is assessed.

The aim of this study was to establish a simple model describing the microbial reduction of a cleaning process by only using physical parameters of a given cleaning process (time and temperature) together with microorganism-specific inactivation parameters. The \Microbiological Inactivation Equivalent (MIE) unit" representing the time-temperature integral of a dish treatment process for a specific microorganism was developed. Microbiological reduction in suspension and dishwasher tests was tested in parallel. The microorganism-specific inactivation parameters were adjusted by fitting the MIE units to the experimental reduction factors gained. The mean square deviation between reduction factors and MIE units calculated was on average < 1 (Enterococcus faecium: 0.87, Micrococcus luteus: 0.79) in suspension tests and 1.09 (Enterococcus faecium) and 1.03 (Micrococcus luteus) in dishwasher tests. The MIE model can be used as a simplified method to predict the hygienic performance of a specific cleaning process under well-defined conditions.

Micelles and 4d- or 5d-transition metal ions have been proved to be effective catalysts for the oxidation of 1-pentanol by Ce(IV) in aqueous medium under pseudo 1st order reaction conditions at 258C. Although cationic micelles show a speed retarding effect, anionic SDS micelles accelerate the reaction rate. The Ir(III) and Ru(III) catalysed reactions show shorter half-lives at micromolar concentration. Active Ce(IV) species are also identified and an explanation of the different catalytic activities of metal ions and micelles is presented. The accumulation of the substrate in the Stern-layer of the SDS micelles is detected. The reaction product is confirmed by melting point analysis, a 2,4-DNP test, and by IR and NMR studies.

Many studies have been conducted on the removal of heavy metals from industrial wastewater using biosurfactants, but few papers have been published on the removal of heavy metals from soil contaminated with crude oil using this method. The aim of this study is to evaluate the performance of rhamnolipid biosurfactants in removing nickel, chromium, and cadmium from soil contaminated with crude oil. In this study, first rhamnolipid was produced from Pseudomonas aeruginosa PTCC1340 and then confirmed by Thin-Layer-Chromatography (TLC) and Fourier-Transformation-Infrared-Spectroscopy (FTIR). In the next step, a sandy soil (2 mm diameter) was mixed with the crude oil (API = 32.83, viscosity = 6.21cp) at 258C for 2 weeks. The washing parameters included temperature, pH and rhamnolipid dosage. Based on our results, the heavy metal removal of nickel, chromium and cadmium from soil contaminated with crude oil at the optimum condition (258C, 0.8 g/L and pH 11) was 43.05%, 34.73% and 52.81%, respectively. Based on the results, rhamnolipids are found to have considerable potential for removing heavy metals especially cadmium, and the soil washing by the produced biosurfactant leads to the removal of heavy metals without the destructive effects of chemical surfactants and subsequently reduces environmental pollution. Therefore, this biosurfactant rhamnolipid may have a good potential for application in bioremediation of crude oil contamination.

The Cloud Point Extraction (CPE) of Pb(II) ion, using Triton X-114/ alanine and Triton X-114/phenyalanine as biodegradable systems, was carried out. The experimental results are expressed by four responses to surfactant concentration, amino acid concentration and temperature variations: extent of solute extraction (E), remaining solute (Xm,w) and surfactant (Xt,w) concentrations in dilute phase and volume fraction of coacervate (}C) at equilibrium. An empirical smoothing method was used, where the results were represented on three dimensional plots using the Box-Behnken design (BBD) and the response surface methodology (RSM). High extraction efficiencies (94% with alanine and 98% with phenylalanine) are reached in optimal conditions. Thereby, solute concentration reduction in the dilute phase is about 4 and 12 times with alanine and phenylalanine, respectively. The pH effect is also studied. Finally, the possibility of recycling the surfactant/amino acid system by pH change is proved.

Focusing on the leakage problem in high temperature and high salinity oil fields (reservoir temperature 1208C-1308C, formation water salinity 220000 mg/L), a gel-blocking system is proposed using a polymer and a phenolic prepolymer. Specifically, it addresses the short storage time issue of synthetic phenolic prepolymer by introducing p-hydroxybenzoic acid to modify and effectively extend its lifespan. The additional introduction of c-aminopropyl triethoxysilane (KH550) improves the wall-adhesion of this system. The proposed gel-blocking system shows good on-site application results in a western China oil field.