Volume 44, Issue 5

We represent an applicable problem that arises when long chain surfactant fatty alcohol sulfate FAS is used in washing process. Octadecyl fatty alcohol sulfate C 1 8-FAS is known for its strong washing performance, however it has the disadvantages of high Krafft point and its long dissolution rate. We demonstrate the factors that affect dissolution rates of FAS-surfactants, and how one can vary these factors in order to achieve particular dissolution rate. In this study, we have used a reproducible method for determining the rate of dissolution of anionic surfactants tablet and the effect of, temperature, hardness of FAS-tablets, stirring rate, FAS chain length, mixing with other surfactants and additives on the rate of dissolution of FAS have been studied.

Titanium dioxide is a well-known UV-absorber but it can also be used for initiating chemical reactions by ultra-violet radiation. By doping this semiconductor with carbon, interstate energy levels between the energy bands are formed. This offers the possibility not only to use ultra-violet light, but also visible light to activate the catalyst. In a cyclic photo-catalytic process inorganic radicals are generated from the surrounding atmospheric water and oxygen. These radicals then oxidize organic compounds e. g. aromatic and aliphatic hydrocarbons or inorganic molecules e. g. nitrogen oxides and carbon monoxide, respectively, to carbon dioxide, nitrates and water as end-products, which can readily be assimilated by vegetation. Potential applications are found in self-cleaning surfaces and the reduction of air and water pollution, where its superhydrophilicy and high specific surface areas can be utilized.

The influence of different surface active ether carboxylic acids as spin finishes on polyester fibre friction has been studied. The fibre friction was indirectly assessed through measurements of yarn tensile forces during the melt-spinning process. After manufacturing, the friction of fibre against steel was evaluated using the method of inclined plane. Results for the static fibre-steel friction coefficient obtained are in good agreement with the yarn tensile force data. The influence of different finishing agents as lubricants on the fibre friction was revealed.

The requirements for general and hygienic cleanliness are steadily increasing. Therefore the textiles used in food industry as well as in other hygienically demanding areas have to fulfil certain hygiene standards. The assurance of these microbiological quality is of increasing significance. National and international standards, guidelines as well as laws in some European countries ask for a professional reprocessing and advise clearly against washing the laundry in households. In commercial laundries the implementation of EN 14065 (Laundry Processed Textiles – Risk Analysis and Biocontamination Control System) (RABC system) ensures a defined microbiological quality of processed textiles. EN 14065 is published as a European standard and offers a powerful technique to perform a risk analysis and with it achieve any constant microbiological quality of expedition textiles. However, it does not contain any microbiological limits. This paper focuses on microbiological limits and hygiene instructions in laundry processes to fulfil the requirements of hygienically demanding areas such as food industry. Therefore hundreds of microbiological samples were taken at relevant process steps in nine laundries before and after installation of the RABC system. Samples were taken from wet and dry textiles, textile close surfaces and the interior of hands of the employees. Additionally water samples were analysed and the disinfection effect of washing procedures was investigated with biomonitors containing Staphylococcus aureus and Enterococcus faecium. The results show that the RABC system can constantly improve and guarantee the hygienic quality of the expedition textiles. Laundries with RABC system can easily fulfil the needs of hygienically demanding areas like food industry. Limit and/or orientation values for almost all relevant process steps as well as recommendations for sampling are set up.

The aim of this work is to investigate the micellization and adsorption thermodynamics (Δ m icH°, Δ mic G°, Δ mic S°, Δ ads H°, Δ ads G°, Δ ads S°) for three novel anionic Gemini surfactants with the same structure except the spacer length of the polymethylene chain have been synthesized based on nonylphenol (NP). The surface tension at cmc (γ cmc ) and critical micelle concentration (cmc) of the surfactants in aqueous solutions have been investigated. C 20 values (surfactant concentration in the solution phase that will reduce the surface tension of the solvent by 20 mNm −1 ) were also obtained. The critical micellar concentration (cmc) and the minimum average area per surfactant molecule (A min ) at the air-water interface of Gemini surfactant decrease with increasing number of methylene moieties in the spacer and, consequently, with the enhanced hydrophilic character of the molecule. The results were discussed with particular emphasis on the effect of the length spacer on the hydrophilic character of the spacer group. The surface studies of the molecules confirm that the exothermic values of the differential enthalpy of micellization (Δ mic H°) decrease as the methylene moieties are lengthened. Moreover, the values of the free energy (Δ mic G°) and entropy (Δ mic S°) of micellization indicate an entropy driven phenomenon for all surfactants. The effect of length spacer on surfactant adsorption for Gemini surfactants was utilized to calculate such thermodynamic parameters as the free energy of adsorption (Δ ads G°) and the heat of adsorption (Δ ads H°). The low value of Δ ads H° is an evidence for the physical adsorption of anionic surfactants. The relatively large value of entropic contribution (TΔ ads S°) indicates that the adsorption of anionic surfactants is entropically governed.

A synthetic process of Disodium of Mono-Alkyl polyoxyethylene Ether Citrate was developed in this paper. The structure of intermediate and products were indicated by infrared spectroscopy. The physico-chemical properties of aqueous solution of products were also investigated. The results show that products are excellent emulsifiers, with the low surface tension in 27–30 mN/m and good wetting power, and possess different foaming behavior in hard water and distilled water.