RESUMEN
The influence of iron ions at concentrations of 0.2, 0.5, and 1.0 g/L on optical brighteners of the groups stilbene and biphenyl in solution and on cotton fabric was investigated. Both groups of optical brighteners are intended for detergent formulations. The influence of iron ions was studied by absorption and fluorescence spectra in solution and by whiteness degree, identifying color differences using CIEL*a*b* coordinates and Ultraviolet Protection Factor (UPF) of cotton fabrics. The obtained results in solutions and cotton fabrics showed different behavior of optical brighteners stilbene and biphenyl in the presence of iron. Stilbene compounds with metal ions produced new species capable of absorbing in the UV-B region of the spectrum. A biphenyl compound in combination with iron had no effect on the absorption properties. Both optical brighteners were influenced by iron ions in the sense of fluorescence quenching. The influence of iron ions in single- and two-bath treatments of cotton fabrics after one cycle on whiteness degree and UPF was negligible.
RESUMEN
The textile finishing industry is known as a very fragmented and heterogeneous industrial sector dominated mainly by small and medium enterprises (SMEs). As with many other industrial sectors in Europe, it is obliged to act more sustainably in regard to increasingly limited natural resources such as water. This paper presents in-depth survey of wastewater reuse programmes over the last ten years covering the European textile finishing industry. Different wastewater treatment solutions developed are presented and discussed. Special attention is given to the project AquaFit4Use (7th Framework Programme), where almost five years of project work has resulted in valuable know-how practices in water reuse for the most water consuming sectors in Europe i.e. paper, food, chemical and textile. Only the latter is discussed in this paper. The main negative impacts by the textile finishing sector on the environment are still related to intensive water consumption and wastewater discharge, characterised by greater amounts of organic chemicals and colouring agents, low biodegradability, and high salinity. End of pipe treatment of such complex effluents in order to produce reusable water is not feasible. Therefore, separation of waste effluents regarding their pollution level and their separate treatment was the basic approach used in the project. As a result waste effluents with a big reuse potential could be effectively treated by combination of conventional treatment technologies. Proposed water treatment scenarios enable more than 40% reduction in fresh water consumption. Since different guidelines of minimum water quality to be safely reuse in textile processes exist at this stage this issue is discussed as well.
