NEW RECYCLING TECHNOLOGY FOR SUSTAINABLE FINISHING OF POLYAMIDE FABRICS

Sustainable finishing technologies of polyamide fabrics concentrate on the high use of water, energy, and chemicals in the wet processing. A solution is to change the technology in order to reduce the water consume by recycling wastewater after appropriate treatment. This study was undertaken to examine the feasibility of recycling coloured wastewater from polyamide dyeing with acid dyes in new preparation phases, after removing colour using hydrogen peroxide activated with catalysts from resins functionalized with amines and saturated with Fe (III). Analysing the wastewater colour removal process, it has been found that the efficiency of the discolouration is high. Subsequently, wastewater from real dyeing and after dyeing rinsing processes have been discoloured using the tested technology, and the treated water has been recycled as it is or mixed with fresh water (1:1) in new degreasing/washing (scouring) phases of polyamide fabric preparation. High degrees of whiteness and small colour differences have been obtained, especially for one of the studied dyes. For the second dye, although the obtained degree of whiteness was high, the calculated colour difference was higher then 1 unit in most cases. Better results were obtained using treated wastewater mixed with fresh water. It was concluded that hydrogen peroxide catalysed oxidation process can remove efficiently the colour from polyamide dyeing wastewater, obtaining improved water quality that is suitable for reuse in textile preparation stages such as scouring.