The deposits of disperse dyes on dyed polyester fibres is an important problem in polyester fibre dyeing that should be tackled, properly. These dyes deteriorate the wash, rubbing and sublimation fastness as well as the brightness of the dyed fibres, especially deep-dyed one. Therefore, clearing these surface dyes is of profound importance. Conventionally, a reduction clearing process is used for the removal of the surface dyes in which sodium dithionite as a reductant, and sodium hydroxide as an alkaline, are used. Unfortunately, this process is not environment friendly and the derivatives of its chemicals are toxic to human health. In recent years, numerous researches have been conducted on the removal of surface disperse dyes by alternative less-pollutant and efficient processes. Using surfactants, enzymes, and other reductants; oxidative clearing, plasma, electrochemical methods and the application of easily clearable synthesized dyes are among these alternative processes. Each of these proposed processes has its own pros and cons, and they have special needs. In this research, ozone nano-microbubbles oxidation method was used to remove surface disperse dyes, the samples were dyed in concentrations of 4% and 6%, and then they were exposed to ozone micro-nanobubbles for 15 and 30 minutes and the results were compared with those associated to conventional reduction clearing method. The samples were eva‎luated by various techniques including measurement of color coordinates using reflectance spectrophotometer, eva‎luation of rubfastness and wash fastness, fabric strength measurement, determination of water uptake rate, imaging using scanning electron microscope (SEM) and finally Fourier Transform Infrared (FTIR) spectroscopy. According to the results, following treatment of the dyed polyester fabric with ozone nano-microbubbles, lightness of the fabric increased by more than 3. In the case of wash and rubbing fastness, ozone nano-microbubbles oxidation resulted similar to the results reported for the conventional reduction clearing method. Additionally, ozone nano-microbubbles oxidation could also account for the reduction in fabric strength and the increase in water uptake by more than 50%. According to the results, it seems that the oxidation is not limited to the surface and has also penetrated inside. If it is possible to optimize the method of removing polyester surface disperse dyes using ozone micro-nanobubbles in such a way that the strength is reduced less, this method is a suitable method and a good alternative to the conventional reduction clearing method.

حسين ايزدان

داود سعيدي

فرزانه علي حسيني , زهرا طالبي مزرعه شاهي