Use of ultrasonic energy for enhancing the dyeing performances of polyamide fibers with olive vegetable water

The present study reports the valorization of the olive vegetable water in natural dyeing. HPLC analysis of the phenolic extract obtained from the used olive vegetable water showed that the predominant flavonoid compounds were luteolin and apigenin. Hydroxytyrosol and various phenolic acids were also identified. This abundant waste was used as a possible dye bath for dyeing polyamide fabrics in conventional and ultrasonic techniques. It was found that these synthetic fibers possess high affinity to the olive vegetable water giving brownish shades with generally good fastness properties. Factors affecting the dyeing performances such as pH, temperature, and duration of the dyeing time were studied. Ultrasonic dyeing showed marked improvement in the dye uptake compared to the conventional heating. The results also showed that the use of this method enhanced some fastness properties compared to the conventional method. Moreover, it was found that using ultrasonic technique can reduce the concentration of polyphenols so that it reduced the chemical oxygen demand COD and biological oxygen demand BOD5 better than conventional heating method.