Nizar Meksi

Improving dyeability of modified cotton fabrics by the natural aqueous extract from red cabbage using ultrasonic energy.

The concern regarding sustainable utilization of available resources is growing due to its global importance. In this paper, the dyeability of cotton fabrics with natural colorant extracted from red cabbage was improved by applying cationic groups on cotton fibers. Modification of cotton was carried using acid tannic, Rewin Os, Denitex BC and Sera Fast as cationic agents. The dyeing process was done by ultrasonic energy. The effects of the cationising agent amount, the dye bath pH, the dyeing temperature and duration, on the sonicator dyeing quality were studied. The performances of this process were evaluated by measuring the colour yield (K/S) and the dyeing fastness of the coloured cotton. Besides, modified cotton fibers were characterized by morphology analysis (SEM) and Fourier transform infrared (FTIR) spectra and compared to untreated cotton. Moreover, a two-level full factorial design was employed to optimize the sonicator dyeing process. Mathematical model equation and statistical analysis were derived by computer simulation programming applying the least squares method using Minitab 15. Best dyeing conditions were found to be: 10%, pH 11, 60min and 100°C respectively for the Sera Fast amount, dye bath pH, dyeing duration and temperature.

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.

Application of anthocyanins as natural dye extracted from Brassica oleracea L. var. capitata f. rubra: dyeing studies of wool and silk fibres

Abstract Brassica oleracea L. var. capitata f. rubra (Red Cabbage) dye is composed mainly of natural pigment called anthocyanins used as a natural colourant. Wool and silk fibres were dyed with the aqueous extract obtained from red cabbage. The dyeing process was investigated and the combined effects of dyeing conditions on the colour yield parameter (K/S) were studied. Resulted fastness to wash, rubbing and light of the dyed fabrics were evaluated. Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD5) of the residual effluent were measured. Best dyeing conditions were found to be: 50 g/100 mL, pH 2, 60 min and 100 °C, respectively, for the red cabbage weight, pH, dyeing duration and temperature. Good fastnesses properties were found in both cases: for wool and silk fabrics. It was found also that the calculated biodegradability ratio (COD/BOD5) of the residual bath of dyeing wool and silk with red cabbage extract are lower than 1.5 which means that these baths are biodegradable.