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

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.

Sustainability issues of ultrasonic wool dyeing with grape pomace colourant.

In this study, the ultrasound technique was investigated to dye wool fabrics with the natural extract obtained from grape pomace as a way of reducing time, temperature and environmental impact. Indeed, this natural material was very rich in total polyphenolic compounds and total flavonoids (which are, respectively, 310 (mg GAE/L) and 75 mg (CE/L)). Further, Fourier Transform Infrared Spectroscopy showed that the major chemical groups identified in the extracted dye and in the dyed wool fabrics are characteristics of phenolic compounds. The experimental findings of the dyeing process showed that ultrasound method could improve obviously the dye exhaustion and fixation which resulted in improving considerably the colour yield (K/S) and the fastness properties of dyed fabrics compared to the conventional heating method.

Green dyeing process of modified cotton fibres using natural dyes extracted from Tamarix aphylla (L.) Karst. leaves.

This research work involves an eco-friendly dyeing process of modified cotton with the aqueous extract of Tamarix aphylla leaves. During this process, the dyeing step was carried out on modified cotton by several cationising agents in order to improve its dyeability. The influence of the main dyeing conditions (dye bath pH, dyeing time, dyeing temperature, salt addition) on the performances of this dyeing process were studied. The dyeing performances of this process were appreciated by measuring the colour yield (K/S) and the fastness properties of the dyed samples. The effect of mordant type with different mordanting methods on dyeing quality was also studied. The results showed that mordanting gave deeper shades and enhanced fastness properties. In addition, environmental indicators (BOD5, COD and COD/BOD5) were used to describe potential improvements in the biodegradability of the dyebath wastewater. Further, HPLC was used to identify the major phenolic compounds in the extracted dye.

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.

Development and optimisation of a non conventional extraction process of natural dye from olive solid waste using response surface methodology (RSM).

Dyes obtained from different natural sources have emerged as an important alternative to synthetic dyes. In this study, optimisation of natural colorant non-conventional extraction technique from olive waste was investigated using response surface methodology. The combined effects of extraction conditions on total phenolic content (TPC) and relative color strength (K/S) were studied using a three-level three-factor Box-Behnken design. The optimum conditions for dye extraction were found to be 0.14mol/L, 62.11min, 71.23°C and 4.5g for sodium hydroxide concentration, extraction time, temperature, and mass of the waste, respectively. The efficiency of extraction under these optimum conditions was found to be 1133.86mg/L of phenolics and relative colour strength (K/S) equal to 23.22. Further, Fourier Transform Infrared Spectroscopy was used to identify the major chemical groups in the extracted dye.