Environmentally friendly dyeing of wool and silk fabrics with natural colorant of turnsole (Chrozophora tinctoria L.).

With the increasing demand for environmentally friendly dyes, natural dye has become an attractive option replacing toxic synthetic dyes. Within the framework of this research, the natural dye of Chrozophora tinctoria L. was extracted using the microwave-assisted extraction method under different operating conditions. The influence of different factors influencing the extraction process (such as pH, extraction time, and microwave power) on the extraction efficiency was investigated by means of a multilevel three-factor design. The suggested model has a high coefficient of determination, indicating high predictability and good approximation. Optimal microwave extraction process conditions were obtained at a value of microwave power equal to 650 W, at a pH of 5 during a period of 3 min. Dyed wool and silk fabrics showed very good washing and light fastness properties.

A novel natural source Vicia faba L. membranes as colourant: development and optimisation of the extraction process using response surface methodology (RSM).

In this research paper, an eco-friendly extraction process of dyes from Vicia faba L. membranes was developed. In this regard, the influence of independent process factors like the weight of material, the extraction time, the temperature and the sodium hydroxide concentration on the natural dye extraction from Vicia faba membranes was investigated. The optimisation of the extraction conditions and the effect evaluation of the different operating parameters were carried out using a Box-Behnken design under response surface methodology. The optimum conditions were found to be 66 °C, 90 min, 5 g and 0.1628 mol·L-1 for extraction temperature, time, mass of the material and sodium hydroxide concentration, respectively. The efficiency of this extraction process under these optimum conditions was evaluated by measuring the total phenolic content (TPC), the total flavonoid content and the relative colour yield (K/S). In these operating conditions, good fastness ratios were observed for the dyed fabrics.

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.

Optimisation of the recovery of carotenoids from tomato processing wastes: application on textile dyeing and assessment of its antioxidant activity.

The present study has been focused on the extraction of natural pigments from tomato industry waste. At first, different solvents and solvents mixture were compared to determine which one is the best for extracting carotenoids compounds from tomato by-products. A mixture of hexane and acetone gave the highest carotenoids extraction yield among the others examined. The extraction conditions were optimised using a five-level-five-factor central composite design. Under optimal conditions, solvent solid ratio 90, hexane percentage in the solvent mixture 60, extraction duration 50, number of extractions 4 and extraction temperature 35 °C, the yield of carotenoids was 80.7 µg/g. The coloured extract of tomato by-products was applied on textile fabrics to investigate the dyeing characteristics and antioxidant activities. The results indicate that extract can be applied on textile fabrics (wool, silk and polyamide) to produce coloured clothing with acceptable antioxidant properties.

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.