Dyeing Of Cotton Fabrics In Deep Eutectic Solvent

Reactive dyes have become the main dyes for cotton fabrics due to their complete chromatogram and good color fastness.However,conventional aqueous dyeing of cotton fabrics with reactive dyes is considered to be environmentally unfriendly.Because much water and salt is required to promote dyeing.Reactive dyes are easily hydrolyzed in water,and the discharged dyeing wastewater contains a lot of salt and reactive dyes,which is very harmful to the ecological environment and human health.Although there have been many researches on the new technology of cotton fabric dyeing in recent years,it is difficult to meet the industrial application and promotion of dyeing technology due to different problems such as poor dyeing quality,environmental pollution,and high cost.The non-toxic,harmless and non-polluting environmentally friendly characteristics make natural dyes gradually replace traditional reactive dyes in the dyeing process of cotton fabrics,and endow textiles with multi-functional properties and increase the added value of fabrics.However,dyeing with natural dyes could bring about problems such as unsatisfactory dye uptake and color fastness.In response to the above problems,this paper proposes a new method for dyeing cotton fabrics,using a hydrophobic eutectic solvent(HDES)thymol-menthol and a trace amount of water to form an emulsion system to dye cotton fabrics.Firstly,the reactive dyeing of cotton fabrics in the thymol-menthol emulsion dyeing system was studied.Take K/S and levelness as indicators to determine the best dyeing process of reactive dyes in emulsion system.According to the results of K/S,levelness,penetration,color fastness and lifting power,the thymol-menthol emulsion dyeing system was compared with conventional aqueous dyeing system.The results showed that the cotton fabric can obtain high K/S value,good levelness,splendid dye penetration and color fastness without adding salt in the thymol-menthol emulsion dyeing system.Based on Lagergren pseudo-first-order and pseudo-second-order dynamics models,the dyeing process of cotton fabrics with reactive dyes in conventional aqueous dyeing system and emulsion dyeing systems were studied.The fixing kinetics of two systems was in accordance with the pseudo-second-order dynamics models.The fixation rate of thymol-menthol emulsion dyeing system was similar to conventional aqueous dyeing system.In addition,the reusability of HDES was studied.After using 5 dyeing cycles,the dyed fabric always had a high K/S value.According to the results of ultraviolet absorption spectrum,thymol-menthol did not remain on the dyed fabrics,and it had no negative impact on the chemical structure and physical properties of cotton fabrics.This dyeing method greatly reduced the discharge of wastewater and the consumption of chemicals.It had considerable potential for promoting the sustainable development of the textile industry.This article also studied the dyeing of cotton fabrics with natural dyes in the thymol-menthol emulsion dyeing system.Firstly,the cotton fabric with sodium carbonate solution was immersed in a system of high-speed mixing of mulberry anthocyanin dye extract and menthol-thymol for dyeing.The effect of mulberry anthocyanin solution p H,dyeing temperature and time on cotton fabric dyeing effect was discussed.The results showed that the K/S value of cotton fabric dyed at 60°C for 40 min at p H 3 of mulberry anthocyanin solution was 2.17 times that of conventional aqueous dyeing system,and had good UV protection performance,UPF value could reach 37.84,UVA penetration rate was3.82%.Dyed cotton fabrics also had good antibacterial properties.The antibacterial rates against Escherichia coli and Staphylococcus aureus were 94.57% and 87.96%,respectively.In addition,the dyed fabric had an antioxidant activity of 95.71%,showing its good antioxidant properties.The thymol-menthol dyeing system of cotton fabrics consumed less water.It increased the dye uptake rate of anthocyanin dyes,significantly reduced water resource consumption and dyeing wastewater discharge.