| The textile dyeing and finishing process emits large amounts of waste water with toxic chemicals.To reduce pollution,human is calling for a new textile economy by developing environmentally friendly processes and technologies.Many researchers are working on replacing chemical dyes with natural dyes.And plant dyes are the most important part of natural dyes due to their easy availability.Researchers used agricultural and forestry waste as raw materials to dye textiles that were not only rich in colour,but also had high functional added-value,such as antibacterial,anti-UV,anti-oxidant and flame retardant.These studies can truly contribute to the sustainable development of the textile industry and have great potential for development and market prospects.Aloe vera contains more than 200 different bioactive substances with moisturising,anti-inflammatory,immunomodulatory,anti-UV,antibacterial,antifungal and antitumour properties,and are widely used in medicine,food,and skin care products.In recent years,aloe vera has been used to prepare different types of textile composites involved in medical textiles,beauty textiles,UV protection textiles,even in textile dyeing and printing.In most industrial production,aloe vera products produce large amounts of waste rinds,some of which was used as fertiliser,feed or fermentation substrate for biogas,but the overall utilisation and the economic value was low.Research for textile dyeing and finishing still suffers from low fastness and non-durable finishing effects currently.The aim of this study is to increase the economic value of waste aloe vera rinds and obtain an environmentally friendly process that endows natural textiles a durable antibacterial and anti-UV effect.Active substances were extracted of from aloe vera rinds using different extraction systems and their chemical composition were analysed by a series of tests.Finally,the extracts were used for dyeing and functional finishing of natural textiles and finished fabric properties were evaluated.1.Antibacterial performances of silk fabric finished by aloe anthraquinonesThe natural antibacterial substances from aloe vera rinds were extracted by ultrasonic assisted extraction method in ethanol aqueous solution.The substances were aloe anthraquinones(AA)analysed by Fourier Transform Infrared(FTIR)Spectroscopy.Then the silk fabrics were treated with aloe anthraquinones by linkage of β-cyclodextrin(β-CD)which has a hydrophilic outer cavity and hydrophobic inner cavity.Antibacterial activity and washing stability tests showed that the treated silk fabrics exhibited excellent and durable antibacterial properties.The antibacterial rate of treated fabrics against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were 99.48% and 99.89%and remained higher than 89.14% and 84.18%,respectively,after being washed 30 times.Furthermore,cell compatibility tests results showed that the treated silk fabrics had good cell compatibility.2.Silk textile finished with natural dyes and UV resistance agents from agricultural waste Aloe vera rindsThe natural UV resistant dyes from aloe vera rinds were extracted by cellulase assisted extraction method in acid or alkaline solutions.The optimum extraction conditions were obtained using single factor experiment: pH 8,65 °C,60 min,and a cellulase dosage of 35 mg/g.The UV spectral analysis,FTIR spectrum and total polyphenol and flavonoid content test results showed that the extracts mainly included polyphenols and flavonoids.Then the optimum conditions for dyeing silk fabrics with extracts were investigated: pH 4,concentration 100%,90 °C,60 min.The dyed fabrics,without the addition of additional mordant,obtained a colour depth(K/S)of 7.945 and good colour-fastness to washing and rubbing.The ultraviolet protection factor(UPF)of dyed fabrics was 2076 and transmittance of UVA was 0.06%.After 25 washing cycles,the UPF was 1241 and transmittance of UVA was 0.10%,which was much higher than standard recommended.3.Comparative study of silk,wool,and cotton fabrics dyeing and finishing with Aloe vera rinds extractsThe AA and natural UV resistant dyes from aloe vera rinds dyes were co-finished onto silk,wool and cotton fabrics modified with β-CD,to obtain multifunctional fabrics with excellent performance.The finished silk was red-brown and had a UPF value of526.6 and transmittance of UVA was 0.25%,which was much higher than standard recommended.The antibacterial rates of finished silk against E.coli and S.Aureus were95.52% and 97.96%,respectively.Washing stability tests showed that the finished silk had satisfactory washing resistance.Similarly,the finished wool was dark red-brown and had a good UV protective property.The antibacterial rates of finished wool against E.coli and S.Aureus were 82.55% and 84.96%,respectively.The washing stability was also good.The finished cotton was light pink and had a good UV protective property.The antibacterial rates of finished cotton against E.coli and S.Aureus were 94.49% and99.66%,respectively.The finished cotton had good washing stability in antibacterial property.In summary,this study provides a theoretical basis for the extraction of aloe verabased plant dyes and their use in textile dyeing and functional finishing,as well as for the widespread use of plant dyes in industry. |
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