| Coffee and black tea are highly popular beverages worldwide.Thanks to its unique flavor,aroma,and beneficial health benefits,the total consumption of coffee and black tea beverages has skyrocketed worldwide.However,with the continuous increase in processing and consumption,the production of hot drink by-products such as spent coffee grounds and spent black tea leaves is also rapidly increasing.According to statistics,millions of tons of coffee grounds and tea leaves by-products are produced globally every year.For a long time,coffee grounds and black tea leaves have been regarded as low value materials and randomly discarded,resulting in disposal methods such as landfill or incineration that not only directly lead to the loss of biomass resources,but also pose significant risks to the ecological environment and human health during this process.At present,research has shown that coffee grounds and black tea leaves contain rich nutrients and bioactive components,with functional characteristics such as antioxidant,anti-inflammatory,antibacterial,and tumor inhibition.They can also be used as a low-cost and easily available source of natural biological colorants,and have potential application value in textile dyeing and finishing.Protein fibers such as wool and silk have good affinity for natural dyes.However,there are certain limitations when dyeing cotton fibers,resulting in poor dyeing performance.This is mainly because the high negative charge density on the surface of cotton fabric and negative anionic natural dyes have coulomb repulsion,which makes it difficult to combine fibers with dyes.Therefore,one of the effective methods for dyeing cotton fibers with natural dyes is to minimize the repulsive force as much as possible.In this work,the application of coffee and black tea hot drink by-products in the dyeing and functional finishing of wool,silk,and cotton fabrics was fully explored.The main research content and conclusions are as follows:(1)The experiment used an environmentally friendly extraction process to study the influence of solvent extraction system factors on the extraction efficiency of natural dyes from coffee grounds and black tea leaves.Thermogravimetric analysis,Fourier transform infrared spectroscopy,surface morphology analysis,and elemental composition analysis were conducted on the dye powder of coffee grounds and black tea leaves.The feasibility of using extracted coffee grounds and black tea leaves waste as plant soil fertilizers was also evaluated.The results showed that the optimal extraction conditions were as follows: using an ethanol/alkali solvent system to control the liquid to material ratio of 50:1,adding a small amount of 5% sodium bicarbonate solution to a 50% ethanol solution to adjust to p H=8,and extracting at a temperature of80° C for 60 minutes.As for the extraction of black tea leaves dyes,compared with five solvent systems: ethanol solvent,acid solvent,ethanol/acid solvent,alkali solvent,and ethanol/alkali solvent,the highest flavonoid content was obtained in the ethanol/alkali solvent system.UV absorption spectroscopy and Fourier transform infrared spectroscopy analysis confirmed the presence of caffeine plant alkaloid compounds,flavonoids,and polyphenols in coffee grounds and black tea leaves extracts in an ethanol/alkali solvent system.Thermogravimetric analysis shows that natural dyes in coffee grounds and black tea leaves have good thermal stability under optimal extraction conditions and are suitable for textile dyeing and finishing processes.By conducting p H analysis and evaluation on the soil and its mixture with extracted coffee grounds and black tea leaves processing waste,it was found that it can ultimately be safely returned to the soil as plant fertilizer and benefit plants.This provides a sustainable disposal method for reducing the landfill of precious resources such as coffee grounds and black tea leaves,and to some extent,achieves the recycling and reuse of waste.(2)Apply natural dyes from coffee grounds and black tea leaves to dyeing wool and silk fabrics,and characterize the K/S value,color fastness,antioxidant,UV protection,and antibacterial activity of the dyed wool and silk fabrics.The results showed that wool and silk fabrics treated with coffee grounds and red tea dyes exhibited varying degrees of brown color,indicating good dyeing performance.Among them,when the fabric type is the same,the K/S value of the fabric dyed with red tea dye is greater than that of coffee grounds.The color fastness of dyed and finished fabrics meets the requirements of industrial scale.By dyeing,various bioactive substances such as caffeine,melanin,catechins,polyphenols,and flavonoids can be efficiently transferred to wool and silk fabrics.SEM images confirm the attachment of natural dye particles from coffee grounds and black tea leaves on the surface of wool and silk fibers,thereby endowing the dyed and finished fabric with antioxidant,UV protective,and antibacterial properties.The successful dyeing and functional finishing of natural dyes from coffee grounds and black tea leaves on wool and silk fabrics in this chapter will expand the value-added application of hot drink by-products in the textile field.(3)Provided a green and environmentally friendly surface modification method for cotton fabrics to enhance their affinity for natural dyes.Using an environmentally friendly hot water bath to extract fish scale protein from grass carp scales as a natural cationic modifier for pre dyeing modification of cotton fabrics,EDTA solution,citric acid,and acetic acid solution were selected for fish scale demineralization treatment.Dyeing and finishing of fish scale protein modified cotton fabric using natural dyes from coffee grounds and red tea leaves were carried out,and the dyeing p H of the modified fabric was optimized.By characterizing the cotton fabric’s K/S value,SEM scanning electron microscopy,color fastness,antioxidant performance,UV protection performance,and antibacterial activity,the effects of different types of demineralization solutions on fish scale protein modification,cotton fabric dyeing effect,and biological function were analyzed and explored.The results showed that compared with the dyed cotton fabric without fish scale protein modification,the K/S value of the dyed cotton fabric modified with fish scale protein increased to varying degrees.Considering that a low p H value in the dyeing bath may cause loss of fabric strength,p H=4.8 was ultimately chosen as the p H value for cotton fabric dyeing bath.Demineralization treatment greatly improved the effect of fish scale protein modified cotton fabric.The results showed that the K/S value of the modified cotton fabric after demineralization treatment was the most significant,and the difference in K/S value of the modified cotton fabric after different types of demineralization solution treatment may be related to the p H value of the demineralization treatment environment and the demineralization reaction products.Among them,the K/S value of cotton fabric dyed with black tea leaves dye and modified after EDTA demineralization treatment is the highest,at 7.7195.After demineralization treatment,coffee grounds and black tea leaves natural dye dyeing and finishing modified cotton fabrics have good washing resistance,dry and wet friction resistance,and light fastness levels,meeting the requirements of industrial scale.At the same time,compared with the control group,the UV protection performance,antioxidant activity,and antibacterial activity of the modified cotton fabric after demineralization treatment were significantly improved,achieving the biological functional finishing of cotton fabric. |
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