Effect of Alkaline Pre-Treatment and Temperature on Cotton Uptake of Sorghum Husk Extract

Abstract

Sorghum is a staple food around the world. As the demand for the grain soars, there is an equivalent increase in the quantity of sorghum husk generated. Sorghum husk is a promising resource as a natural functional dye. Sorghum is enriched with phytochemicals such as tannins, phenolic acids and anthocyanins which have health benefits. Colorant from the husk was used to dye cotton. Cotton was pretreated with alkaline and dyed at a temperature range of 80°C-130°C. An untreated sample was used as control. The colorant was extracted from Sorghum husk with ultrasound-microwave machine and 70% ethanol//30% water with 1ml HCl per 100 ml as solvent at 55°C for 20 mins. The extraction yield was yield of 16.7%. Ultrasound-microwave-assisted extraction method with blended solvent 70% ethanol/30% water with HCl significantly improved extraction of biocolorants from sorghum husk. The extracted colorant was used to dyed alkaline treated fabric and the fabric had better colorfastness to laundry, crocking and light and better UV protection. The optimum dyeing temperature was 100°C. The use of sorghum husk as a source of colorant can find application in industry and significantly add value to the sorghum plant and reduce the disposal of sorghum husk.