Colouration of Polyester Using Bio-Shell Microcapsules: Efficient Resource and Waste Water Management

Abstract

The present work aimed at efficient utilization of resources viz., water, dyes and chemicals (without using any supportive chemical) for colouration of polyester. The method of complex coacervation was attempted for obtaining the microcapsules. Bio-shelled (gelatin and gum acacia) microcapsules of disperse dyes were analysed for their resource efficient auxiliary chemicals free colouration on polyester (PET) over conventionally dyed one. The remnant liquor recovered from colouration of polyester was recycled for subsequent three colouration cycles (without treatment) showing negligible shade difference and the fastness rating. The effluent of fourth colouration cycles treated with primary water treatments and was found to be translucent, neutral in pH and low effluent load (TDS >231 ppm, BOD >114 mg/l, and COD > 469 mg/l). The solids recovered from bath were analyzed and found to be nontoxic (LD50 > 8000) as well. Cost of disperse dye microcapsules was calculated to be USD $ 4.17 /kg. Cost involved in microencapsulated colouration is much lower (USD $ 2.19) than conventional process of colouration (USD $ 3.93) due to absence of auxiliary chemicals, post treatment, much lower electrical energy consumption. Thus, microencapsulated colouration is easily adoptable in existing process line of polyester colouration, which leads to small liquid discharge of low effluent load.