An approach for the valorization of bio-waste pistachio shells (Pistacia vera L.): Dyeing of cellulose-based fabrics

The waste management subject is a very important issue today and in the future. Therefore, lots of scholars are endeavoring to investigate the valorization of wastes from different sources, such as paper, metal, glass, and vegetables. In this study, the pistachio soft and hard shells, as an industrial waste material, were used as natural dye sources. For this purpose, waste were collected from Gaziantep province in the south of Türkiye. Then, the soft and hard pistachio shells that had been dried in the shadow were investigated in terms of FTIR analysis and then used as a dyestuff source in the dyeing of cotton fabrics with the help of bio-mordants and metal mordants. Additionally, the antioxidant capacity of the soft and hard shell of pistachio was assessed through the DPPH and FRAP assay methods, and the antibacterial activities were tested against Staphylococcus aureus and Escherichia coli for selected dyed samples. A spectrophotometer was used to determine the CIE L*a*b* color values and (K/S) of cotton fabrics that had been dyed. The results exhibited that the tested wastes could be useful for the coloration of the cotton fabrics, and depending on the used natural dye source, mordanting agent, and mordanting method, the colors were found to have changed, but in general, light brown-ecru-brown colors were observed in the dyed samples. Meanwhile, the fastness of the samples was examined, and the sources were found to exhibit limited light fastness values but good or perfect washing, rubbing, and perspiration fastness. In conclusion, the evaluated conditions were found to be useful for the coloration of cotton, and even more importantly, the pistachio soft and hard shells were observed to reveal great potential for use in textile dye houses as a natural dye source.