Soil biodegradation of functional fabrics: a lab-scale study

The textile materials’ stability in the natural environment is a cutting-edge topic: on the one hand, significant durability is required for specific applications (i.e., geotextiles) to guarantee long-life performances; on the other hand, when textile materials are discarded, it is preferable that they can be easily degraded without causing secondary polluting products. In this framework, this research was based on a biodegradation study carried out on cotton fabrics treated with (i) polypyrrole, (ii) chitosan and (iii) chitosan+natural dye (Figure 1a). These finishings were imparted to confer particular properties and functions to the textile substrate that can range from color to antibacterial features and electrical conductivity. In controlled lab-scale experiments, bare cotton and the different functional fabrics were buried in commercial compost-enriched soil. Using bare cotton as a control, the study aimed to investigate the behavior of the treated cotton fibers over time (10, 30 and 90 days) in order to understand if the considered finishings promoted or delayed the natural biodegradation process. Physical–chemical changes after the different periods of biodegradation were determined using electron microscopic, thermal and spectroscopic analyses, in addition to specific characterizations on the basis of the treatment type, such as surface resistivity measurements for polypyrrole-coated samples or the determination of surface hydrophilicity variation for chitosan-treated samples. The main results showed that, in general, the coating/finishing seems to protect the cotton substrate in the first stage of biodegradation and the extent of this shield effect depends on the treatment type (i.e., polypyrrole partly loses conjugation and efficiently preserves the integrity of cotton fabric, Figure 1b). As a perspective, the (ongoing) study of the biota communities in the adopted soil after fabric burial can enrich the knowledge about the biodegradation pathways of differently treated textile materials (in collaboration with CNR-IPSP, Torino).