Comparison of biodegradation of low-weight hydroentangled raw cotton nonwoven fabric and that of commonly used disposable nonwoven fabrics in aerobic Captina silt loam soil

Abstract

The increasing use of synthetic disposable nonwoven products generates a large amount of non-biodegradable solid waste. In an effort to enhance the use of raw cotton in nonwoven wipes applications, this study compares the biodegradation of low-weight nonwoven fabrics (around 50 g/m2) made of mechanically pre-cleaned raw cotton, rayon, polypropylene (PP), and polylactic acid (PLA) in a Captina silt loam soil. The biodegradation rates of raw cotton and rayon fabrics were fitted to the first-order kinetics model with half-life values of 12.6 and 7.6 days, respectively. The slightly faster disintegration of cellulose structure for rayon was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectra, and distinct morphological changes in the fiber (cracks and breakage were prevalent in raw cotton, whereas the thinning and merging of fibers occurred in rayon) were observed during their biodegradation. PLA and PP nonwoven fabrics exhibited no weight loss during the burial periods studied, but showed some evidence of oxidation in ATR-FTIR spectra. The breaking and burst strengths of PLA fabric decreased by 45% and 23% of the original strengths, respectively, while neither significantly decreased in PP fabric. The results suggest that mixing raw cotton or rayon low-weight nonwoven wastes with surface soil provides an alternative disposal method, but this land application could not be recommended for PLA and PP nonwoven wastes.