Impacts of organic matter digestion protocols on synthetic, artificial and natural raw fibers

As microplastic studies grow, environmental concerns of all kinds of fibers are currently investigated. However, there is a gap in data regarding the impacts of digestion protocols on fibers integrity. This work focuses on the impact of five commonly used digestion protocols on the seven most produced fibers in traditional textile: three synthetics (polyamide 6.6 (PA 6.6), polyethylene terephthalate (PET) and polyacrylonitrile (acrylic)), one artificial (viscose), two vegetal natural (cotton and flax) and one animal natural (wool). The protocols to be tested were selected based on the literature: 10% KOH at 40 °C for 24 h; 10% KOH at 60 °C for 24 h; diluted NaClO at room temperature (~20 °C) for 15 h; 30% HO at 40 °C for 48 h; Fenton's reagent with 30% HO for 2 h at room temperature (~20 °C). The fibers were characterized before and after digestion. The effects of those protocols on fibers integrity have been assessed using several of their performance parameters. High degradations were observed for PET with 10% KOH 60 °C whereas almost no impact was observed at 40 °C. HO digestion affects mechanical properties of different fibers, particularly PA 6.6. Both protocols should be avoided for synthetic fibers analyses. NaClO digestion mainly affected flax and viscose. Diluted NaClO at room temperature for 15 h, 10% KOH at 40 °C for 24 h and Fenton's reagent are more appropriate to maintain fibers integrity.