A comparative study on the degradation of cotton linters induced by carbonate and hydroxyl radicals generated from peroxynitrite

Carbonate (CO3 •−) and hydroxyl (HO•) radicals were chemically produced in cotton linter suspensions using peroxynitrite as a radical precursor. Both radicals could degrade cotton linters, as shown by viscosity and GPC-SEC measurements. As evidenced by the viscosity measurements, the presence of oxygen during the cotton linter treatments slightly increased cellulose degradation by both radicals. For the carbonate radical, more than 90% of the viscosity losses could be recovered by reductive NaBH4 treatment before measuring the viscosity, whereas only approximately 40% of the viscosity was recovered after hydroxyl radical degradation and subsequent NaBH4 treatment. This indicates that carbonate radicals mainly abstract H-atoms adjacent to hydroxyl groups, i.e., at C2, C3 and C6. This intramolecular selectivity may reflect a polar effect, whereby hydrogen atom abstractions from these positions are favoured. In addition, abstraction at C6 would be sterically and statistically favoured.