An ESR study of the radical interactions of NOx with lignin-containing pulps and papers and several model lignin compounds

The reactions of alkyl peroxyl radicals with cellulosic and lignin-containing papers have significance in both the problems of brightness reversion and paper aging phenomena. Since transient peroxyl radicals are elusive to ESR and other spectroscopic detection, we have explored the controlled study of the interactions of nitrogen oxides with paper and some model lignin compounds in solution as a comparable model of free radical oxidation. Formations of intermediate iminoxyl and nitroxide radicals are identified by ESR with products in some model systems analysed by GC/MS to elucidate the primary mechanisms of the interactions of these gaseous free radicals with papers and with some simple organic model lignin compounds.