Degradation of cellulosic materials under the alkaline conditions of a cementitious repository for low and intermediate level radioactive waste Part I: Identification of degradation products

In order to assess the potential role of cellulose degradation products as metal-binding chelates in a repository for radioactive waste, different cellulosic materials (pure cellulose, cotton, tissues and recycling paper) were degraded under the chemical conditions of cement pore water (pH 13.3). The degradation products formed were characterised using different separation techniques (HPIEC, HPAEC, GC-MS, MS/MS) and by high resolution H-1-NMR spectroscopy. The main degradation products of pure cellulose are the diastereomeric alpha-isosaccharinic acid (alpha-ISA) and beta-isosaccharinic acid (P-ISA), which accounted for similar to 80% of total dissolved organic carbon formed. Minor components are short chain aliphatic acids such as formic acid, acetic acid, lactic acid and threonic acid comprising less than 10% of total dissolved organic carbon. The degradation of the other cellulosic materials resulted in lower amounts of alpha-ISA and beta-ISA and in higher yields of small organic acids (acetic acid) and of unidentified compounds. The combination of the different MS and NMR techniques unequivocally shows the structural identity of beta-ISA. (C) 1999 Elsevier Science B.V. All rights reserved.