FTIR Analysis of Naturally Aged FeCl3 and CuCl2-Doped Cellulose Papers

This paper shows the results of the Fourier Transform Infrared (FTIR) analysis of cellulose papers doped twenty years ago with 0.1 and 1 M solutions of FeCl3 and CuCl2 respectively and kept in polypropylene bags in the dark. Iron-treated samples appear today highly hydrolysed and oxidised; in particular the excess of metal (treatment with 1 M solutions) brought about the formation of iron(II) oxalate, as shown by the FTIR bands at about 1620, 1358, 1313 and 814 cm-1. Washing and acid treatments removed the low-molecular weight oxidised fractions and iron oxalate, yielding the neat spectrum of oxidised cellulose. Copper-treated samples appear today only partly hydrolysed and slightly oxidised; the excess of metal (treatment with 1 M solutions) was not fully absorbed by cellulose and appears as a saline deposit of copper chloride on the surface. However, traces of copper oxalate have been detected in the FTIR spectrum.