Calvini, P. and Gorassini, A. The Degrading Action of Iron and Copper on Paper. A FTIR-Deconvolution Analysis. Restaurator 23(4), 205-221 (2002).
Samples of FeCl3 and CuCl2 treated cellulose paper were analysed by FTIR before and after accelerated ageing at 90±10°C (sealed tube technique). The main mechanism of Fe(III) degradation appeared to be a strong hydrolysis and dehydration of cellulose chains, with formation of a C4-C5 double bond and C6 oxidation. Cu(II) oxidized the C2- and C3-OH groups to aldehydes and carboxyls, thus opening the pyranose ring, and hydrolyzed and oxidized the C4-OR group with the formation of a C4-C6 b-ketoaldehyde or b-ketoacid. Among the FTIR-deconvolution bands in the 1250-1850 cm-1 region, the ~1660 cm-1 signal is attributed to the unsaturated C=C-CO, and the 1612-1622 cm-1 signal to CO-C-CO group (chelate form of the enol tautomer). These bands, which can only be detected by the deconvolution technique, appear more significant than those of unconjugated CO groups above 1700 cm-1.