Dyes on Archaeological Textiles: Analyzing Alizarin and Its Degradation Products

This research investigates the degradation products and pathway of alizarin in selected conditions of accelerated aerobic degradation. The degradation study is a step toward dye identification on badly faded textiles of archaeological origin. The four major degradation products identified through GC-MS analysis are benzoic acid 4, 2,4-di-tert butyl phenol 5, phthalic anhydride 6, and dimethyl phthalate 7. Benzoic acid and 2,4-di-tert butyl phenol are the major products formed upon thermal degradation, while phthalic anhydride and dimethyl phthalate exist in thermal and peroxide/UV treated specimens. Among the four degradation prototypes of this study, peroxide/uv radiation results in the most accelerated degradation, producing phthalic anhydride 6 as its main degradation product. A degrada tion pathway is also proposed.