Effect of the photocatalytic activity of TiO2 on lignin depolymerization

Lignin is a good candidate for photocatalytic cracking due to the presence of hydroxyl groups. The photocatalytic cracking reaction involves TiO2 as heterogeneous catalyst.In the present work lignin obtained by two different pulping methods is treated under photocatalytic conditions to be depolimerized. Different exposure times to UV radiation were carried out. The results of GS–MS revealed the degradation products of the hemicelluloses contained in the lignin samples. 1 h of exposure to UV radiation shows the best yield in the obtaining of lignin degradation derived compounds; the main products obtained are syringaldehyde, pyrocatechol and raspberryketone, the concentration of syringaldehyde increases 20% and vanillin 30%.

► The influence of photocatalytic treatment time on lignin degradation was evaluated.
► Lignin was successfully degraded under photocatalytic treatment.
► Several phenolic compounds were obtained from the black liquors.
► Better depolymerization of lignin contained organosolv black liquor was observed.