Aqueous Photocatalytic Oxidation of Lignin: The Influence of Mineral Admixtures

摘要

The photocatalytic oxidation (PCO) of UV-irradiated aqueous solutions containing lignin onTiO2was studied for the influence of ferrous ions. The addition ofFe2+, up to 2.8 mgL?1, tothe acidic lignin solution leads to the drastic, for about 25%, increase in PCO efficiency. Afurther increase in ferrous ion concentration results in a decrease in PCO efficiency of lignin.The maximum PCO efficiency, up to 9.2 mgW?1h?1, was observed in neutral and slightlybasic media: the oxidation mechanism with OH-radicals seems to prevail. Also, the differencein the PCO performance with a different attachment mode of titanium dioxide on the catalystsupport was observed. Sprayed catalyst exhibited 1.5 times higher efficiency than the oneattached by submersion, although sprayed one was easily resuspended in acidic ligninsolutions. The efficiency of the N-doped photocatalyst active in visible light was observed tobe negligible with lignin.