Photocatalytic Reduction of Cr(VI) on Hematite Nanoparticles in the presence of Oxalic and Citric Acids under UV and visible light

KRETSCHMER IMME; SENN, ALEJANDRO M.; JORGE M. MEICHTRY; RALF DILLERT; DETLEF BAHNEMANN; MARTA I. LITTER

Conferencia; SPEA10; 2018

Under λ ≥ 310 nm, hematite nanoparticles (nHm, 3 mM) gave very rapid Cr(VI) (300 µM, pH 3) photocatalytic reduction in the presence of 2 mM citric acid (Cit) or oxalic acid (Ox). Experiments in the absence of donors or with 0.1 M MeOH or 2-PrOH showed negligible reaction. Homogeneous experiments with FeCl3 instead of nHm showed an even faster Cr(VI) reduction in the presence of Cit and Ox. At  > 495 nm, a good Cr(VI) transformation took place with both donors and nHm, but lower than under UV light; in contrast, the decay is negligible in the homogeneous systems. Cr(VI) photocatalytic reduction was negligible at  > 600 nm. The behaviour was explained taking into account the absorbing species and the different mechanisms taking place under each condition.