Tungsten/bismuth – based catalysts for the degradation of 5-fluorouracil cytostatic drug in water by solar-LED photocatalysis

Abstract

A new series of photocatalysts, including WO3, Bi2O3 and Bi2WO6, were prepared for the photo-oxidation of 5-Fluorouracil (5-FU) in water, as a model of cytostatic drug, under solar-LED irradiation. The materials were hydrothermally prepared under the same experimental conditions, and the effect of incorporating an activated carbon during the synthesis and further post-treatments in air or nitrogen atmosphere were investigated. All photocatalysts were thoroughly characterized by complementary techniques analyzing their morphologies and physicochemical properties, which differed based on the type of semiconductor used. In general, the addition of carbon led to an increased porosity (SBET= 20–50 m2/g), a reduced band gap (Eg= 2.7–2.9 eV) and a lower crystallite size compared to the original semiconductor. The photocatalytic performance of the materials depended also on the thermal post-treatment, while N2 treatment improved the efficiency of Bi-carbon composites, the air treatment did not influence the pure semiconductors. The 5-FU degradation varied as WO3 (10 %) < Bi2WO6 (36 %) < Bi2O3 (68 %) after 100 min under solar-LED irradiation, while their corresponding carbon-metal composites always improved the performance. In particular, the conversion of 5-FU after 100 min of reaction was 64 % and 84 % for Bi2WO6-3C and Bi2WO6-3C-n, while the carbon-Bi2O3 composite achieved total photodegradation of 5-FU (kapp= 43.89 ×10−3 min−1) after ∼100 min of reaction and under solar-LED irradiation.