Kinetics of 5-fluorouracil degradation by heterogenous TiO2 photocatalysis

Abstract

Cytostatic drugs represents a category of pharmaceutical products used in cancer treatment, and among them 5-fluorouracil is the most common. Drugs used in cancer treatment are inhibiting and even destroying the cells, acting in a non-selective manner and therefore being considered to present carcinogenic, genotoxic, mutagenic and teratogenic potential. About 15% of the administered 5-fluorouracil is eliminated from human body without any transformation and therefore ends up in the wastewater system. Due to the fact that removal of 5-fluoruracil and other pharmaceutical products using conventional wastewater treatment is incomplete and inefficient, there is a need for more performant degradation technologies such as advanced oxidation processes. Among them, photocatalytic oxidation using titanium dioxide represents one of the most efficient removal technology for hazardous organic compounds. UV/TiO2 degradation of 5-fluorouracil was investigated in the aim to optimize process operational parameters: pH = 7, photocatalyst dose = 100 mg/L, irradiation time = 180 min. The degradation kinetic of 5-fluorouracil was found to follow Langmuir – Hinshelwood model and degradation rate constant kr=3.74 x 10-6 M min-1 and equilibrium constant of 5- fluorouracil adsorption on photocatalyst particles Kad = 9505 M-1 were determined.