Ibuprofen degradation in aqueous solution by using UV light

Abstract

Recent regulation policies are focusing on the presence of priority and emerging pollutants in water, among them, pharmaceutical residues are of particular public concern since trace of these molecules is commonly found in drinking and superficial waters. Progresses in innovative technologies for wastewater treatment are mandatory in order to improve their abatement efficiencies for water source prevention and reclamation. The OH⋅-based technologies, a group of different techniques usually called advanced oxidation processes (AOPs), can be used to mineralize organic pollutants. In particular, combined treatments based on UV light appear to be more eco-friendly, also giving very interesting removal efficiencies if opportunely devised. Moreover, many of the commonly detected pharmaceutical compounds are susceptible to degradation by UV at disinfection doses. In this paper, the removal of ibuprofen (IBP)—a widely used non-steroidal anti-inflammatory drug (NSAID)—from synthetic water streams was explored using a lab-scale experimental device, consisting of a batch reactor equipped with a lamp emitting monochromatic UV light at fixed wavelength and intensity (254 nm; 400 mJ m−2). IBP initial concentration (CIBP0) was varied in the range 30–60 mg L−1. The treatment time, the initial IBP concentration, pH and the presence of nitrates were investigated by several sets of experiments in order to study their effect on IBP degradation, showing very promising results. IBP removal of 75% was obtained at pH 6.0 with a concentration of NaNO3 of 10 mg L−1 and at pH 6.6 with an initial concentration of ibuprofen of 60 mg L−1. Moreover, a reaction mechanism has been proposed, which fits well in the experimental results, and the kinetic constants of 0.026 and 0.015 were statistically evaluated.