Photocatalytic Degradation of Losartan with Bismuth Oxychloride: Batch and Pilot Scale Demonstration

Abstract

The solar-induced semiconductor photocatalytic process is one of the greenest and most promising technologies for the elimination of pharmaceuticals in aqueous media. In the context of this study, a bismuth oxychloride (BiOCl) photocatalyst was fabricated and characterized by its morphology, crystallographic structure, and optical properties. Its photocatalytic efficiency was tested towards the degradation of Losartan (LOS), a medication used to treat high blood pressure, in water using a solar simulator. The as-prepared BiOCl exhibited significant photocatalytic efficiency, achieving complete degradation of 0.3 mg/L LOS in short periods of irradiation (15–30 min). The examined system showed optimal efficiency using 500 mg/L of BiOCL (kapp = 0.21 min−1) and pH 3 (kapp = 0.32 min−1). However, LOS removal significantly decreased in environmentally relevant water matrices, including wastewater (kapp = 0.006 min−1) and bottled water (kapp = 0.023 min−1). Additional tests carried out in synthetic water matrices showed that the LOS degradation rate was reduced by more than 40% in the presence of humic acid (kapp = 0.016 min−1) and bicarbonates (kapp = 0.029 min−1), while chlorides did not affect the overall efficiency. Moreover, photogenerated holes and singlet oxygen were the dominant oxidative species. The efficiency of the BiOCl photocatalyst towards LOS degradation was further studied using a flat plate pilot-plant scale photoreactor. It was found that more than 75% of LOS was removed after 100 kJ/L of accumulated solar irradiation. The results obtained in the pilot-plant unit confirmed the suitability of BiOCl as a potential photocatalytic material.