Pharmaceuticals such as β-blockers have been widely recognized as a continuous threat to the
environment. These compounds are discharged into the aquatic environment, while the traditional
wastewater treatment plants cannot perform their efficient removal. Nadolol, a representative of the
β-blockers family, has been detected in the treated wastewater at a concentration of 20 ± 0.5 ng/dm3
. Although nadolol is helpful for humans, it shows a certain level of toxicity to aquatic organisms.
Since bicarbonates are present in natural waters, observing their influence on the stability of
pharmaceuticals detected in natural waters is essential. Therefore, nadolol has been subjected to
photolytic degradation in the presence/absence of bicarbonates under different types of irradiation
(simulated solar (SS), UV-LED, and UV irradiation). Due to bicarbonates in water, it is essential to
discover their effect on the photolytic stability of nadolol in water. In the presence of 3 mmol/dm3
bicarbonate, the efficiency of direct photolysis is decreased under UV and UV-LED irradiation. In
contrast, under SS irradiation presence of bicarbonates showed a slightly positive effect on nadolol
degradation. Bicarbonates are a known radical scavenger, which explains their tendency to lower the
degradation efficiency of nadolol under irradiation, where most radicals are formed.
