Efficient removal of propranolol from water using PbO2-coated Ti/Sb-SnO2 electrode: Mechanistic insights from experiments and DFT with ecotoxicological assessment

Abstract

Widely used and highly toxic beta-blocker, propranolol (PRL), was efficiently removed from water using a stable Ti/Sb-SnO₂/PbO₂ anode for the first time. Over a 90-min treatment, >94 % of PRL was degraded at 50 mA/cm². Current density and PRL concentration were found to be crucial for the PRL degradation rate, while Na₂SO₄ concentration and the initial pH value had a minimal effect on the outcome. Under optimized conditions, a high production of reactive species was achieved. HO^• dominated the initial 40 min, whereas${\mathrm{SO}}_4^{•-}$ and $O_2^{•-}$ became more relevant as the process continued. Degradation intermediates were unraveled and the degradation mechanism was thoroughly described, innovatively integrating both experimental and theoretical insights. Despite increased toxicity of the treated PRL solution, the overall environmental impact remains low thanks to high levels of acute toxicity, that is, 0.23 g/dm³. In comparison to deionized water, the degradation rates in spiked tap water (86 %) and rain samples (84 %) were lower, which also affected the mineralization rate. The anode's excellent reusability was confirmed by 10 repeated experiments with over 81 % of PRL removed. This research presents an encouraging approach to mitigating pharmaceutical pollution in various water bodies using a simple, efficient, and scalable experimental setup.