Evaluation of advanced oxidation processes for β-blockers degradation: a review

This study summarizes the results of scientific investigations on the removal of the three most often used β-blockers (atenolol, metoprolol and propranolol) by various advanced oxidation processes (AOP). The free radical chemistry, rate constants, degradation mechanism and elimination effectiveness of these compounds are discussed together with the technical details of experiments. In most AOP the degradation is predominantly initiated by hydroxyl radicals. In sulfate radical anion-based oxidation processes (SROP) both hydroxyl radicals and sulfate radical anions greatly contribute to the degradation. The rate constants of reactions with these two radicals are in the 10⁹-10¹⁰ M^-1 s^-1 range. The degradation products reflect ipso attack, hydroxylation on the aromatic ring and/or the amino moiety and cleavage of the side chain. Among AOP, photocatalysis and SROP are the most effective for degradation of the three β-blockers. The operating parameters have to be optimized to the most suitable effectiveness.