Oxidation of bisoprolol in heated persulfate/H2O systems: Kinetics and products

The oxidative removal of dissolved aqueous bisoprolol (BIS) fumarate, prescribed to treat hypertension, by thermally activated sodium persulfate (Na2S2O8: SPS) was investigated in a phosphate buffer solution at pH 7.0 and different temperatures. The results showed that BIS disappearance was pseudo-first order for 1-4 half-lives and the resulting rate constants observed from 40 to 70 degrees C fit the Arrhenius equation, yielding apparent activation energy of 119.8 (+/- 10.8) kJ mol(-1). The observed aqueous phase BIS degradation half-lives ranged from 1.9 (+/- 0.1) to 93.7 (+/- 6.3) min. The effect of various inorganic additives on maintaining high reaction stoichiometric efficiency (RSE) and SPS activation was studied. The results indicated that only HCO3- slightly affected BIS degradation rate although full degradation was noticed at 60 degrees C. A test on BIS spiked local commercial mineral water showed full degradation of BIS after 1 h of reaction. HPLC/MS analysis showed the presence of intermediate oxidized products. The high RSE obtained demonstrated that the use of thermally activated SPS is a suitable advanced oxidation process for the degradation of pharmaceutical compounds in water. (C) 2011 Elsevier B.V. All rights reserved.