Synergetic degradation of atenolol by hydrodynamic cavitation coupled with sodium persulfate as zero-waste discharge process: Effect of coexisting anions

Abstract

This research investigates atenolol (ATL) removal from the aqueous solution by a combination of hydrodynamic cavitation (HC) and sodium persulfate (HC-PS) as zero-waste discharge process. The effect of pH, reaction time, PS dose, initial ATL concentration, coexisting anions and natural organic matters (NOMs) has been studied. The highest ATL removal by HC and HC-PS processes was obtained at pH 3 and 6, respectively. The presence of coexisting anions viz., Cl-, NO3?, I? , SO42? , and PO43?promoted the degradation of ATL, while the efficiency of ATL degradation was inhibited by the presence HCO3? and CO32? anions and NOMs. The highest synergetic and strongest inhibition effect of ATL degradation by the HC-PS process was observed in the presence of SO42?ions (synergetic index value, 4.61) and CO32? ions (synergetic index value, 0.44). Radical trapping experiments showed that the relative contributions of hydroxyl and sulfate radical to degrade ATL were 41.7 and 58.3, respectively. In case of HC-PS process, degradation initiated with the protonation of ATL in the presence of free active radicals was followed by the ether bond cleavage, oxidation of primary and secondary amine moieties, and finally mineralization. The HC-PS process is proved to be a potential treatment method to destroy pharmaceutical pollutants from water and wastewater sources.