Simultaneous degradation of 30 pharmaceuticals by anodic oxidation: Main intermediaries and by-products. (April 2021)

• Record Type: Journal Article
• Authors: Calzadilla, Wendy; Espinoza, L. Carolina; Diaz-Cruz, M. Silvia; Sunyer, Adrià; Aranda, Mario; Peña-Farfal, Carlos; Salazar, Ricardo
• Is Part Of: Chemosphere. Volume 269(2021)
• Publication Date: 2021-04
• Subjects: Anodic oxidation -- Boron-doped diamond electrode -- Hydroxyl radical -- Pharmaceuticals -- Secondary effluent; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.128753
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The anodic oxidation (AO) of 30 pharmaceuticals including antibiotics, hormones, antihistaminics, anti-inflammatories, antidepressants, antihypertensives, and antiulcer agents, in solutions containing different supporting electrolytes media (0.05 M Na2 SO4, 0.05 M NaCl, and 0.05 M Na2 SO4 + 0.05 M NaCl) at natural pH was studied. A boron-doped diamond (BDD) electrode and a stainless-steel electrode were used as anode and cathode, respectively, and three current densities of 6, 20, and 40 mA cm −2 were applied. The results showed high mineralization rates, above 85%, in all the tested electrolytic media. 25 intermediaries produced during the electrooxidation were identified, depending on the supporting electrolyte together with the formation of carboxylic acids, NO3 −, SO4 2− and NH4 + ions. The formation of intermediates in chloride medium produced an increase in absorbance. Finally, a real secondary effluent spiked with the 30 pharmaceuticals was treated by AO applying 6 mA cm −2 at natural pH and without addition of supporting electrolyte, reaching c.a. 90% mineralization after 300 min, with an energy consumption of 18.95 kW h m −3 equivalent to 2.90 USD m −3 . A degradation scheme for the mixture of emerging contaminants in both electrolytic media is proposed. Thus, the application of anodic oxidation generates a high concentration of hydroxyl radicals that favors the mineralization of the pharmaceuticals present in the spiked secondary effluent sample. Highlights: Almost total mineralization of 30 pharmaceuticals by Anodic Oxidation in different electrolytic media. Anodic oxidation in NaCl produces chlorinated intermediaries and their formation increase at higher current densities. Simultaneous mineralization of 30 pharmaceuticals by AO in a secondary effluent from a wastewater treatment plant. More than 25 organic intermediaries generated during electrolysis were identified.