Unraveling the time evolution and post mortem changes of nanometric MnOOH during in situ oxidation of ciprofloxacin by activated peroxymonosulfate

Author(s)

Nunez-de la Rosa, Yeison ; Durango, Luis Guillermo Cuadrado ; Forim, Moacir Rossi ; Nascimento, Otaciro Rangel ; Hammer, Peter ; Aquino, Jose M.

• Document type: Journal article
• Source: APPLIED CATALYSIS B-ENVIRONMENTAL; v. 327, p. 11-pg., 2023-02-17.

Abstract

Nanometric MnOOH compound was synthesized by a green approach, characterized, and used to remove ciprofloxacin (CIP) antibiotic by in situ chemical oxidation using peroxymonosulfate (PMS). The effects of varying concentrations of MnOOH, PMS and pH, on morphological, structural, chemical, and electrochemical changes were studied during and after the experiments. The CIP molecule was completely oxidized and partially mineralized (>60%) after 6 h under acidic conditions. The mechanism of CIP degradation was induced by PMS activated oxidants (HO center dot and 1O2) and, to a lesser extent, directly on the surface of MnOOH. The latter process was evidenced by transmission electron microscopy showing the formation of an amorphous shell (MnO2) over MnOOH crystallites, as verified using X-ray photoelectron spectroscopy and the subsequent increase of the charge transfer resistance that hindered a further electron transfer to the PMS oxidant. Such behavior is recoverable when using a freshly prepared PMS solution. (AU)

• FAPESP's process: 14/50918-7 - INCT 2014: for the Biorational Control of Pest-Insect and Phytopathogens
• Grantee: Maria Fátima das Graças Fernandes da Silva
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 19/07943-4 - Comparative study of homogeneous and heterogeneous systems with nano/micrometric particles for the degradation of organic pollutants through in situ homolysis of oxidants
• Grantee: José Mario de Aquino
• Support Opportunities: Regular Research Grants