Cerium oxide nanoparticles: Biosynthesis, characterization, antimicrobial, ecotoxicity and photocatalytic activity

Abstract

The present work aims to synthesize and characterize cerium oxide nanoparticles (CeO2-NPs) for application in the photodegradation of methylene blue – MB and methyl orange -MO. CeO2-NPs were prepared by biosynthesis method using Matricaria recutita extract. Minimal inhibitory concentration (MIC) was used to evaluate the antimicrobial activity against E. coli, S. aureus and K. pneumoniae. Microcrustacean Artemia salina was used for the ecotoxicity test. Central Composite Rotational Design (CCRD 22 and 23) was used to determine the ideal condition for the biosynthesis process and photocatalytic tests, respectively. CCRD 22 indicated the variables of extract concentration and time were significant 6 mg L−1 and 120 min, respectively with the higher yield of nanoparticles (15.71%), and CeO2-NPs crystallite diameter of 16.36 nm. CCRD 23 determined the ideal condition to [MB.MO] = 60 mg L−1, [CeO2-NPs] = 1 g L−1 and pH = 4, with 93% for the dyes photodegradation, indicating a pseudo-first order model (k = 0.0139 min−1). CeO2-NPs showed photocatalytic stability after 6 cycles. Ecotoxicity of CeO2-NPs did not show mortality for A. salina in the 10–2.5 mg mL−1. Therefore, it was possible to synthesize metallic nanoparticles of cerium oxide, with great potential for application as a nanophotocatalyst.