Sono-assisted preparation of highly-efficient peroxidase-like Fe 3O 4 magnetic nanoparticles for catalytic removal of organic pollutants with H 2O 2

Abstract

Fe 3O 4 magnetic nanoparticles (Fe 3O 4 MNPs) with much improved peroxidase-like activity were successfully prepared through an advanced reverse co-precipitation method under the assistance of ultrasound irradiation. The characterizations with XRD, BET and SEM indicated that the ultrasound irradiation in the preparation induced the production of Fe 3O 4 MNPs possessing smaller particle sizes (16.5 nm), greater BET surface area (82.5 m 2 g −1) and much higher dispersibility in water. The particle sizes, BET surface area, chemical composition and then catalytic property of the Fe 3O 4 MNPs could be tailored by adjusting the initial concentration of ammonia water and the molar ratio of Fe 2+/Fe 3+ during the preparation process. The H 2O 2-activating ability of Fe 3O 4 MNPs was evaluated by using Rhodamine B (RhB) as a model compound of organic pollutants to be degraded. At pH 5.4 and temperature 40 °C, the sonochemically synthesized Fe 3O 4 MNPs were observed to be able to activate H 2O 2 and remove ca. 90% of RhB (0.02 mmol L −1) in 60 min with a apparent rate constant of 0.034 min −1 for the RhB degradation, being 12.6 folds of that (0.0027 min −1) over the Fe 3O 4 MNPs prepared via a conventional reverse co-precipitation method. The mechanisms of the peroxidase-like catalysis with Fe 3O 4 MNPs were discussed to develop more efficient novel catalysts.