Synergistic Removal of Cr(VI) with Stable Nanozerovalent Iron Particles and Ultrasound Assistance in the Presence of Organic Additives

CANCELADA, LUCIA; MEICHTRY, JORGE M.; DESTAILLATS, HUGO; LITTER, MARTA I.

ACS Engineering Au

ACS

Año: 2024

2694-2488

Commercial stable zerovalent iron nanoparticles(nZVI) (NSTAR, not activated) combined with ultrasound (US)were tested for Cr(VI) reductive removal (0.3 mM, pH 3, Fe/Crmolar ratio of 3:1) in the presence of the carboxylic acids (CAs)ethylenediaminetetraacetic acid (EDTA, 1 mM) or citric acid (Cit,2 mM), in a system open to the air. No Cr(VI) decay up to 180min was observed under US when only NSTAR nanoparticles wereused, while other previously tested commercial nZVI (N25)showed about 40% decay in a few minutes but without furtherCr(VI) removal. The addition of EDTA and Cit enabled Cr(VI)removal with NSTAR in the absence of US without prior activationof the particles. A pseudo zero-order kinetics was followed, yielding32 and 49% removal with EDTA and Cit, respectively. When US was applied, these values almost doubled, reaching 59 and 88% forEDTA and Cit, respectively. A mechanism for Cr(VI) decay was proposed. The present results indicate that the simultaneous use ofUS and CAs allows for a synergistic Cr(VI) removal by NSTAR avoiding the need of an activation step of the nanoparticles, with amore effective result of Cit compared with EDTA.