Innovative iron oxide foams for the removal of micropollutants by Catalytic Wet Peroxide Oxidation: Assessment of long-term operation under continuous mode

NIETO-SANDOVAL, JULIA; DI LUCA, CARLA; GOMEZ-HERRERO, ESTHER; INCHAURRONDO, NATALIA; MUNOZ, MACARENA; MARTÍNEZ DE PEDRO, ZAHARA ; CASAS, JOSÉ A.

Journal of Environmental Chemical Engineering

Elsevier

Año: 2021 vol. 9

2213-3437

This work aims to develop highly stable iron oxide foams for the continuous CatalyticWet Peroxide Oxidation (CWPO) of micropollutants in a structured fixed-bed reactor.Homogeneity and adhesion of the active phase were achieved by adjusting thepreparation methodology. Three structured catalysts based on Al2O3, SiC and ZrO2foams were obtained with Fe content of 2.5, 2.1 and 0.90 % wt., respectively. Thecatalytic foams were tested in the CWPO of a mixture of three pharmaceuticals(metronidazole (MNZ), sulfamethoxazole (SMX) and carbamazepine (CBZ)), with aconcentration of 100 µg L-1 each.The catalysts resulted active and stable up to 200 h of CWPO carried out at ambientconditions, with the exception of Fe/ZrO2, which showed a progressive deactivation dueto the iron leaching from the solid. An increase in space time led to an enhancedperformance achieving remarkable conversion levels of 73%, 83% and 90% for MNZ,SMX and CBZ, respectively. The effect of H2O2 dose was also evaluated revealing thedevelopment of competing side reactions for supra-stoichiometric dosages. Moreover,the scavenging effect of the water matrix was assessed operating in presence of humicacid as representative natural organic matter (NOM). In this case, the conversion levelsfor SMX and CBZ resulted alike to the ones obtained for ultrapure water and only aslight decrease in MNZ removal rate was detected. After 400 h of usage at differentsteady-state conditions, the outstanding catalytic performance of Fe/Al2O3 and Fe/SiCwas sustained in the long-term operation.