The photocatalytic reduction of NO3− to N2 with ilmenite (FeTiO3): effects of groundwater matrix
EntityUAM. Departamento de Ingeniería Química
10.1016/j.watres.2021.117250Water Research 200 (2021): 117250
Funded byThis work has been supported by AEI (10.13039/501100011033) through the project PID2019-106884GB-I00 and Comunidad de Madrid through the project P2018/EMT-4341. A.R.R thanks the Post-Doctoral scholarship awarded by the public agency São Paulo State Research Foundation (FAPESP), grant #2018/09697-8. J. Carbajo wants to thank the Ministerio de Ciencia, Innovación y Universidades (MICIU) for a grant under the Juan de la Cierva_Incorporación programme (IJCI-2017-32682)
ProjectGobierno de España. PID2019-106884
SubjectsGroundwater; Ilmenite; Nitrate; Photo-reduction; Water conditioning; Química
Rights© 2021 The Author(s)
Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
This work analyzes the role of natural groundwater, as well as the effect of HCO3−, Ca2+, Mg2+, K+, SO42- and Cl− concentrations, upon the photocatalytic nitrate reduction using ilmenite as catalyst and oxalic acid as hole scavenger. The nitrate removal and the selectivity towards N2 are significantly limited compared to previous experiments using ultrapure water matrix. Calcium (Ca2+), bicarbonate (HCO3−) as well as pH are claimed as the major controlling factors related to the process yield. Thus, Ca2+ promotes the formation of insoluble oxalate microcrystals, reducing the amount of hole scavenger available. The presence of HCO3− leads to a steeply increase in the pH value, favoring the adsorption onto the ilmenite surface of ions OH−instead of NO3−, NO2− and C2O42. The aforementioned issues are overcome by working with C2O42−/NO3− ratio well above the stoichiometric one, that also maintains the pH value in an acid range. A completed depletion of the starting NO3−, the no detection of either NO2− or NH4+ in the aqueous phase, and a selectivity towards N2 above 95% were achieved using two times the stoichiometric dose
Google Scholar:Silveira, Jefferson E. - Ribeiro, Alyson R. - Carbajo Olleros, Jaime - Pliego Rodríguez, Gema - Zazo Martínez, Juan Antonio - Casas de Pedro, José Antonio
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