Selective reduction of nitrate to N2 using ilmenite as a low cost photo-catalyst

Juan A. Zazo; P. García-Muñoz; G. Pliego; Jefferson E. Silveira; P. Jaffe; Jose A. Casas

doi:10.1016/j.apcatb.2020.118930

Selective reduction of nitrate to N₂ using ilmenite as a low cost photo-catalyst

Juan A. Zazo, P. García-Muñoz, G. Pliego, Jefferson E. Silveira, P. Jaffe, Jose A. Casas

Research output: Contribution to journal › Article › peer-review

23 Scopus citations

Abstract

This work assesses the feasibility of using natural ilmenite as catalyst in NO₃⁻ photo-reduction with oxalic acid as reducing agent. The experimental set-up includes a magnetically stirred batch reactor equipped with a medium pressure Hg UV-lamp (30 W/m²). Experiments were carried out under N₂ atmosphere at 25 °C, using 1–2 times the stoichiometric amount of C₂O₄^2- to reduce NO₃⁻ to N₂. The reduction of NO₃⁻ to N₂ via NO₂⁻ is, by far, the main route. Concurrently, the generation of NO_x (g) via NO₃⁻ and NO₂⁻ reduction is also observed. The complete NO₃⁻ and C₂O₄^2- removal and a selectivity towards N₂ > 93 % is achieved by using the stoichiometric C₂O₄^2- dose after 210 min, without the generation of undesirable NH₄⁺. The residual NO₂⁻ concentration was lower than 0.5 mg N/L. Besides, doubling the C₂O₄^2- dose allowed the complete removal of nitrogen from the aqueous phase with a N₂ selectivity > 97 %.

Original language	English (US)
Article number	118930
Journal	Applied Catalysis B: Environmental
Volume	273
DOIs	https://doi.org/10.1016/j.apcatb.2020.118930
State	Published - Sep 15 2020

All Science Journal Classification (ASJC) codes

Catalysis
General Environmental Science
Process Chemistry and Technology

Keywords

Ilmenite
Intensification
Nitrate
Photo-reduction
Selectivity

Access to Document

10.1016/j.apcatb.2020.118930

Cite this

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title = "Selective reduction of nitrate to N2 using ilmenite as a low cost photo-catalyst",

abstract = "This work assesses the feasibility of using natural ilmenite as catalyst in NO3− photo-reduction with oxalic acid as reducing agent. The experimental set-up includes a magnetically stirred batch reactor equipped with a medium pressure Hg UV-lamp (30 W/m2). Experiments were carried out under N2 atmosphere at 25 °C, using 1–2 times the stoichiometric amount of C2O42- to reduce NO3− to N2. The reduction of NO3− to N2 via NO2− is, by far, the main route. Concurrently, the generation of NOx (g) via NO3− and NO2− reduction is also observed. The complete NO3− and C2O42- removal and a selectivity towards N2 > 93 % is achieved by using the stoichiometric C2O42- dose after 210 min, without the generation of undesirable NH4+. The residual NO2− concentration was lower than 0.5 mg N/L. Besides, doubling the C2O42- dose allowed the complete removal of nitrogen from the aqueous phase with a N2 selectivity > 97 %.",

keywords = "Ilmenite, Intensification, Nitrate, Photo-reduction, Selectivity",

author = "Zazo, {Juan A.} and P. Garc{\'i}a-Mu{\~n}oz and G. Pliego and Silveira, {Jefferson E.} and P. Jaffe and Casas, {Jose A.}",

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doi = "10.1016/j.apcatb.2020.118930",

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T1 - Selective reduction of nitrate to N2 using ilmenite as a low cost photo-catalyst

AU - Zazo, Juan A.

AU - García-Muñoz, P.

AU - Pliego, G.

AU - Silveira, Jefferson E.

AU - Jaffe, P.

AU - Casas, Jose A.

PY - 2020/9/15

Y1 - 2020/9/15

N2 - This work assesses the feasibility of using natural ilmenite as catalyst in NO3− photo-reduction with oxalic acid as reducing agent. The experimental set-up includes a magnetically stirred batch reactor equipped with a medium pressure Hg UV-lamp (30 W/m2). Experiments were carried out under N2 atmosphere at 25 °C, using 1–2 times the stoichiometric amount of C2O42- to reduce NO3− to N2. The reduction of NO3− to N2 via NO2− is, by far, the main route. Concurrently, the generation of NOx (g) via NO3− and NO2− reduction is also observed. The complete NO3− and C2O42- removal and a selectivity towards N2 > 93 % is achieved by using the stoichiometric C2O42- dose after 210 min, without the generation of undesirable NH4+. The residual NO2− concentration was lower than 0.5 mg N/L. Besides, doubling the C2O42- dose allowed the complete removal of nitrogen from the aqueous phase with a N2 selectivity > 97 %.

AB - This work assesses the feasibility of using natural ilmenite as catalyst in NO3− photo-reduction with oxalic acid as reducing agent. The experimental set-up includes a magnetically stirred batch reactor equipped with a medium pressure Hg UV-lamp (30 W/m2). Experiments were carried out under N2 atmosphere at 25 °C, using 1–2 times the stoichiometric amount of C2O42- to reduce NO3− to N2. The reduction of NO3− to N2 via NO2− is, by far, the main route. Concurrently, the generation of NOx (g) via NO3− and NO2− reduction is also observed. The complete NO3− and C2O42- removal and a selectivity towards N2 > 93 % is achieved by using the stoichiometric C2O42- dose after 210 min, without the generation of undesirable NH4+. The residual NO2− concentration was lower than 0.5 mg N/L. Besides, doubling the C2O42- dose allowed the complete removal of nitrogen from the aqueous phase with a N2 selectivity > 97 %.

KW - Ilmenite

KW - Intensification

KW - Nitrate

KW - Photo-reduction

KW - Selectivity

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