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 %.
All Science Journal Classification (ASJC) codes
- General Environmental Science
- Process Chemistry and Technology