Photocatalytic selective oxidation of ammonium to dinitrogen by FeOx-MgO activated persulfate under solar-light irradiation

The selective oxidation of ammonium nitrogen (NH4+-N) to dinitrogen (N2) by advanced oxidation processes (AOPs) is of paramount significance, but it is still a great challenge. In this study, a novel composite (FeOx-MgO) was synthesized to activate persulfate (PS) for selective oxidation of ammonium (NH4+) to N2 under simulated solar-light irradiation (hv). The results demonstrated that the conversion of NH4+ to ammonia (NH3) on the basic sites of FeOx-MgO was a key step for the selective oxidation of NH4+. Fe(IV) species formed in FeOx-MgO/PS/hv system could enhance both the efficiency and N2 selectivity of the NH4+-N oxidation through the oxidation of ammonia hydride to N2. The 100 % NH4+-N removal and over 95.5 % N2 selectivity could be achieved after 30 min when initial pH was in range of 2-10, and the initial NH4+-N concentration was 30 mg N/L. This study could provide a promising technology for the selective oxidation of NH4+-N to N2 in water and wastewater.

Automated summary

In this study, a novel composite (FeOx-MgO) was synthesized and used to selectively oxidize NH4+ to N2 under simulated solar-light irradiation. The results showed that the conversion of NH4+ to NH3 on the basic sites of FeOx-MgO was crucial for the selective oxidation. The FeOx-MgO/PS/hv system exhibited high efficiency and selectivity in converting NH4+-N to N2.