A novel control strategy for N2O formation by adjusting Eh in nitrite/Fe(II–III) carbonate green rust system

Abstract In order to improve the generation amount of nitrous oxide (N 2 O), the process of nitrite (NO 2 − ) reduction was studied by Fe(II–III) carbonate green rust (GR(CO 3 2− )). The results indicated that 97.1% NO 2 − was degraded, and over 71.3% N 2 O was achieved by the oxidation of GR(CO 3 2− ) to Fe 3 O 4 ; 14.1% N 2 , 4.7% NH 4 + and 3.0% NO 3 − were also formed in the denitrification process; the removal efficiency for total nitrogen (TN) was 89.6%; the optimal reaction condition was NO 2 − 10.71 mM, pH 9.5 and an initial E h (the maximum value of E h reached at the beginning of the process) of −473 mV. The generation of different reduction products was dependent on the initial E h of the reaction system. Based on the adjustment of initial E h , the formation order of reduction products was as follows: N 2 O, N 2 and NH 4 + . Additionally, compared with initial nitrite concentration, pH played a decisive role in the initial E h of the NO 2 − /GR(CO 3 2− ) system. The high amount of N 2 O generated by the adjustment of initial E h provides new insight into the NO 2 − /GR(CO 3 2− ) system.