https://doi.org/10.1016/j.ijggc.2015.03.027
In the above paper, the influence of Ni concentration (0.01-0.09 mol/L) was investigated. The results (Figure 4a) showed that the ammonia escape reduction was increased with the increase of Ni concentration from 0.01 to 0.09 mol/L. Compared to the experiment without Ni addition, ammonia escape reduces by about 30% at 0.06 mol/L, which proves that the complex has a good effect on reducing ammonia.
The authors also reported the influence of ammonia concentration (1-9%) and found that although more ammonia was escaped with the increase of ammonia concentration, the ammonia control efficiency was enhanced to 55%.