Degradation mechanism of ammonia nitrogen synergistic with bromate under UV or UV/TiO2

Bromate (BrO 3 − ) and ammonia nitrogen (NH 4 + ) are both typical environmental pollutants: BrO 3 − has been categorized as one of the Group 2B carcinogen by IARC; an excess of NH 4 + might result in the eutrophication of water. The existence of NH 4 + could inhibit the transformation of bromide (Br − ) to bromate (BrO 3 − ). However, the interaction of NH 4 + and BrO 3 − during the removal process is not clear. This study intends to disclose the mutual relationships of ammonia nitrogen and bromate ions under UV irradiation or UV/TiO 2 conditions. Without UV irradiation, BrO 3 − and NH 4 + were both stable even under the presentation of each other. Under UV irradiation or UV/TiO 2 conditions, BrO 3 − and NH 4 + promoted the degradation of each other, showing the synergistic degradation mechanism. In the neutral environment, both of BrO 3 − and NH 4 + could be transformed effectively. Furthermore, NH 4 + accelerated the transformation of BrO 3 − to Br − at the reaction beginning and the existence of BrO 3 − is beneficial for the transformation of NH 4 + to N 2 .