An alternative scheme of biological removal of ammonia nitrogen from wastewater-highly dispersed Ru cluster @mesoporous TiO2 for the catalytic wet air oxidation of low-concentration ammonia

Ammonia nitrogen wastewater is the most abundant and widely distributed wastewater. In this work, a highly dispersed heterogeneous metal catalyst Ru@TiO2 was successfully fabricated by a one-pot method for the catalytic wet air oxidation (CWAO) of ammonia. These catalysts were characterized by different techniques, indicating that Ru clusters were dispersed uniformly on the TiO2 surface, and some Ru atoms were embedded in the TiO2 framework. This structure can afford excellent catalytic performance, such as 0.5%Ru@TiO2 catalyst offers a 95.5% conversion under the condition of 2 MPa at 190 degrees C in 6 h without adding alkali. Ammonia concentration can be reduced from 200 ppm to less than 10 ppm to meet emission standards. And the selectivity of ammonia oxidation products can be adjusted and controlled according to the reaction conditions. Besides, the kinetics and mechanism of CWAO of ammonia were studied, which provided a theoretical basis for its industrial application.