Trace amount of RuO2 loaded on TiO2 nanowires for efficient electrocatalytic degradation of ammonia nitrogen in wastewater

It is imperative to develop efficient and environmentally friendly technologies to remove ammonia nitrogen from the wastewater. Herein, RuO2 nanoparticles decorated TiO2 nanowires (RuO2/TiO2 NWs) were fabricated for efficient electrocatalytic degradation of ammonia nitrogen. TiO2 NWs were prepared on Ti mesh by hydrothermal treatment in NaOH solution, with diameter of 80–100 nm and length of ∼3 µm. Then RuO2 nanoparticles were decorated on TiO2 NWs by electrodeposition and annealing in air at 450 ℃. The effects of current, pH, initial ammonia concentration and chloride ion concentration on ammonia nitrogen degradation were investigated, and the possible degradation mechanism was discussed. After three hours of degradation in ammonia nitrogen waste liquid with NH4+-N concentration of 200 mg•L−1 and Cl- concentration of 2000 mg•L−1, the ammonia nitrogen removal rate of RuO2/TiO2 NWs reaches 99.876%. The mass loading of Ru is only 16.2 μg•cm−2, suggesting an extremely high ammonia nitrogen degradation efficiency. Electrochemical test shows that the conductivity of RuO2/TiO2 NWs is significantly enhanced as compared with that of TiO2 NWs. RuO2/TiO2 NWs also show good stability after 100 h of constant current test at 20 mA•cm−2 in ammonia nitrogen degradation. The prepared material can be used as an effective catalyst for the degradation of ammonia nitrogen in wastewater.