Mineralization of cyanides via a novel Electro-Fenton system generating ?OH and ?O2-

作者：Tian, Lei; Chen, Peng; Jiang, Xun-Heng; Chen, Li-Sha; Tong, Lin-Lin; Yang, Hong-Ying; Fan, Jie-Ping; Wu, Dai-She; Zou, Jian-Ping^*; Luo, Sheng-Lian

来源：Water Research, 2022, 209: 117890.

DOI：10.1016/j.watres.2021.117890

• Advanced oxidation processes
• Cyanides
• Mineralization
• Electro-Fenton
• Nitrates

Traditional methods of cyanides' (CN-) mineralization cannot overcome the contradiction between the high alkalinity required for the inhibition of hydrogen cyanide evolution and the low alkalinity required for the efficient hydrolysis of cyanate (CNO-) intermediates. Thus, in this study, a novel Electro-Fenton system was constructed, in which the free cyanides released from ferricyanide photolysis can be efficiently mineralized by the synergy of center dot OH and center dot O-2(-). The complex bonds in ferricyanide (100 mL, 0.25 mM) were completely broken within 80 mM under ultraviolet radiation, releasing free cyanides. Subsequently, in combination with the heterogeneous Electro-Fenton process, center dot OH and center dot O-2(-) were simultaneously generated and 92.9% of free cyanides were transformed into NO3 within 120 min. No low-toxic CNO- intermediates were accumulated during the Electro-Fenton process. A new conversion mechanism was proposed that CN- was activated into electron-deficient cyanide radical (center dot CN) by center dot OH, and then the center dot CN intermediates reacted with center dot O-2(-) via nucleophilic addition to quickly form NO3-, preventing the formation of CNO- and promoting the mineralization of cyanide. Furthermore, this new strategy was used to treat the actual cyanide residue eluent, achieving rapid recovery of irons and efficient mineralization of cyanides. In conclusion, this study proposes a new approach for the mineralization treatment of cyanide-containing wastewater.

• 单位
  东北大学; 南昌航空大学; 南昌大学