The simple cyanide and complex cyanide in the wastewater are electrolyzed to produce a chemical reaction on the anode and cathode to electrolyze the cyanide into carbon dioxide and nitrogen. Using this principle can effectively remove cyanide pollution in wastewater.
(1) The chemical reaction at the anode
For simple cyanide, the first stage reaction is:
CN-+2OH--2e→CNO-+H2O
The reaction proceeded very violently, and then two reactions in the second stage occurred:
2CNO-+4OH--6e→2CO2↑+N2↑+2H2O
CNO-+2H2O→NH4++3CN-
During the electrolysis process, a part of ammonium is produced.
For coordination cyanide, the reaction process is as follows: (Here is a copper as an example)
Cu(CN)32-+6OH--6e→Cu++3CNO-+3H2O
Cu(CN)32-→Cu++3CN-
The following reactions occur when table salt is added to the electrolytic medium:
2Cl--2e→2[Cl]
2[Cl]+CN-+2OH-→CNO-+2Cl-+H2O
6[Cl]+Cu(CN)32-+6OH-→Cu++3CNO-+6Cl-+3H2O
6[Cl]+2CNO-+4OH-→2CO2↑+N2↑+6Cl-+2H2O
(2) The chemical reaction at the cathode
2H++2e→H2↑
Cu2++2e→Cu
Cu2++2OH-→Cu(OH)2↓[1]