Electrolytic treatment of cyanide-containing wastewater

- Sep 18, 2020-

Electrolytic treatment of cyanide-containing wastewater

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 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]