Enhanced Carbon Nitride Film Electrode Photoelectrocatalytic Of Copper Cyanide Complexes And Synchronous Recovery Of Cu By Peroxydisulfate

Cyanides are widely used in electroplating,mining,and metallurgy industries due to their unique properties for complexing metals.As a consequence,it generate large amounts of metal cyanide containing wastewater.Therefore,this wastewater must be disposed of to discharge into environment.In this work,the copper cyanide complex wastewater is used as the treatment object.The rapid degradation of the copper cyanide complex by the combination of photoelectric oxidation and the persulfate advanced oxidation technique allows the recovery of copper as much as possible at the cathode.In this paper,g-C₃N₄ thin film electrode was used as the anode,titanium?Ti?plate,graphitic carbon felt?GCF?and graphitic carbon felt modified by polyaniline?PANI/GCF?were used as cathodes,respectively,using photoelectrocatalytic?PEC?oxidation and persulfate oxidation degradation of copper cyanide complex.The main contents and results of this paper are as follows:1.There is no obvious recovery of Cu on the titanium plate cathode in the preliminary experiment.Therefore,using adsorption performance of GCF as the new cathode was selected in the following experiments.First,various processes,including PEC,PS oxidation,and PEC with PS addition?PEC/PS?,were compared for copper cyanide complex removal.The addition of PS improved greatly the photoelectrocatalytic efficiency for the oxidation of CN^-and the recovery of Cu on the cathode.The effect of the amount of K₂S₂O₈ was investigated in detail.The removal efficiency of CN^-and Cu recovery can reach up to 86.23%and 82.11%,respectively,with 1 mM K₂S₂O₈ at 1.0 V bias potential.Combined with the SEM,EDS and XPS analysis of the electrode surface,it was concluded that the copper was oxidized and existed in precipitation and photoanode in the form of CuO.Conversely,the liberated Cu⁺/Cu²⁺ions were electrochemically reduced to element Cu on the surface of graphitic carbon felt cathode.As a result,copper was recovered from the wastewater of copper cyanide complexes.Electron spin resonance and radical quenching experiments analysis showed that the oxidation of CN^-is assigned to sulfate radical oxidation and non-radical oxidation processes.2.In order to further improve the percentage of copper deposited onto the cathode,the PANI/GCF electrode was prepared by using GCF as the substrate and used as a new cathode in the photoelectrocatalytic system with the addition of persulfate.The results showed that compared with PANI/GCF and GCF electrode,the recovery ratio of copper on the cathode is increased from 32.07%to 57.69%,which indicates that PANI has a great effect on the recovery of copper on the cathode and no longer contains the precipitation in the solution,fully achieve the purpose of our recycling copper.By changing the CV cycle to prepare different PANI content of the cathode,the results show that the removal efficiency of CN^-,the recovery efficiency of Cu,the ideal of copper recovery distribution and the morphology of cathode is best when the number of cycles is10 turns.Through the characterization of cathode and anode,it can be determined that copper is recovered on the cathode in the form of zero valent copper and recovered on the anode in the form of copper oxide and cuprous oxide.