Preparation Of Ni/r Go-pac Particle Electrode And Electrocatalytic Treatment Of Cu-edta Wastewater

Heavy metal complex refers to a stable complex formed by the coordinate bond of free heavy metal ions and complexing agent in water,which has the characteristics of high water-solubility,biodegradability and durability.The traditional electrocatalytic method to decomplex heavy metal complexes and recover heavy metals faces the problems of few active sites,long mass transfer distance and high energy consumption.Aiming at the problem of high-efficiency decomplexation of heavy metal complex and the simultaneous recovery of heavy metal,the catalytic particle electrode was proposed in the electrocatalytic treatment of Cu-EDTA in this thesis,using activated carbon（PAC）and reduced graphene oxide（r GO）as the carrier,and nickel as the catalyst.The efficiency and mechanism of Cu-EDTA decomplexation and copper recovery were investigated.The study determined that the optimal calcination temperature and time of the particle electrode was600℃and 4 h,and the best mass ratio of PAC to r GO was 8:2.The addition of nickel promoted the electrocatalytic decomplexation efficiency of Cu-EDTA.The nickel on Ni/r GO_0.2-PAC_0.8 particle electrode prepared was mainly composed of Ni⁰ and Ni O.The copper deposited on Ni/r GO_0.2-PAC_0.8 after electrolysis was mainly composed of Cu⁰ and Cu O.The effects of different operating parameters and conditions on the decomplexation of Cu-EDTA and copper recovery were studied.When the molar ratio of Cu²⁺to EDTA was 1:1,the initial p H of the wastewater was 3.15,the current density was 1.6 m A cm^-2,a flow rate was 5 m L min^-1,and the electrolyte was 0.01mol L^-1 Na₂SO₄,the decomplexation efficiency of Cu-EDTA and total complexing copper（TCCu）reached 99.8%and 99.6%,respectively,the recovery efficiency of total copper（TCu）reached 94.0%.During the decomplexation process,the nitrogen in Cu-EDTA was almost completely converted to NO₃^-.At the same time,HCOOH and other small organic substances were produced during the decomplexation process.The detection results of free radicals showed that the addition of catalyst nickel can promote the production of·OH.The electrochemical performance test proved that Ni/r GO_0.2-PAC_0.8 has a lower hydrogen evolution potential and a higher oxygen evolution potential.Cu-EDTA decomplexation in Ni/r GO_0.2-PAC_0.8 system was completed by electro-reduction process.Cu²⁺in Cu-EDTA was first reduced to Cu⁺,then reduced to Cu⁰ through 1 electron transfer and deposited on the particle electrode to achieve copper recovery.When Cu²⁺was separated from Cu-EDTA,the complexing structure of Cu-EDTA was destroyed,and the remaining EDTA structure in the solution was further oxidized into small molecules by the hydroxyl radicals generated in system.