Experimental Study On The Treatment Of Copper-containing Wastewater By Controlled Electrodeposition

Electrochemical method is used to treat copper-containing wastewater.It has the characteristics of high efficiency and simple operation,but the current efficiency is very low,only about 40%.The copper powder obtained is large and the particle size distribution is not uniform.The effects of copper ion concentration,current density and dust removal time on the particle size and current efficiency of copper wastewater were studied in a self-made electrodeposition reactor.Determine the best process conditions through single factor analysis:at room temperature,stainless steel plate is used as cathode,graphite is used as anode,electrolyte pH is 2.4,Cu（Ⅱ）concentration is 0.10 mol/L,current density is 0.4 A/cm²,and powder is removed With a period of30 s,a fine copper powder with an average particle size of 3.2μm can be obtained,and the current efficiency can reach 73%.Secondly,under optimized process conditions,three surfactants,PVP（polyvinylpyrrolidone）,SDS（sodium dodecyl sulfate）and Tween 80（Tween 80）were added to the copper-containing wastewater,and the effect of surfactants was investigated.The influence law of copper powder particle size and current efficiency,and further analysis of the chemical reactions that three surfactants may participate in during the electrodeposition process.The results show that the average particle size of the copper powder produced in the electrolyte system with 1 g/L of PVP is 2.32μm,and the current efficiency is up to 83%;in the electrolyte system with the addition of SDS of 1 g/L,copper is produced The average particle size of the powder is 1.21μm,and the current efficiency is up to 76%;in the electrolyte system with 1 g/L of Tween80,the average particle size of the produced copper powder is 2.54μm,and the current efficiency is up to 58%.The C=O bond in PVP and SDS is complexed with Cu（Ⅱ）to form Cu（PVP）₂and(C₁₂H₂₅-OSO₃^-)₂Cu（Ⅱ）,which can promote the deposition process of Cu（Ⅱ）on the electrode surface and improve current efficiency.Among the three additives,SDS has the most significant effect on copper powder particle size and current efficiency.Finally,the influence of SDS surfactant on the Cu（Ⅱ）electrocrystallization nucleation process was studied.The results showed that the copper electrocrystallization process in the electrodeposition process conforms to the Scharitker-Hill 3D nucleation/growth mechanism,and the addition of SDS makes the deposition potential shift positive.,Which reduces the cathodic polarization;when the SDS concentration increases from 0.5 g/L to 1 g/L,the SDS structure changes from a long chain to a spherical micelle.When the potential is-0.2 V～-0.25 V,the Cu（Ⅱ）electrocrystallization process proceeds gradually When the nucleation mode proceeds,the nucleation relaxation time is prolonged,and the nucleation rate is reduced;the Cu（Ⅱ）electrocrystallization process in the-0.28 V potential region is transformed into instant nucleation,the nucleation relaxation time is shortened,and the nucleation rate is accelerated.