A Study On Electrochemical Treatment Process Of Spent Nitric Acid Etching Solution Containing Cu

The copper-containing waste etching acid produced by the PCB industry is a kind of hazardous waste,which exhibits a large amount with difficulty to be treated.The metal ions such as copper and nickel are harmful to the environment.In response to the call for national ecological environment protection,such hazardous waste must be disposed properly with metal resources recovered.The price of copper has grown significantly in recent years.In this thesis,the electrochemical treatment methods are developed for waste nitric acid etching solutions containing copper and nickel,in terms of the following three aspects:?1?Electrolysis method to remove and recover copper from waste nitric acid etching solutionOnly change the current density and voltage during electrolysis,and observe the changes of various indexes in the process,including recovery rate,coulombic efficiency,energy consumption and cathode copper morphology and tensile strength.It is found through experimental data that nickel does not deposit at the cathode;the deposition rate of copper increases with the increase of current density or voltage;the longer the electrolysis time,the higher the recovery rate of copper,which is 98%.Comprehensive comparison of various factors,200.0 A·m^-2 is the most suitable electrolysis condition,at which the deposition rate is about 0.25 kg·m^-2·h^-1,the current efficiency is about 85%,the energy consumption is around1500 kWh·t^-1,a good deposition morphology is observed,and the tensile strength of electrodeposited copper can reach 226 MPa,which meets the copper recovery requirements.?2?Effects of additives on copper electrodeposition from waste nitric acid etching solutionThe quality of electrodeposited copper was further improved by adding additives.The effects of thiourea,smoke suppressant,PEG and gelatin on the electrodeposition process,the influence on the deposition morphology,crystal structure and tensile strength of copper were investigated.The smoke agent has a deteriorating effect on the electrodeposition of copper.Gelatin,PEG and thiourea on the contrary,have a promoting effect on this process,The effect of these additives is ordered as thiourea>gelatin>PEG,5 mg·L^-1 thiourea addition is the optimal concentration,the sediment layer with this concentration of thiourea addition is the most flat and compact,and the tensile strength is up to 286.45 MPa.?3?Study on the application of Cu containing waste nitric acid etching solution treatment and resource utilization technologyAn electrolysis treatment process suitable for the waste acid sample was preliminarily designed based on the results of electrolysis test and additive experiment.The process uses a conventional electrolytic cell,an electrodialysis device,and a cyclone electrolysis device to form a set of equipment with a disposal capacity of 150 m³ per month,at the same time,copper recycling can be achieved.