Development Of Electrochemical Ozone Generator Based On Nano-PbO₂

Ozone is a clean and strong oxidant,which is widely used in disinfection,wastewater treatment and other fields.Due to its decomposable nature,it can only be produced and used in situ.Electrochemical ozone synthesis technology with membrane electrode integration has the advantages of low energy consumption,high efficiency and small equipment volume,so it has a broad application prospect in the future.PbO₂ is an excellent material suitable for electrochemical ozone production,but it cannot be denied that it has certain risks to the environment,so pollution generated throughout its life cycle must be reduced.In this paper,electrochemical ozone generator based on lead recycling and reuse is studied,the main contents are as follows:Firstly,two different methods of hydrolysis and water bath were used to prepare nano-sized lead dioxide.The effects of oxidant content,p H,time and temperature on the crystal phase and particle size of nano-sized PbO₂ were investigated,and several representative samples were selected for electrochemical characterization.The experimental data showed that the higher p H and the longer reaction time in the water bath method can lead to a denser agglomeration of nanoparticles.As the temperature increases,the agglomerates change from spherical porous particles to stellate particles.Its synthesis is not controllable,and the minimum particle size is 30?40nm.In the hydrolysis method,the temperature has almost no effect on the crystal phase and particle size,which are about 7 nm.The electrochemical performance test also showed that the nanometer PbO₂prepared by hydrolysis method had better ozone production performance.Then the nano-PbO₂ synthesized by water bath and hydrolysis method under the best conditions was used as the anode catalyst,and the ordinary reagent PbO₂ was used as the comparison.The ozone production performance of the three catalysts was compared.Meanwhile,the effects of current density,temperature and flow rate on the output,current efficiency,voltage and energy consumption of the ozone generator were investigated.It was found that PbO₂ prepared by hydrolysis method had the best ozone production performance,and the ozone production increased with the increase of current density.The lowest energy consumption was 168 Wh(gO₃)^-1 at 900 m A cm^-2,and the maximum efficiency was 8%at1200 m A cm^-2.Therefore,the optimal current density was determined to be 900?1200 m A cm^-2.As the temperature of the electrolyte rises,the voltage will decrease continuously,but the lowest energy consumption will be achieved at 25 ^oC.It is also found that the performance of ozone generator can be improved by increasing the flow rate appropriately.When the flow rate is 1.33 m L s^-1,the maximum current efficiency is about 11%,and the energy consumption is about 136 Wh(gO₃)^-1.Finally,in order to realize the recycling of lead resources and reduce people's environmental concerns about lead-containing ozone generators,the process route of recycling waste lead paste to prepare nano-PbO₂ was put forward.Combined with ICP,XRD and SEM,the recovery rate and intermediate products of the process were investigated,and the recovered nano-PbO₂ was used as anode catalyst in electrochemical ozone generator.It was found that the lead recovery was 99.47%,and the output and energy consumption of the ozone generator were comparable to that of the nano-PbO₂ prepared by hydrolysis of pure Pb(CH₃COO)₄.