Experimental Study Of Surface Catalysis Of Silica On Dielectric Barrier Discharge Ozone Generation

The development of society has made people's demand for spiritual life more and more strong,so people gradually focus on environmental pollution,medical health and other fields.Due to the property of strong oxidizing and environmental friendliness,ozone is more and more widely used in drinking water disinfection,sewage treatment,medical health and so on.The ozone generator needs to further increase the ozone production rate and ozone concentration to meet people's ozone demand for high concentration and low energy consumption.However the ozone yield of ozone generators is always much lower than the theoretical value now.In the past research,most scholars focused on the optimization of the dielectric barrier discharge structure,electrode material,power supply and discharge parameters,but the ozone concentration and ozone yield can never be greatly improved.Although filling the catalytic material in the discharge space can achieve good results,it is still not a suitable way to study the enhancement effect of the catalytic material on ozone generation.Loading catalytic materials on the surface of the dielectric plate is an ideal method to study the mechanism of catalytic materials to enhance ozone generation.In this paper,silica is used as catalytic material to study the mechanism of silica enhanced ozone generation in the parallel-plate dielectric barrier discharge reactor.Silica is loaded onto the dielectric plate successfully using the sol-gel method.The effect of silica on ozone generation under different discharge parameters is investigated,and combined with the characterization results of XPS,FTIR and other characterization methods to reveal the reaction mechanism of silica enhanced ozone generation preliminarily.The main conclusions are as follows:(1)with the increase of dipping times,the thickness of silica film increases,and the thermal conductivity of the dielectric plate loaded with silica film decreases.(2)Loading silica on the surface of the dielectric plate will not affect the discharge pattern and the gas flow state in the discharge space.(3)With the increase of silica film thickness,the discharge power increases first and then decreases.(4)Silica can promote the ozone generation.When the thickness of silica film is 940 nm ozone concentration and ozone yield can maximally increase by 7.1%and 72.6%at 5 kHz and 1 slpm,respectively.However,too thick silica will be detrimental to ozone generation.This is because too thick silica reduces the thermal conductivity of the dielectric plate loaded with silica,which is not conducive to the heat dissipation of the discharge structure,the ozone decomposition rate is accelerated,so that the ozone concentration decreases.(5)XPS and other characterization results show that:loading silica on the surface of the dielectric plate can introduce hydroxyl groups on the surface of the dielectric plate and significantly increase the specific surface area of the dielectric plate.This plays a vital role in the silica surface catalysis for ozone generation by dielectric barrier discharge.(6)The strong adsorption capacity of silica is an important reason for its enhanced ozone generation.On the one hand,strong adsorption capacity can improve the retention time of short-lived active substances.On the other hand,the catalytic effect of silica on ozone is manifested in enhancing the surface reaction generated by ozone.Silica has a strong adsorption effect,so it can adsorb more reactive particles,thereby generating more ozone on the surface of the dielectric plate,which in turn improves the performance of the ozone generator.