NaTaO₃/BC+PMS Dual-effect Catalytic System For Degradation Of Organic Pollutants

In the process of rapid industrialization,a large amount of highly toxic,difficult-to-biodegradable industrial wastewater has been produced,which poses a threat to human health and water ecological environment.As a semiconductor photocatalyst,the perovskite-type oxide sodium tantalate has high UV absorption efficiency and excellent thermal and chemical stability.However,sodium tantalate exists outstanding catalytic activity against visible light,low utilization rate of visible light,high photogenerated carriers recombination,defects such as serious agglomeration and poor adsorption performance,which is limited in the practical application of water treatment.In this article,through non-metal doping and biochar composite modification of sodium tantalum,a composite catalyst with excellent adsorption and oxidative degradation properties was prepared,which improved the application of sodium tantalate catalyst in the field of visible light catalysis,and further introduction of persulfate PMS built a dual-effect catalytic system to achieve rapid and efficient removal of refractory organic pollutants.（1）The non-metal doping modification of sodium tantalate catalyst can improve the visible light utilization rate of sodium tantalate catalyst and reduce the recombination rate of photogenerated carriers.Sodium tantalate catalyst was doped with S by hydrothermal method.The degradation effect of S-doped sodium tantalite（S/Ta=20%）on MB was about 20%higher than that of pure sodium tantalate.Sodium tantalate was doped with C by one-step solvothermal method with ethylene glycol as the solvent.The degradation effect of C-doped sodium tantalate（with only ethylene glycol as the solvent）increased by 27%compared with that of pure sodium tantalate.In the experiment,S-doped sodium tantalate was used to compound with straw biochar（BC）,while improving the adsorption performance of the catalyst,the visible light absorption of the catalyst was further improved,and the photogenerated carrier current was reduced.When adjusting BC/NaTaO₃=30%（the loading ratio of BC in the composite catalyst）,the catalytic performance was greatly improved.（2）Peroxymonosulfate（PMS）was introduced to construct a dual-effect catalytic system,and the reaction parameters were optimized to promote the catalytic reaction rate and improve the catalytic activity.The optimal amount of reactant in the dual-effect catalytic system was determined,and the stability of the system was verified by four rounds of repeated experiments.At the same time,the dual-effect catalytic system had high adaptability to different p H and matrix anions in water.In the treatment of dyes and antibiotics refractory pollutants showed relatively excellent catalytic removal ability.（3）A process experiment of treating simulated azo dye wastewater with a dual-effect catalytic system in a pilot plant of photocatalysis+ultrafiltration+nanofiltration was carried out.The results showed that the device can greatly reduce the chromaticity of dye wastewater within 2 hours,and the total organic carbon in the water can be reduced to a certain extent.At the same time,the Ca²⁺,Mg²⁺,and SO₄^2-in the water are retained to a certain extent after ultrafiltration and nanofiltration treatment,and the Cl^-was almost completely permeated.This experiment provides a new idea for expanding the application of photocatalytic technology and the application of dual-effect catalytic system in the practical treatment of organic wastewater.