Study On Treatment Of Pyridine Containing Wastewater By Catalytic Ozonation With Magnetic Activated Carbon

Pyridine containing wastewater is a typical toxic industrial wastewater that is difficult to be degraded.Catalytic ozonation process can effectively treat it,but there is still a problem that catalysts are not easy to be separated and recycled.Magnetic catalysts can solve this problem.In this paper,Fe₃O₄ or NiFe₂O₄ were loaded on powder activated carbon respectively by alkaline co-precipitation method and hydrothermal method,and four kinds of magnetic activated carbon were prepared as catalysts.The magnetic activated carbon was characterized by XRD,SEM,EDS,FTIR and BET analysis,and the best magnetic activated carbon was selected as catalyst by oxalic acid degradation experiment,magnetic separation experiment and metal ion leaching experiment.The catalytic ozonation of pyridine was performed.And the effects of different catalyst dosages,different ozone concentrations and pH values on the degradation of pyridine and ozone decomposition were studied.The kinetics of pyridine degradation,kinetics of ozone degradation and ozone utilization were analyzed.The characterization results showed that Fe₃O₄ or NiFe₂O₄ were successfully loaded on activated carbon.In the oxalic acid degradation experiment,the oxalic acid concentration was 100mg/L,the catalyst dosage was 0.3g/L,the ozone concentration was 30mg/L,and the ozone flow rate was 1L/min.C-Fe₃O₄?precipitation method?showed the optimal catalytic performance,and the oxalic acid removal rate was 90.34%.,which probably because of its large specific surface area?BET result?.And it had better magnetic separation performance,because the Fe₃O₄ loaded by this method had better spinel structure?XRD result?.The leaching rate of metal ions was low,and the concentration of iron ions in the solution was 1.027mg/L after oxalic acid degradation reaction..So this magnetic activated carbon was chosen as the catalyst in this paper.In the pyridine degradation experiment,the initial concentration of pyridine was 8mg/L.When the catalyst dosage was 0.2g/L and the ozone concentration ranged from 8mg/L to 32mg/L,the pyridine removal rate ranged from 17.11%to 50.72%.The higher the ozone concentration was,the faster the pyridine degradation velocity and the faster the ozone decomposition velocity.When the ozone concentration was 16mg/L and the catalyst dosage ranged from 0 to 0.3g/L,the higher the catalyst dosage was,the faster the pyridine degradation velocity was in the early stage of the reaction.When the catalyst dosage was 0.05g/L,the pyridine degradation was the highest after the reaction and the removal rate was 44.25%,which was because the catalyst dosage was the best.At the same time,the higher the amount of catalyst,the faster the ozone decomposition velocity.When the concentration of ozone was 16 mg/L,the amount of catalyst added was 0.05 g/L,and the pH value ranged from 3 to 11,acidic conditions inhibited pyridine degradation and ozone decomposition,while alkaline conditions promoted pyridine degradation and ozone decomposition.The removal rate of pyridine was only 2.86%when pH was 3,and reached 81.08%when pH was 11.·OH was detected during the reaction,and the higher the ozone concentration,the higher the yield of OH.Tert-butanol inhibited pyridine degradation.Ozone water concentration was 16 mg/L and catalyst dosage was 0.05g/L.When 200mg/L tert-butanol was added,the total degradation of pyridine decreased from 2.27mg/L to 1.29mg/L.When the ozone water concentration was 16 mg/L,the TOC removal rate of pyridine was almost zero.When 0.05g/L catalyst was added,the TOC removal rate was 17.45%,which improved the salinity of pyridine.The fitting equation of pyridine degradation was obtained through experiments:-r1=k1C₁1.3067C₂0.7519.C₁ is the dosage of catalyst and C₂ is the concentration of OH-.The ozone decomposition fitting equation was obtained:-r₂=k₂c₁^1.1812C₂^0.492.c₁ is the dosage of catalyst and c₂ is the concentration of OH'.The ozone water concentration was 16mg/L,and the catalyst dosage ranged from 0 to 0.3g/L.When the dosage was 0.05g/L,the ozone utilization rate was the highest.Keeping the catalyst dosage constant,the higher the ozone concentration was,the lower the ozone utilization rate was.Keeping the catalyst and ozone content unchanged,the higher the pH was,the higher the ozone utilization was.