Study On Photocatalytic Oxidation-membrane Separation Coupling Process Performance Of TIO2 Nanotubes

Different morphology TiO2 nanotubes photocatalysts were synthesized by the hydrothermal method in this paper based on the unique structure and excellent performance of TiO2 nanotubes,and its application performances in photocatalytic oxidation-membrane separation coupled reaction device were investigated by photodegrading Acid red B wastewater experiment.The coupled reaction device contains photocatalytic reaction zone and membrane separation zone,and aeration device at the bottom of photocatalytic reaction zone could make wastewater circularly flow by connecting pipe and cir-culating pipe.The results showed that the degradation efficiency of Acid red B both increased firstly and then decreased with its concentration and aeration rate increase,and acidic condition was conducive to Acid red B degradation,suitable wastewater concentration,aeration rate and pH value were 12 mg/L,0.10 m3/h and 3.The wastewater degradation efficiency could increase when hydrothermal reaction time and calcination temperature increased from 6 h-12 h and 300℃-400℃respectively,while it could lead to opposite change rules when hydrothermal reaction time and calcination temperature increased from 12 h-24 h and 400℃-500℃ respectively.Although TiO2 nanotubes dosage increase was conducive to increase its suspension concentration,it also caused the deposition of TiO2 nanotubes,and suitable dosage was 0.8 g/L.The influence of air rising on TiO2 nanotubes suspension concentration mainly occurred during the two minutes at the end of air rising,and the time that TiO2 nanotubes concentration reached the maximum value in membrane separation zone was little than that of photocatalytic reaction zone.The increase of areation rate at the bottom of and air rinsing time intervals could reduce membrane fouling effectively;membrane fouling increased with hydrothermal reaction time increasing,while it firstly decreased and then increased with calcination temperature increasing.Based on the principle of keeping high photocatalytic degradation performance and reducing membrane fouling maximumly,suitable areation rate,air rinsing time intervals,hydrothermal reaction time and calcination temperature were 0.035 m3/h,30 min,12 h and 400℃ respectively.The membrane fouling under intermittent running was lower than that uner continuous running,and the presence of online backwashing for a long-running would reduce membrane fouling effectively in order to prolonging membrane life.Compared to load type TiO2/MCM-41 and commercial TiO2 catalysts,homemade TiO2 nanotubes had better photocatalytic degradation performance,and the fouling degree of TiO2 nanotubes on membrane was close to that of TiO2/MCM-41,while it was lower than that commercial TiO2 significantly.