Study On Membrane Fouling Characteristics Of Photocatalytic - Membrane Separation And Coupling Process

A kind of suspension type coupling reaction device of photocatalytic-membrane separation(referred to as the reaction device) was designed in this paper. First of all, the basic operation conditions of the reaction device were determined, and the influence of its operating parameters on membrane fouling were studied; Thereafter, the pollution characteristics of TiO2/MCM-41 catalysts to membrane module was mainly studied, and the photocatalytic degradation and suspension performance of TiO2/MCM-41 catalyst were also examined.The experimental results showed that the best aeration rate of photocatalytic zone, concentration of acid red B, additive quantity of TiO2 catalyst was 0.15 m3/h, 18 mg/L and 1.0 g/L respectively. The membrane flux declining rate was a rising trend along with the increase of concentration of commercial TiO2 catalyst, transmembrane pressure difference, aeration rate in photocatalytic zone, the interval of air flushing on circulating pipe, however, which firstly increased then decreased and declined continuously with the increase of pH value and the aeration rate in membrane bottom respectively. Therefore, the best concentration of commercial TiO2 catalyst was 1.0 g/L, transmembrane pressure difference was 0.015 Mpa, aeration rate in photocatalytic zone was 0.15 m3/h, the interval of air flushing on circulating pipe was 50 min, the pH value was 3, aeration rate in membrane bottom was 0.042 m3/h. The degree of membrane fouling was reduced by CaCl2 electrolyte, but it increased by Na2S04 and NaCl in wastewate; The membrane flux declining rate was increased by acid red B in reaction system, but it only increased by 2% after run 10 h.The wastewater degradation rate of TiO2/MCM-41 firstly increased then dicreased respectively with the increase of TiO2 load and ultrasonic time of TiO2/MCM-41, the dicrease of MCM-41 and TiO2/MCM-41 size. However, the membrane flux declining rate was minimum at TiO2 load of 80%, in the meantime it firstly dicreased then increased with the dicrease of MCM-41 size, continuously increased with the dicrease of TiO2/MCM-41 size and firstly increased then dicreased with ultrasonic time of TiO2/MCM-41. The appropriate MCM-41 size, TiO2 load, TiO2/MCM-41 size and ultrasonic time of TiO2/MCM-41 were 0.61 μm,30%,11.26 μm and 60 min respectively; the appropriate MCM-41 size of TiO2/MCM-41 whoseload of 80% was 0.78 μm. The membrane flux declining rate of TiO2/MCM-41 catalyst was reduced 39.30% compared with commercial TiO2 catalyst after running 20 h, and when aeration rate in membrane bottom was 0.042 m3/h and online backwash, it was reduced 33.36% and 40.76% of the former compared to the latter of 19.09% and 23.72% respectively. And the photocatalytic degradation rate of 3.5 h and suspension concentration of the former of 100%,0.850 g/L (0.839 g/L) were increased by 10.07%,0.048 g/L (0.050 g/L) than the latter of 89.93%,0.802 g/L (0.789 g/L), so the TiO2/MCM-41 catalysts has high photocatalytic degradation activity and suspension concentration, and whose pollution degree to membrane module was low.