Study On The Salt Effect Of Photocatalysis Of Phenol And Preparation And Reusability Of Magnetic Photocatalyst

The influence of different concentrations of NaCl, KCl, KBr, CaCl2,KNO3 and Na2SO4 electrolytes on the photocatalytic degradation rate of benzyl phenol aqueous solution at 323K was studied experimentally, and the kinetic curves of photocatalysis were determined with spectrophotometer. All kinds of electrolytes have prohibitive action on the photocatalytic degradation of benzyl phenol with the action strengthened as the electrolyte concentration increases; and the strength of salt effect depends mainly on anion while not on cation. The order of salt effect of anion on the studied system is Br->SO42->Cl-. The salt effect of photocatalysis processs might be related with the caputer and stabilization of photo-induced holes of photocatalyst surface by anion and the short circuit between photo-induced electron-hole pairs on the surface of photocatalyst induced by the electrical conductive action of cation.By coating TiO2 on active carbon impreganated with magnetic materials a magnetic photocatalyst is produced. The catalyst thus obtained has both magnetic and photocatalytic properties and can be recovered conveniently under magnetic field. The optimal composition and calcination temperature are Fe3O410%,TiO260%, active carbon 30% and 450℃, respectively. The recovery of magnetic photocatalyst can reach 95%, and no obvious decrese of photocatalytic activity is noticed after three times reuse. Study has been conducted on the photocatalyst of TiO2 loaded on active carbon. It is found that the activity of TiO2/active carbon is much higher than pure TiO2 and also higher than the mechanical mixture of TiO2+ active carbon. The catalytic activity of TiO2/active carbon depends on the ratio of carbon used and the treatment temperature, and the best activity can be identified for the carbon content of 30% and treatment temperature of 450℃. The usage of photocatalyst can affect photodegradation efficiency of phonel, and the optimal value is found to be 0.5g/L. In addition, recovery of TiO2/ active carbon by flocculation method is studied, and the optimal condition is as follows: pH 8-9, using PAC and PAM mixture as floculant with PAC concentration being 2ml/100ml. No obvious decrease in performance is found after 4 times reuse of the recovered catalyst with floculation method, however some degree of decrease can be noticed after 5 or 6 times reuse.