Synthesis, Characterization And Photo Catalytic Study Of ZnB₂O₄(B=Al,Mn,Cr) Composite Oxide

The essay is about using glucose as complex agent, three kinds of compositeoxides Zn-Al-O, Zn-Cr-O and Zn-Mn-O were prepared through the sol-gel method.The structure and catalytic properties were characterized by means of XRD, FT-IR,H₂-TPR, FS, DRS and TEM. 300W high pressure Hg-lamp (365nm) was used aslamp-house of micro-beam, and these three substances were used as catalyst, theinitial concentration of the phenol solution was 100mg/L and the amount of thecatalyst was 1g/L, and the bottom of the reactor was pressed into a certain amount ofair, then 3h light catalyzing reaction was carried out through the UV light. Thecatalytic activity was checked by degradation rate and COD removal of phenolsolution under the UV light irradiation. The experiments of photocatalyticdegradation phenol were used to investigate the activity of three catalysts and the bestcatalyst was selected. The effects of some factors such as calcinations temperatures,initial concentration of phenol, initial pH, and the amount of the catalyst andconcentration of oxidants were studied. Furthermore, we found that the Fe dopedcatalyst could enhance the catalytic activity for photocatalytic degradation phenol. Catalysts Zn-Fe_x-Al_2-x-O (x=0.01, 0.03, 0.05, 0.08, 0.1, 0.8) were prepared by sol-gelmethod and compared with Zn-Al-O catalyst to study the effects of doping Fe onphotocatalytic degradation of phenol.The XRD patterns showed that the spinel phase catalysts ZnAl₂O₄, ZnCr₂O₄and ZnMn₂O₄ were obtained by preceding preparation method. Photo catalyticactivity analysis indicated that composite oxides ZnAl₂O₄ was shown the best photo-catalytic activity. The DRS spectrum showed doping makes the light absorptionincrease and the spectrums of Zn-Fe-Al-O show red shift. The results of experimentof photocatalytic degradation of phenol showed that the optimum doping content is0.1. Finally, we chose ZnAl₂O₄ as catalyst and optimized reaction condition, theresult showed: calcinations temperatures is 800℃, initial concentration of phenol is20mg/L,initial pH is 5,amount of catalytic is 1g/L and adequacy concentration ofoxidants, catalysts have high photocatalysis.The kinetics of photocatalytic oxidation reaction for phenol solution was studiedin spinel catalyst, the results showed that the reaction was the first-order and velocityof reaction was coincident with multiphase catalytic kinetic equation:Langmuir-Hinshelwood equation.