The Study On Catalyzed Ozonation Of P-CNB In Water By Si-FeOOH

The hydroxyl ferric oxide becomes the research hot spot in the technology of catalyzedozonation because of its stability and efficiency. But it,s found that there exists someshortcomings; such as easily broken,the low physical intensity,the active constituentdissolve easily,difficult to recycle. Therefore,it become study concern that through add metalions or other components to improve the physical and chemical properties of FeOOH. In thisstudy, contact the iron(â…¢) salt solution with the sodium silicate/hydroxide mixture during thesynthesis of the Si-FeOOH, and characterize the structure and the surface properties.Meanwhile take p-chloronitrobenzene (p-CNB) as the target,research the influence of removalrule in the process of degradate p-CNB of catalytic ozone. The conclus follows :The Fe-Si complexes formed in the process of addingsilica to FeOOH can effectivelyincrease the surface area, and the particle strength of Si-FeOOH, retardate the iron oxidecrystallization, reduce weight loss phenomenon of FeOOH, and make the amorphousstructure of Si-FeOOH more stable.In the sole ozone oxidation of p-CNB, the removal efficiency of p-CNB was increasedwith the increment of concentration of ozone and increased with the decrement of initialconcentration of p-CNB. The removal efficiency of p-CNB was affected by temperature. Theremoval efficiency of p-CNBwas increased with the raising of temperature.Si-FeOOH and FeOOH have strong catalytic activity in the catalytic system, the catalyticremoval rate of p-CNB reach to 57% to 71% and 86%. The reaction rate constant of p-CNBwere 2 times and 1.5 times higher as the solo ozonation. The Si/Fe ratio influenced thecatalytic effect, the best catalyst effect is abtained when the Si/Fe ratio is 0.33. Both positiveand negative correlation exist between the amout of catalyst and the removal efficiency ofp-CNB.The removal efficiency increases slowly with the amount of catalyst between0-500mg/L, on the contrary, the removal efficiency decrease when the amount of catalyst isover 500mg/L. The pH of solution has a significant influence on the catalytic activity incatalyst systems. Si-FeOOH and FeOOH have no activity on the condition of acidic solution;the removal efficiency of p-CNB in the catalyst systems is lower than the solo ozoneoxidation of p-CNB on the alkaline solution; catalysts have full scope catalytic activity underneutral conditions. The add of tert-butyl alcohol has effectively declined the removalefficiency of p-CNB in the catalyst systems, that indirectly prove that the Si-FeOOH catalyticozonation follows the oxidationmechanism of hydroxyl radical.The physical strength gradually increase , the solution turbidity decrease ; the visualdisinegration gradually degree with the Si/Fe ratio increases. Dissolved iron ofSi-FeOOH (0.33) was 0.105mg/L, in the meanwhile, dissolved iron of FeOOH was 0.29mg/L.Reuse experiments confirmed : Si-FeOOH(0.33) has a much higher catalytic effection thanFeOOH. Therefore, Si-FeOOH is more suitable than FeOOH in project practice.