Catalytic Ozonation Of Nitrobenzene In Aqueous Solution With Ammoniated Activated Carbon Fiber Or Fe₃O₄ Nanoparticles

The catalytic ozonation is a kind of advanced oxidation technology for water treatment,which is widely used in degrading the organic contaminants with complex composition.The ammonia-modified activated carbon fiber(ACF)and Fe304 nanoparticles catalyzed ozonation of nitrobenzene in water were investigated.The effects of factors that affect the reaction rate were roundly studied.The main work done in this paper as follows:1.A series of ammonia-modified activated carbon fiber(ACF)were prepared via hydrothermal method.Nitrobenzene was selected as model pollutant to evaluate the catalytic ozonation activity.The structure and properties of the catalysts were studied by means of X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET),and the Fourier transform infrared spectroscopy(FT-IR).The effect of operating variables was investigated as a function of pH value,hydrothermal temperature of ACF,ozone dosage,system temperature and the initial concentration of nitrobenzen.The reaction mechanism of catalytic oxidation was proposed by measuring the degradation rate of organic compounds after adding the tert-butyl alcohol.The results showed that the specific surface area of activated carbon fiber decreased with the increasing of hydrothermal temperature.The number of surface acidic groups decreased significantly after hydrothermal treatment.It demonstrated that removal rate of nitrobenzene with catalytic ozonation is higher than ozonation alone.Ammoniation processing led to the internal rearrangement of carbon atoms.Under the same conditions,the removal rate of nitrobenzene is increasing with the increasing of the pH in solution.It was found that the ACF which was made under hydrothermal treatment with a temperature of 120? has the highest degradation efficiency of nitrobenzene,the degradation rates were 85.7,92.0%,95.2%,respectively,so 120? is considered to be the optimal hydrothermal temperature.Ozonation processes were significantly influenced by tert-butyl alcohol,which confirmed that ACF catalytic ozonation follows a radical-type mechanism.2.Fe3O4 nanoparticles were synthesized by an ultrasonic-assisted reverse co-precipitation method.Their catalytic activities were evaluated by nitrobenzene degradation in aqueous solution in presence of ozone.The activity of Fe304 with different Fe2+/Fe3+ mole ratio was studied to find the optimal proportion.The effects of concentration,temperature were investigated.The results illustrate that ozonation combined with Fe3O4 for removal of TOC is more efficient than ozonation alone.The optimal mole ratio of Fe2+/Fe3+ was found to be?1:1.The optimal temperature is 3 50C,The degradation rate increased with the decreasing initial concentration.