Treat Environmental Pollutants In Water By Sulfated CeO₂Fenton-like Reaction And Copper Ligand Complexes

The thesis centers around the two common environmental pollutants in water, organic dye and inorganic nitrite, and is comprised of two studies of the degradation of azo dye AO7and the removal of nitrite.In the second chapter of the thesis, nano ceria prepared by precipitation method was pretreated and modified simply in various ways. Degradation of AO7was employed to evaluate the catalytic activity of the pretreated ceria samples in the presence of H2O2in pre-adsorbed mode (AO7pre-adsorbed on CeO2before the addition of H2O2) and pre-mixed mode (CeO2pre-mixed with H2O2before the addition of AO7). Two sulfated ceria samples (H2SO4-CeO2and Na2SO4-CeO2) exhibit enhanced catalytic performance in both modes compared with un-pretreated bare CeO2. XRD, BET, FTIR and potentiometric titration methods were used to characterize the pretreated ceria samples. The sulfated samples display stronger surface acidity due to the sulfate ions anchored on their surface. Raman and XPS measurement were carried out to analyze the samples after reacting with H2O2. A mechanism to explain the improved catalytic activity of sulfated CeO2is proposed that the active surface peroxide species (≡Ce(Ⅲ)-O2H-), which are excessive due to the over-complexation of H2O2with surface Ce3+sites, can be decomposed into high-active hydroxyl radicals under surface acidic environment spontaneously.In the third charpter of the thesis, three ligands including diethylene triamine (DETA),2,2’-bis (pyridylmethyl) amine (bpa) and N,N-di(pyrrolyl-a-methyl)-N-methylamine (H2dpma) were chosen to synthetize model complexes of copper nitrite reductase. The model complexes and model complexes loaded on SBA-15mesoporous materials were investigated in the tests of nitrite adsorption and removal. The high-temperature and alkaline conditions are favor to the reaction of the copper ligand complexes and nitrite so the nitrite removal was accelerated. In order to separate the reacted copper ligand complexes by centrifugation, the three copper ligand complexes were loaded on SBA-15. Only Cu(H2dpma)H2OCl2/SBA-15with the best loading performance shows the outstanding ability to adsorb and remove nitrite. Its isothermal adsorption removal curve is close to the Freundlich isotherm adsorption model.