Effects of calcium substitute in LaMnO3 perovskites for NO catalytic oxidation

La1-x Cax MnO3 (x=0-0.3) perovskite-type oxides were synthesized by citrate sol-gel method. The physical and chemical properties were characterized by X-ray diffraction (XRD), Brumauer-Emmett-Teller method (BET), X-ray photoelectron spectroscopy (XPS), NO+O2 -TPD (temperature-programmed desorption), activated oxygen evaluation and H2 -TPR (temperature-programmed reduction) technologies. The results showed that NO catalytic oxidation activity was significantly improved by Ca substitution, especially for lower temperature activity. The La0.9 Ca0.1 MnO 3 sample showed the maximum conversion of 82% at 300 oC. The monodentate nitrates played a crucial role for the formation of NO2 . The reducibility of Mn 4+ ions and reactivity of activated oxygen were favorable for the catalytic performances of NO oxidation.     

微生物法对黑臭水体底泥的修复作用

黑臭水体污染问题日益严峻,其中水体污染物沉积于底泥中带来的污染不可忽视。主要分析了原位修复方法中的生物修复法对黑臭水体底泥的修复作用,发现光合细菌、反硝化细菌与生物促生剂对黑臭水体底泥有一定的修复作用,光合细菌可有效降低COD、BOD_5、TN、TP浓度,光合细菌与反硝化细菌均可降解上覆水体中的COD_(Cr)、NH_3-N、TN、TP,同时反硝化细菌可提高脱氮速率。生物促生剂可以促进水体中COD_(Cr)、NH_3-N和TP的降解。