A facile one-step co-precipitation method was demonstrated to fabricate amorphous sulfurcontaining calcium phosphate （SCP） nanoparticles, in which the sulfur group was in-situ introduced into calcium phosphate. The ...A facile one-step co-precipitation method was demonstrated to fabricate amorphous sulfurcontaining calcium phosphate （SCP） nanoparticles, in which the sulfur group was in-situ introduced into calcium phosphate. The resulting SCP exhibited a noticeable enhanced performance for Pb（II） removal in comparison with hydroxyapatite （HAP）, being capable of easily reducing 20 ppm of Pb（II） to below the acceptable standard for drinking water within less than 10 min. Remarkably, the saturated removal capacities of Pb（II） on SCP were as high as 1720.57 mg/g calculated by the Langmuir isotherm model, exceeding largely that of the previously reported absorbents. Significantly, SCP displayed highly selective removal ability toward Pb（II） ions in the presence of the competing metal ions （Ni（II）, Co（II）, Zn（II）, and Cd（II））. Further investigations indicated that such ultra-high removal efficiency and preferable affinity of Pb（II） ions on SCP may be reasonably ascribed to the formation of rodlike hydroxypyromorphite crystals on the surface of SCP via dissolution-precipitation and ion exchange reactions, accompanied by the presence of lead sulfide precipitates. High removal efficiency, fast removal kinetics and excellent selectivity toward Pb（II） made the obtained SCP material an ideal candidate for Pb（II） ions decontamination in practical application.展开更多
CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and ...CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and lower activity at high temperatures (> 200 °C) than the S‐CeZr catalysts. The sulfation ofCeZr was studied in terms of surface acidity, redox properties and NO adsorption‐desorption bytemperature‐dependent experiments and in situ infrared spectroscopy. S‐CeZr displayed high concentrationsof acidic sites and increased surface acidities, but poor reducibility compared with CeZr.The high acidity of S‐CeZr was attributed to the presence of Br?nsted acid sites, arising mainly fromthe surface sulfates. Because the surface was covered with sulfate species, S‐CeZr showed lower NOadsorption and weaker oxidation ability than CeZr. The adsorption of NH3 on the Br?nsted acid sites restricted the reaction with NO at low temperatures, but the selective catalytic reduction cycle occurred easily at relatively low temperatures (150 °C), and the weakly bound nitrite was partially activated on the S‐CeZr catalyst at relatively high temperatures (300 °C). The catalytic mechanisms for the CeZr and S‐CeZr catalysts at 150 and 300 °C were also studied.展开更多
文摘A facile one-step co-precipitation method was demonstrated to fabricate amorphous sulfurcontaining calcium phosphate （SCP） nanoparticles, in which the sulfur group was in-situ introduced into calcium phosphate. The resulting SCP exhibited a noticeable enhanced performance for Pb（II） removal in comparison with hydroxyapatite （HAP）, being capable of easily reducing 20 ppm of Pb（II） to below the acceptable standard for drinking water within less than 10 min. Remarkably, the saturated removal capacities of Pb（II） on SCP were as high as 1720.57 mg/g calculated by the Langmuir isotherm model, exceeding largely that of the previously reported absorbents. Significantly, SCP displayed highly selective removal ability toward Pb（II） ions in the presence of the competing metal ions （Ni（II）, Co（II）, Zn（II）, and Cd（II））. Further investigations indicated that such ultra-high removal efficiency and preferable affinity of Pb（II） ions on SCP may be reasonably ascribed to the formation of rodlike hydroxypyromorphite crystals on the surface of SCP via dissolution-precipitation and ion exchange reactions, accompanied by the presence of lead sulfide precipitates. High removal efficiency, fast removal kinetics and excellent selectivity toward Pb（II） made the obtained SCP material an ideal candidate for Pb（II） ions decontamination in practical application.
基金supported by the Science Fund for Yong Scholars at Changchun University of Science and Technology(XQNJJ-2014-15)~~
文摘CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and lower activity at high temperatures (> 200 °C) than the S‐CeZr catalysts. The sulfation ofCeZr was studied in terms of surface acidity, redox properties and NO adsorption‐desorption bytemperature‐dependent experiments and in situ infrared spectroscopy. S‐CeZr displayed high concentrationsof acidic sites and increased surface acidities, but poor reducibility compared with CeZr.The high acidity of S‐CeZr was attributed to the presence of Br?nsted acid sites, arising mainly fromthe surface sulfates. Because the surface was covered with sulfate species, S‐CeZr showed lower NOadsorption and weaker oxidation ability than CeZr. The adsorption of NH3 on the Br?nsted acid sites restricted the reaction with NO at low temperatures, but the selective catalytic reduction cycle occurred easily at relatively low temperatures (150 °C), and the weakly bound nitrite was partially activated on the S‐CeZr catalyst at relatively high temperatures (300 °C). The catalytic mechanisms for the CeZr and S‐CeZr catalysts at 150 and 300 °C were also studied.
