separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed b...separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed by dispersing magnets in a dimethylformamide （DMF） solution con- taining two metal-organic framework （MOF） precursors, namely ZrCI4 and 2-aminobenzenetricar- boxylic acid. This method is simpler and more efficient than previously reported step-by-step method in which magnets were consecutively dispersed in DMF solutions each containing one MOF precursor, and the obtained Fe304@UiO-66-NH2 with three assembly cycles has a higher degree of crystallinity and porosiW. The core-shell Fe3O4@UiO-66-NH2 is highly active and selective in Knoevenagel condensations because of the bifunctionality of UiO-66-NH2 and better mass transfer in the nano-sized shells. It also has good recycling stability, and can be recovered magnetically and reused at least four times without significant loss of catalytic activity and framework integrity. The effects of substitution on the reactivity of benzaldehyde and of substrate size were also investigated.展开更多
Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-cont...Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-containing reagent is required.The temperature of 60 ℃,NaOH concentration of 0.10 mol/L;stirring rate of 900 r/min and the reaction time of 10 min are the optimal conditions.The results show that the siderite recovery in magnetic separation increased from 26.9% to 88.8% after surface magnetization.Magnetization kinetic equation is expressed as 1 [1(e0.269)]1/3 = Kt.Activation energy for the magnetization reaction is 4.30 kJ/mol.VSM,SEM and XPS were used to characterize the siderite,and results show that the saturated magnetization(rs) of siderite increased from 0.652 to 2.569Am2 /kg,the magnetic hysteresis was detected with a coercive force of 0.976 A/m after magnetization;Fe2P3/2 electron binding energy changed which reflects the valence alteration in iron on the surface and the formation of ferromagnetic Fe3O4.展开更多
In this work, we report the synthesis of magnetic sulfur-doped Fe_3O_4 nanoparticles (Fe_3O_4:S NPs) with a novel simple strategy,which includes low temperature multicomponent mixing and high temperature sintering. Th...In this work, we report the synthesis of magnetic sulfur-doped Fe_3O_4 nanoparticles (Fe_3O_4:S NPs) with a novel simple strategy,which includes low temperature multicomponent mixing and high temperature sintering. The prepared Fe_3O_4:S NPs exhibit a much better adsorption performance towards Pb(Ⅱ) than bare Fe_3O_4 nanoparticles. FTIR, XPS, and XRD analyses suggested that the removal mechanisms of Pb(Ⅱ) by Fe_3O_4:S NPs were associated with the process of precipitation (formation of PbS), hydrolysis,and surface adsorption. The kinetic studies showed that the adsorption data were described well by a pseudo second-order kinetic model, and the adsorption isotherms could be presented by Freundlich isotherm model. Moreover, the adsorption was not significantly affected by the coexisting ions, and the adsorbent could be easily separated from water by an external magnetic field after Pb(Ⅱ) adsorption. Thus, Fe_3O_4:S NPs are supposed to be a good adsorbents for Pb(Ⅱ) ions in environmental remediation.展开更多
基金supported by the National Natural Science Foundation of China (21203017)Open Fund of State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (N-11-3)+1 种基金Program for Liaoning Excellent Talents in University (LNET)the Funda-mental Research Funds for the Central Universities (DC201502020304)~~
文摘separation is an attractive alternative to filtration or centrifugation for separating solid catalysts from a liquid phase, Here, core-shell Fe3O4@UiO-66-NH2 nanohybrids with well-defined structures were constructed by dispersing magnets in a dimethylformamide （DMF） solution con- taining two metal-organic framework （MOF） precursors, namely ZrCI4 and 2-aminobenzenetricar- boxylic acid. This method is simpler and more efficient than previously reported step-by-step method in which magnets were consecutively dispersed in DMF solutions each containing one MOF precursor, and the obtained Fe304@UiO-66-NH2 with three assembly cycles has a higher degree of crystallinity and porosiW. The core-shell Fe3O4@UiO-66-NH2 is highly active and selective in Knoevenagel condensations because of the bifunctionality of UiO-66-NH2 and better mass transfer in the nano-sized shells. It also has good recycling stability, and can be recovered magnetically and reused at least four times without significant loss of catalytic activity and framework integrity. The effects of substitution on the reactivity of benzaldehyde and of substrate size were also investigated.
基金the financial support from the National Natural Science Foundation of China(No.51274256)
文摘Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-containing reagent is required.The temperature of 60 ℃,NaOH concentration of 0.10 mol/L;stirring rate of 900 r/min and the reaction time of 10 min are the optimal conditions.The results show that the siderite recovery in magnetic separation increased from 26.9% to 88.8% after surface magnetization.Magnetization kinetic equation is expressed as 1 [1(e0.269)]1/3 = Kt.Activation energy for the magnetization reaction is 4.30 kJ/mol.VSM,SEM and XPS were used to characterize the siderite,and results show that the saturated magnetization(rs) of siderite increased from 0.652 to 2.569Am2 /kg,the magnetic hysteresis was detected with a coercive force of 0.976 A/m after magnetization;Fe2P3/2 electron binding energy changed which reflects the valence alteration in iron on the surface and the formation of ferromagnetic Fe3O4.
基金supported by the National Natural Science Foundation of China (B21271179, 21607101)Program for New Century Excellent Talents in University (NCET-13-0364)+1 种基金China Postdoctoral Science Foundation Funded Project (2016M590363)State Key Program of National Natural Science Foundation of China (21436007)
文摘In this work, we report the synthesis of magnetic sulfur-doped Fe_3O_4 nanoparticles (Fe_3O_4:S NPs) with a novel simple strategy,which includes low temperature multicomponent mixing and high temperature sintering. The prepared Fe_3O_4:S NPs exhibit a much better adsorption performance towards Pb(Ⅱ) than bare Fe_3O_4 nanoparticles. FTIR, XPS, and XRD analyses suggested that the removal mechanisms of Pb(Ⅱ) by Fe_3O_4:S NPs were associated with the process of precipitation (formation of PbS), hydrolysis,and surface adsorption. The kinetic studies showed that the adsorption data were described well by a pseudo second-order kinetic model, and the adsorption isotherms could be presented by Freundlich isotherm model. Moreover, the adsorption was not significantly affected by the coexisting ions, and the adsorbent could be easily separated from water by an external magnetic field after Pb(Ⅱ) adsorption. Thus, Fe_3O_4:S NPs are supposed to be a good adsorbents for Pb(Ⅱ) ions in environmental remediation.
