Porous carbons are extensively applied in gas separation, water purification, catalytic reaction, and electrochemical processing, attributing to their high specific surface area, large pore volume, chemical inertness,...Porous carbons are extensively applied in gas separation, water purification, catalytic reaction, and electrochemical processing, attributing to their high specific surface area, large pore volume, chemical inertness, and good mechanical and thermal stability. The templating method is widely used to synthesize porous carbons with the controlled pore structure. Among them, preparation of diatomite-templated carbons attracts increasing attention because the obtained carbon has unique developed macropores and exhibits the promising application in adsorption and support of large-sized molecules. Macroporous diatomite-templated carbons are prepared by using additive or inherent solid acid sites of diatomite as the catalyst. The obtained carbons showed tubular and pillared macroporous structures, and had a few mesopores and micropores. However, the carbons possessed the small specific surface area and micropore volume, and thus showed the low adsorption capacity of small-sized molecules, such as methylene blue (MB). In this case, enhancement of porosity, especially microporosity, is necessary.展开更多
Saponite has been widely used in a number of industrial fields because of the higher surface acidity and thermal stability when compared with other clay minerals (Alexander and Dubois, 2000; Casagrande et al., 2005). ...Saponite has been widely used in a number of industrial fields because of the higher surface acidity and thermal stability when compared with other clay minerals (Alexander and Dubois, 2000; Casagrande et al., 2005). Due to its limited natural resource, synthesis of saponite has attracted much attention during the last two decades (Vogels et al., 2005; Bisio et al., 2008). The main aim of this study is to investigate occupancy of Al ions and its effect on the structure of synthetic saponites.展开更多
The interlayer clay-organic complex is an important clay-organic association in sedimentary environments. The interlayer region of clay minerals not only provides storage space for organic matter, but also possesses s...The interlayer clay-organic complex is an important clay-organic association in sedimentary environments. The interlayer region of clay minerals not only provides storage space for organic matter, but also possesses solid acid sites; and these acid sites were proposed to be involved with the transformation of organic matter into liquid and gaseous hydrocarbons. However, the effect of the organic matter storage in the interlayer space of clay minerals on the hydrocarbons generation has not been made clear. In this study, the interlayer complex of 12-aminolauric acid (ALA) and Na+-montmorillonite (Na+-Mt), labeled as ALAinter-Mt (Na), was synthesized to investigate the role of the interlayer space of montmorillonite in hydrocarbon generation. Simply mixed ALA-Mt complex [ALA-Mt (Na)] was also prepared for comparison. The pyrolysis of ALA and ALA-Mt complexes was studied using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and a high temperature-pressure system (a confined gold capsule-autoclave system).展开更多
Organoclays synthesized with small organic cations can effectively adsorb hydrophobic organic compounds (HOCs), and the hydrophobic siloxane surfaces of clay minerals have been considered as the main adsorption sites ...Organoclays synthesized with small organic cations can effectively adsorb hydrophobic organic compounds (HOCs), and the hydrophobic siloxane surfaces of clay minerals have been considered as the main adsorption sites for HOCs. Therefore, reducing charge density of clay minerals which can effectively increase the exposed siloxane surface areas has been generally used to enhance the adsorption capacity of organoclays towards HOCs. In this work, we will present a new method to increase the exposed siloxane surface areas of the synthesized organoclays and enhance their adsorption capacity. Firstly, the original inorganic cations on montmorillonite were exchanged with Li+, and then part of the Li+ (i.e., 20% to 60% of the montmorillonite’s CEC) were further exchanged with tetramethylammonium cation (TMA). After that ,the samples were heated at 200 ℃ for 12 h to make sure most of the Li+ were transferred to montmorillonite layers. With this method the layer charge of montmorillonite can be effectively reduced while the layered structure of montmorillonite will be preserved by pre-exchanged TMA. Finally, the remaining Li+ cations were further exchanged with TMA. The structural and adsorptive characteristics of the resulting organoclays were compared with those synthesized using traditional method (i.e., first reducing the charge density and then exchanging TMA).展开更多
In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some...In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some of the substituting cations, e.g. Cr3+, V3+ and Mn2+, improve the catalytic activity of magnetite in heterogeneous Fenton reaction through the enhancement of hydroxyl radical OH production and the pollutant adsorption.展开更多
文摘Porous carbons are extensively applied in gas separation, water purification, catalytic reaction, and electrochemical processing, attributing to their high specific surface area, large pore volume, chemical inertness, and good mechanical and thermal stability. The templating method is widely used to synthesize porous carbons with the controlled pore structure. Among them, preparation of diatomite-templated carbons attracts increasing attention because the obtained carbon has unique developed macropores and exhibits the promising application in adsorption and support of large-sized molecules. Macroporous diatomite-templated carbons are prepared by using additive or inherent solid acid sites of diatomite as the catalyst. The obtained carbons showed tubular and pillared macroporous structures, and had a few mesopores and micropores. However, the carbons possessed the small specific surface area and micropore volume, and thus showed the low adsorption capacity of small-sized molecules, such as methylene blue (MB). In this case, enhancement of porosity, especially microporosity, is necessary.
文摘Saponite has been widely used in a number of industrial fields because of the higher surface acidity and thermal stability when compared with other clay minerals (Alexander and Dubois, 2000; Casagrande et al., 2005). Due to its limited natural resource, synthesis of saponite has attracted much attention during the last two decades (Vogels et al., 2005; Bisio et al., 2008). The main aim of this study is to investigate occupancy of Al ions and its effect on the structure of synthetic saponites.
文摘The interlayer clay-organic complex is an important clay-organic association in sedimentary environments. The interlayer region of clay minerals not only provides storage space for organic matter, but also possesses solid acid sites; and these acid sites were proposed to be involved with the transformation of organic matter into liquid and gaseous hydrocarbons. However, the effect of the organic matter storage in the interlayer space of clay minerals on the hydrocarbons generation has not been made clear. In this study, the interlayer complex of 12-aminolauric acid (ALA) and Na+-montmorillonite (Na+-Mt), labeled as ALAinter-Mt (Na), was synthesized to investigate the role of the interlayer space of montmorillonite in hydrocarbon generation. Simply mixed ALA-Mt complex [ALA-Mt (Na)] was also prepared for comparison. The pyrolysis of ALA and ALA-Mt complexes was studied using thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and a high temperature-pressure system (a confined gold capsule-autoclave system).
文摘Organoclays synthesized with small organic cations can effectively adsorb hydrophobic organic compounds (HOCs), and the hydrophobic siloxane surfaces of clay minerals have been considered as the main adsorption sites for HOCs. Therefore, reducing charge density of clay minerals which can effectively increase the exposed siloxane surface areas has been generally used to enhance the adsorption capacity of organoclays towards HOCs. In this work, we will present a new method to increase the exposed siloxane surface areas of the synthesized organoclays and enhance their adsorption capacity. Firstly, the original inorganic cations on montmorillonite were exchanged with Li+, and then part of the Li+ (i.e., 20% to 60% of the montmorillonite’s CEC) were further exchanged with tetramethylammonium cation (TMA). After that ,the samples were heated at 200 ℃ for 12 h to make sure most of the Li+ were transferred to montmorillonite layers. With this method the layer charge of montmorillonite can be effectively reduced while the layered structure of montmorillonite will be preserved by pre-exchanged TMA. Finally, the remaining Li+ cations were further exchanged with TMA. The structural and adsorptive characteristics of the resulting organoclays were compared with those synthesized using traditional method (i.e., first reducing the charge density and then exchanging TMA).
文摘In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some of the substituting cations, e.g. Cr3+, V3+ and Mn2+, improve the catalytic activity of magnetite in heterogeneous Fenton reaction through the enhancement of hydroxyl radical OH production and the pollutant adsorption.
