： The structures of Mg-Al-CO3 and Zn-Al-CO3 hydrotalcites have been studied by means of XRD,IR and TG-DTA.Although both have the same crystal structures,their thermal stabilities are quite different.During the therma...： The structures of Mg-Al-CO3 and Zn-Al-CO3 hydrotalcites have been studied by means of XRD,IR and TG-DTA.Although both have the same crystal structures,their thermal stabilities are quite different.During the thermal decomposition process,Mg-Al-CO3 hydrotalcite exhibits two steps- desorption of interlayer water occurs at 200℃ ,followed by dehydroxylation of the brucite-like layers and loss of carbonate at 400℃ ,Zn-Al-CO3 hydrotalcite decomposes in one step-the desorption of interlayer water, structural water and carbon dioxide occurred at the same time at 200℃ . The results of a theoretical study indicate that the bond strengths of OH-CO3-OH and OH-H2O-CO3-OH in Mg-Al-CO3 hydrotalcite are stronger than those in Zn-Al-CO3 hydrotalcite.It has been shown that the thermal stability of Mg-Al-CO3 hydrotalcite is higher than that of Zn-Al-CO3 hydrotalcite.展开更多
Cu-Zn-AI-CO3 layered double hydroxide （LDH）, with a Cu to Zn mole ratio of 5：1 and a （Cu＋Zn） to AI mole ratio of nearly 2, was prepared and its calcined product （CLDH） was obtained. Batch sorption studies were...Cu-Zn-AI-CO3 layered double hydroxide （LDH）, with a Cu to Zn mole ratio of 5：1 and a （Cu＋Zn） to AI mole ratio of nearly 2, was prepared and its calcined product （CLDH） was obtained. Batch sorption studies were conducted to investigate removal of phenylalanine from water with CLDH. The results show that CLDH can be used as an effective adsorbent and its sorption capacity is higher than that of Mg-A1--CO3-LDH. The maximum adsorption was observed at pH 6.7. A maximum adsorption capacity is 37.25 mg/g. The adsorption processes follow the Lagergren＇s first order kinetic model. The adsorption data are fitted well with the Langmuir isotherm equation. The thermodynamic parameters were calculated, and the negative △G and positive △H indicate that the adsorption processes are spontaneous endothermic in nature. The mechanism of adsorption also suggests that the benzoate molecules are tilted, forming an angle with the hydroxyl layers.展开更多
文摘： The structures of Mg-Al-CO3 and Zn-Al-CO3 hydrotalcites have been studied by means of XRD,IR and TG-DTA.Although both have the same crystal structures,their thermal stabilities are quite different.During the thermal decomposition process,Mg-Al-CO3 hydrotalcite exhibits two steps- desorption of interlayer water occurs at 200℃ ,followed by dehydroxylation of the brucite-like layers and loss of carbonate at 400℃ ,Zn-Al-CO3 hydrotalcite decomposes in one step-the desorption of interlayer water, structural water and carbon dioxide occurred at the same time at 200℃ . The results of a theoretical study indicate that the bond strengths of OH-CO3-OH and OH-H2O-CO3-OH in Mg-Al-CO3 hydrotalcite are stronger than those in Zn-Al-CO3 hydrotalcite.It has been shown that the thermal stability of Mg-Al-CO3 hydrotalcite is higher than that of Zn-Al-CO3 hydrotalcite.
基金Project (21176263) supported by the National Natural Science Foundation of ChinaProject (2009RS3039) supported by Hunan Provincial Postdoctoral Special Foundation of ChinaProject (09JJ3026) supported by Hunan Provincial Natural Science Foundation of China
文摘Cu-Zn-AI-CO3 layered double hydroxide （LDH）, with a Cu to Zn mole ratio of 5：1 and a （Cu＋Zn） to AI mole ratio of nearly 2, was prepared and its calcined product （CLDH） was obtained. Batch sorption studies were conducted to investigate removal of phenylalanine from water with CLDH. The results show that CLDH can be used as an effective adsorbent and its sorption capacity is higher than that of Mg-A1--CO3-LDH. The maximum adsorption was observed at pH 6.7. A maximum adsorption capacity is 37.25 mg/g. The adsorption processes follow the Lagergren＇s first order kinetic model. The adsorption data are fitted well with the Langmuir isotherm equation. The thermodynamic parameters were calculated, and the negative △G and positive △H indicate that the adsorption processes are spontaneous endothermic in nature. The mechanism of adsorption also suggests that the benzoate molecules are tilted, forming an angle with the hydroxyl layers.
