The XRD patterns of different calcined layered double hydroxides(CLDH) and their ultraviolet absorbing and screening properties have been investigated. It has been found that a calcined layered double hydroxide(CLDH) ...The XRD patterns of different calcined layered double hydroxides(CLDH) and their ultraviolet absorbing and screening properties have been investigated. It has been found that a calcined layered double hydroxide(CLDH) containing zinc is very effective in absorbing and screening ultraviolet radiation. The crystal structure of a CLDH containing zinc is similar to that of ZnO and is not related to the crystal structure of Al 2O 3. It is not a simple combination of zinc oxide and aluminium oxide but a calcined layered double hydroxide in which part of the Zn 2+ cations is replaced by Al 3+ cations.展开更多
Solutions of Mg(NO3)2·6H2O, Al(NO3)3·9H2O, NaOH and Na2CO3 were mixed in a rotating liquid memb rane reactor. The crystal growth process of Mg Al CO3 hydrotalcite was then studied by adding different amounts...Solutions of Mg(NO3)2·6H2O, Al(NO3)3·9H2O, NaOH and Na2CO3 were mixed in a rotating liquid memb rane reactor. The crystal growth process of Mg Al CO3 hydrotalcite was then studied by adding different amounts of water to the resulting slurry during the crystallizing process. The initial 6 hours of the crystallization was found to be the key period controlling crystal growth. Adding 150 to 250mL of water to the reaction system at the beginning of crystallization affords Mg Al CO3 hydrotalcite with relatively small particle size and large aspect ratio.展开更多
文摘The XRD patterns of different calcined layered double hydroxides(CLDH) and their ultraviolet absorbing and screening properties have been investigated. It has been found that a calcined layered double hydroxide(CLDH) containing zinc is very effective in absorbing and screening ultraviolet radiation. The crystal structure of a CLDH containing zinc is similar to that of ZnO and is not related to the crystal structure of Al 2O 3. It is not a simple combination of zinc oxide and aluminium oxide but a calcined layered double hydroxide in which part of the Zn 2+ cations is replaced by Al 3+ cations.
文摘Solutions of Mg(NO3)2·6H2O, Al(NO3)3·9H2O, NaOH and Na2CO3 were mixed in a rotating liquid memb rane reactor. The crystal growth process of Mg Al CO3 hydrotalcite was then studied by adding different amounts of water to the resulting slurry during the crystallizing process. The initial 6 hours of the crystallization was found to be the key period controlling crystal growth. Adding 150 to 250mL of water to the reaction system at the beginning of crystallization affords Mg Al CO3 hydrotalcite with relatively small particle size and large aspect ratio.
