Preparation of Layered Double Hydroxide Material and Research Adsorption Capacity
|School||Harbin Engineering University|
|Keywords||LDHs CO2 pressure hydrothermal adsorption|
Layered double hydroxides(LDHs), also well-known as hydrotaleite-like compounds, have been the subject of intense research because of their wide applications as catalysts, catalyst precursors, anion exchangers, acid absorbents, bioactive nanocomposites, photoactive materials, drug delivery, and so on. Although these solids are easily synthesized by coprecipitation, hydrothermal reproducible and inexpensive synthesis procedures are still needed in order to control some of the properties, such as crystallinity, particle-size distribution, and specific surface area. In this sense, new synthetic route that leads to solids of high quality in terms of size uniformity, morphology, and crystallinity need to be found, which are much better than those of solids prepared by the conventional method.The NiAl-LDHs nanoerystallites were synthesized by CO2 pressure method, for the first time. The powers were characterized at the length by XRD, TG-DSC, FT-IR, TEM and SEM. Results show that LDHs nanoerystallites with high crystallinity be successfully prepared by the CO2 pressure method. The effects of the aging temperature, aging time and pressure on crystallization and morphology were also discussed. The results indicate that crystallization becomes to better and the morphology tend to perfect, with increasing the aging time, aging temperature and the power of reaction system, It is found that the molar ratio of high temperature (180℃) can result in impurity easily. In addition, XRD, TEM, FT-IR and N2 adsoiption-desorption technique characterized in detail the thermal stability and the pores distributed of calcination products(LDO).The results show that calcination products(LDO) with porous materials and high specific surface area is prepared by the CO2 pressure method.So far, the synthesis route of the transition metals LDHs possessing high crystallinity and well shapes has not been discovered,which blocks the applications in optical, magnetic, and electronic properties. Basis of the transition metals LDHs, NiFe-LDHs nanoerystallites with pure phase and high crystallinity were synthesized by CO2 pressure method about 5 hours at 150℃. It shows further the superiority of CO2 pressure method.The NiAl-LDHs and calcined NiAl-LDHs by CO2 pressure and hydrothermal method is used for adsorption research of methyl orange pollutant. The results of experiment showed that Ni-Al LDHs prepared by the CO2 pressure possess better adsorption effects by traditional hydrothermal method, because of porous structure and high specific surface area. Due to the structure memory effect of LDHs, the calcined NiAl-LDHs show more effective remove rate for methyl orange pollutant than NiAl-LDHs. In order to obtain the best technological conditions for adsorption methyl orange pollutant, the effects of adsorption time, temperature, addition amount on the removal rate were also investigated.In the final, the absorption research of Ni-Fe LDHs were discussed.