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In summary, strategies to control the size and morphology of ZIF-8 crystals
through hydrothermal synthesis were presented in this thesis. In general, this
was done by systematically tuning the compositional and process parameters
through variation of synthesis parameters and addition of various surfactants.
Increasing the molar ratio of Hmim/Zn2+ can decrease the particle size,
while decreasing the concentration of reagents can increase the particle size
from nm to ?m and change the particle morphology from sphere to rhombic
dodecahedron. However, reaction temperature and time has little effect on the
growth of granular properties of final products, because the formation of ZIF-8
materials in aqueous solutions is a very rapid process.
While the type of zinc salts used as a reagent has no apparent effect on the
mean particle size and morphology of the resulting ZIF-8 crystals, products
prepared using zinc chloride or zinc acetate dihydrate as the zinc source will
have narrower particle size distribution compared to products prepared using
zinc nitrate hexahydrate.
Adding a very small amount of surfactant can effectively decrease the
particle size from ?m to nm and change the morphology from rhombic
dodecahedron to truncated cube. Upon examining different kinds of cationic and
anionic surfactants, it is concluded that this phenomenon is due to the long
hydrophobic hydrocarbon chain of surfactants, which can adsorb on the

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