Search

The relationships between the fractal evolution and catalytic behavior of the resultant catalysts were deeply explored via SAXS method and other characterizations. The applicability and reliability of fractal theory are therefore proved.

TiO2-supported clinoptilolite (TiO2/CP) was synthesized in the presence of F− ions. Various characterizations demonstrated that the particle size of loaded TiO2 increased linearly with an increase in the temperature and concentration of F− ions. In particular, the additive F− ions were favored to produce the mutually independent co-exposed {001} and {101} facets of loaded TiO2, while TiO2/CPs synthesized in the absence of F− ions were dominated by the thermodynamically stable {101} facet. As photocatalysts for the removal of crystal violet or methyl orange dyes under UV-irradiation in aqueous solutions, TiO2/CPs (ACP6) synthesized in the presence of F− ions significantly improved the degradation efficiency, as compared to ACP3 obtained in the absence of F− ions. These results elucidated that the highly energetic {001} exposed facet, large particle size and fine dispersion of loaded TiO2 in TiO2/CP accounts for its best photocatalytic performance. The effected mechanism of operational parameters on the degradation performances is proposed.

Nanoprecursors used as a structural promoter (SP) were prepared by a hydrothermal method and named sol-SP. After centrifugation, the supernatant and precipitate were denoted as solution-SP and solid-SP, respectively. The effect of the additive amount on the structures and properties of the synthesized clinoptilolite was investigated using various characterization techniques. The activation energies of crystallization kinetics during induction and growth periods were calculated. The results showed that the induction period is the control step during the synthesis of clinoptilolite, while additive sol-SP or solid-SP was beneficial to shorten the induction period and therefore enhance the formation of the crystal nucleus. When their pre-crystallization time was too long or the additive amount was too much, the impure phase (phillipsite) in the synthesized clinoptilolite was easily generated. Although the addition of solution-SP had no obvious effect on the induction period, it promoted the growth of crystals after nucleation. Finally, the adsorption performances for CO2 and CH4 were preliminarily assessed using synthetic clinoptilolite as the adsorbent, showing the promising application for the separation of CO2/CH4.

Hydrophobic clinoptilolite (CP) was successfully synthesized via a silanization method using methyltriethoxysilane (MTS) or diethoxydimethylsilane (DMTS) as silane coupling agents. The structural and textural properties of the resultant hydrophobic CP were characterized using various methods. The effect of the amount of MTS or DMTS additive on the induction (nucleation) and growth of CP were also investigated, and the apparent activation energy values for induction and growth periods were calculated, suggesting that the induction period is kinetically controlled, while the rapid growth process is thermodynamically controlled. Meanwhile, DMTS modification enhanced the hydrophobicity of CP compared with its MTS-modified counterpart and pure CP. Finally, various ZnO-supported CPs were used as photocatalysts for the removal of crystal violet from aqueous solution, demonstrating that ZnO/hydrophobic CP has the largest adsorption capacity and best removal performance. These results suggest that hydrophobic CP, as an adsorbent or support, has the most potential for applications in separation and catalysis.

Nanoprecursors used as a structural promoter (SP) were prepared by a hydrothermal method and named sol-SP. After centrifugation, the supernatant and precipitate were denoted as solution-SP and solid-SP, respectively. The effect of the additive amount on the structures and properties of the synthesized clinoptilolite was investigated using various characterization techniques. The activation energies of crystallization kinetics during induction and growth periods were calculated. The results showed that the induction period is the control step during the synthesis of clinoptilolite, while additive sol-SP or solid-SP was beneficial to shorten the induction period and therefore enhance the formation of the crystal nucleus. When their pre-crystallization time was too long or the additive amount was too much, the impure phase (phillipsite) in the synthesized clinoptilolite was easily generated. Although the addition of solution-SP had no obvious effect on the induction period, it promoted the growth of crystals after nucleation. Finally, the adsorption performances for CO

TiO