Effect of organosilane/polymer ratio on adsorption properties of periodic mesoporous ethane-silica

Oxide-Clay Mineral as Photoactive Material for Dye Discoloration

Titanium and zirconium oxides (TiO2 and ZrO2, respectively) were obtained from alkoxides hydrolyses, and then deposited into palygorskite clay mineral (Pal) to obtain new materials for photocatalytic applications. The obtained materials were characterized by structural, morphological, and textural techniques. X-ray diffraction (XRD) results confirmed the characteristic peaks of oxides and clay transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of the modified palygorskite with both oxides showed that the clay was successfully modified by the proposed method. The increase in the specific surface area of the clay occurred when TiO2 and ZrO2 were deposited on the surface. The photocatalytic activity of these materials was investigated using the Remazol Blue anion dye under UV light. The evaluated systems presented high photocatalytic activity, reaching approximately 98% of dye discoloration under light. Thus, TiO2–Pal and ZrO2–TiO2–Pal are promising clay mineral-based photocatalysts.

Effects of Hydrothermal Treatment and Template Removal on the Adsorption and Structural Properties of SBA-16 Mesoporous Silica

The evolution of the adsorption and structural properties of large-pore SBA-16 silica samples was studied in relation to hydrothermal treatment and template removal procedures. These samples were synthesized using the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer Pluronic F127 as the structure-directing agent and tetraethyl orthosilicate as the silica source in the presence of hydrochloric acid (low concentration) and sodium chloride under various hydrothermal treatment conditions. The concomitant use of the recently reported two-step template removal procedure, which combines solvent extraction and low-temperature calcination, afforded the SBA-16 samples with large pore volumes, high surface areas, uniform cages and uniform cage openings as demonstrated by nitrogen and argon adsorption isotherms measured at −196°C. Small-angle X-ray diffraction spectra confirmed the existence of the Im3m symmetry group (body-centred cubic pore structure) for the samples studied. The efficiency of the aforementioned template removal method was confirmed via thermogravimetric analysis.

Periodic Mesoporous Organosilica Nanocubes with Ultrahigh Surface Areas for Efficient CO₂ Adsorption

Ultrahigh surface area single-crystals of periodic mesoporous organosilica (PMOs) with uniform cubic or truncated-cubic morphology and organic/inorganic components homogeneously distributed over the whole frameworks have successfully been prepared by a sol-gel surfactant-templating method. By tuning the porous feature and polymerization degree, the surface areas of the obtained PMO nanocubes can reach as high as 2370 m²/g, which is the highest for silica-based mesoporous materials. The ultrahigh surface area of the obtained PMO single crystals is mainly resulted from abundant micropores in the mesoporous frameworks. Furthermore, the diameter of the nanocubes can also be well controlled from 150 to 600 nm. The materials show ultrahigh CO₂ adsorption capacity (up to 1.42 mmol/g at 273 K) which is much higher than other porous silica materials and comparable to some carbonaceous materials. The adsorption of CO₂ into the PMO nanocubes is mainly in physical interaction, therefore the adsorption-desorption process is highly reversible and the adsorption capacity is much dependent on the surface area of the materials. Moreover, the selectivity is also very high (~11 times to N₂) towards CO₂ adsorption.

Hybrid periodic mesoporous organosilica designed to improve the properties of immobilized enzymes

Hybrid organosilica supports synthesized with pore size adjusted to enzyme dimensions provide high stability in organic solvent systems and prevent leaching.

Toward tunable adsorption properties, structure, and crystallinity of titania obtained by block copolymer and scaffold-assisted templating

Nanostructured titania and composite titania materials were synthesized for the first time by a one-pot strategy in an aqueous solution containing Pluronic P123 block copolymer and suitable precursors. The strategy can be considered as more facile, environmentally friendly, and less expensive as compared to the existing ones that require use of organic solvents. In the case of composites, silica and alumina particles were used as a structure protecting scaffold and composite components. This synthesis strategy allowed tuning of adsorption and structural properties of the resulting materials; namely, the specific surface area was varied from 84 to 250 m(2) g(-1), total pore volume from 0.11 to 0.46 cm(3) g(-1), and the pore width from 5.6 to 11.2 nm. All samples studied but one showed exclusively anatase phase, and the composites obtained with silica scaffold showed tunable degree of crystallinity. The proposed approach to tailoring the surface and structure properties of titania is especially important for the development of high performance materials for photocatalysis, lithium-based batteries, and dye-sensitized solar cells.