Mi Mi Wan

Facile template-free synthesis of porous g-C3N4 with high photocatalytic performance under visible light

Porous g-C3N4 was synthesized by a facile template-free method to control the reaction of polymer according to Le Chateliers principle. The resulting porous g-C3N4 material has high Brunauer–Emmett–Teller (BET) surface area (201–209 m2 g−1) and large pore volume (0.50–0.52 m3 g−1), and shows a ten times enhanced photocatalytic activity for methyl orange (MO) photodegradation under visible light (λ > 420 nm) irradiation.

Fabrication of a new MgO/C sorbent for CO2 capture at elevated temperature

A synergistic effect between a self-dispersion of MgO and biomass-derived carbon in the adsorption of CO2 is reported for the first time. Magnesia and carbon mixed particles are formed in situ during the carbonization of magnesium acetate on activated carbon made from coconut, increasing the accessibility of basic sites for CO2 adsorption. With these complementary effects of the hierarchical structural support, the composite containing 20% magnesia can trap 5 times more CO2 than 20% MgO/SiO2, in the harsh instantaneous adsorption of CO2 at 100 and 150 °C, offering a new candidate for the adsorption of CO2 in flue gas vents.

Novel CO2-capture derived from the basic ionic liquids orientated on mesoporous materials.

Two new basic ionic liquids (ILs) are designed and synthesized in order to conquer the challenge arising from the capture of CO2 in flue gas whose temperature is over 373 K, and they possess a suitable basic strength to adsorb CO2 at 393 K with the capacity of 22-49 mg g(-1). After these ILs are immobilized on mesoporous alumina or silica, equimolar CO2 capture is realized at 393 K for the first time. Besides, these adsorbents can be regenerated at 443 K to form a feasible cycle for controlling CO2 emission in flue gas. Theoretical calculations indicated the key role played by the mesoporous support in promoting CO2 adsorption via electrostatic interactions between support and ILs. An unwonted promotion of the supports ζ-potential on the performance of ILs is revealed, which induces the immobilized ILs to be oriented in a favorable dispersion, enhancing the efficiency of ILs in the CO2 adsorption at elevated temperature. This study proposes a new strategy for the sustainable development of novel adsorbent.

Sustained Release of Heparin on Enlarged-Pore and Functionalized MCM-41

Mesoporous silica MCM-41 and SBA-15 were chosen to study the adsorption and release of bulky biomolecule heparin, in order to develop new heparin controlled delivery system and expand the application of mesoporous materials in life science. To explore how the structure of support such as pore size and surface state affects the accommodation and release of heparin, we used decane as swelling agent to enlarge pores of MCM-41, introduced amino groups for improving the biocompatibility of support, and controllably retained templates in the as-synthesized sample. The influence of modification on the structure of samples was investigated by XRD and N(2) adsorption-desorption, whereas their performance of adsorbing and releasing heparin was assessed with that of toluidine blue method. Both enlarged pore and organic modification significantly promoted the adsorption and prolonged the release of heparin in MCM-41, and the release was characterized with a three-stage release model. The mechanism of heparin release from mesoporous material was studied by fitting the release profiles to the theoretical equation. As expected, some mesoporous composites could release heparin in the long term with tuned dosage.

A novel porous MgO sorbent fabricated through carbon insertion

A new strategy utilizing carbon insertion to synthesize a highly efficient CO2-capturer through self-dispersion of MgO by co-existing carbon is reported in this paper. Carbon-adulterated magnesia is formed in situ during the carbonization of magnesium acetate for the first time, suppressing the aggregation of MgO nanoparticles and increasing the accessibility of basic sites for CO2. With few carbon particles (about 2%) inside as the adulterant, the porous MgO composites have a surface area of greater than 200 m2 g−1 and a high CO2 adsorption capacity of up to 28 mg g−1 at 473 K, offering a new candidate material for adsorbing CO2 in flue gas vents.

Novel phenol capturer derived from the as-synthesized MCM-41

Novel phenol-capturer was prepared by modifying the as-synthesized mesoporous silica MCM-41 with tetraethylenepentamine (TEPA), not only saving the energy and time for removal of template, but also opening the way to utilize the micelles for adsorption. Once the organic modifier was distributed in the template micelle of MCM-41 to form a web within the mesoporous channel, the composite could adsorb more phenols in gas stream than activated carbon for the first time. With an unwanted high adsorption capacity, this mesoporous silica-amine composite represented potential application for trapping phenols, especially in tobacco smoke to protect environment.

Promoting immobilization and catalytic activity of horseradish peroxidase on mesoporous silica through template micelles

New concept on the promotion of immobilization and catalytic activity of enzyme on mesoporous silica through template micelles is proposed and realized in this paper. Proper P123 templates are controllable retained in the as-synthesized SBA-15, not only to anchor the horseradish peroxidase (HRP) guest, but also to establish the crowding-like microenvironment around the enzyme. The influence of retaining templates on the pore structure of SBA-15, immobilization, and catalytic activity of HRP is studied, and the possible process of template removal is proposed. Ethanol refluxing of 6 h is conformable to prepare the optimal mesoporous support characterized with the retained templates of about 8%. With the assistance of retained templates in SBA-15, up to 49 mg g(-1) of HRP can be immobilized, 100% more than that on calcined SBA-15. Furthermore, the thermal stability, the resistance of pH variation and denaturing agent urea, and the recycle usage of HRP immobilized are obviously elevated, paving a novel and low-cost route to develop enzyme catalysts.

One-pot synthesis of a hierarchical PMO monolith with superior performance in enzyme immobilization

A novel hierarchical periodic mesoporous organosilica (PMO) monolith is synthesized by using N,S-bis[3-(triethoxysilyl)propyl]-carbamothioic acid for the first time, in order to fabricate a highly efficient enzyme immobilizer. The hierarchical monolith is spontaneously formed with mild shearing force without further additives, in which the primary particles can be selectively prepared to be inter-connected with each other end to end to form a net-like framework throughout the whole monolith, and the inorganic/organic composition is finely controlled by adjusting the initial composition of the silica precursors. As the result, an ordered net framework with micrometer sized macropores and large mesopores is simultaneously obtained together with a high organic content, favoring high enzyme immobilization, in which they demonstrate an enhanced adsorption capacity, superior immobilization stability and good reusability. Especially, the PMO monolith can adsorb 126 mg g-1 of horseradish peroxidase (HRP), higher than double that of the power-like analogue (38 mg g-1); and the bioactivity is three times higher than that of the free enzyme, indicating the strong advantages of morphology assistance in enzyme immobilization.

Novel selective adsorbent derived from hierarchical rockery-like MCM-41 monolith

The design and preparation of a new “self-protected” mesoporous adsorbent is reported for the first time, in order to selectively adsorb tobacco specific nitrosamine (TSNA) carcinogens in environmental tobacco smoke (ETS). Hierarchical rockery-like MCM-41 monoliths with the tunable hollow structure and macropores are synthesized under special conditions by controlling the formation and connection of primary particles: through self-assembly and flow induced orientation, the initial formed prism-like primary particles are compelled to form circular disc- or ellipse-like secondary structures, and these domains connect together to form flats that are linked by small flats to yield units on millimeter scale, finally these units are randomly crooked to generate monoliths at centimeter level. These monolithic materials have similar textural properties, surface state and the same primary particles as common MCM-41, but they exhibit unique selectivity in the capture of TSNA in cigarette smoke. They also avoid unnecessary trapping of accompanying particles, which is realized for the first time because of the morphology-induced new function, opening a new way to create superior selectivity in complicated adsorption processes, where the target is adhered on the particles in a gas stream.

Multiple functionalization of SBA-15 mesoporous silica in one-pot: fabricating an aluminum-containing plugged composite for sustained heparin release

To fabricate an efficient releaser of heparin, which is an extensively used anticoagulant, aluminum containing plugged mesoporous silica SBA-15 is prepared using a one-pot synthesis process. A suitable aluminum additive in the starting mixture enables plugs to be formed inside hexagonal channels and Al species to be incorporated into the mesostructure, evidence for which is provided by powder X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), N2 sorption measurements and 27Al MAS NMR tests. Incorporation of aluminum in SBA-15 reduces the negative charge (Zeta-potential) and tailors the surface roughness of the channel through forming plugs, and the former significantly improves heparin adsorption while the latter retards heparin release. As a result, these modified composites adsorb 2-4 times more heparin than parent SBA-15 and release 60-130% more of the drug over several weeks; the sample possessing both an Al-component and plug structure can sustain release of heparin for 6 weeks, demonstrating the increased efficiency of multiply functionalized SBA-15 in the controllable release of heparin and offering a valuable clue for design of novel drug releasers.