Ting Ting Zhuang

Directly transforming as-synthesized MCM-41 to mesoporous MFI zeolite

Mesoporous MFI zeolite is fabricated through impregnating a structure-directing agent into as-synthesized MCM-41 followed by dry-gel conversion to transform amorphous silica to zeolite crystal. The original surfactant in the as-synthesized MCM-41 is used as the necessary mesoporogen to direct the mesopore genesis of zeolites, using the process of streaming to spur the transformation and tailoring the texture of mesoporous ZSM-5 by adjusting the Si : Al ratio in the MCM-41 source. The resulting sample is characterized by X-ray diffraction, IR spectroscopy, TEM and N2 adsorption to evaluate the textural properties of the mesoporous zeolite. Two kinds of nitrosamines with different structures are used as probe molecules to survey the adsorption function of the resulting mesoporous zeolite. Mesoporous zeolites exhibit good adsorption capacities and exceed either microporous zeolite or mesoporous silica. This synthesis strategy omits the fabrication and removal of the carbon template and simplifies the synthesis process of mesoporous zeolites, saving energy and time.

Solvent-free surface functionalized SBA-15 as a versatile trap of nitrosamines

Dispersion of copper oxide via a solvent-free method enables mesoporous silica SBA-15 to become a versatile trap of nitrosamines, exhibiting a high capability to capture volatile nitrosamines and tobacco special nitrosamines (TSNA). 3%CuO/SBA-15 can remove 85% of N-nitrosopyrrolidine (NPYR) in gaseous flow, one fifth more than that by the analogous via one-pot method, while 5%CuO/SBA-15 traps all N-nitrosonornicotine (NNN) in solution with a concentration of 0.6 mmol l−1, superior to NaY zeolite. The dispersion of the copper guest in SBA-15 is assessed by XRD, H2-TPR, NO2-TPD and UV-Vis methods.

Eliminating carcinogenic pollutants in environment: Reducing the tobacco specific nitrosamines level of smoke by zeolite-like calcosilicate

Trapping carcinogens such as tobacco-specific nitrosamines (TSNA) in environmental tobacco smoke (ETS) is a challenge for the application of zeolite in environment protection because most TSNA exist in the particles whose size exceed the micropores of zeolites. In this paper, a new strategy to intercept the particles and to trap the TSNA in smoke by use of the porous calcosilicate material with fiber-like morphology plus two-dimensional eight-ring channel system is depicted and assessed. Owing to the specific fiber-like morphology and chemical composition, zeolite-like calcosilicate CAS-1 can effectively intercept the particles and thus reduces the TSNA level of mainstream smoke in the range of 30-60% once it is added into the cigarette filter, which is superior to zeolite NaA additive with the same amount. Moreover, the importance of morphology of zeolite-like porous materials on the adsorption of nitrosamines in smoke is reported for the first time.

Adsorption of nitrogen oxides by the moisture-saturated zeolites in gas stream.

This investigation examined the instantaneous adsorption of NO(x) by moisture-saturated zeolites at ambient temperature. Among the zeolites studied, Faujasite exhibited the highest adsorption capacity owing to its relatively large pore size. Besides, the influence of cation was demonstrated by comparing the adsorption of zeolites with different cation densities (NaX vs. NaY, mesoporous silica MCM-48-like vs. Faujasite) and treatments (ion exchange of NaY with Cu(2+)). For the adsorption of NO, the effects of gas flow rates and pre-adsorbed hydrocarbons such as benzene, acetaldehyde or 1,3-butadiene were evaluated. It was proven that zeolite could efficiently capture nitrogen oxides in gas stream even it had been saturated by moisture, which will be valuable for the protection of environment and public health.

New efficient Al-containing SBA-15 materials for removing nitrosamines in mild conditions

SBA-15 was modified by incoporating acidic zeolite fragments or plugging, and showed a significantly enhanced efficiency for the removal of nitrosamines in mild conditions. The impact of pore structure and acidicity of mesoporous materials on their adsorptive feature is examined, in comparison with those coated with copper oxide, in order to prepare new functional materials for environment protection.

New development in nanoporous composites: novel functional materials for capturing nitrosamines in airstreams

The latest progresses of the series of research on the trapper of nitrosamines are reported in this paper, involving the attempts to elevate the selective adsorption of zeolites through enhancing adsorbent-adsorbate interaction, in order to prepare the new functional nanoporous materials with high efficiency to eliminate the carcinogenic pollutants in environment and to protect public health. Incorporation of metal oxide such as copper oxide in NaY accelerated adsorption of volatile nitrosamines and anthracene, and moreover, coating zirconia onto the zeolite could dramatically suppress the release of nitrogen oxides in the decomposition of N-nitrosopyrrolidine (NPYR) during temperature-programmed surface reaction (TPSR) process.

Generating selective adsorptive sites on activated carbon

Micro-control of activated carbon surface by metal oxides was performed, in order to eliminate nitrosamines in environment, especially in cigarette smoke for the first time. Coating alumina and zinc oxide can promote the adsorption of nitrosamines in activated carbon, opening new avenues to generating selective adsorption sites on amorphous material through the modification on the polarity of surface.

Investigation on the adsorption of nitrosamines in zeolites

The function of zeolites as the capturer of nitrosamines is depicted in this paper. N -nitrosodimethylamine (NDMA) and N -nitrosopyrrolidine (NPYR) can be selectively adsorbed by zeolite NaY or NaZSM-5 in solution or gaseous phase. The adsorption capacity of zeolite is discussed in terms of adsorbate-adsorbent interaction, involving their pore structure and electrostatic attraction along with the impact of adsorption temperature. In addition, one of the tobacco specific nitrosamines, N′ -nitrosonornicotine (NNN), is also employed as a probe to explore how the bulky nitrosamines are adsorbed by zeolites. The especial function of adsorption enables zeolites to be utilized for removal of nitrosamines in environment.