Yi Cao

Efficient CO2 Capturer Derived from As-Synthesized MCM-41 Modified with Amine

A new strategy to synthesize a highly efficient CO(2) capturer by incorporating tetraethylenepentamine (TEPA) into as-synthesized MCM-41 (AM) is reported. The amine guest can be distributed in the micelle of the support, forming a web within the mesopore to trap CO(2) molecules and resulting in a high adsorption capacity for CO(2) up to 237 mg g(-1). Four samples of the as-synthesized MCM-41 with a different amount or type of surfactant are employed as supports to investigate the influence of micelles on the CO(2) adsorption, and the spokelike structure of the micelle in the channel of the support is proven to be essential to the distribution of guest amine. Among these supports, the AM sample is the most competitive due to the advantages of energy and time saving in preparation of the support along with the resulting higher CO(2) adsorption capacity. At the optimal loading of 50 wt % TEPA, the AM-50 sample exhibits a high adsorption capacity of 183 mg g(-1) in the sixth adsorption cycle at 5 % CO(2) concentration.

Fabrication of photoluminescent ZnO/SBA-15 through directly dispersing zinc nitrate into the as-prepared mesoporous silica occluded with template

Photoluminescent ZnO/SBA-15 mesoporous materials are prepared by directly grind zinc nitrate into the as-prepared samples occluded with template, and this solvent-free method not only saves time and energy, but also enables a large amount of zinc oxide to be highly dispersed in the channels of mesoporous silica. The resulting composites exhibit photoluminescence (PL) properties with the ZnO quantum confinement, and the dispersed ZnO in SBA-15 illustrates a similar UV emission to crystalline ZnO nanostructures. Besides, this photoluminescence is used to try to detect the nitrosamine content in solution by quenching PL spectra for the first time, suggesting potential applications of ZnO/SBA-15 in sensing carcinogens such as N′-nitrosonornicotine (NNN) in the environment.

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.

Removal of volatile nitrosamines with copper modified zeolites

Copper oxide was used to modify zeolite NaY, NaZSM-5, NaA and mesoporous siliceous SBA-15, in order to strengthen their ability to remove volatile nitrosamines. Selective adsorption, temperature programmed surface reaction (TPSR) and FTIR along with TG-MS methods were employed to study the impact of copper modification on the ability of zeolite to adsorb and catalytically degrade nitrosamines. Due to the special interaction between the –N–NO group of nitrosamines and the copper in the zeolite, nitrosamines can be very easily trapped by the copper modified zeolite, and this precedes or is the first step that leads to the catalytic reaction. Moreover, modification of copper oxide enabled the zeolite to degrade nitrosamines such as N-nitrosopyrrolidine (NPYR) at lower temperatures. It is practical to use the copper modified zeolites to treat mainstream smoke or add them to tobacco, reducing further the levels of nitrosamines in cigarette smoke compared with using the zeolite alone.

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.

Attempts on preparing mesoporous basic material MgO/SBA-15

Abstract Novel porous materials with mesoporous structure and strong basicity were successfully prepared by dispersing MgO on SBA-15 in three different methods, including impregnation, microwave irradiation and their combination, through magnesium acetate path. The efficiency of microwave irradiation was proven to be very high, but it fails to directly disperse magnesia itself on SBA-15, and the lack of ions in surface of carrier was excluded to account for this failure. Aluminiferous SBA-15 had been synthesized and employed as the carrier to support MgO, possessing a higher stability in impregnation to resist the corrosion of magnesium acetate solution and being beneficial for generating more basic sites. Finally the possibility of in situ modifying SBA-15 in its synthesis process was discussed.

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.

Zeolite multifunctional materials as the menthol carrier and nitrosamines trapper

The attempt of utilizing zeolite as the multifunctional additive to carry given guest and to trap nitrosamines in smoke was reported for the first time. After the menthol was adsorbed by zeolite, the composite was added onto tobacco rod. The release of menthol took place when the hot coal of the burning cigarette approached the zeolite. At the same time, the zeolite reduced the nitrosamines level of cigarette smoke. The thermal release of menthol from zeolite was measured by a temperature programmed desorption (TPD) method. Most zeolites studied in this work showed a main desorption peak below 500 K with the exception of NaY, which displayed two desorption peaks around 545 and 650 K. In addition, the zeolite additives reduced about 30% of nitrosamines in the side stream smoke.

Functionalization of silica by in-situ grafting hydrotalcite

A series of bifunctionalized siliceous porous materials were prepared by in-situ grafting hydrotalcite on substrate SiO 2 , and their acid-basic properties have been assessed by use of CO 2 and NH 3 -TPD (temperature programmed desorption). Both stronger basic and acidic sites formed on the modified silica at the same time and the base strength could reach as high as H->+22.5. Yet the amount of acidic and basic sites increased simultaneously. Also, judged from the results of catalytic conversion of isopropanol, grafting hydrotalcite on silica could enhance the acid centers, which promoted the production of propene. The resulting porous composites could selectively adsorb N -nitrosopyrrolidine (NPYR), a typical volatile nitrosamine, and exhibited to be potential candidate as a special absorbent.