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

Abstract

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 21 , superior to NaY zeolite. The dispersion of the copper guest in SBA-15 is assessed by XRD, H 2 -TPR, NO 2 -TPD and UV-Vis methods.

Multiple Functionalization of Mesoporous Silica in One‐Pot: Direct Synthesis of Aluminum‐Containing Plugged SBA‐15 from Aqueous Nitrate Solutions

“…[67,68] Copper-containing zeolites are well known in environmental protection to selectively adsorb nitrogen oxides, [68,69] and the incorporation of copper in mesoporous SBA-15 can improve the adsorption of NO 2 . [70] As such, TPSR of NPYR have been performed on the xCu1Si samples to evaluate their actual catalytic properties. Figure S5 and Table 4 describe the catalytic behavior of xCr1Si samples in the TPSR test of NPYR.…”

“…As the copper content increases from trace to 0.18 wt % in the xCu1Si samples, their catalytic activity tardily increases and the amount of NO x determined during the TPSR process is enhanced from 28 to 41 lmol g -1 , which indicates the catalytic function of copper in the degradation of volatile nitrosamines. [59,70] Nontheless, the highest catalytic efficiency emerges for the 3Cu1Si sample because it only has a trace amount of copper. The structural features of 3Cu1Si are another factor that account for its high catalytic function; the imperfect condensation of the silica skeleton results in a reduced order and the existence of plugs and a large amount of micropores in the channels or pore walls, so that a higher catalytic property is acquired.…”

Microwave‐induced degradation of nitrosamines trapped in zeolites

“…[41 -43] Though copper modifier could establish some active sites on amorphous silica, its activity was only slightly enhanced because lack of ordered pore structure in the host made it difficult to anchor the NDPA molecules. On the basis of these results, it is safe to infer that dispersion of metal oxide such as copper oxide on porous materials can promote the microwave-induced degradation of NDPA in solution, probably due to the hot-spot effect [14] ; Likewise, adsorption of NDPA in siliceous materials such as SBA-15 or amorphous silica seems involving a kind of synergy between the surface silanol groups of host and the copper guest [39] so that optimal distribution of copper sites in the porous support is crucial for adsorption of nitrosamines.…”

“…[35] There are plenty of Si-OH on the surface of silica and SBA-15, say, about 4.5-4.6 Si-OH groups per square nanometre on the former and 3.7 Si-OH groups per square nanometre on the latter. [36 -38] Once NDPA molecule enters the channel of SBA-15, it could be anchored by the surface Si-OH, [39] and then degraded by microwave. Surface silanol groups played a crucial role in the adsorption by mesoporous silica because they were able to form hydrogen bond with the N atoms of amino groups and/or the O atom in the nitroso group of nitrosamines.…”

“…Surface silanol groups played a crucial role in the adsorption by mesoporous silica because they were able to form hydrogen bond with the N atoms of amino groups and/or the O atom in the nitroso group of nitrosamines. [39] Dispersion of copper oxide on SBA-15 was at the expense of surface Si-OH for each copper cation reacted with three Si-OH groups, [40] so the MCS1 sample showed similar activity to SBA-15 and the highest performance emerged on the sample of MCS10 (Table 1). Through the comparison of MCSn and CSn sample, the influence of preparation on the copper modification could be seen.…”