The Effect of Temperature and Time of the Hydrothermal Treatment in the SBA-15 Synthesis Process on the Structure and Textural Properties and the Ability to Reduce the Evolution of Tars in Tobacco Smoking

Abstract

Different SBA-15 (SBA, Santa Barbara Amorphous) materials were synthetized at different temperature and time during of the hydrothermal treatment. The obtained SBA-15 were characterized by N2 adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (DRX), and density in order to establish the influence of these variables on their properties. Mixtures of the obtained catalysts with 3R4F tobacco were prepared and smoked under the ISO 3308 conditions. Temperature of the hydrothermal treatment slightly affects the tars that evolved in the smoking process of the corresponding catalyst tobacco mixtures. Contrarily, the time of the hydrothermal treatment has a marked effect on the reductions of toxic compounds in the smoke. Developed porosity has a positive correlation with the observed tar reduction, whereas the apparent density has a negative correlation with the reduction in toxicity. Moreover, the removal of the supernatant liquors during the hydrothermal treatment does not strongly modify the properties of the materials and may represent an interesting simplification of the process.

Effect of Time, Temperature and Stirring Rate Used in the First Step of the Synthesis of SBA-15 on Its Application as Reductor of Tars in Tobacco Smoke

“…The smoking experiments were developed following the methodology used in previous works, and the analysis of the results obtained were analyzed and presented in a similar way [32,45]. The reductions were calculated as the amount of a given compound or family of compounds obtained in the smoke when smoking the reference tobacco (without the catalyst), minus the amount obtained when smoking in the presence of the catalyst, divided by the amount obtained without the catalyst, expressed as a percentage.…”

“…The SBA-15 materials were prepared with TEOS (tetraethyl orthosilicate) as a silica source using the method described by Zhao et al [45] and modified by Juárez-Serrano et al [32]. In the first step of the synthesis (precipitation), a solution of 65.63 mL of HCl 1.6 M (using HCl 11.32 M, from Merck) was prepared to dissolve 1.75 g of Pluronic P123 surfactant (triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer, from Sigma-Aldrich, Schnelldorf, Germany).…”

“…After 1 h, 3.67 g of TEOS, tetraethyl orthosilicate (from Sigma-Aldrich) was added to the mixture and maintained under the selected time, temperature, and stirring rate conditions. The hydrothermal treatment was run according to the modification described in [32], i.e., the precipitate was filtered, resuspended in 1/3 of the mother liquor in order to reduce the volume of the container, then transferred to closed bottles and kept at 80 • C during 24 h under static conditions. In that reference, it was shown that this treatment was as efficient as the one described by Zhao et al in their original paper [45], both to develop the SBA-15 structure and properties and to reduce the toxicants in the smoking application.…”

“…Nevertheless, there are very few works studying the effect of the SBA-15 synthesis variables on the reduction of tobacco smoke toxicants. In a previous paper [32], we reported the effect of time, temperature, and the amount of supernatant liquor in the hydrothermal SBA-15 treatment on the properties of the material synthesized as well as the effect on the tobacco toxicity reduction. In order to provide more insight on the effect of the SBA-15 synthesis variables on its effect as a tobacco toxicant reducer, the objective of the present paper is analyzing the influence of the time and the stirring rate during the initial SBA-15 precipitation stage prior to the hydrothermal treatment.…”

Effect of Reaction Time and Hydrothermal Treatment Time on the Textural Properties of SBA-15 Synthesized Using Sodium Silicate as a Silica Source and Its Efficiency for Reducing Tobacco Smoke Toxicity

“…In previous works [41,42], we have reported the effect of different variables such as temperature, time or stirring rate at different steps of the synthesis using TEOS as a precursor. The objective of the present work was to synthetize SBA-15 materials using sodium silicate as silica source (an easier handling and lower cost reactant as compared to TEOS) at different hydrothermal treatment and reaction times.…”