Effect of Silica Alumina Ratio and Thermal Treatment of Beta Zeolites on the Adsorption of Toluene from Aqueous Solutions

Abstract

Abstract:The adsorption of toluene from aqueous solutions onto hydrophobic zeolites was studied by combining chromatographic, thermal and structural techniques. Three beta zeolites (notated BEAs, since they belong to BEA framework type), with different SiO 2 /Al 2 O 3 ratios (i.e., 25, 38 and 360), before and after calcination, were tested as adsorbents of toluene from aqueous media. This was performed by measuring the adsorbed quantities of toluene onto zeolites in a wide concentration range of solute. The adsorption data were fitted with isotherms whose models are based on surface heterogeneity of the adsorbent, according to the defective structure of beta zeolites. The thermal treatment considerably increases the adsorption of toluene, in the low concentration range, on all BEAs, probably due to surface and structural modifications induced by calcination. Among the calcined BEAs, the most hydrophobic zeolite (i.e., that with SiO 2 /Al 2 O 3 ratio of 360) showed the highest binding constant, probably due to its high affinity for an organophilic solute such as toluene. The high sorption capacity was confirmed by thermogravimetric analyses on BEAs, before and after saturation with toluene.

Insights into Adsorption of Chlorobenzene in High Silica MFI and FAU Zeolites Gained from Chromatographic and Diffractometric Techniques

“…Actually, the physical method based on adsorption processes is a recuperative method exploited for in situ water treatments which combines high flexibility of the system, efficiency even at low concentration levels, low energy, cheap operating costs, and possible waste reductions [3]. Different adsorbent materials can be employed, and their efficiency depends on the host-guest interactions between sorbent and sorbate [4][5][6][7][8][9][10][11][12][13]. In general, carbonaceous adsorbents are low cost materials, widely employed in remediation technology.…”

“…This work is part of a wider study aimed at systematically evaluating the adsorptive capacity of high silica zeolites (HSZ) (e.g., mordenite, ZSM-5, faujasite, beta, ferrierite [4,7,10,29,30]) for fuel-based compounds differing in chemical properties (e.g., polarity, functional groups, size, host-guest interactions, etc. ), which can provide useful information to accurately predict the behavior of HSZs as well as improve their individual performance.…”

“…The main advantages are related to their high surface area and porous structure, high specific capacity and organic pollutants selectivity. Additionally, fast kinetics, mechanical, biological and chemical stability make them promising and efficient adsorbents [4,[6][7][8][26][27][28]. Furthermore, their high thermal stability guarantees the possibility of regeneration through thermal treatments in order to reintroduce them in new adsorption processes [5,[29][30][31][32][33].…”

Study of adsorption of selected organic species from aqueous solution on nh4be ta zeolite

“…Values of molar ratio SiO 2 /Al 2 O 3 are the data showing acidity of the surface of aluminosilicate and for NH 4 BETA it amounts to 25.00, which shows a bigger acidity of the surface of this zeolite compared to Y or 4A zeolite. BETA zeolites possess active centers of different intensity as regards Lewis and Brönsted acidity (Bodroza et al, 2015;Peulić D., 2018;Sarti et al, 2017;Sladojevic et al, 2016;Tomizawa T., et al, 2008;). Adsorption capabilities of NH 4 BETA zeolites for selected organic adsorbates, EDTA and H 2 C 2 O 4 , were examined exactly for that purpose.…”

Editorial for Special Issue “New Insights in Stability, Structure and Properties of Porous Materials”

“…In this issue, the Sarti et al [11] contribution is dedicated to this topic and is focused on the adsorption of toluene from aqueous solutions onto hydrophobic beta zeolites by combining chromatographic, thermal, and structural techniques. This work highlights the differences in adsorption properties…”