Defining Reactivity of Solid Sorbents: What Is the Most Appropriate Metric?

Abstract

A series of solid sorbent materials, including alumina (Al 2 O 3 ), magnesia (MgO), titania (TiO 2 ), silica (SiO 2 ), and carbon, of widely varying physical properties, have been studied as sorbents for two toxic substances: sulfur dioxide gas (SO 2 ) and chemical warfare surrogate 2-chloroethyl ethyl sulfide (2-CEES, ClCH 2 CH 2 SCH 2 CH 3 ). Sorbent surface areas, average pore sizes, pore volumes, surface hydroxyl groups, and nitrogen adsorption-desorption isotherms were measured. Surface areas varied from 18 m 2 /g to over 1000 m 2 /g, pore volumes from 0.04 to 1.2 cm 3 /g, and pore diameters from 1.7 to 4.9 nm. Breakthrough studies of SO 2 and 2-CEES sorption yielded information about the effectiveness of each sorbent. Carbon samples worked well for 2-CEES but not SO 2 , while silica samples were poor for both. The best MgO and TiO 2 samples were good for both SO 2 and 2-CEES, and overall, the highest surface area (459 m 2 /g) TiO 2 sample was the superior sorbent. The important features for an effective sorbent under the conditions employed are high surface area and high pore volume, possessing isolated surface -OH groups, mesoporous nature, and a polar surface (Lewis base and Lewis acid sites).

Modification of Titanium Dioxide with Graphitic Carbon from Anthracene Thermal Decomposition as a Promising Method for Visible- Active Photocatalysts Preparation

“…A very broad band in the range of 3700-2600 cm -1 characteristic of the O-H stretching mode of interacting hydroxyl groups and the symmetric and asymmetric O-H stretching modes of molecular water coordinated for Ti 4+ ions can be observed for all tested samples (35). A weak band at 3672 cm -1 assigned to stretching mode of different types of free hydroxyl groups is observed in TiO 2 modified with carbon samples (6).…”

The Photocatalytic Performance of Benzene- Modified TiO2 Photocatalysts under UV-vis Light Irradiation

“…In Figure 2 symmetric and asymmetric O-H stretching modes of molecular water coordinated to Ti 4+ ions (54) and the band at 1640-1630 cm -1 is assigned to the molecular water bending mode (55). In all spectra in the ν(OH) region one band with a maximum at 3665-3700 cm −1 , which characterizes the stretching modes of Ti 4+ -OH surface hydroxyl groups was possible to observed.…”

Photocatalytic degradation of acetic acid in the presence of visible light-active TiO 2 -reduced graphene oxide photocatalysts

“…Crystal structures and relative phase compositions of obtained photocatalysts were analyzed using X-ray powder diffraction analysis (X PRO Philips diffractometer) with Cu-K␣ radiation ( = 1.54056 Å). Titania anatase-over-rutile ratio was calculated in a way described previously [20,21]. The standard uncertainties were estimated from fivefold XRD measurements of the same sample.…”