Comparison of Adsorbents Containing Carbon Nanotubes for Express Pre-Concentration of Volatile Organic Compounds from the Air Flow

Abstract

New composite adsorbents including silica supports (silica, aerosilogel, and diatomite) and carbon materials (multiwall carbon nanotubes and pyrolytic carbon) have been prepared and characterized. The analytical capabilities of the produced sorbents have been evaluated by their efficiency in the express pre-concentration of volatile organic compounds (butanol and phenols) from the air stream. The prepared surface-layered adsorbents containing multiwall carbon nanotubes placed onto the surface of aerosilogel by use of the carbon vapor deposition method with preloading cobalt nanostructures as a catalyst were found significantly more efficient than traditionally used graphitic carbon-based adsorbents Carbopacks B, C, and X. Additionally, a new adsorbent composed of diatomite Porochrome-3 support coated with a pyrocarbon layer was prepared. This low surface area composited adsorbent allowed both quantitative pre-concentration of phenol and isomeric cresols from the air and their thermal desorption. The developed adsorbents provided fast pre-concentration of selected phenols with a concentration factor of 2 × 103 in 5 min and were used for gas chromatographic determination of analytes in the air at low concentration levels starting from several μg/m3 with a flame ionization detector.

Composites Based on CaCl2-CaBr2 Salt System for Adsorption Applications: Designing the Optimal Sorbent for Gas Drying and Air Conditioning

“…Indeed, very often, composite materials demonstrate more impressive results than nonmodified traditional sorbents. The modified sorbents demonstrate affinity to both organic [12][13][14] and inorganic [15,16] compounds/pollutants. The composites materials "Salt inside a porous matrix" (CSPM) are characterised by a high sorption ability (0.4-1.4 g/g) caused by the reaction of salt confined into matrix pores with water, methanol or ammonia [17][18][19].…”

Preconcentration of Volatile Organic Compounds on Carbon Magnetic Sorbents in the Analysis of Air by Using the Configuration Change of the Sorbent Bed during the Transition from Sorption to Thermodesorption GC-FID

“…Particles of these materials that are too fine prevent their direct use for the preconcentration of trace impurities in the analysis of air due to the low permeability of the sorption layer in the tube [17]. The possible solution to this problem is using adsorbents in which the nanocarbon particles are immobilized on the surface of the solid phase carriers, such as porous polytetrafluoroethylene [18,19] or silica [20][21][22][23]. Another option is using aggregated or sintered nanocarbon particles such as microdispersed sintered nanodiamonds [24].…”