Evaluation of the Sorbent Properties of Single‐ and Multiwalled Carbon Nanotubes for Volatile Organic Compounds through Thermal Desorption–Gas Chromatography/Mass Spectrometry

Abstract

Carbon nanotubes (CNTs) possess well‐defined structural and chemical characteristics coupled with a large surface area that makes them ideal as sorbent materials for applications where adsorption processes are required. The adsorption properties of carboxylated derivatives of multiwalled carbon nanotubes (COOH‐MWCNT) and singlewalled carbon nanotubes (COOH‐SWCNT), together with their nonfunctionalized counterparts (MWCNT and SWCNT) for 48 common atmospheric volatile organic compounds (VOCs) were determined using thermal desorption–gas chromatography/mass spectrometry (TD‐GCMS). The CNTs exhibited similar recoveries for many of the VOCs compared to the standard sorbent materials, Carbopack X and Tenax TA. However, VOCs with electron donor–acceptor (EDA) properties such as carbonyls, alkenes, and alcohols exhibited poorer recoveries on all CNTs compared to Carbopack X and Tenax TA. The poor recoveries of VOCs from the CNTs has important implications for the long term use and storage of CNTs, because it demonstrates that they will become progressively more contaminated with common atmospheric VOCs, therefore potentially affecting their surface‐based properties.

Active and passive adsorption of 47 trace atmospheric volatile organic compounds onto carbon nanotubes

“…VOCs that were found in the Carbopack X/Tenax multisorbent tube but not in the SWCNT sorbent tube are isopropyl alcohol, isoprene, benzene, nonanal, octanal, hexanal, methyl isobutyl ketone and acetophenone. The results from sampling agree with the functional group trends observed previously during the loading of the VOC standards onto the CNT materials, 24 except for benzene and 1,2,4-trimethylbenzene. The discrepancies between the benzene ratios in sample tubes and in VOC standards tubes were deemed to be an artifact interference error.…”

“…Thermogravimetric analysis (TGA), Raman spectroscopy and inductively coupled plasma-mass spectrometry (ICP-MS) characterisation of the CNTs have been reported previously. 24 VOC standards used for the analysis were obtained from Sigma-Aldrich (St Louis, USA), Merck (Hohenbrunn, Germany), Alfa Aesar (Heysham, Lancaster, UK) and Fluka (Buchs, Switzerland) with purities not less than 97%, except for the following compounds: 1,2,3-trimethylbenzene (93.9%) from Fluka and methacrolein (95%) from Sigma-Aldrich. The neat chemicals were diluted with the appropriate amount of methanol (Schedelco, Malaysia) to prepare (by serial dilutions) VOC standards solution for analysis.…”

“…Several studies have also shown that CNTs are excellent sorbents for organic species, and have been used in solid phase extraction, chromatographic analysis, and sensor development, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] although to the best of our knowledge there are few reports that examine adsorption of volatile organic compounds (VOCs) at their trace atmospheric level (ppb (v/v)). [24][25][26] This leads to concerns whether gaseous VOCs that are naturally present in the atmosphere could spontaneously be introduced into the CNTs during their storage and transportation, thereby affecting their desirable surface features as well as inuencing their toxicological properties. Adsorbed VOCs can potentially become involved in chemical reactions, generating unwanted side products, affecting reaction rates, or acquiring false positives or inaccurate data for CNTs when used in other applications.…”

Dynamic and static removal of benzene from air based on task-specific ionic liquid coated on MWCNTs by sorbent tube-headspace solid-phase extraction procedure

“…Also, the leukemia can be seen in human exposure to benzene (Smaelnejad et al 2015). Due to benzene toxicity in human health, some of variable methods including adsorption (Smaelnejad et al 2015;Lashaki et al 2016;Gomez et al 2016;Gou and Bahrami Yarahmadi 2019;Ncube et al 2017;Jamshidzadeh and Shirkhanloo 2019;Bagheri Hosseinabadi et al 2019), photo-catalytic oxidation (Palau et al 2012;Weon and Choi 2016;Boulamanti and Philippopoulos 2008;Shang et al 2002), thermal oxidation and bio filtration (Wong et al 2015;Mohamed et al 2016) were used for removal of VOC's or BTEX from air. Among them, the adsorption process based on carbon sorbents (CNTs, NG, NGO) was used to remove VOCs from air.…”

Coal Temperature Variation Mechanism during Gas Desorption Process

“…A large number of studies showed that the coal temperature is closely related to coal gas desorption. e higher the temperature, the larger the desorption rate [1][2][3][4][5][6][7][8][9][10][11]. Temperature changes during gas adsorption and desorption were tested using a gas outburst simulator [12,13].…”