Carbon nanotube sponges as an enrichment material for aromatic volatile organic compounds

•A porous carbon nanotube sponge was developed as a preconcentrator.•The sponge showed a high adsorption capacity and rapid thermal desorption.•Good enrichment enabled trace detection (ppb) of aromatic volatile organic compounds.•Breakthrough curves for multicomponent mixtures showed displacement effects.•Adsorption kinetic and isotherm models were fitted to the experimental data. Sensitive methods are required for in situ monitoring of volatile organic compounds (VOCs). Herein, carbon nanotube (CNT) sponges were investigated as a new type of adsorbent for enriching trace aromatic VOCs. A square pillar configuration (3 mm × 3 mm × 45 mm, 5 mg) of a CNT sponge was enclosed in a glass tube (4 mm i.d.). After accumulating the sample vapor, a direct current pulse (26 V, 0.5–3.0 s) through the CNT sponge allowed narrow desorption bandwidths of 0.48−0.84 s (with a photoionization detector) and 1.2 s (with a flame ionization detector) and high desorption efficiency (>96.5%). Gas chromatographic analysis of a nine-component VOC mixture (100 mL adsorption volume) gave enrichment factors of 88 (benzene) to 323 (toluene and m-xylene) with detection limits in the range of 0.9−2.6 ppb (v/v). These results demonstrate that CNT sponges are a promising preconcentrator material for trace detection of VOCs. The adsorption breakthrough experiments exhibited good correlation with the kinetic adsorption and Langmuir isotherm models. The maximum adsorption capacities of the CNT sponge increased in the order benzene (0.13 mg/g)