Department of Chemistry and Nanoscience & Technology Institute, Wonkwang University, 460 Iksandaero, Jeonbuk, 54538, Republic of Korea.
Ssufine Corporation, 460 Iksandaero, Iksan, Jeonbuk, 54538, Republic of Korea.
J Chromatogr A. 2019 Nov 8;1605:460363. doi: 10.1016/j.chroma.2019.460363. Epub 2019 Jul 10.
A carbon nanotube (CNT) sponge was synthesized and examined as an adsorptive material for a thermally desorbed preconcentrator for volatile organic compounds (VOCs). The porous sponge-like material, retaining the intrinsic properties of individual multiwalled (MW) CNTs, was fabricated using spray pyrolysis chemical vapor deposition (CVD). The square pillar form of the CNT sponge was enclosed in a 1/4″ glass tube with fittings for flow-through sampling. Flow of a direct current through the CNT sponge allowed rapid thermal heating to a surface temperature of 264.7 ℃ at a rate of 481.5 ℃/s and a narrow desorption bandwidth of 0.74 s. The preconcentration concept was validated using gas chromatographic analysis of an aromatic VOC mixture, including benzene, toluene, ethylbenzene, and o-xylene (BTEX) vapors at concentrations of 100 parts per billion (ppb). With an adsorption volume of only 100 mL, the enrichment factor of each analyte was 300 (B), 240 (T), 210 (E), and 200 (X), enabling sensitive measurements with limits of detection at the parts per trillion level. Sequential desorption experiments confirmed that a single desorption process evaporates all the analytes inside the preconcentrator with >96% efficiency. There was no humidity effect and no sign of performance degradation after continuous operation for 45 repeated cycles. These results demonstrate that CNT sponges are a suitable material for the enrichment and sensitive determination of VOCs at trace levels. Thus, CNT sponge preconcentrators are advantageous in a variety of applications that permit fast and accurate real-time measurements, including ambient air and workplace air monitoring.
一种碳纳米管（CNT）海绵被合成并作为热解吸预浓缩器的吸附材料来检测挥发性有机化合物（VOCs）。这种多孔海绵状材料保留了单个多壁（MW）CNT 的固有特性，是通过喷雾热解化学气相沉积（CVD）制造的。CNT 海绵的方柱形式被封装在一个 1/4"的玻璃管中，配有用于流动采样的配件。通过 CNT 海绵的直流电流流动允许快速热加热，表面温度以 481.5°C/s 的速率达到 264.7°C，解吸带宽较窄，为 0.74s。使用气相色谱分析包括苯、甲苯、乙苯和邻二甲苯（BTEX）蒸气在内的芳香族 VOC 混合物验证了预浓缩概念，这些蒸气的浓度为 100 十亿分之一（ppb）。通过仅 100 mL 的吸附体积，每个分析物的浓缩因子分别为 300（B）、240（T）、210（E）和 200（X），从而可以在检测限达到万亿分之一水平的情况下进行灵敏测量。顺序解吸实验证实，单个解吸过程以 >96%的效率蒸发预浓缩器内的所有分析物。在连续运行 45 个重复循环后，没有湿度影响，也没有性能下降的迹象。这些结果表明 CNT 海绵是痕量水平下富集和灵敏测定 VOCs 的合适材料。因此，CNT 海绵预浓缩器在允许快速准确实时测量的各种应用中具有优势，包括环境空气和工作场所空气监测。
