Graphene Oxide Thin Films for Detection and Quantification of Industrially Relevant Alcohols and Acetic Acid

Abstract

Industrial environments are frequently composed of potentially toxic and hazardous compounds. Volatile organic compounds (VOCs) are one of the most concerning categories of analytes commonly existent in the indoor air of factories' facilities. The sources of VOCs in the industrial context are abundant and a vast range of human health conditions and pathologies are known to be caused by both short- and long-term exposures. Hence, accurate and rapid detection, identification, and quantification of VOCs in industrial environments are mandatory issues. This work demonstrates that graphene oxide (GO) thin films can be used to distinguish acetic acid, ethanol, isopropanol, and methanol, major analytes for the field of industrial air quality, using the electronic nose concept based on impedance spectra measurements. The data were treated by principal component analysis. The sensor consists of polyethyleneimine (PEI) and GO layer-by-layer films deposited on ceramic supports coated with gold interdigitated electrodes. The electrical characterization of this sensor in the presence of the VOCs allows the identification of acetic acid in the concentration range from 24 to 120 ppm, and of ethanol, isopropanol, and methanol in a concentration range from 18 to 90 ppm, respectively. Moreover, the results allows the quantification of acetic acid, ethanol, and isopropanol concentrations with sensitivity values of (3.03±0.12)∗104, (-1.15±0.19)∗104, and (-1.1±0.50)∗104 mL^-1, respectively. The resolution of this sensor to detect the different analytes is lower than 0.04 ppm, which means it is an interesting sensor for use as an electronic nose for the detection of VOCs.

Keywords: VOC; acetic acid; air quality; electronic nose; ethanol; impedance spectroscopy; indoor air; industrial environment; isopropanol; layer-by-layer films; methanol; volatile organic compounds.

Figure 1

Impedance (a) and impedance angle (b) spectra of the sensor devices when exposed to atmospheres with different concentrations of acetic acid (I), ethanol (II), methanol (III), and isopropanol (IV).

Figure 1

Impedance (a) and impedance angle (b) spectra of the sensor devices when exposed to atmospheres with different concentrations of acetic acid (I), ethanol (II), methanol (III), and isopropanol (IV).

Figure 2

Impedance magnitude and impedance angle at a fixed frequency of 10⁴ Hz for different concentrations of acetic acid (a), ethanol (b), methanol (c), and isopropanol (d) in air. The lines between the experimental points are guidelines.

Figure 3

(a) PCA score plot after analyzing all the measured data for the detection of acetic acid, ethanol, methanol, and isopropanol in air at different concentrations; (b) evolution of PC1 components as a function of solvent volume; (c) evolution of PC2 components as a function of solvent volume.

Figure 3

(a) PCA score plot after analyzing all the measured data for the detection of acetic acid, ethanol, methanol, and isopropanol in air at different concentrations; (b) evolution of PC1 components as a function of solvent volume; (c) evolution of PC2 components as a function of solvent volume.