The effect of graphite composition on polyaniline film performance for formalin gas sensor

Abstract

The invention of formalin gas sensors based on polyaniline (PANI) has been developed which arranged by PANI|graphite composite form. The reaction between amine and formaldehyde produced a Schiff base that alters the resistance of PANI film as a function of formaldehyde concentration. The response of the sensor was measured in variations of graphite composition with 3%, 10%, and 25%. The results showed similar patterns in all concentrations of formalin. However, the sensor response at 10% and 25% graphite decreased dramatically. The formalin with concentration 400 ppm shown the response with 3% graphite was 1.62 times greater than 25%. Addition of too much graphite makes the absorption area on the PANI surface becomes less because the graphite covered it. In this case, the sensor performance was still stable and functional, but the measured resistance seems smaller because the sensor conductivity level more dominated by graphite. Therefore, composites of polyaniline and graphite can be used as sensors to detect the presence of formaldehyde gas.                     KEY WORDS: Formalin, Graphite, Polyaniline, Resistance, Sensors   Bull. Chem. Soc. Ethiop. 2020, 34(3), 597-604.  DOI: https://dx.doi.org/10.4314/bcse.v34i3.14