Radiation synthesis of gas sensor based on polyaniline nanoflake-poly vinyl alcohol) film for four hazardous gases (NH3, CO2, H2S and phenol)

Document Type : Original Article

Authors

1 NCRRT

2 Polymer Chemistry Department, National Center of Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt.

3 ncrrt

Abstract

In this study, a low-cost conductive composite membrane consisting of polyaniline nano-flake which dispersed in a polyvinyl alcohol has been prepared through in-situ polymerization technique. The polymerization of polyaniline is carried out based on polyvinyl alcohol using ammonium per sulfate as an oxidizing agent at low temperatures (–5°C) in acid medium at pH 3 1M (HCl) followed by exposure to gamma irradiation leading to crosslinging of (PVA/PANI) membranes and for enhancement formation of polyaniline nano-flake. The produced film is in the emeraldine oxidation state and fully protonated which can detect the hazardous gases (NH3, H2S, CO2 and phenol gas) through changing in the color and electrical conductivity. The gas-sensing property of (PVA/PANI) film was examined at ambient conditions of temperature and pressure. The observed is the variation in sensing property of (PANI-PVA) films corresponding to the type of gases in order NH3 ≥ H2S ≥ CO2 ≥ phenol gas. The product films of (PVA/PANI) before and after four gases adsorption were characterized by scanning electron microscopy, infrared spectroscopy, UV–Vis spectroscopy and XRD. TEM images of (PANI) obtained in form 2D-polyaniline nano-flake is confirmed. Furthermore, the incorporation of gas molecules onto the (PVA-PANI) films for four gases adsorption and their conductivity changing was examined. It was observed that the conductivity was changed according to the chemical structure changing of PANI as confirmed by FTIR data. It was found that, the electrical conductivity of all blended films decreases by exposure to the gas.

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