Polypyrrole and its composites with various cation exchanged forms of zeolite X and their role in sensitive detection of carbon monoxide
Composites of polypyrrole and various cation exchanged forms of zeolite X were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and thermo-gravimetric analysis (TGA). The effects of cation type, zeolite content, cyclic interval, and CO concentration on CO interactions with PPy were investigated. The sensitivity of the synthesized composites was found to obey the following order: Na+-X/PPy > H+-X/PPy > Fe+-X/PPy > Cu+-X/PPy > PPy depending upon the ionic radius of the cation present in the zeolite–polymer composites and the electronegativity. The sensitivity of the Na-X/PPy composite increased from 25.49% to 50.06% as the zeolite content was increased from 10% to 60% (w/w%). This increase in the sensitivity on increasing the zeolite content is due to the increase in the surface area of the composite. The sensitivity of Na-X/PPy at 500 ppm for CO was found to be 56.02, 50.28, 44.79 and 38.66% during the 1st, 2nd, 3rd and 4th cyclic intervals, respectively.