Evaluation of the effect of heating on the ion exchage capacity of polyaniline

• Thermal stability of polyaniline has been evaluated in the present manuscript for its probable application for elevated temperature ion exchange separations.
• Structural modifications occurring in polyaniline, upon heat treatment were studied using thermogravimetry, UV–vis and FTIR.
• High resolution infrared spectroscopy is being reported for the characterization of gaseous decomposition products of PAni, subjected to 300 °C.
• Superior thermal stability of polyaniline compared to conventional anion exchangers is revealed in the present studies.

Thermal stability of polyaniline was evaluated to assess its use as ion-exchanger at elevated temperatures. Thermogravimetric analysis of salt (chloride) and base form of polyaniline revealed the decomposition pattern and volatile products. Structural modifications in PAni upon heating upto 500 °C were studied using UV–vis spectroscopy, Fourier Transform Infrared spectroscopy, and viscometry. The gaseous decomposition products of polyaniline were identified using high resolution infrared spectroscopy for the first time. Anion exchange capacity of polyaniline, in terms of ionizable chlorine, determined using Energy Dispersive X-ray Fluorescence spectrometry, was found to be 3.25 meq g−1. Polyaniline was found to retain ∼90% of the original capacity on heating upto 200 °C. These studies evinced the superior thermal stability of polyaniline over conventional anion exchangers.

Thermal stability of polyaniline was evaluated at temperatures. It was found that polyaniline retains about 90% of the original capacity on heating upto 200 °C.Figure optionsDownload as PowerPoint slide