A study on fabrication of polypyrrole@lignin composite and electrical sensing and metal ion adsorption capabilities

Abstract

In this study, a hybrid composite composed of a conducting polymer (polypyrrole, PPy) and lignin was prepared via a simple dispersion polymerization method. The successful preparation of the conductive PPy@lignin composite was confirmed using Fourier-transform infrared spectroscopy. The electrochemical properties of the composite were examined using cyclic voltammetry and compared with those of the pristine PPy. In addition, both materials were evaluated and compared in terms of their electrical sensitivity toward toxic chemicals and adsorption of heavy metal ions. The sensing capability was studied by embedding the materials in agarose gel, and the responses toward target analyte, such as ammonia were monitored as a function of analyte concentration. A linear response to ammonia at low concentrations (10？100 nM) was observed in the case of PPy@lignin. The heavy metal (133Cs) ion adsorption behavior was analyzed by measuring the adsorption profile as a function of time and adsorbate amount. The adsorption occurred rapidly with 99% ion removal within 2 h. Moreover, the adsorption behavior was found to be better fitted to pseudo-second-order kinetics and the nonlinear Freundlich model. The results conclusively prove that the PPy@lignin composite has the potential for simultaneous detection and removal of toxic substances. The study is expected to provide valuable insights for future research on lignin-based composites via synergistic combinations with conducting polymers.