Interaction of anionic dyes with polyaniline implanted cellulose: Organic π-conjugated macromolecules in environmental applications

Abstract

The selective response of most of the adsorbents towards a particular dye creates problem in launching them as adsorbent in real field applications. Owing to that we have synthesized organic macromolecule of polyaniline implanted cellulose through vapor phase polymerization method. Polyaniline implanted cellulose was found as a cationic charge transport medium and thus enthusiastically chosen to observe its interaction with anionic dyes as adsorbent media. The prepared material was found crystalline in X-ray diffraction (XRD) measurement. Field emission scanning electron microscopy (FESEM), Raman spectroscopy and optical absorbance, measurements were carried out to explore its physical properties. The polyaniline implanted cellulose substrate has shown excellent adsorptive response with anionic dyes of methyl orange (MO) and eosin yellow (EY). More than 97% removal efficiency was observed at optimum experimental conditions for both the dyes and the MO dye adsorption process followed Langmuir isotherm strictly. However, Freundlich isotherm model has shown better fit for equilibrium adsorption data of EY dye onto polyaniline implanted paper. Kinetic analysis indicated the applicability of second order kinetic model with involvement of intra-particle diffusion. The polaron and bipolaron charged defect states in the polyaniline chain played the key role in adsorption of anionic dyes through chemical interaction. Thus it appeared as an efficient adsorbent for anionic dyes with wide range of selectivity.