Polyaniline-based adsorbents for aqueous pollutants removal: A review

Water contamination by a variety of pollutants, such as conventional pollutants (e.g. heavy metals and organics) and emerging micropollutants (e.g. personal care products and endocrine disrupting compounds) is of great concern. Various technologies have been developed to address this critical challenge. Among them, adsorption by polyaniline (PANI)-based nanocomposites, has gained growing research interest recently due to their unique electrical characteristics and many other benefits, such as facile synthesis, low cost, excellent environmental stability, simple acid-base doping/dedoping process, reactive NH– groups, and tunable properties. This paper provides a comprehensive review of the typical PANI-based adsorbents and their properties. Moreover, the removal of various aqueous contaminants (including heavy metals and metalloids, organic dyes and emerging pollutants) by PANI-based adsorbents is discussed and assessed. The unique doping/dedoping of PANI-based adsorbents alters the morphology, pore size, surface charge and functional groups of the adsorbents, leading to enhanced adsorbent-adsorbate interactions and thus adsorption performance. The adsorption mechanisms of aqueous pollutants by PANI-based adsorbents include electrostatic interactions, van der Waals forces, π–π interactions, hydrogen bonding, chelating and/or complexation effects. Finally, the future outlooks on aqueous pollutants removal by PANI-based adsorbents are presented.