Critical Assessment of Polyaniline-based Biocomposites for Removal of Toxic Heavy Metals from Aqueous Media

Abstract

Polyaniline (PANI) is useful for the adsorption of hazardous substances because of its multiple N-containing functional groups, high adsorption capacity, superior selectivity and chemical durability. Although it is cheap and easy to synthesize, PANI has low processability and mechanical strength, which can be overcome by preparing composites of PANI with biomass waste. Biomass waste is a rich source of useful biopolymers, judicious use of which can also solve the problem of biomass-waste management. Furthermore, biomass waste provides excellent support and possesses functional groups, which help to synergistically remove potentially toxic elements (PTEs) from wastewaters. Composites of PANI have shown tremendous potential in the removal of PTEs from wastewaters. More recently, the focus of studies have been on PANI-based inorganic composites. Considering the environmental impact of these materials, use of PANI-based biosorbents would be more economical, environmentally friendly and promising. This review discusses the mechanisms of removal of PTEs by PANI biocomposites, factors affecting adsorption, characteristics and role of different biomass materials in the removal of PTEs, their advantages and limitations. This article also discusses the potential use of waste microbial biomass-polyaniline composites, which has not been fully explored thoroughly. The vast potential for future research has also been acknowledged, though much more study is needed before this method can be used to its full potential.