Polyaniline-based compounds as sorbents and photoactive materials for environmental remediation: sunrise or sunset?

Environmental deterioration and the scarcity of fresh water have become imperative global issues to be solved nowadays. Polyaniline (PANI) and PANI nanocomposites have gained popularity in addressing different types of issues. In the field of environmental remediation, combining electrostatic and hydrophobic segments in their backbone, recently these materials have shown promising results in the abatement of both organic (mainly hazardous dyes) and inorganic (mainly toxic metals) pollutants. Even though many methods have developed to synthesized PANI of good quality in terms of conductivity, stability and porosity, all these approaches are based on the use of toxic stoichiometric oxidants (typically metals in high oxidation state) and lead to the production of carcinogenic coproducts (i. e. benzidine and trans-azobenzene). In line with the growing environmental sensitivity and the necessity of clean products, we have recently addressed our efforts on the development of environmentally friendly protocols to produce “green” PANI and PANI composites. Herein, we report a brief overview of our results on the synthesis of PANI and its composites by environmentally friendly approaches and our recent goals in the abatement of VOCs and NO2 from air matrices and dyes, hydrocarbons and metals from water. We will show how it is possible to tune the adsorption properties of the polymer and finally a new generation of photoactive PANI/TiO2 floating materials will be discussed.