Selective sequestration of perfluorinated compounds using polyaniline decorated activated biochar

Poly- and perfluorinated compounds (PFCs) in wastewater could induce the poisonous effects to the living beings throughout the world. In this present investigation, polyaniline (PANI) decorated activated biochar (AB) hybrid composite (AB@x%PANI, x = 0%, 25%, 50%, 75%, and 100% of PANI) was fabricated for PFCs adsorption via in situ chemical oxidation and co-precipitation with calcination. The physical and chemical properties of AB@x%PANI before and after adsorption were characterized by FTIR, PXRD, XPS, FE-SEM with EDX, HR-TEM, ¹³C NMR, and TGA analysis. Batch experiments for the effect of contact time, initial PFCs concentration, solution pH, and co-existing cations were conducted for the maximum adsorption capacity of as-synthesized adsorbents. The AB@75%PANI hybrid composite exhibited higher adsorption capacity for the removal of perfluorooctanoic, perfluorooctanesulfonic, and perfluorohexanesulfonic acids than powdered activated carbon, AB, PANI, AB@25%PANI, and AB@50%PANI. The adsorption isotherm and kinetic results demonstrated that the adsorption system using AB@75%PANI hybrid composite followed pseudo-second-order and Langmuir isotherm models. The PFCs adsorption by AB@75%PANI was mainly governed by various interaction forces such as hydrogen bonding, electrostatic attraction, hydrophobic interaction, and surface complexation in the presence of co-existing cations. These findings shed light on how to selectively eliminate PFCs from wastewater.