Removal of Polycarboxylic Benzoic Acids Using Polyaniline-polypyrrole Copolymer: Experimental and DFT Studies

This work focuses on the removal of hemimellitic, trimellitic, and pyromellitic acids from aqueous solution using polyaniline-polypyrrole copolymer. The experimental data indicate that the adsorption is well described by the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorbed quantities of hemimellitic, trimellitic, and pyromellitic acids are 79.94, 93.55, and 111.29 mg/g, respectively. The thermodynamic study shows that the adsorption was a spontaneous and endothermic process. The adsorption mechanism was investigated using the density functional theory (DFT) at the B3LYP/6-31G(d). The theoretical data show that the adsorbate molecules were physisorbed via their carboxylic groups on the hydrogen atoms in amine groups of the polyaniline-polypyrrole. All the results suggest that the PANi-PPy copolymer is an efficient recyclable adsorbent for wastewater treatment.