Physicochemical Assessment of Selected Conductive Polymers for Probable Mercury Remediation in Wastewater—Experimental and DFT Approach

Abstract

Mercury contamination in aquatic environments poses significant risks to ecosystems and human health, underscoring the need for effective remediation technologies. This research examines the physicochemical properties of the synthesised polymer materials, and DFT calculations were used as an initial step for material development to validate our experimental outcomes for the prepared polymers: polyaniline (PANI), polyethersulfone (PES), and polyamidoamine (PAMAM). Furthermore, DFT studies were used to elucidate structure–property relationships in polymers, serving as performance predictors for mercury adsorption and selectivity, as well as for their applicability in electronic sensors. The characterisation techniques indicated the high functional group densities of PAMAM dendrimers for effective chelation, while the semi-crystalline structure of PANI improves metal binding. DFT calculations reveal that PAMAM exhibits the smallest HOMO–LUMO energy gap, indicating a high reactivity towards mercury ions. Binding energies indicate that PAMAM forms the most stable single-ion complex; PAM1Hg (0.242 eV, 23.37 kJ mol−1), whereas PES exhibits enhanced interaction at elevated mercury concentrations, resulting in stable multi-Hg complexes, PES3Hg (0.136 eV, 13.13 kJ/mol). The findings indicate that nitrogen-rich functional groups and aromatic systems play a crucial role in mercury binding, highlighting the promise of conductive polymers for creating effective adsorbents aimed at mercury remediation in industrial wastewater.