1,2,4,5-Benzene Tetracarboxylic Acid-Doped Polyaniline/Protonated Carbon Nitride Nanostructures for Cr(VI) Adsorption in Water

This work outlines the fabrication of a nanocomposite, namely, 1,2,4,5-benzene tetracarboxylic acid-doped polyaniline/protonated carbon nitride (H4BTC-PANI/pC3N4) through a straightforward two-step process. Various advanced analytical tools validated the formation of the composite. Subsequently, the adsorption characteristics of the prepared composite for the uptake of Cr(VI) ions were assessed via batch adsorption experiments. Removal equilibrium and kinetic approaches clearly demonstrated the simulation of adsorption data via Langmuir and pseudo-second-order models. The thermodynamic analysis disclosed that the removal of Cr(VI) ions by the H4BTC-PANI/pC3N4 material was a spontaneous, endothermic procedure associated with an increase in surface site availability randomness. It was found that by using 0.25 g/L of adsorbent dose at pH 2, almost 97.1% of the chromium was eliminated within an equilibrium time of 90 min. Furthermore, the maximum adsorbed amount was 1229 mg·g–1, exceeding the capabilities of most similar adsorbents. The composites retained a significant adsorption capacity for Cr(VI) even after undergoing five regeneration cycles, demonstrating excellent reusability. Monte Carlo (MC) calculations were executed to search for the most stable configuration and adsorption energies of H4BTC on pC3N4, PANI on H4BTC/pC3N4, and Cr(VI) removal on H4BTC-PANI/pC3N4 surfaces in the aqueous system. The experimental findings indicated that H4BTC-PANI/pC3N4 holds significant promise as a cost-effective material for removing hexavalent chromium from wastewater, showcasing considerable potential for practical use.