Effective mercury removal by a new imidazole-functionalized polyamide for wastewater treatment: experimental and theoretical studies

Mercury, a highly toxic heavy metal, poses a significant threat to human life and the environment. A new imidazole-functionalized polyamide (IFPA) was synthesized, demonstrating its potential as a promising adsorbent for efficiently removing Hg(ii) ions from aqueous and wastewater solutions. The polyamide achieved up to 100% removal at a concentration of 15 ppm. IFPA was characterized using various spectroscopic techniques. Thermal properties revealed high thermal stability up to 400 °C. Scanning electron microscopy and powder X-ray diffraction revealed the crystalline nature of the polymer. Adsorption studies explored the influence of pH, contact time, concentration, and temperature. The adsorption process followed Langmuir and Freundlich isotherm models simultaneously, indicating a combined adsorption mechanism. Kinetic studies suggested chemisorption via a pseudo-second-order model. Thermodynamic analysis indicated the adsorption to be endothermic and spontaneous. IFPA exhibited efficient regeneration and reusability for at least three cycles. Furthermore, it removed 99% of Hg(ii) ions from a wastewater sample, demonstrating its efficacy as an adsorbent for environmental remediation. Interestingly, density functional theory simulations revealed that van der Waals forces primarily drive Hg(ii) ion adsorption throughout the polymer chain. This study underscores the potential of IFPA as a promising adsorbent for mercury removal from wastewater, instilling optimism about its future applications in environmental remediation.