Ultra-fast extraction of gold using spherical N-rich polymers

In this study, we crafted nitrogen-laden microspheres known as PEI-GA, employing a straightforward, single-step synthesis at ambient temperature. We further validated their capacity as autonomous adsorbents, capable of achieving efficient, targeted, and swift extraction of gold ions (Au(III)) from aqueous media. The high nitrogen content of PEI, combined with its electrochemical adsorption ability, enables effective adsorption and reduction of Au(III) ions into gold nanoparticles, significantly enhancing the adsorption capacity and selectivity. PEI-GA exhibits an ultra-fast adsorption rate, achieving over 99 % Au(III) recovery in just 1 min at a concentration of 100 mg/L (m/V = 0.5 g/L). Moreover, even at higher concentrations (300 mg/L), the process only takes 5 min. The maximum adsorption capacity of PEI-GA reaches 2078 mg/g, following the Langmuir model and pseudo-second-order kinetics. PEI-GA also demonstrates excellent selectivity and recyclability, recovering over 95 % of gold ions from simulated e-waste solutions and maintaining 90 % recovery efficiency after five cycles. DFT calculations suggest that AuCl₄ − tends to form multicentric coordination with N atoms in PEI-GA. This study highlights the cost-effectiveness of PEI-GA for Au(III) recovery, which can be further optimized through calcination or regeneration.