Turning E-waste into value: Innovative metal recovery using low-density concrete: Experiments and simulations

The recovery of valuable metals from e-waste leachates is essential for advancing circular economy strategies and reducing environmental risks. This study examined Low Density Concrete (LDC), a waste material, as a sustainable adsorbent for the recovery of Ni 2+ , Mn 2+ , Zn 2+ , and Fe 2+ /Fe 3+ . This is the first study that evaluated the performance of LDC in metal recovery from a real leachate produced by the anaerobic digestion of alkaline batteries and municipal solid waste. The one-factorial method was employed to find the effect of the pH and adsorbent mass on results. The adsorption behavior was then studied using three different isothermal models: Freundlich, Langmuir, and Temkin. The findings indicated that pH significantly influenced metal removal, with ion exchange predominating in acidic conditions (pH < 5) and adsorption-precipitation mechanisms becoming more significant near neutral pH. Optimal performance was achieved at pH = 7 and an adsorbent dosage of 0.10 g. The most significant parameter influencing metal removal efficiency was pH, as determined by ANOVA. To enhance process prediction, both Response Surface Methodology (RSM) and Artificial Neural Network (ANN) models were developed. ANN had a better predictive accuracy ( r > 0.98) than RSM. Material characterization such as FTIR, SEM-EDS, and TGA, confirmed metal uptake and associated surface and structural changes. Finally, an environmental impact assessment using the Leopold Matrix indicated that LDC exhibits lower environmental impacts compared to conventional adsorbents. These findings support the potential of LDC as a green, low-cost material for metal recovery from complex e-waste leachates. • Recovered Ni 2+ , Mn 2+ , Zn 2+ , Fe 2+ /Fe 3+ ions from e-waste leachate using concrete waste. • LDC showed dual adsorption–ion exchange behavior under varying pH conditions. • ANN predicted adsorption capacity with r > 0.98, surpassing RSM performance. • Freundlich model confirmed multilayer adsorption on heterogeneous LDC surface. • EIA proved LDC greener than GO regarding water, energy, and human health impact.