BioMagnetic-graphene-aminoclay nanocomposites for sustainable adsorption and precious metal recovery from industrial waste effluents

Abstract

The recovery of precious metals from waste effluents using low-cost adsorbents is arousing widespread attention. This attention is driven by the depletion of natural resources, increasing industrial demand for these metals, and intensified awareness of environmental protection. In response to the growing trend of waste valorization, we have developed a novel, cost-effective, and environmentally friendly adsorbent that combines bio-magnetic nanoparticles derived from bacterial biofilm waste with graphene oxide (GO) and aminoclay. This biomag-GO-aminoclay nanocomposite adsorbent is synthetised using a simple, environmentally friendly and scalable sonication-assisted electrostatic stabilization approach. The adsorption performance for precious metal is demonstrated for silver ions recovery showing exceptional adsorption with nearly 100 % uptake of Ag⁺ ions across a wide pH range (pH 2–9), rapid adsorption kinetics, a high maximum sorption capacity (98.04 ± 5.6 mg/g) and 100 % silver recovery over five adsorption-desorption cycles. Furthermore, the biomag-GO-aminoclay facilitates the in-situ reduction of Ag⁺ ions to Ag⁰, thereby enhancing the economic viability of producing value-added silver products while promoting sustainable environmental remediation practices. Overall, this research underlines the potential of new biomag-GO-aminoclay adsorbent as a versatile and effective solution for recovering precious metals from industrial waste streams, offering a pathway towards both economic benefit and environmental stewardship.