From Waste to Wealth: Covalent Organic Frameworks for Gold Detection and Recovery from Secondary Sources
Salma Abubakar, Asmaa Jrad, Gobinda Das, Thirumurugan Prakasam, Samer Aouad, Mark A. Olson, Ali Trabolsi
Abstract
Gold is a precious element, renowned for its diverse applications in catalysis, biomedicine, and electronics, largely due to its remarkable stability and superior conductivity. However, the escalating global demand and intensive mining activities have prompted a shift toward exploring gold recovery from alternative and secondary sources. Traditional gold recovery techniques, such as hydrometallurgy and cyanidation, are efficient yet notorious for their toxic byproducts, necessitating the pursuit of more sustainable methods. This review explores the potential of covalent organic frameworks (COFs) as cutting-edge materials for gold detection and adsorption. COFs are distinguished by their precise architecture, inherent porosity, and customizable functionalities, rendering them exceptionally suited for the selective capture of gold. First, we present an overview of the fundamental COF gold adsorption mechanisms, including coordination chemistry, hydrogen bonding, electrostatic interactions, and reduction processes. This is followed by examining COF synthesis methods, functionalization techniques, and composite engineering strategies that optimize their stability and adsorption efficiency. The review further highlights recent advancements in the utilization of COFs for gold sensing, recovery from electronic waste, and adsorption at trace concentrations. Finally, we address the current challenges in the application of COFs in this domain and propose future research directions. This comprehensive review serves as an invaluable resource for advancing gold extraction through COF-based materials, ultimately contributing to innovative and sustainable gold recovery practices.