Integrating Mechanochemical Synthesis of a Pyridinium-Based Graphitic Ionic Framework into an Eco-Friendly Gold Recycling Process

Abstract

Most gold extraction and electronic waste (e-waste) recycling rely on highly toxic lixiviants, resulting in substantial environmental harm. The use of volatile organic solvents in the synthesis of adsorbents for gold extraction further complicates this problem. In response, this work introduces a sustainable green chemistry approach from material synthesis to gold recovery. A novel crystalline pyridinium-based graphitic ionic framework (GIF-4) was developed via a solvent-free mechanochemical method. This method demonstrates both sustainability and scalability. GIF-4 achieves high adsorption capacity, fast adsorption kinetics, and stability over repeated cycles for Au(III). Coupled with an environmentally benign NBS/H2O leaching system, GIF-4 enabled efficient gold recovery from e-waste, achieving superior removal in a real-scenario test. The Biwer-Heinzle environmental assessment method quantitatively identifies that the integrated process has a notably lower output environmental burden compared to conventional methods. This study proposes a complete, sustainable, and efficient green chemistry route for gold recycling from e-waste.