Realistic Approach for Recovering Gold from Waste Electronics by Thiourea Leaching and Adsorption Using a Covalent Porphyrin/Triphenylamine-Based Porous Polymer

Recovering gold from electronics waste (e-waste) is essential for conserving valuable resources and reducing improper disposal's environmental impact. However, the selective recovery of gold from e-waste is a significant challenge due to its heterogeneous nature and existing inappropriate recovering processes. Considering these issues, in this study, we investigated a promising approach for recovering gold from waste random access memory (WRAM). For that, we synthesized a porous nanonet polymer (Por-net) through a one-pot Friedel–Crafts polymerization method containing multiple functional groups, i.e., porphyrin and triphenylamine, within a single framework material, acting as a bifunctional chelating ligand. The adsorption results were significantly influenced by the pH conditions. Around 1250 mg g–1 capacity of Au was recovered under realistic experimental conditions in an acidic medium. Moreover, the adsorption isotherm and kinetic study revealed the Langmuir model and pseudo-second-order kinetic fittings for the Au adsorption on Por-net. Properties such as the high surface area and structure of Por-net as well as the Au@Por-net polymer were comprehensively characterized by X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), thermogravimetric analysis (TGA), solid-state 13C cross-polarization magic angle spinning (CP-MAS) NMR, N2 sorption analysis field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), electron paramagnetic resonance (EPR), ultraviolet (UV)–visible, time-resolved photoluminescence, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The results showed its efficient potential for recovering gold from real e-waste sources. Por-net showed excellent desorption efficiency, recyclability, selectivity, and chemical stability. At last, the economic feasibility of Por-net for the purpose of recovering gold from e-waste is also explored. The present work represents a greener and feasible approach to promoting sustainable development, circular economy, and responsible waste management using an effective porous polymer as a scaffold.