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

Abstract

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 13 C cross-polarization magic angle spinning (CP-MAS) NMR, N 2 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 ewaste 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.

An N-Rich Polymer for the Selective Recovery of Gold from Wastewater

“…Among these, adsorption is a commonly used and advantageous method because of its simple synthesis of adsorbent materials, ease of operation, and low cost. Numerous adsorbent materials, such as resin [11,12], covalent organic frameworks (COFs) [13,14], metal-organic frameworks (MOFs) [15][16][17], and polymers [18,19], have been employed for adsorption. Polymers are commonly used as adsorbent materials for gold recovery.…”