Recovering gold from electronic wastewater is of great significance in alleviating the shortage of metal resources and reducing environmental pollution, especially considering the increasing number of discarded electronic devices. However, the ultra-low concentration of gold and the competitive interference of various metals pose significant challenges. In this work, we used Fe 3 O 4 nanoparticles and quaternary ammonium salt to recover gold from electronic wastewater. The method achieved a gold recovery efficiency of 98.2 % within just 3 min. The mechanism of gold recovery was investigated using techniques such as SEM, EDX, FT-IR, XPS, and XRD. The Au (III) ions were complexed with tetrabutylammonium nitrate to form the [N 4444 ][AuCl 4 ] complex, and this complex then aggregated with Fe 3 O 4 nanoparticles to form nanoclusters, while Fe (II) ions on the surface of Fe 3 O 4 nanoparticles reduced the Au (III) ions to Au (0). This study proposed a mechanism of complexation-aggregation-reduction-separation to recover gold. On application to a simulated electronic wastewater, the method exhibited excellent selectivity for Au (III), achieving a recovery efficiency of 99.1 %. The regeneration of Fe 3 O 4 nanoparticles can be readily performed by ultrasound, retaining a 96.7 % recovery rate of Au (III) even after six consecutive cycles. This study proposed the combination of Fe 3 O 4 nanoparticles and quaternary ammonium salt for gold recovery, which provided an environmentally friendly solution to address the increasing demand for precious metal resources in industry.
Youmei Xu,Yuchao Chen,Mengxia Wang,Yufei Shu,Siyu Cao,Zhongying Wang
Nitrophenol wastewater treatment and extracting and reusing precious metals from electronic wastewater have recently gained considerable attention. In this study, polyaniline-based membranes showcased remarkable gold recovery capability from electronic wastewater, effectively reclaiming 100% of gold on the membrane surface even in the presence of competing metal cations. The prepared Au@PmPD membrane, characterized by its high specific surface area and abundant Au nanoparticles (NPs), demonstrated excellent catalytic activity and stability, maintaining near 100% conversion efficiency in reducing 4-NP to 4-AP in the presence of NaBH4 over extended durations. Compared with the conventional physical mixing method, our in situ formation of the Au@PmPD membrane highlights the superior distribution of Au NPs and active sites for enhanced catalytic efficiency. It eliminates the need for additional steps to load Au NPs onto the membrane, resulting in a more straightforward and efficient process. Overall, this research provides a sustainable approach to repurposing waste into precious resources and offers a promising solution for the efficient treatment of persistent organic pollutants in wastewater, aligning with the principles of a circular economy.
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