From waste to precious: recovering and anchoring Au from electronic wastewater onto poly(m-phenylenediamine) membranes for catalytic nitrophenol conversion†

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.