In-situ active sites analysis of bifunctional metal-organic frameworks for coupled adsorption and electrochemical oxidation of PPCPs

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-04, Vol.486, p.150322, Article 150322
• Main Authors: Zhang, Shuchi, Leng, Wenhua, Zhang, Shufeng, Lu, Huijie, Xu, Xinhua, Zang, Zhengyang, Wu, Donglei
• Format: Article
• Language: English
• Subjects: Active site; In-situ electrochemical spectroscopy; Mass/charge transfer; Molecular electrocatalyst; Pharmaceutical wastewater
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.150322

[Display omitted] •MOFs act as dual-functional adsorbents and electrocatalysts for the removal of PPCPs.•Real active sites of MOFs are pinpointed using in-situ electrochemical methods.•Fe-MOFs exhibit high efficacy and stability in practical wastewater treatment. Pharmaceuticals and personal care products (PPCPs) pose a significant wastewater pollution concern. While electrochemical oxidation is promising, it struggles with slow mass transfer. To address this, we propose a novel strategy utilizing bifunctional metal–organic frameworks (MOFs) that couple an adsorbent with an electrocatalyst. The real active sites within iron-based MOFs responsible for the adsorption of PPCPs are MIL-101(Fe) molecules, while the in-situ formed active sites, α-FeOOH, accelerate the charge transfer under bias, contributing to the electrooxidation of PPCPs. The rapid destruction of adsorbed organics on the dual-functional electrode surface enables to release adsorption sites. This, in turn, paves the way for fast and efficient re-adsorption of PPCPs molecules, consequently promoting mass transfer. Iron-based MOFs exhibit excellent adsorption capacity (∼60 mg g−1 for sulfosalicylic acid, ∼15 mg g−1 for acetaminophen) and electrooxidation ability (94 % removal in 2 h, 31.2 kWh kg−1 COD) with good stability in realistic pharmaceutical wastewater treatment. This study offers a novel strategy for removing PPCPs using molecular electrocatalysts and provides new insights for designing and constructing MOFs for refractory wastewater treatment.