上海交通大学李浩团队报道了硅约束氢在纳米级零价铁上的高效除氟反应。相关研究成果于2025年1月15日发表在《美国化学会杂志》。

由于广泛使用具有坚固碳-氟（C-F）键的有机氟化合物，脱氟反应变得越来越重要。特别是，由于广泛和持久的全氟烷基和多氟烷基物质在环境和人体中的积累，在温和条件下对其进行有效的除氟至关重要。

该文中，研究证明，具有明显质子亲和力的表面改性硅酸盐，可以通过从nZVI中提取电子与结合的质子反应，将活性氢（H）限制在纳米级零价铁（nZVI）上，从而在环境条件下产生受限的活性氢（H*），以实现有效的除氟。硅酸盐中暴露的硅阳离子（Siσ⁺）充当路易斯酸位点，通过形成Siσ⁺F-C来激活C-F键，大大降低了亲核H*攻击的能量势垒，从而促进了选择性C-F加氢脱氟和随后的氟固定。

在柱流反应器中，硅酸盐改性的nZVI有效地去除了浓度在0.24至24μmol/L范围内的全氟辛酸（PFOA），脱氟效率为75-92%，是nZVI的8倍，产生了环保的烷基羧酸作为主要产物。除了PFOA，这种新型nZVI还实现了其他有机氟化合物的深度脱氟，包括全氟辛烷磺酸盐和氟喹诺酮类，显示出其优越的脱氟潜力。

附：英文原文

Title: Silicate-Confined Hydrogen on Nanoscale Zerovalent Iron for Efficient Defluorination Reactions

Author: Minzi Liao, Shengxi Zhao, Guangming Zhan, Jiajie Liang, Zhilin Li, Fengfeng Dong, Yitao Pan, Hao Li, Lizhi Zhang

Issue&Volume: January 15, 2025

Abstract: Defluorination reactions are increasingly vital due to the extensive use of organofluorine compounds with robust carbon–fluorine (C–F) bonds; particularly, the efficient defluorination of widespread and persistent per- and polyfluoroalkyl substances under mild conditions is crucial due to their accumulation in the environment and human body. Herein, we demonstrate that surface-modified silicate of pronounced proton affinity can confine active hydrogen (H) onto nanoscale zerovalent iron (nZVI) by withdrawing electrons from nZVI to react with bound protons, generating confined active hydrogen (H*) for efficient defluorination under ambient conditions. The exposed silicon cation (Siσ+) of silicate functions as a Lewis acid site to activate the C–F bond by forming Siσ+...F––C and substantially lowers the energy barrier of nucleophilic H* attack, thereby facilitating selective C–F hydrodefluorination and subsequent fluorine immobilization. In a column flow reactor, silicate-modified nZVI efficiently removes perfluorooctanoic acid (PFOA) of concentrations ranging from 0.24 to 24 μmol/L with 75–92% defluorination efficiencies, 8 times higher than those of nZVI, generating environmentally friendly alkyl carboxylic acids as the primary products. Besides PFOA, this novel nZVI also realizes deep defluorination of other organofluorine compounds, including perfluorooctanesulfonates and fluoroquinolones, demonstrating its superior defluorination potential.

DOI: 10.1021/jacs.4c14261

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c14261