Isolation anchoring strategy for fabricating high-loading uniformly dispersed iron-based catalysts toward selective removal of phenolic compounds

Abstract

Developing uniformly dispersed iron-based catalysts with high metal loading for selective removal of the phenolic compounds was a fundamental challenge in environmental catalysis. An isolation anchoring strategy was devised to prepare the uniformly dispersed nitrogen-doped porous carbon encapsulating iron catalyst (β-Fe@NC) with the Fe loading up to 16.33 wt%, which was attributed to a dual protective effect including anchoring effect of the 8-hydroxyquinoline (8-HQ) and isolation effect of the β-cyclodextrin (β-CD), effectively anchoring the iron and inhibiting the agglomeration of the iron nanoparticles (NPs) during high temperature pyrolysis. As a demonstration, β-Fe@NC achieved almost 100% 4-CP removal in 25 min and performed an excellent kobs (0.325 min−1). Moreover, β-Fe@NC showed highly selective removal performance for phenolic compounds based on the hydrophobic interaction between catalysts and contaminants. The quenching experiments and EPR detection demonstrated that the main reactive oxygen species (ROSs) was singlet oxygen (1O2). Notably, the β-Fe@NC/PMS system exhibited an extremely low activation energy (11.54 KJ/mol) and was even competent for pollutant removal at 0 °C. This work provides a valuable insight for the design of uniformly dispersed iron-based catalysts and the activation of PMS to selectively remove phenolic compounds.