Lamellar cluster-like grown FeCo layered double hydroxides as stable peroxymonosulfate activators at wide circumneutral pH

Abstract

The development of effective and reliable Fenton-like catalytic systems in circumneutral pH is a longstanding interest. Metal-organic framework derivatives become promising catalyst candidates due to high catalytic accessibility and structural flexibility, but their stability remains in doubt. Herein, a MIL-88A self-templating strategy to synthesize structurally decentralized FeCo-layered-double hydroxide (FeCo-LDH, M−FCL) was proposed. The well-constructed M−FCL3 presented superior peroxymonosulfate (PMS) activation for nearly 100 % sulfamethazine (SMT) degradation within 15 min, which was virtually wobble-slight in the pH = 2.5 ∼ 10.5 range. The performance decrease at limiting pH was mainly ascribed to activity-blocked of M−FCL3 by analyzing the involved reaction substrates and reactive oxygen species. In specific, the hydrolytic detachment or excessive aggregation of surface-active FeCo-LDH occurred at limiting pH with unbalanced hydrolysis-coprecipitation. Especially, theoretical calculations further exposed that the loss of dominated active Co site and the formation of inert SMT+ dissociating species were detrimental to the catalytic process in acidic environments. Nevertheless, the well-founded resistance of the constructed M−FCL3/PMS system to interference and its ability to operate for a long period proved its potential for application in near-neutral environments. This work raised concern for the variations of Fenton-like catalysis at limiting pH, promoting the application of MOF-derived LDH for environmental remediation.