Activation Mechanism of a Peroxymonosulfate‐based Fenton‐like System with Birnessite and Cu2+ Modified Birnessite.

The peroxymonosulfate (PMS) activation mechanism is closely related to the structure/configuration of the "active site" of the Fenton‐like catalysts. In this paper, it is shown that Cu2+ chemically bonds the surface of birnessite at the Mn vacancy site to form triple‐corner‐sharing inner‐sphere surface complexes (Cu‐Bir), which regulates the PMS activation mechanism. Birnessite/PMS Fenton‐like system degrades phenol via a non‐radical mechanism, which involves high valent Mn(V)=O generated from the surface reaction of Mn(III) with adsorbed PMS. While Cu‐Bir initiates an additional radical mechanism that involves reactive oxygen species of ⋅O2− and 1O2, and the k value of 5Cu‐Bir is 1.9 times higher than that of Bir. The Fenton‐like reaction mechanism of the Cu‐Bir/PMS system is thus proposed as a radical and non‐radical cooccurrence mechanism, which involves a synergistic effect that the radical pathway accelerates the regeneration of Mn(III) for the non‐radical pathway, and the non‐radical pathway assists to produce 1O2 for the radical pathway. [ABSTRACT FROM AUTHOR]