Hierarchical\nAnion Exchange and Reverse Electron Transfer\nin Layered Double Hydroxides/Peroxymonosulfate System for Roxarsone\nElimination

Roxarsone (ROX) is the main form of arsenic pollution\nin the world,\nand developing effective methods for its elimination is beneficial\nto human health and the ecological environment. Herein, we report\nglutaraldehyde cross-linked chitosan-encapsulated CoCe-LDH (layered\ndouble hydroxides) as an outstanding catalyst for the advanced oxidation\nof ROX and the efficient adsorption of inorganic arsenic. 100% of\nROX and more than 98.5% of As(III)/As(V) were eliminated, and over\n99.3% of remaining inorganic arsenic was oxidized to low-toxicity\nAs(V) in the peroxymonosulfate (PMS) activation system, and some specific\nproperties of LDH are considered the main reasons. The hierarchical\nanion exchange has been confirmed to be beneficial for constructing\na high-concentration PMS interlayer microenvironment. The unique reverse\nelectron transfer process induced 100% selective production of singlet\noxygen. This work not only develops an advanced ROX removal method\nbut also provides a new understanding of the LDH-based advanced oxidation\nprocess.