Facile synthesis of three-dimensional Mn3O4 hierarchical microstructures for efficient catalytic phenol oxidation with peroxymonosulfate

Abstract

Hierarchical porous materials have a wide application prospect in heterogeneous catalysis because they can provide plentiful surface active sites and well-developed mass transfer channels while being easily separable, as compared with their nanosized counterparts. In this study, three-dimensional hausmannite (Mn3O4) hierarchical micron-sized materials (Mn3O4-H) were synthesized by a simple room-temperature aqueous solution route. The catalytic performance was evaluated by activation of peroxymonosulfate (PMS) to oxidize phenol, a model organic pollutant, in aqueous solution. The Mn3O4-H showed a higher efficiency in activating PMS for phenol oxidation than two Mn3O4 nanomaterials, i.e., nanoparticles and nanorods, attributed to the higher specific surface area and more surface reactive sites arising from the hierarchical structure. The Mn3O4-H also showed high catalytic stability, with low Mn leaching during phenol degradation tests. Phenol degradation reaction kinetics followed the pseudo-first-order rate laws, and the reaction was accelerated at higher temperature. In addition, the effects of important operation parameters such as catalyst loading and PMS concentration on catalytic performance of Mn3O4-H were evaluated. The present research provides a facile approach for synthesis of green and effective catalytic materials to be used in PMS-based advanced oxidation processes for environmental remediation.