Facile synthesis of Mn-Fe oxides on palygorskite as an activator of peroxymonosulfate for methylene blue removal via a nonradical pathway

Peroxymonosulfate-based advanced oxidation process (PMS-AOP) is a well-known wastewater treatment technique for organic pollution in nowadays. In this work, a novel nanocomposite catalyst of palygorskite (PG) coated by MnO 2 and Fe 3 O 4 (PMM) was successfully synthesized to activate PMS, achieving 97.8 % of 50 mg/L methylene blue (MB) degraded within 300 min. Evidenced experiments confirmed that plentiful reactive oxygen species (ROS) of 1 O 2 , O 2 •– , SO 4 •– and • OH were all detected in a PMM/PMS system and 1 O 2 was certified to be the main dominator in the degradation of MB. A great synergistic effect was existed among MnO 2 , Fe 3 O 4 , and PG, and MnO 2 was regarded as the major active site to substantially accelerate the degradation of MB by PMM/PMS via the nonradical pathway. Multi-metal oxides readily enhanced high oxygen vacancies generated on the surface of catalyst, resulting in a low reaction activation energy ( E a =26.91 kJ/mol) and promoting 1 O 2 generation. These novel findings advanced the application of PMM as a promising nanocatalyst on PMS activation for the removal of organic dyes from wastewater. • Palygorskite-MnO 2 -Fe 3 O 4 as a highly efficient catalyst for heterogeneous activation peroxymonosulfate was fabricated. • An obvious synergistic effect among MnO 2 , Fe 3 O 4 and PG in PMM was observed. • The oxygen vacancies of PMM facilitated the generation of 1 O 2 for a non-radical pathway of MB elimination. • Degradation pathways of MB in PMM/PMS were proposed.