Microwave-assisted continuous-flow preparation of magnetic composite MgFe2O4/UU-200 as efficient photocatalytic aqueous pollutant remediation

Abstract

Current research aims to engineer sustainable and efficient materials for photocatalysis, which is still challenging in the industry. Magnesium ferrite (MgFe₂O₄) was incorporated into UU-200 frameworks under microwave-aided continuous flow, scalably producing hybrid MgFe₂O₄/UU-200 materials at 120 °C and within 10 min. The reaction yield reached approximately ∼74.5 %, and the production rate was ∼3.09 g/h. The nanocrystallites of MgFe₂O₄ were effectively incorporated into UU-200 frameworks during the reaction between Bi³⁺ ions and ligands, resulting in heterostructures with enhanced visible light absorption and magnetic properties. Under visible light irradiation, the sample prepared with a Bi³⁺/MgFe₂O₄ molar ratio of 2 exhibited the optimum photocatalytic removal efficiencies of ∼93 % for Cr⁶⁺ and ∼87% for Rhodamine B (RhB) from aqueous solutions, giving the highest photoreduction rates of 0.0124 min⁻¹ and 0.0093 min⁻¹, respectively. In addition, simultaneous decolourisation tests demonstrated that these structures effectively removed pollutants from the binary solution. The analyses revealed that photoinduced electrons photocatalytically reduced Cr⁶⁺ to Cr³⁺, while h⁺ and OH radicals predominantly drove the dye degradation. Notably, the produced MgFe₂O₄/UU-200 was rapidly isolated from the suspension solution using a magnet, thereby reducing its loss into the environment. The study presents an effective strategy for the scalable production of magnetic and visible-light-active MgFe₂O₄/UU-200 catalysts for photocatalytic water decontamination.