▎ 摘　　要

Magnetite (Fe3O4), a core-shell material (SiO2@Fe3O4), and reduced graphene oxide-Fe3O4 (referred as rGO-MN) were used as supports of a specific highly active TiO2 photocatalyst. Thermal treatments at 200 or 450 degrees C, different atmospheres (air or N-2), and TiO2:support weight ratios (1.0, 1.5, or 2.0) were investigated. X-ray diffractograms revealed that magnetite is not oxidized to hematite when the core-shell SiO2@Fe3O4 materialor a N-2 atmosphere (instead of air) in the thermal treatmentwas employed to prepare the TiO2-based catalysts (the magnetic properties being preserved). The materials treated with N-2 were first tested for degradation of imazalil (a well-known fungicide) in deionized water. The best compromise between the photocatalytic activity, magnetic separation, and Fe leached (1.61mgL(-1), i.e., below the threshold for water reuse in irrigation) was found for the magnetic catalyst prepared with SiO2@Fe3O4, an intermediate TiO2:support ratio (1.5), and treated at 200 degrees C under N-2 atmosphere (i.e., SiO2@Fe3O4-EST-1.5-200-N-2). This material was then tested for the treatment of imazalil in a synthetic wastewater, SW (with a chemical composition simulating an effluent resulting from fruit postharvest activity). This SW has a pH of 4.2 and the experiments were carried out at this natural pH(0) and at neutral conditions (keeping pH at 7 along the reaction). The magnetic catalyst was more active than bare TiO2 for the treatment of imazalil in SW at natural pH. Since Fe leaching was observed (3.53mgL(-1)), added H2O2 enhanced both imazalil degradation and mineralization. Conveniently, these catalysts can be readily recovered by using a conventional magnetic field, as demonstrated over three consecutive recycling runs.