Construction of a stable porous composite with tunable graphene oxide in Ce-based-MOFs for enhanced solar-photocatalytic degradation of sulfamethoxazole in water

• Tunable GO in Ce-MOFs promoted the photocatalytic performance. • The composite facilitates the charge transfer in photocatalysis. • •O 2 – has been identified as the major reactive oxygen species. • Steady-state concentrations of ROS have been calculated. • This composite shows better water stability than the pristine Ce-MOFs. Pharmaceutically active compounds (PhACs) are ubiquitously detected in water matrices, arousing growing concern. Effective abatement of these toxic environmental contaminants is challenging but of great importance. Ce-based MOFs have been considered novel metal–organic framework (MOFs)-based photocatalysts in water treatment. However, limited light absorption ability, fast recombination of photogenerated carriers, and water stability limited the further application. Here, the UiO-66 (Ce) was successfully constructed onto the surface of a series of graphene oxide (GO) (1 mg ∼ 7.5 mg) in situ. GO with oxygen-containing functional groups (OCFGs) increased the adsorption (∼45 %) of the trace amount of sulfamethoxazole (SMX) (200 μg/L) over the interfaces and enhanced the degradation efficiency of SMX. The composite with the optimal ratio (GO@ UiO-66 (Ce)-5) significantly increased the charge separation ability and produced a large number of reactive oxygen species (ROS). •O 2 – was proved to be the major driving reactive substance for SMX degradation with the calculated steady-state concentration of 2.5 × 10 -9 M (∼1.37 times higher with bubbled oxygen), which is much higher than that of detected •OH (1.62 × 10 -14 ). Major operational parameters including dissolved oxygen, initial solution pH, and catalyst dosages were investigated systematically. Several intermediates were identified by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-MS/MS). By choosing the strategy, MOFs were closely bonded to the surface of the GO matrix, making the leakage of Ce ions inhibited obviously (∼3 times) in the water treatment process. This study offers useful guidance for improving the performance of existing photocatalytic materials for PhACs removal.