Solar photocatalytic degradation of emerging contaminants using NH2-MIL-125 grafted by heterocycles

This work reports the photocatalytic performance of NH2-MIL-125 grafted by heterocycles for the removal of contaminants of emerging concern under solar light. Grafting NH2-MIL-125 with different heterocyclic carboxaldehydes reduces the band gap, thanks to the performance of the heterocycle as an antenna for light absorption. Grafting with 3-pyridinecarboxaldehyde (3PA) results in the best light harvesting for the degradation of acetaminophen in different water matrices. The abatement of additional emerging contaminants, i.e., antipyrine and sulfamethoxazole, was also evaluated. The photocatalytic performance depends on the nature of the target compound. Trapping experiments conclude that superoxide radicals are the main reactive species involved in the photodegradation process, while electrons and hydroxyl radicals play a minor role. The 3PA-grafted photocatalyst shows remarkable constant performance in a novel analysis in a continuous flow regime, achieving total conversion of acetaminophen (ACE) for 16 h on stream. The results herein described provide a comprehensive insight into the solar photocatalytic degradation of emerging contaminants using NH2-MIL-125 grafted by aromatic heterocycles.