Synthesis, characterization and heterogeneous photo-Fenton-like catalyst activity of a novel inorganic-organic 2D framework based on reduced α-Keggin phosphomolybdate

Abstract

A novel inorganic-organic 2D framework [CuI2CuII2(L)4(PMoV3MoVI9O40)(H2O)] (CuLPMo12) [L = 4-(4H-1,2,4-triazol-4-yl)pyridine)] based on reduced α-Keggin phosphomolybdate was hydrothermally synthesized and fully characterized. CuLPMo12 was found to be an efficient heterogeneous photo-Fenton-like catalyst for the degradation of dyes including methyl orange (MO), methylene blue (MB) and rhodamine B (RhB). The Fenton-like catalyst activity study of CuLPMo12 was carried out by employing RhB as model dye, because it had the best catalytic effect on RhB degradation. The degradation of RhB was affected by initial pH value and concentration of RhB solution, concentration of H2O2 and CuLPMo12 dosage. The optimum conditions for RhB degradation in the photo-Fenton-like progress were determined, the color of RhB could be completely removed in 5 min and the total organic carbon (TOC) removal was up to about 81.8% in 3 h under these conditions. These data were superior to that of similar compounds reported by other groups. Moreover, this system could work in a wide pH range and the optimum pH value was 7. Working at neutral pH made it be more convenient to operate than the acidic traditional Fenton system. UV–Vis spectroscopy results confirm that the N-deethylation and the conjugated chromophore cleavage reactions occurred simultaneously in a stepwise manner during RhB degradation process. Mechanism research indicates that the active species, such as 1O2,•OH, and •O2H/O2•− were responsible for RhB degradation. The better stability and recyclability of CuLPMo12 suggest that the present photo-Fenton-like system has potential in practical wastewater treatment.