Spectroscopic and kinetic studies on the degradation of methylene blue using the supramolecular coordination polymer [(Ph3Sn)4Fe(CN)6] as catalyst

The structure of the supramolecular coordination polymer (SCP), [(Ph3Sn)4Fe(CN)6], 1, consists of octahedral [Fe(CN)6]4− building blocks which are connected by the TBPY-5 configured Ph3Sn(CN…)2 fragments creating 3D-network structure that contains terminal cyanide groups. The catalytic behavior of the SCP 1 was utilized for Fenton and photo-Fenton degradation of methylene blue dye (MB). The plot of kinetic degradation indicates pseudo first-order rate with respect to the MB dye concentration, Kobs. = 0.071 min−1. On the other hand, the observed rate constant of the photo catalytic degradation of MB equals to 1.45 min−1 indicating that irradiation enhances, significantly, the rate of degradation of MB dye. Discoloration of the dye was obtained in less than 3 h. Meanwhile, the conjugated structure and the phenyl rings of the MB molecule were destroyed or even broken down into small organic acids and inorganic ions, as indicated by FT-IR spectra. Disodium salt of terephthalic acid photoluminescence probing technology and radical scavenging measurements were carried out to identify the reactive oxygen species. The different parameters that affect MB degradation rate were evaluated. Moreover, the efficiency of recycled the SCP 1 and the mechanism of degradation of MB dye was investigated.

Graphical abstractThe catalytic behavior of the SCP [(Ph3Sn)4Fe(CN)6], was utilized for Fenton and photo-Fenton degradation of methylene blue dye which obeys pseudo first-order rate. The photo catalytic degradation of MB indicated that irradiation enhances, significantly, the rate of degradation of MB dye. Photoluminescence probing technology suggested that the reaction of MB degradation mainly involved the generation and participation of hydroxyl radicals. The different parameters that affect MB degradation rate and the mechanism were investigated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► [(Ph3Sn)4Fe(CN)6] was used as catalyst for Fenton and photo-Fenton degradation of methylene blue. ► The reaction is pseudo first-order rate which is significantly enhanced by irradiation. ► Photoluminescence indicated that the reactive oxygen species are the •OH radicals. ► Different parameters that affect MB degradation rate and mechanism were investigated.