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

Abstract

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.=0.071min−1. On the other hand, the observed rate constant of the photo catalytic degradation of MB equals to 1.45min−1 indicating that irradiation enhances, significantly, the rate of degradation of MB dye. Discoloration of the dye was obtained in less than 3h. 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.