Heterogeneous UV/Fenton-Like Degradation of Methyl Orange Using Iron Terephthalate MIL-53 Catalyst

Pham Dinh Du,Nguyen Mau Thanh,Vo Thang Nguyen,Pham Ngoc Hoai,Dinh Quang Khieu,Huynh Thanh Danh

doi:10.1155/2020/1474357

Abstract

The synthesis and degradation of methyl orange (MO) in an ultraviolet-assisted heterogeneous Fenton-like process via the iron terephthalate (MIL-53) catalyst are demonstrated. MIL-53 material was characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectra (DR-UV-Vis), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherms. It was found that the obtained material shares an identical pattern of the MIL-53 structure with high crystallinity and also demonstrates the mesoporous phase with a pore diameter of around 4.2 nm and specific surface area, SBET, of 88.2 m2·g−1. MIL-53 with UV irradiation exhibits high catalytic activity for MO degradation by hydrogen peroxide. The factors affecting the efficiency of MO decomposition including pH of the solution, H2O2 concentration, catalyst dosage, initial MO concentration, and reaction temperature were addressed. The present catalyst is stable after four recycles with slight catalytic activity loss which makes it a potential candidate for environmental restoration.

Highlights

TWater pollution by dyes and pigments is a concern for the development of communities
E X-ray diffraction (XRD) patterns of MIL-53 synthesized at different hydrothermal temperatures are shown in Figures 1(c) and 1(d). e samples synthesized at temperatures of 100, 120, and 150°C exhibit diffraction peaks which are typical for the MIL-53 structure
Terephthalic acid (TA) and the obtained MIL-53 samples were characterized by Fourier-transform infrared spectroscopy (FT-IR) spectra (Figure 3). e spectrum of TA exhibits characteristic absorption bands in which the typical peaks are C O stretching vibration (1681 cm−1), OH bending vibration (1,423 and 937 cm−1), and C-H bending vibration of the benzene ring (784 cm−1) [28]. e MIL-53 samples synthesized at 100°C and 120°C present the typical vibrational bands of the carboxylic acid function in the region of 500–1,750 cm−1 indicating the presence of terephthalic acid residual, and the formation of the MIL-53 phase is incomplete at these temperatures

Summary

Introduction

TWater pollution by dyes and pigments is a concern for the development of communities. Fenton-like processes are treatment procedures involving the in situ generation of the active hydroxyl radical (OH) that has a high standard potential (E° 2.80 V/SHE) and can nonselectively oxidize almost all organic compounds into CO2, H2O, and inorganic ions [9, 10]. It has been shown that the Fenton process can be further enhanced with UV light illumination [12, 13], which can be explained by an increase in OH radical production due to the decay of the photoactive Fe(OH)2+ This homogeneous Fenton catalytic procedure requires a concentration of 50–80 ppm of iron, which is much larger than allowable level (the standard of 2 ppm guided by European Community Directives) [13]. Some factors affecting the formation of MIL-53 have been studied. e heterogeneous UV/Fentonlike system using the MIL-53 catalyst for methyl orange degradation has been addressed

Experimental

Catalyst Characterization

Fe 2s Fe 2p

Catalytic Activities