Review on the Removal of Dyes by Photodegradation Using Metal-Organic Frameworks Under Light Irradiation

Mekonnen Endashaw

doi:10.7176/cmr/12-1-03

Abstract

Metal–organic frameworks are coordination network/polymer with organic ligands containing potential voids. MOFs are a class of porous polymeric material, consisting of metal ions linked together by organic bridging ligands. Different Metal-organic framework compounds of Zn, Fe, Al, Cr, Co, and Cd have been successfully synthesized using different synthesis method under ambient conditions by different scholars. The photocatalytic activity of these MOFs was investigated by the degradation of different organic dyes (such as: MO, MB, DTBP, Orange G., RhB, RBB, and phenol) in aqueous solution under light irradiation. These MOFs exhibits a promising photocatalytic activity for efficient dye degradation under UV –visible light depending on their band gap differences. The effect of electron acceptors (H 2 O 2, KBrO 3 and (NH 4 ) 2 S 2 O 8 ) addition on the photocatalytic performance of MIL-53(Fe) on MB dye was also evaluated. The photocatalytic performance of this MOF was enhanced by the presence of electron scavengers by prolonging the hole-electron recombination. As a photocatalyst, the most remarkable feature of MOFs is the observation of reverse shape selectivity in which large molecules that cannot access the interior of the micropores are degraded significantly faster than those others that can enter into the pores. Keywords : Metal organic frameworks, photodegradation, photocatalysts, dyes, electron scavengers, and reverse shape/size selectivity. DOI : 10.7176/CMR/12-1-03 Publication date: January 31 st 2020

Highlights

Dyes make our world beautiful, they bring us pollution
Synthesis Methods of metal-organic framework (MOF) Some reaction parameters are needed to be considered in order to reproduce the MOF materials
MOFs have high thermal stability, excellent crystallinity, high surface area and larger pore volume. They have a promising photocatalytic activity for the removal of different organic dyes by photodegradation upon irradiation of lights with different wavelength depending on their band gap differences

Summary

INTRODUCTION

Dyes make our world beautiful, they bring us pollution. Color is the first contaminant to be recognized in wastewater and has to be removed before discharging into water bodies or on to land. Dye wastewater usually consists of a number of contaminants including acids, bases, dissolved solids, toxic compounds, and colored materials. They can have acute or chronic effects on exposed organisms, which depend on the concentration of the dye and the exposed time. Conventional dye removal methods, including physical, chemical, and biological processes, have been used intensively as a solution for the problem These methods have disadvantages such as impacts on health, high cost and difficulty in recycling. It is a problem because of these dye compounds in wastewater ordinarily contain one or several benzene ring and cannot be decomposed in chemical and biological processes. Sometimes they are referred to as hybrid inorganic-organic frameworks and a subset of which are inorganic coordination polymers (Wilkinson et al, 1987)

Composition of MOFs

CONCLUSION