Enhanced heterogeneous Fenton oxidation of organic pollutant via Fe-containing mesoporous silica composites: A review

One of the efficient processes used in water remediation is Fenton reactions, which are classified as homogeneous and heterogeneous. The soluble iron-based homogeneous Fenton process suffers from problems such as limited operating pH and high production of ferrous hydroxide sludge. In this regard, heterogeneous Fenton processes have been developed in which dissolved iron are replaced by solid catalysts containing iron. Recently, the development of new composites that combine active metal/metal oxide nanoparticles with porous supports that can be used in a heterogeneous Fenton process has received much attention. Among the porous materials, mesoporous silica with high surface area and high pore volume and capable of loading and dispersing catalytically active components has been widely used as catalyst support. Iron-based silica composites have shown high catalytic activity in the decomposition of hydrogen peroxide and the production of hydroxyl radicals facilitating the removal of organic pollutants. This article reviews recent advances in the use of iron-containing silica catalysts in the removal of organic pollutants from aqueous solutions by the heterogeneous Fenton process. The results show that the catalytic activity of various iron species in silica supports is significantly increased compared to unsupported iron oxides. The large cavities of the silica support facilitate the mass transfer processes, and the high surface area of these materials increases the number of active sites, allows more contaminant access to these sites. Strategies for enhancing the catalytic performance of iron/silica composites include the simultaneous loading of metals and the preparation of bimetallic catalysts, the design of multimodal pore supports, surface functionalization to better distributed active sites in the composite, the use of radiation, ultrasound, and electrolysis. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Fenton reactions, classified as homogeneous and heterogeneous, are efficient processes used in water remediation. Heterogeneous Fenton processes, using solid catalysts containing iron instead of dissolved iron, have shown higher catalytic activity compared to unsupported iron oxides. Iron-containing silica composites have been widely used for the removal of organic pollutants from aqueous solutions.