Review on the application of modified iron oxides as heterogeneous catalysts in Fenton reactions

Abstract

Heterogeneous Fenton reaction is an advanced oxidation process which has gained wide spread acceptance for higher removal efficiency of recalcitrant organic contaminants under wide range of pH compared to homogeneous reactions. Conventionally, iron oxides are used as heterogeneous catalysts for Fenton oxidation system because of their abundance, easy separation and lower cost. This paper reviews the substitution of iron in an iron oxide with other transition metals as a mean to improve the properties of the iron oxide towards higher performance for contaminant degradation. Several studies have reported enhanced performance resulted from this substitution based on two possible mechanisms. First is the conjugation of redox pairs of iron species and imported active ion in hydroxyl radical production cycle. Second: the generation of oxygen vacancies as active sites on the surface of catalyst via adjustments for unequal charge substitutions. This class of catalysts is anticipated to work effectively for treatment of various recalcitrant wastewaters using Fenton oxidation system. Subsequently, the stability of the produced catalyst needs to be examined under various experimental conditions to prevent the adverse effects of transition metals on the receiving environment.

Interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials: A review

“…Iron-based materials possess the advantages of high Fenton activity, low cost, negligible toxicity, and easy recovery (Pereira et al, 2012;Rahim Pouran et al, 2014). Hence, they become a superior type of heterogeneous Fenton catalysts, which can degrade phenolic compounds, dyes, insecticides, etc.…”

A Comparative Study on a Cationic Dye Removal through Homogeneous and Heterogeneous Fenton Oxidation Systems

“…In light of this, a number of solutions have been proposed to overcome the shortcomings of homogeneous Fenton reaction. Application of chelating agents, 11 and heterogeneous catalysts, 11,16 are examples to stabilize the iron in the solution and expand the applicable pH range of the reaction. Large numbers of heterogeneous iron compounds such as zero-valent iron (ZVI), 17 clays, silica, zeolites, 18 and iron minerals, 16 have been studied for dye wastewater treatment through Fenton reaction.…”

Removal of Phenol from Wastewater Using Fenton-Like Reaction over Iron Oxide–Modified Silicates

“…Modification of iron oxides to improve their performance in organic pollutant degradation can be achieved by substitution with other transition metals [12]; however, introduction of heavy metals may be questionable from the point of view of the secondary contamination with catalytic leachates. It is also known that nanoscale materials are characterized with different properties compared to their bulk phase [8,13,14].…”