Removal of organic pollutants from water by Fe2O3/TiO2 based photocatalytic degradation: A review

The occurrence of persistent organic pollutants (POPs), such as dyes, pharmaceuticals and endocrine disrupting compounds in the aquatic environment is attracting significant concerns worldwide due to their bioaccumulation, toxicity, and potential risk to the environment. These contaminants are produced daily in large amounts and released onto water bodies intentionally or accidently. Conventional wastewater treatment plants are inefficient for the degradation of these pollutants. Thence, the development of sustainable and effective techniques for the removal of POPs is essential. In this sense, the application of photocatalysis for the removal of POPs is a promising, effective and sustainable technology. TiO2 is the most common studied photocatalyst due to its low-cost, availability and non-toxicity. However, TiO2 exhibits a high band gap around 3.2 eV, which restricts its use under visible light. In this regard, attempts have been investigated to shift the adsorption of TiO2 to visible light by reducing its band gap energy to below 3.2 eV. Doped photocatalyst is a successful approach to reduce the band gap energy of TiO2. Fe2O3 is considered an ideal dopant due to its unique properties such as magnetic properties and low bandgap. Fe2O3-TiO2 has shown remarkable performance for the removal of POPs as well as successful recovery and reusability of the photocatalyst after the treatment process. This review attends at providing deep insights on the synthesis methods of Fe2O3-TiO2, particularly, the sol–gel method. The photoactivity of Fe2O3-TiO2 towards POPs is also presented along with the parameters that influence the photodegradation process. Future research needs are also addressed.