Fenton-like Catalysts Based on Supported Cu for Dyes’ and Pharmaceuticals’ Removal Using Only H ₂ O ₂ and/or O ₂ as Oxidants: A Review Focused on the Last 10 years

Homogeneous Fenton and Fenton-like systems have been studied for more than 100 years. Applications in environmental remediation require the immobilization of metals with this kind of activity onto suitable supports. These metals need to be in adequate oxidation states. With the growing interest in sustainability and the strict regulations about liquid effluents, heterogeneous Fenton and Fenton-like systems are being studied more and more, mainly if they can be applied with low investment costs. Not only supports but also active phases must be present with an adequate particle size. Catalysts' physicochemical and physical properties need to be tailored to specific applications. Nanoscience has demonstrated that metallic and oxide nanoparticles present different properties than bulkier particles' sizes. Particularly some of them present enzyme-like activities when a nanometric size is achieved, and they have been named nanozymes. Copper with different particle sizes (up to nanoparticles) supported onto different oxides and supports (with other transition metals), without additional energy input, may be especially attractive for practical uses in advanced oxidation processes (AOP). In AOP, ^•OH radicals and other species oxidize organic and inorganic compounds. Multicatalytic systems including Cu and magnetite may be efficient with only hydrogen peroxide and/or O₂ as oxidants to produce these active species. This review presents the main results in this field (including multimetallic supported catalysts) for mainly the last 10 years.