Current trends in the use of zero-valent iron (Fe0) for degradation of pharmaceuticals present in different water matrices

Abstract

Zero-valent iron (Fe0) has recently been proposed as a potential candidate for the degradation of pharmaceuticals, because Fe0 can release dissolved iron species, activate molecular oxygen, and react with oxidant species. Additionally, due to its small particle size and large surface area, this catalyst can provide better degradation results, compared to traditional processes. This work focuses on the elimination of pharmaceuticals present in different water matrices, considering the potential harm that these substances can cause in the environment. The mechanisms of pharmaceutical removal using Fe0 particles include reduction, adsorption, precipitation, and oxidation processes. Most studies have focused on oxidation processes in the presence of Fe0 and radicals derived from oxidants such as hydrogen peroxide (H2O2), ozone (O3), peroxysulfate (SO52−), peroxodisulfate (S2O82−), and oxygen (O2). Most of the results have shown that high percentages of pharmaceuticals can be removed, degraded, and mineralized. The mechanisms of oxidation and the parameters that influence the degradation of pharmaceuticals, as well as the possible degradation pathways, are discussed here. This review provides information on trends of different processes that use Fe0, considering aspects such as particle size, type of matrix, the pharmaceuticals studied, and the results obtained that can improve understanding of new advances in the field of advanced oxidation processes (AOPs) for the degradation and elimination of pharmaceuticals.