Iron Oxide and Hydroxides for the Removal of Heavy Metals from Wastewater

Due to their remarkable adsorptive qualities, low cost, and wide availability, iron oxides and hydroxides have attracted a lot of interest as efficient materials for the removal of heavy metals from wastewater. The mechanisms by which iron-based minerals, such as ferrihydrite, magnetite, haematite and goethite interact with heavy metals through ion exchange, co-precipitation, and adsorption are covered in detail in this chapter. In order to maximise metal uptake efficiency, the importance of surface chemistry, particle size and mineral crystallinity is emphasised. This study critically examines developments in iron oxide functionalisation and modification to improve their capacity and selectivity for particular metals, including cadmium, lead and arsenic. While there are naturally occurring iron oxides/hydroxides, it is possible to synthesise them, coupling the synthesis with surface modifications, and these are usually monitored or verified using easily accessible instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). This integration of the iron oxides/hydroxides with materials in nanotechnology and polymers has been beneficial for the removal of both heavy metals and other pollutants, such as organic ones, which highlights the versatility of the materials. The ability of the materials to be regenerated for further use makes them attractive in the wastewater treatment industry and in terms of environmental beneficiation. This chapter, therefore, provides a comprehensive analysis of iron oxides and hydroxides, highlighting their crucial role in developing sustainable wastewater treatment systems and reducing heavy metal pollution.