Yu Liang;Hongfeng CHEN;Jianming Xu;Mingxia Wang;Wenfeng Ta

iron (hydr)oxides;al substitution;structural properties;interfacial reactions;hematite;crystallize

Isomorphic substitution of Fe3+ by Al3+ in iron (hydr)oxides is ubiquitous in natural environments. Al substitution inevitably leads to changes in the microstructures, physicochemical properties, and surface reactions of iron (hydr)oxides, which may have great impacts on the sequestration of nutrients and contaminants in soils and aquatic environments. Over the past decades, the structural properties and surface reactivity of Al-substituted iron (hydr)oxides have been intensively studied. Iron (hydr)oxides in various structural forms and with different Al substitution amounts present highly diverse structure and Al content and potential in many frontier fields of environmental issues. A timely summarize of the structural properties and interfacial reactions of the most common and representative well-crystallized (goethite and hematite) and poorly crystallized (ferrihydrite) iron (hydr)oxides under Al substitution is highly demand. Herein, the effects of Al substitution on the structural properties and surface activity of iron (hydr)oxides was clarified according to the microstructure, crystal facets, surface site type and density, interfacial reaction mechanisms, and modeling parameters of iron (hydr)oxides. This review systematically elucidates how Al substitution affects the structural properties and surface reactions of iron (hydr)oxides, providing theoretical guidance for further exploring the mineralogical characteristics and environmental geochemical behavior of iron (hydr)oxides.