Nanoparticulate Iron Oxides for Aquatic Chromium Remediation: Mechanisms, Advances, and Environmental Prospects

Abstract

Chromium especially its carcinogenic hexavalent form (Cr(VI)) is the worst danger to the water security and the health of the people because of its persistence and mobility. This review is a critical analysis of the use of nanoparticulate iron oxides (Fe-NPs) as a multifunctional and sustainable system of Cr removal in an aqueous system. It describes the synthesis and characteristics of the principal Fe-NPs phases such as magnetite, hematite and goethite, and clarifies the synergetic actions of adsorption reduction and co-precipitation by which they capture and detoxify Cr. The article also discusses high-technology engineering approaches, including surface functionalization and composite formation, that improve performance, stability, and recoverability. The major operation variables affecting the extent of removal such as water chemistry and the characteristics of nanoparticles are discussed. Even with their good laboratory efficacy, serious issues of up-scale, long-term stability, and overall environmental safety evaluations are brought into the limelight. The review summarizes by highlighting future research needs, which are the creation of smart, scalable, and benign-by-design systems of Fe-NPs to fill the gap between the potentially promising nanomaterial science and actual field-scale water remediation technology.