Sustainable removal of hexavalent chromium using MOFs, adsorption mechanisms and modeling studies

Hexavalent chromium [Cr(VI)] is a highly toxic and carcinogenic pollutant commonly released from electroplating, leather tanning, textile, and pigment industries, posing severe risks to environmental and human health. Conventional remediation approaches, including chemical precipitation, ion exchange and membrane filtration, often face challenges such as high operational cost, sludge generation and limited selectivity. Metal-organic frameworks (MOFs), owing to their ultrahigh surface areas, tunable pore structures, and chemical versatility, have emerged as promising materials for Cr(VI) removal. MOFs can simultaneously adsorb Cr(VI) through electrostatic interactions and functional group binding, while redox-active metal centers and photocatalytic properties enable in situ reduction to the less toxic trivalent chromium [Cr(III)]. This adsorption–reduction mechanism enhances removal efficiency and detoxification, distinguishing MOFs from conventional adsorbents. This review systematically discusses the sustainable removal of Cr(VI) using MOFs, with emphasis on adsorption-driven and catalytic mechanisms. Adsorption isotherm models, kinetic studies, and thermodynamic analyses that provide insights into the underlying removal processes. Finally, future perspectives on designing robust, cost-effective and multifunctional MOFs are highlighted to advance their application in real-world water treatment systems.