Mechanochemical approach to gallate bioMOFs: efficient synthesis and Cr(vi) removal from aqueous and soil systems

Abstract

Heavy metal atoms, such as chromium, lead, cadmium, and others, are harmful to health and the environment and can cause irreversible impacts at certain concentrations. Given the hazards and increasing levels of chromium in aquatic and soils systems due to anthropogenic activities, it is important to implement heavy metal adsorption technologies for sustainable and green development. Here, two bioMOFs were synthetized via mechanochemistry, a solvent-free and environmentally friendly method that enables faster reactions compared to conventional solvothermal synthesis. Both MOFs use gallate as the organic linker, and the reactions were performed using a vibratory ball mill. The Fe-gallate MOF was obtained after 15 minutes of milling and the Mg-gallate MOF, after 60 minutes of milling, both significantly faster than what was reported before. The maximum Cr(VI) removal efficiency (29%) was obtained with the mechanochemically synthesized Fe-gallate. The material was further applied to Cr-rich soil samples, confirming its efficiency in chromium removal from complex matrices. These findings reinforce the potential of mechanochemistry as a sustainable route for the synthesis of advanced materials, particularly bioMOFs, providing greener alternatives from material selection to synthesis and application.