Optimized scalable synthesis and granulation of MIL-88B(Fe) for efficient arsenate removal

Abstract

Arsenic contamination has adverse health effects on human, and metal-organic frameworks (MOFs) are suitable adsorbents for its removal. The small-scale synthesis and high cost hindered the application of MOFs in arsenic removal. The challenge resulted from the strict synthesis conditions, like harsh temperature or pressure and the use of toxic organic solvents such as N, N-Dimethylformamide, etc. We reported herein an optimized method for scalable synthesis of MIL-88B(Fe) in innocuous ethanol solvent under benign conditions (low temperature, normal pressure, and no pretreatment of reactants). Synthetic parameters, such as the ratio of reactants, temperature, reaction time, and purification process, were optimized to achieve scalable preparation of the product. The scale-up produced MIL-88B(Fe) presents extraordinary adsorption capacity (128.99 mg/g) towards toxic arsenate in water. Furthermore, we shaped the MOFs powder into millimeter-scale granules by using the bio-compatible binding agents and flash freezing treatment. The composite also outperforms in arsenate adsorption capacity than that of commercially available products. Additionally, a 250-hours dynamic column adsorption operation proves that the composite can guarantee a safe concentration level of arsenate effluent. The well-shaped porous structure of composite facilitates its application and avoids secondary pollution in real scenarios, demonstrating applicable prospects as filters for water purification.