Simultaneous efficient adsorption and photocatalytic degradation of methylene blue over iron(III)-based metal-organic frameworks: a comparative study

Here, we prepared a series of Fe-based metal organic frameworks (MOFs), including MIL-53(Fe), NH2-MIL-53(Fe), MIL-88B(Fe) and NH2-MIL-88B(Fe), via an oil bath process and used them to remove methylene blue under visible light. A comparative study of NH2-MILs and Fe-MILs was conducted. The experimental results showed that the presence of amino groups could improve the adsorption capacities of NH2-MILs, which was attributed to hydrogen bonding interactions and pi-pi stacking between the amino groups of the dye molecules and the amino-functionalized MOFs. The photocatalytic activities of NH2-MILs under visible light were higher than those of Fe-MILs, owing to the enhancement of visible-light absorption, the decrease in the band gap and the improvement of the adsorption capacity. After several photodegradation experiments, the catalytic activities decreased and could be restored by irradiating the catalysts with ultraviolet light. This study indicated that the amino-functionalized materials had great potential for wastewater treatment and resource utilization.