Adsorption and heterogenous Fenton-like reactivity of NH2-MIL-88B towards toxic dyes removal

Organic pollutants especially those with high toxicity and non-degradability are severely threatening environmental and human beings. Compared with traditional methods, advanced oxidation methods such as Fenton degradation have gained much attention thanks to their distinct advantages. Herein, NH2-MIL-88B was fabricated via solvothermal method and used in rhodamine b (RhB) removal from aqueous solution. We emphasized on activation effect on structure and RhB removal ability change. Different from other reports, it is found that activation didn’t induce the valence state change of Fe in the sample. But the adsorption ability was significantly increased, which synergistically led to the enhanced heterogeneous Fenton-like degradability. The prominently increased adsorption was ascribed to the increased surface area induced by activation. Synergistic effect of enhanced adsorption and heterogeneous Fenton-like degradation enables NH2-MIL-88B with optimized parameters to remove RhB totally with initial concentration of 50 mg/L in 60 mins. RhB adsorption on NH2-MIL-88B followed Langmuir adsorption isotherm and the adsorption behavior abided by pseudo-second-order kinetics. It was proposed that activation would directly increase adsorption and indirectly increase heterogeneous Fenton-like degradation. This synergistic effect endow NH2-MIL-88B with great performance. Our research here could provide clues for exploiting strategies to improve ability of existed MIL(Fe)-type heterogenous Fenton-like catalyst and fabricating novel products. [Display omitted] •NH2-MIL-88B crystals with bipyramidal hexagonal prism morphology were fabricated.•Activation significantly increased RhB removal ability of NH2-MIL-88B.•Increased RhB removal is ascribed to both adsorption and catalysis enhancement.•Mechanism refers to direct adsorption and indirect catalysis improvement was proposed.