2,3-pyridinedicarboxylic acid-modified MIL-88A(Fe) for enhanced peroxymonosulfate activation to degrade organic contaminants

Metal-organic framework (MOF)-based composites have shown a great application potential in photoassisted persulfate activation process and environmental remediation. Herein, 2,3-pyridinedicarboxylic acid (PDA) is firstly used to improve the catalytic activity of MIL-88A(Fe). The composite catalysts are effectively synthesized using a solvothermal method. At an 80.2 mg modification level of PDA, the catalyst [MIL-88A(Fe)-PDA-3] could achieve 98.20 % removal of AR18 (acid red 18) through the visible-light-assisted peroxymonosulfate (PMS) activation. It is 7.8-fold increase than pristine MIL-88A(Fe). The suitable conditions for AR18 elimination are 0.4 g/L MIL-88A(Fe)-PDA-3, 1.5 mM PMS and pH = 10. The interplay between influencing factors is explored by a response surface methodology. The quenching studies and EPR tests indicate the generation of active species such as center dot OH, SO4 center dot-, O-1(2), O-2(center dot-), and Fe-IV--O in the reaction system, with center dot OH playing a significant role for AR18 degradation. A potential mechanism is proposed based on the above results. This study offers a fresh perspective for the development of efficient MOFs materials.