NDI modification strategy to construct MOFs composites for high-performance photocatalytic degradation towards ofloxacin

NDI-modified MOF material (NDI/MFe) was synthesized by strong covalent amide bonds. • NDI/MFe = 1:1.5 exhibited great OFL photodegradation efficiency, which was two times for NH 2 -MIL-53(Fe). • The modification of NDI provides an effective pathway of electron transmission and accelerates the transformation of electron. Given the excessive enrichment of fluoroquinolone antibiotic ofloxacin (OFL) in aqueous ecosystems, naphthalimide derivative H 4 BINDI (H 4 BINDI = N , N ’-Bis(5-isophthalic acid) naphthalenediimide) covalently modified NH 2 -MIL-53(Fe) (denoted as NDI/MFe) was synthesized through a solvothermal strategy, grafted onto the framework via covalent amide bonds. The physicochemical properties of the modified MOF composites were comprehensively characterized, and their photocatalytic degradation capability for OFL was assessed under complex aqueous solutions and coexisting ions. In addition, NDI/MFe = 1:1.5 composite achieved a two-fold improvement in OFL photodegradation efficiency relative to initial NH 2 -MIL-53(Fe). Such a prominent performance enhancement originates from the introduction of NDI moieties and the construction of covalent amide bonds. Free radicals and electron capture experiments verified that •O 2 ⁻, •OH, and e⁻ served as active species with distinct functions in the photocatalytic system. The refractory OFL molecules could be eventually mineralized into low-toxicity small molecular substances. This study not only provides an effective strategy for mitigating antibiotic water pollution and also offers a new insight into the further development of high-performance MOF composites. This study prepared a covalently modified MOF photocatalyst NDI/MFe by grafting naphthalimide derivative H 4 BINDI onto NH 2 -MIL-53(Fe) via amide bonds for ofloxacin (OFL) degradation. Characterizations confirmed successful amide linkage formation, improved visible-light absorption and charge separation. The 1:1.5 composite doubled degradation efficiency, removing over 80% OFL in 50 min. Active species included •O 2 ⁻, •OH and photogenerated charges. The catalyst showed good stability after four cycles. OFL was mineralized into CO 2 and H 2 O. This work provides a feasible covalent modification strategy for high-performance MOF photocatalysts in antibiotic wastewater treatment. Download: Download high-res image (115KB) Download: Download full-size image