Construction of NiP/Ni(OH)2/Ag-ZIF photocatalyst with 2-methylimidazole framework for rapid removal of tetracycline

Abstract

Tetracycline (TC) is a kind of antibiotic that is difficult to be degraded by photocatalysis due to its stable molecular structure, and no ideal photocatalyst has been developed so far, thus developing a photocatalyst that can efficiently remove TC remains a challenge. In this work, a novel ternary photocatalyst of NiP/Ni(OH)2/Ag-ZIF (NNA) with 2 −Methylimidazole framework was constructed via a facile liquid phase reaction, in which the NiP is amorphous with particle size of about 3–5 nm, the Ni(OH)2 is nano-flake crystal with a one-dimensional diameter of about 200 nm, and the Ag-ZIF is a octahedral crystal with a side length of 4 µm. The NiP nano particles covered on the surface of Ni(OH)2 nanosheeps to form NiP/Ni(OH)2 heterojunction with flower-like structure and large BET area of 393.11 m2 g−1, which was further assembled with Ag-ZIF to form NiP/Ni(OH)2/Ag-ZIF composite with double heterojunction. The as-constructed NNA shows high removal capacity for TC, while 10 mg NNA was added into 100 mL 60 mg/L TC solution and exposed in visible light for 60 min, 91.3% of TC was removed. Meanwhile, the NNA shows good stability and reusability, which is attribute to the reversible of adsorption and desorption process of NiP/Ni(OH)2 for TC and the excellent photo-corrosion resistance of Ag-ZIF. The radical trapping and electron spin resonance (ESR) tests manifested that the superoxide radical (O2-) and the hydroxyl radical (·OH) play the key role in the degradation of TC.