Green synthesis of luminescent La-MOF nanoparticle from waste poly(ethylene terephthalate) for high-performance in Fe(III) detection

Developing luminescent metal–organic frameworks (MOFs) capable of high-efficiency Fe3+ sensing has aroused great attraction in the fields of biology, chemistry, etc. However, previous solvothermal methods are limited by organic solvent usage, time consuming, high pressure, and high-energy consumption. Herein, we propose the waste-to-MOF strategy towards the scale-up production of La-MOF nanoparticles through the ball milling of recycled poly(ethylene terephthalate) (PET) bottles and La(NO3)3⋅6H2O. PET goes on alkaline hydrolysis to form 1,4-benzenedicarboxylic acid sodium salt (Na2BDC) and ethylene glycol by ball milling. Subsequently, BDC reacts with La3+ to form La-MOF. The as-prepared La-MOF crystal nanoparticles possess a rod-like morphology with the size of few hundred nanometers. Additionally, La-MOF nanoparticles display high selectivity and sensitivity for Fe3+ detection. The quenching constant and limit of detection are 5.29 × 103 (mol·L−1)−1 and 0.147 μmol·L−1, respectively, thus surpassing many advanced Fe3+ sensors. According to the result of density functional theory, the high Fe3+ detection performance of La-MOF is related to the complexing of Fe3+ with La-MOF, which leads to the gradual dissociation of the coordination bond between terephthalic acid and La3+. It is anticipated that the mechanochemistry milling-based waste-to-MOF strategy provides a new platform for the massive production of functional MOFs in a green manner.