Recycling waste plastic to construct ultra-stable and multifunctional metal-organic framework for fast efficient dye adsorption and acetone vapor detection

Plastic pollution and water pollution are currently two major environmental problems. Exploring a strategy that can convert waste plastics into high value-added functional materials will be an effective solution to relieve above issues. Herein, we realized that the waste plastic of polyethylene terephthalate (PET) was converted into ultra-stable and multifunctional 3D pillared-layer Eu-based metal-organic framework (MOF) material (labelled as Eu-PET) through one-pot solvothermal method. The effects of reaction conditions on the waste plastic PET upcycling were explored in detail. The Eu-PET exhibits excellent Congo red (CR; Concentration: 1 g/L) adsorption capacity of 2312 mg/g in 2 hours at nature pH (2988.11 mg/g at pH = 4). Moreover, the influence parameters containing dye concentration, adsorbent dosage, pH, temperature and simulated dye wastewater were studied. The adsorption mechanism was explained by pseudo-second order and Langmuir models, revealing the adsorption of CR on Eu-PET was mainly defined by electrostatic interaction, hydrogen bonding interaction and π-π interaction. Furthermore, Eu-PET as fluorescent sensor, a portable Eu-PET fluorescent film was developed. Experiments have shown that a noticeable fluorescent quenching response occurred within 10 seconds contact to acetone vapor, and the theoretically detectable limit (LOD) was as low as 0.048% (v/v), and Eu-PET/acetone system was static quenching. Finally, Eu-PET has excellent water, acid-base and thermal stability, and recyclability over 7 cycles of CR adsorption and acetone detection. This work opens an avenue for the green recycling/utilization of plastic waste, providing meaningful insights into the effective processing of dyes wastewater and fluorescence sensing of volatile organic compounds.