Fabrication of amorphous metal-organic framework in deep eutectic solvent for boosted organophosphorus pesticide adsorption

Abstract

Herein, we describe a new and sustainable strategy of directly constructing the amorphous metal-organic framework (MOF) through the use of deep eutectic solvent (DES) for the highly effective and efficient adsorption of organophosphorus pesticide from contaminated water. The as-obtained products possessed nanosize morphology (as small as 40 nm), hierarchical pores ranging from 1.16 to 12.3 nm, high porosity up to 0.5954 cm3 g−1, and abundant unsaturated metal centers. The presence of structural disorder increased the number of active sites and promoted the diffusion of target molecules, leading to enhance host-guest interactions. These properties were beneficial for the application of the material in the enrichment adsorption of profenofos. The amorphous UiO-66 with the highest content of defect disorder (4.408) displayed a remarkably high affinity toward profenofos, resulting in an exceptional adsorbate uptake capacity over 1300 mg·g−1. This is a three-fold enhancement compared to its crystalline counterpart. And its performance surpassed that of most previously reported absorbents. Additionally, the adsorption behavior and mechanism of amorphous UiO-66 toward profenofos were elucidated by high-revolution X-ray photoelectron spectroscopy (XPS) and various models. The results revealed a multi-layer heterogeneous adsorption, involving multiple sorption process. The profenofos adsorption mechanisms over amorphous UiO-66 mainly rely on hydrogen bonding, Zr-O-P bonds, and P-Zr bonds. Moreover, the amorphous UiO-66 exhibited outstanding regeneration and reusability characteristics, making it a stable and promising adsorbent for water remediation. Its efficient and rapid removal of pollutants holds great potential for practical applications, while also providing guidelines for the design and optimization of next-generation sorbent.