Simultaneous extraction of diverse organic pollutants from environmental water using a magnetic covalent organic framework composite.

Polycyclic aromatic hydrocarbons (PAHs), tetracyclines (TCs), and triphenylmethane dyes (TDs) are common organic pollutants, which may threat the human health or natural microbial communities. In this work, we report a novel multifunctional sorbent based on core-shell magnetic carboxylate-functionalized covalent organic frameworks composites (Fe3O4@COF-COOH) for the simultaneous adsorption of these target analytes via mixed-mode solid phase extraction. The behaviors of the synthetic composite for the adsorption of PAHs, TCs, and TDs were evaluated based on the Freundlich and Langmuir isotherm models. In combination with quantum chemistry calculations, it was found that the multiple interactions including π-π stacking, hydrogen bonding, and electrostatic attractions were existed between COF-COOH and guest molecules. The extraction parameters were optimized, and a novel simultaneous absorption-stepwise desorption (SASD) strategy for the enrichment of PAHs, TCs, and TDs was proposed. By coupling with HPLC-DAD method, the validation results revealed good linearities (R2 ≥ 0.9882) for all analytes. High sensitivity with LODs within the range of 0.003-0.008, 0.02-0.06, and 0.006-0.008 μg L-1 were obtained for PAHs, TCs, and TDs, respectively. High recoveries ranging from 93.6 to 105.8% were obtained with intra-day RSDs of 2.2-6.3% and inter-day RSDs of 3.2-6.5%. The obtained results demonstrated that the proposed SASD strategy using Fe3O4@COF-COOH as sorbents can be extended to other aqueous solutions consisting of trace multi-target analytes.