Mixed matrix membranes based on cellulose acetate recycled from cigarette butts and metal-organic frameworks for thin film solid-phase microextraction: Determination of phenols in environmental waters

The recovery of raw materials from waste is a viable strategy to transition to more circular and greener methodologies. In this study, cigarette filters were recycled to obtain cellulose acetate and re-used as a support for a sorbent material in a microextraction procedure. Thus, this biosorbent was combined with a metal-organic framework (MIL-101(Fe)) and configurated in a membrane format of 300 µm of thickness via solvent casting. The developed mixed matrix membranes were characterized by Fourier-transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and energy dispersion X-ray. Kinetic adsorption studies for a group of 14 phenols (chlorophenols, alkylphenols, and bisphenols) present in waters and partitioning to the membrane systems were performed to gain insights into the extraction mechanisms of the membranes. The kinetics were fitted to pseudo-first order and interparticle diffusion models, with data indicating that chloro‑ and alkyl-phenols were adsorbed faster than bisphenols. Besides, the resulting membranes were utilized in thin film solid-phase microextraction (TF-SPME) in combination with high-performance liquid chromatography (HPLC) with diode array detection (DAD) and fluorescent detector (FLD). The optimized method using these mixed matrix membranes (with dish shape and 1 cm of diameter) required 60 min of extraction with agitation followed by 10 min of desorption in 500 µL of basic ethanol. Low limits of detection, down to 2.13 µg·L-1, were achieved, together with good performance in SPMS and BAGI metrics, with scores of 5.89 and 62.5, respectively. The performance with river waters was accompanied by adequate relative recoveries (74.3–117 %), reproducibility (with inter-day RSD values lower than 18 %), and absolute recoveries (up to 59 %).