Hydrophilic Carboxyl Cotton for in Situ Growth of UiO-66 and Its Application as Adsorbents

Immobilization of metal–organic frameworks (MOFs) on multiple substrates is important and challenging in functional materials fields till date. Cotton is a promising carrier material with excellent performance, such as large specific area, mechanical strength and stability, good biocompatibility, and hygroscopicity. In this study, based on the coordination of carboxyl groups and Zr-OH groups, a novel carboxyl cotton chelator-zirconium-based metal–organic framework (CCC@Zr-MOF) was successfully fabricated. The surface of the cotton was first modified by citric acid. Zr-MOF precursor was grown on the carboxyl modified cotton by coordination bond to prepare Zr₆O₄(OH)₄ cluster modified cotton (CCC@Zr₆O₄(OH)₄). Then, Zr-MOF would form and immobilize on CCC@Zr₆O₄(OH)₄ to obtain CCC@Zr-MOF. The CCC@Zr-MOF was characterized by field emission scanning electron microscope equipped with an energy-dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectra, and Brunauer–Emmett–Teller. The successful formation of Zr-MOF on the surface of cotton has been demonstrated. CCC@Zr-MOF was packed in the pipette tip for the solid-phase extraction to evaluate its adsorption property for phenolic acid compounds from complex matrix sample. The results showed that CCC@Zr-MOF performed an efficient adsorption and selectivity.