PVBA-UiO-66 using a flexible PVBA with multi-coordination groups as mixed ligands and their super adsorption towards methylene blue

Abstract

A series of poly-vinyl benzoic acid (PVBA) and UiO-66 materials (PVBA-UiO-66) were prepared by a mixed-linker approach. Using a flexible PVBA with multi-coordination groups as mixed ligands, mesopores and uncoordinated benzoic groups were introduced into the UiO-66 crystal structures, thus leading to a special structure and functionality. The structure of the PVBA-UiO-66 was characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and nitrogen gas adsorption measurements. The adsorption property toward methylene blue (MB) of PVBA-UiO-66 was studied. The adsorption of MB by UiO-66 and PVBA (43%)-UiO-66 fit the Langmuir model and Freundlich model well. The result showed that PVBA (43%)-UiO-66 has super adsorption capacity as high as 909 mg g⁻¹ for MB owing to the mesopores and the uncomplexed carboxyl groups which were caused by the long PVBA involved in coordination. The adsorption kinetics of MB onto PVBA (43%)-UiO-66 can be well fitted to the pseudo-second-order model. The process of adsorption MB onto PVBA-UiO-66 is spontaneous and thermodynamically favorable at 303, 313 and 323 K.