Characterization of UiO-67 Decoration onto UV-crosslinked-poly(vinyl alcohol) Nanofibes for Adsorption Application

The applications of poly(vinyl alcohol) for remediation of aqueous systems are limited by its solubility. UV crosslinking was initiated using TiO2 and ZnO as photo-catalysts and citric acid as cross-linker during electrospinning of poly(vinyl alcohol) nanofibers. The UiO-67 metal-organic framework was loaded for enhancing adsorption capability. The concentrations of TiO2, ZnO, and citric acid all affected both swelling and solubility. The optimal conditions for photo-crosslinking of poly(vinyl alcohol) nanofibers were 2 %wt of TiO2 and 7.5 %wt of citric acid. This provided insoluble continuous fibers of 60 to 120 nm with a smooth surface. The UiO-67 metal-organic framework was successfully synthesized with high purity using a modified sonochemical method which exposed the UiO-67 to ultrasonic waves for 30 min at room temperature. The synthesized UiO-67 exhibited a cubic close-packed structure. UiO-67 of up to 7 %wt was incorporated into the poly(vinyl alcohol), producing the crosslinked- poly(vinyl alcohol) composite nanofibers containing UiO-67. The composite nanofibers had a higher specific surface area and smaller pore size than the neat poly(vinyl alcohol) nanofibers. This could be due to UiO-67 incorporation producing micropores, which increased the surface area and enhanced phosphate removal.

Automated summary

The research focused on enhancing the insolubility of poly(vinyl alcohol) nanofibers through UV crosslinking and improving adsorption capability with UiO-67 metal-organic framework. By optimizing processing conditions, smooth composite nanofibers were produced with higher specific surface area and smaller pore size, potentially due to the micropores generated by incorporating UiO-67, which led to enhanced phosphate removal.