Electrospun gelatin nanofibers in situ composite with ZIF-67 for eco-friendly and efficient uranium removal

The development of environmentally friendly, operationally simple, and easily separable adsorbents for uranium removal from wastewater holds significant importance. The biopolymer gelatin (Gel) derived from animal collagen has poor water stability, limiting its application in wastewater treatment. By in-situ compositing with ZIF-67, a nitrogen-rich and stable metal-organic framework structure introduced onto the surface of gelatin fibers enhanced the uranium adsorption capacity of gelatin nanofibers and improved the water stability of these fibers. Furthermore, through the natural polyphenolic tannic acid tanning process, it is possible to further increase selectivity of gelatin composite fibers. The gelatin composite nanofibers Gel/ZIF-67 and T-Gel/ZIF-67 were characterized using SEM, FT-IR, XRD, XPS, and contact angle. Adsorption of uranium on both nanofibers were significantly influenced by pH but minimally affected by ionic strength, indicating the inner-sphere surface complexation. The adsorption of uranium onto Gel/ZIF-67 and T-Gel/ZIF-67 followed the Langmuir isotherm model, with theoretical adsorption capacities reaching up to 608.21 mg g-1 and 612.24 mg g-1, respectively. Kinetic modeling analysis revealed that chemical adsorption played a dominant role during the adsorption processes.