Fabrication of zeolitic imidazolate framework-8 functional polyacrylonitrile nanofibrous mats for dye removal

In this work, polyacrylonitrile (PAN) nanofibers were utilized to prepare metal-organic framework (MOF) nanofibrous mats. Herein, 2-methylimidazole (2-MI) was mixed in polymeric solution for electrospinning. Subsequently, zeolitic imidazolate framework (ZIF-8) nanocrystals were growth on the surface of PAN nanofibers through post-treatment. To confirm the structures, ZIF-8/PAN nanofibrous mats were investigated by FTIR, XRD, SEM, and TGA measurements. The results presented uniform ZIF-8/PAN nanofibrous mats were fabricated. Further, ZIF-8/PAN nanofibrous mats were employed for dye adsorption using methylene blue (MB) and malachite green (MG) as models. The optimum dye-adsorption conditions were investigated. The results shown the optimum concentration, temperature and pH value of for MB adsorption were 50 mg/L, 30 °C and pH = 11; for MG absorption were 300 mg/L, 30 °C and pH = 5, respectively. Meanwhile, the results displayed prepared ZIF-8/PAN nanofibrous mats presented well adsorption capacity to MG with a quick adsorption rate, which reached to 1531.94 mg/g. Moreover, MB and MG adsorption isotherms of ZIF-8/PAN nanofibrous mats were best fitted by the Langmuir isotherm model, and the results presented pseudo second-order kinetic equation was more consistent with the MB and MG adsorption processes of the adsorbent. Additionally, ZIF-8/PAN nanofibrous mats are successfully degradation MB under xenon light irradiation.