Zif-7/Psf Mixed Matrix Membranes: Synthesis and Performance for Removal of Chromium from Water

Abstract

In this contribution, a novel nanofiltration mixed matrix membrane (MMM) was prepared by incorporating zeolitic imidazolate framework (ZIF-7) nanoparticles in the polysulfone (PSF) polymer matrix for the removal of chromium ions Cr(VI) from aqueous solution. Results from different techniques (X-ray diffraction, Scanning electron microscope, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface areas and Thermal gravimetric analysis) showed that the ZIF-7 crystals were very standard as reported in the previous studies. Then, ZIF-7/PSF MMMs with three different loadings (5, 15 and 30wt%) were prepared and employed for the removal of Cr(VI) under varying pH and feed concentration. The results showed that the higher rejection with different ZIF-7 loading (5, 15, 30wt%) was achieved at pH 11. Overall, the fabricated ZIF-7/PSF MMMs showed very high levels of rejection for a number of combinations of ZIF-7 loading and chromium feed concentration. With pH 11, the highest rejection (99%) of Cr(VI) is achieved with 15wt% ZIF-7 loading and 500ppm feed concentration. The rejection of 98% of Cr(VI) is achieved with (15wt% ZIF-7 with 50ppm feed concentration), (5wt% ZIF-7 with 500ppm feed concentration), and (30wt% ZIF-7 with 25 and 50ppm feed concentration).