Mixed matrix membranes with highly dispersed UiO-66-NH2 filler for removal of dyes and molybdenum(VI) ions from aqueous solutions

Abstract

In order to develop well-dispersed mixed matrix membranes (MMMs), a preparation strategy of wet filler was proposed. A highly stable UiO-66-NH2 metal organic framework was used as the filler. The MMMs were prepared by incorporating wet UiO-66-NH2 into poly(vinylidene fluoride)(PVDF) matrix for removing Rhodamine B(RhB), Congo red(CR) and molybdenum(VI) ions from aqueous solutions. X-ray diffractometer, Fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy (SEM) and laser particle size analyzer were used to character the structure and morphology of UiO-66-NH2. Also, the MMMs were characterized in terms of FT-IR, SEM, zeta potential, molecular weight cut off, pore size distribution, water contact angle and permeability. Compared with pure PVDF membrane, MMMs showed great improvements in pure water flux and rejection rates of dyes and molybdenum(VI), especially for MMMs decorated with wet fillers. The optimized MMM with 10w % of wet filler content (MW10) exhibited superior pure water flux (231.6 L m−2 h−1, 3.3 times higher than that of PVDF membrane) and high rejection rates for RhB(96.4 %), CR (98.3 %) and molybdenum(VI)(90.3 %). The adsorption experiments were also carried out using MW10. Results indicated that the maximum adsorption capacities of MW10 towards RhB, CR and molybdenum(VI) were 25.29, 16.50 and 36.95 mg g−1, respectively. These adsorptions belonged to chemisorptions. Furthermore, MW10 possessed the favorable stability and antifouling performance. This work provides a promising prospect for manufacturing high-performance MMMs with well-dispersed filler to remove efficiently dyes or molybdenum(VI), and also it perhaps gives a valuable guidance for the development of industrial membranes.