Improving the hydrostability of ZIF-8 membrane by biomolecule towards enhanced nanofiltration performance for dye removal

Abstract

Abstract Zeolitic imidazolate frameworks-8 (ZIF-8)/polymer composite membranes have shown great promise in gas separation, catalysis and biotechnology due to their microporous nature. However, the structural instability against protonation limits the application of ZIF-8 materials in aqueous environments, e.g. water treatment membranes. In this study, a ZIF-8 nanocomposite membrane with satisfactory hydrostability was explored. More specifically, a series of composite ZIF-8 thin film containing DNA molecules were deposited on dopamine-modified polysulfone (PSF) substrates via an in situ growth under ambient conditions. The incorporation of DNA molecules significantly enhanced the hydrophilicity of the composite membrane (water contact angle reduced from 66.9° to 29.2°). Compared with the pure ZIF-8 counterpart, the DNA-containing ZIF-8 membrane exhibited higher water flux, accompanied with higher rejections for organic dyes and inorganic salt ions. More importantly, the DNA-containing ZIF-8 membrane showed significantly enhanced water stability and anti-fouling property during the filtration tests. The utilization of biomacromolecules to stabilize ZIF membrane enables potential applications for ZIF membranes for wider water-related applications.