Poly (N-vinyl imidazole) gel composite porous membranes for rapid separation of dyes through permeating adsorption

In this paper we demonstrate the fabrication and properties of a novel poly (N-vinyl imidazole) (PVI) gel composite porous membrane (GCM) used for rapid separation of dyes through permeating adsorption. The GCMs were fabricated'by in situ crosslinking of PVI precursor on microporous support membranes with the aid of ammonium persulfate (APS). The characterizations of membrane morphology and surface chemistry showed the PVI gel was introduced not only onto membrane surface but also inside membrane pores. The obtained GCMs could nearly completely remove various anionic dyes from water with a high flux ranging from 40 to 120 L/m(2) h under a pressure of 8 cm water column. In an optimized case, the treating capacity of the composite membranes towards sunset yellow (SY) maintains about 79 mg/g with a high flux of 500 L/m(2) h under 0.2 bar. The permeation rates reported here is much higher than that of the conventional nanofiltration process for dye separation (about 10 L/m(2) h.bar). What's more, GCMs can also be used to deploy the separation of dye mixture effectively. It was found that the protonation of PVI in acidic environment is responsible for the rapid adsorption of anionic dyes by electrostatic attraction. GCMs are easily regenerated by a basic solution and the high separation performance can be kept well over at least five adsorption-regeneration cycles. 2017 Published by Elsevier B.V.