A novel smart membrane with ion-recognizable nanogels as gates on interconnected pores for simple and rapid detection of trace lead(II) ions in water

A novel smart membrane with ion-recognizable nanogels as gates on interconnected pores is developed for simple and rapid detection of trace lead(II) ions in water. The membrane is prepared via one-step vapor-induced phase separation (VIPS) method, and featured with interconnected porous structure and Pb 2+ -responsive poly( N -isopropylacrylamide- co -benzo-18-crown-6-acrylamide) (PNB) nanogels on polyethersulfone (PES) membrane pore surfaces as gates. Afforded by such a unique architecture, both high flux and significant responsive characteristics are achieved. With the proposed strategy, the nanogels are fixed onto the membrane pore surfaces during the formation of interconnected porous structure; thus, the immobilization of nanogels onto the membrane pore surfaces does not result in the decrease of pore sizes. The water fluxes of fabricated membranes could be even higher than 6000 kg m −2 h −1 driven by the static pressure of 20 cm water column under gravity at 34 °C, because of the three-dimensionally interconnected porous structures. Due to high sensitivity and selectivity of PNB nanogels on the membrane pore surfaces in response to Pb 2+ ions, the fabricated membranes can efficiently detect Pb 2+ ions with a limit of detection as low as 10 −9 mol/L. With the proposed novel membrane, rapid detection of trace lead(II) ions in water can be easily achieved by simply monitoring the trans-membrane flux change in a gravity-driven membrane module device, which is highly potential and promising in real-time and easy-to-popularize monitoring of drinking water safety and may expand the scope of applications of facile detection techniques.