A bio-inspired green method to fabricate pH-responsive sponge with switchable surface wettability for multitasking and effective oil-water separation

Smart oil-water separation materials with stimuli-responsive wettability surfaces have attracted wide attention. In this paper, a novel, simple and low-cost method is developed to prepare a pH-responsive melamine sponge (MS) with switchable wettability. This approach involves the hydrophobic modification of hexadecyl-trimethoxysilane (HDTMS) on the MS surface modified by polydopamine (PDA) and the Michael addition re-action and Schiff base reaction between 12-aminododecanoic acid (NH2(CH2)(11)COOH) and PDA. Hydrophobic/oleophilic HDTMS and pH-triggered NH2(CH2)(11)COOH enable the functionalized sponge to repeatedly switch between the two extreme wettability under different pH environments. Benefiting from the excellent 3D porous surface structure and smart wettability, the as-prepared sponge can be applied in the on-demand separation of various oil-water mixtures by adsorption or filtration with a separation efficiency over 98.5% and high absorption capacity of 72.7-161.3 g.g(-1). With the assistance of pump-driven, continuous adsorption separation can be achieved in two cases by utilizing the wettability transformation. Moreover, in an alkaline solution, the sponge can quickly release most of the absorbed oil, showing a controllable desorption process. This smart wettability material with simple preparation and green has application potential in controllable oil-water separation and on-demand oil-spills treatment.

Automated summary

Smart oil-water separation materials with switchable wettability have been developed in this paper. A novel method using a pH-responsive melamine sponge has been developed, which can repeatedly switch between hydrophobic and hydrophilic states. The functionalized sponge with excellent 3D porous structure and smart wettability shows high separation efficiency in oil-water mixtures.