A facile and high-efficiency strategy towards instantaneous clean-up of positively-charged microcontaminants by regenerative carboxylated sponge

•A facile and general method to fabricate functionalized PU sponge was proposed.•The modified sponge can effectively remove microcontaminants with high clearances.•The removal of microcontaminants was finished in 1 s.•The modified PU sponge could be used for large-scaled sewage purification.