Functionalized polyurethane sponge based on dopamine derivative for facile and instantaneous clean-up of cationic dyes in a large scale.

Functionalized sponge adsorbent was prepared by a mussel-inspired strategy, which achieved successive modification of material and remained the properties of substrate. The dopamine derivative, DOPAm, was synthesized and adhered to polyurethane (PU) sponge before in situ polymerization with sodium p-styrenesulfonate. The adsorbent showed superior removal efficiency for cationic dyes (98.9 % for methylene blue (MB) at the concentration of 200 μmol/L); it took 1 s only for the adsorbent to adsorb the dyes by swelling and squeezing out the bulk solution simply. Meanwhile, the superior adsorption effect of the adsorbent could be maintained in a wide range of solution pH values from 1 to 13 at room temperature (293 K) in several repeat experiments, due to the slight influence of strong acid and alkali on polysulfonate. With unchanged other experimental conditions, the removal efficiency is still more than 90 % after reusing for 10 times at the different concentrations of MB dye solutions (50, 100, 200 μmol/L). For large-scale wastewater treatment, with the removal efficiency of 80.0 %, the adsorbent could purify 4.1 L wastewater containing MB dye (100 μmol/L) with the maximum flux of 22.2 L/(m·s) without the assistance of any equipment except for a vacuum pump. Therefore, the adsorbent has great possibilities to be applied in high-efficient and convenient treatment of wastewater in a large scale.