Simultaneous removal of Pb(II) and 2,4,6-trichlorophenol by a hierarchical porous PU@PDA@MSNs sponge with reversible “shape memory” effect

• PU@PDA@MSNs sponge were successfully fabricated by PU sponge template and interface grafted route.
• PU@PDA@MSNs sponge possessed reversible “shape memory” effect and hierarchical porous structure.
• PU@PDA@MSNs sponge had plenty of carboxyl groups and amino groups resulted in a favorable adsorption for TCP and Pb(II).
• Adsorption mechanism and promotion in adsorption ability in binary system were discussed.

A hierarchical porous PU@PDA@MSNs sponge with reversible “shape memory” effect was employed in this investigation for the simultaneous adsorption of Pb(II) and 2,4,6-trichlorophenol (TCP). Our strategy was based on facile conjugation of carboxyl groups modified mesoporous silica nanoparticles (MSNs) to poly(dopamine) (PDA) coated polyurethane (PU) sponge (PU@PDA), and the as-prepared PU@PDA@MSNs sponge possessed the advantages of less operation time, convenient adsorbent collection and regeneration owing to its reversible “shape memory” effect. In single system, Pb(II) and TCP adsorption were implemented at pH = 6.0, and their max monolayer adsorption amount at 298 k were 104.2 mg g−1 and 184.2 mg g−1, respectively. However, the binary system exhibited that the coexistence of Pb(II) and TCP could obviously accelerate jointly adsorption at low concentrations, due to partial complexation between Pb(II) and TCP during the 10–30 mg L−1 of Pb(II) and TCP. While at higher concentrations, TCP adsorption was inhibited in relation to the competition from Pb(II), but Pb(II) adsorption was scarcely affected due to its smaller size and strong complexation with amino groups from PU@PDA@MSNs sponge. The PU@PDA sponge could be simply recycled and maintained stability after seven adsorption/desorption cycles in the regeneration steps.

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