Effective coating of crosslinked polyethyleneimine on elastic spongy monolith for highly efficient batch and continuous flow adsorption of Pb(II) and acidic red 18

Adsorption using monolithic adsorbents is an attractive emerging technology for water treatment, but it still remains a great challenge to facilely combine microscopically a well-developed surface functionality with a macroscopic architecture. In this work, we reported a simple, low-cost, and effective method for constructing uniform coating of crosslinked polyethyleneimine (PEI) on monolithic melamine sponge (MS) through pre-modification with polydopamine (PDA), followed by a rotary evaporation-driven crosslinking-surface deposition process. Due to the amine groups-rich surface and highly open porous structure, the resulting monolithic adsorbent (PEI@PDA/MS) exhibited high adsorption capacities and fast adsorption kinetics toward Pb(II) (231.81 mg g(-1); < 100 min) and acid red 18 (AR18, 464.53 mg g(-1); < 180 min). Moreover, PEI@PDA/MS possessed excellent shape memory property and could be manually collected with tweezers, indicating its great operational convenience in recycling. Cyclic adsorption/desorption experiments confirmed its satisfying reusability. Continuous flow adsorption behaviors of the PEI@PDA/MS monolith were further investigated by directly using it as stationary phase, which also exhibited high removal efficiencies for Pb(II) and AR18. Besides, adsorption mechanisms based on the characterization analyses were also proposed. Our study provides an effective strategy for fabricating high-quality PEI-based monolithic adsorbents with great potential to be used in environmental remediation.