Efficient heavy metal sequestration from water by Mussel-inspired polystyrene conjugated with polyethyleneimine (PEI)

Polyethyleneimine (PEI) is a famous chelated reagent for heavy metal capture, but the soluble PEI immobilization always needs complicated chemical procedures. In this work, we explored a simple and green strategy for PEI immobilization and Pb(II) removal by polydopamine (PDA) polymerization. It relies on a cooperative adsorption, originated from the fixation of charged SO3H groups inside polystyrene matrix, and in-situ formation of PDA adjugated PEI by simple reaction at ambient temperature. The PDA interface favors the formation of stable adjugated PEI, and the charged SO3H groups can drive trace heavy metal ions from bulk solution to the vicinity of branched PEI. These hybrid adsorbents exhibit superior selectivity with a distribution coefficient of 5250 mL/g, rapid kinetics (∼50 mins) and satisfactory sorption-regeneration property in Pb(II) removal. An outstanding capacity of ∼ 6200 L water/kg sorbent and trace effluent (<10 μg/L, WHO) was completed in the treatment of the Pb-contaminated stream. In addition, it also works efficiently for various metals, such as Fe(III), Cu(II) and Ni(II) removal. Our work therefore provides a new method for efficient PEI immobilization and brings a new perspective for mitigating the problem of diverse heavy metal contamination.