Dense and robust aminopolycarboxylic acid-decorated porous monoliths for eliminating trace Cu(II) or Zn(II) from water

Abstract

Aminopolycarboxylic acids (APAs) show a strong affinity toward heavy metal species, but straightforward and robust studies on the surface of porous adsorbents with APAs are rarely available. In this study, branched polyethyleneimine (PEI) is directly used to investigate the surface of a microcrystalline cellulose (MC)-supported porous monolith (MC@PEI) through an oil-in-water high internal phase emulsion technique. The residual amines of the covalently immobilized PEI are transformed into dense APAs (MC@PEI-APA). The open-cellular MC@PEI-APA monolith can effectively eliminate trace Cu(II) or Zn(II) from water relative to MC@PEI. Moreover, its adsorption complies with the second-order kinetics and follows the Langmuir adsorption model. MC@PEI-APA shows high adsorption capacities (e.g., 96 mg g−1 for Cu(II)). It also presents stronger metal affinities than the commercial Amberlite IRC-748 adsorbent possibly because of the cooperative ligation of metal species by the relatively dense APA groups of MC@PEI-APA. The proposed adsorbent is durable and has good recyclability.