Ethylenediamine-Modified Hollow Porous Nanospheres for Effective Removal of Chromium (VI)

The synthesis of recyclable adsorbents with satisfactory adsorption properties is more beneficial to their value in environment-related applications. Organic porous polymer has become a potential adsorption material because of its convenient and effective modifiability and relatively high specific surface area. Here, we report for the first time a novel synthesis of ethylenediamine-modified hollow porous nanospheres (HPNs-NH₂) via hyper-crosslinking mediated self-assembly strategy using polylactide-b-polystyrene-b-polyglycidyl methacrylate (PLA-b-PS-b-PGM) triblock copolymers as precursors, followed by further ring-opening of epoxy groups with ethylenediamine (EDA). Owing to the special multistage pore structure, high surface area and a large number of amino active sites, the obtained solid adsorbent HPNs-NH₂ showed high adsorption capacity (493 mg/g) for Cr(VI), and its adsorption performance can still be maintained at a high level after eight cycles. These obvious advantages indicated that HPNs-NH₂ is expected to play an important role in the treatment of hexavalent chromium in sewage.