Performance and mechanism of polypeptidylated hemoglobin (Hb)/iron oxide magnetic composites for enhanced dye removal

Composites of polypeptidylated hemoglobin supported on different iron oxide weights (0.5:1 and 1:1) were developed and demonstrated to function as efficient adsorbents for Eriochrome black-T dye removal. The synthesis of these adsorbents were performed through N-carboxyanhydride (NCA) polymerization at low temperature (4 degrees C) and near-neutral pH for 24 h followed by chemical co-precipitation. The synthesized adsorbents were found to exhibit BET surface area (54-87 m(2)/g), pore volume (0.30-0.35 cm(3)/g), average pore diameter (160-218 angstrom) and average pore width (136-171 angstrom). The developed adsorbents were tested in a batch dye adsorption system. Adsorption was found to follow pseudo-second order kinetics and the Langmuir adsorption capacities were 123, 204 and 217 mg/g for Fe3O4, 0.5:1 and 1:1 adsorbent samples, respectively. Chemical regeneration was successfully carried out using methanol and the reusability of the adsorbents were demonstrated with a decrease in adsorption capacities from similar to 49 to similar to 33 mg/g after the fourth reuse. (C) 2020 Elsevier Ltd. All rights reserved.