Enhanced removal of lead ions and methyl orange from wastewater using polyethyleneimine grafted UiO-66-NH2 nanoparticles

The discharge of wastewater rich in heavy metals and organic substances has led to the deterioration of the ecosystem, resulting in serious environmental and food pollution, and there is an urgent need to treat the pollutants in the wastewater. Metal organic frameworks (MOFs) have the advantages of large specific surface area and pore volume, as well as the designability of their structures, and are extremely promising materials for wastewater treatment. In this work, a novel adsorbent was synthesized by grafting polyethyleneimine (PEI) onto the UiO-66-NH 2 metal framework (PEI@UiO-66-NH 2 ) via glutaraldehyde-assisted reaction. This new type of adsorbent not only exhibits improved chemical stability in water but also shows greatly increased adsorption sites in comparison with the common UiO-66-NH 2 . The various factors that possibly affect the adsorption behaviors of the PEI@UiO-66-NH 2 were systematically studied. The results show that the PEI@UiO-66-NH 2 can nearly reach the adsorption equilibrium of Pb(II) and methyl orange (MO) within 5 min. The theoretical adsorption capacities toward Pb(II) and MO achieve 692.80 mg/g and 497.51 mg/g, respectively. Specifically, the dynamic theoretical adsorption models were established through the study of the dynamic adsorption of pollutants, providing the theoretical guidance for the scale-up experiments of wastewater treatment with this adsorbent. PEI@UiO-66-NH 2 also shows excellent recycling performance for removing Pb(II) and MO. All these results suggest that PEI@UiO-66-NH 2 has a good application prospect for the removal of wastewater containing Pb(II) and MO.