Efficient removal of phosphate by nitrogen and oxygen-rich polyethyleneimine composite

The construction of an efficient phosphate adsorbent is critical for tackling the problem of eutrophication in water bodies, and remains a challenge. In this study, a novel polyethyleneimine (PEI) and pyromellitic dianhydride (PMDA) composite (PEI@PMDA) is synthesized by the amidation reaction and applied as a high efficiency phosphate adsorbent in wastewater. Due to the abundant nitrogen and oxygen-containing functional groups, the adsorption capacity of phosphate on PEI@PMDA has a maximum value of 101.81 mg/g estimated by a Langmuir model. The adsorption of phosphate on PEI@PMDA can be well described by the pseudo-second-order kinetic and the Langmuir models. In addition, the thermodynamics suggests that the phosphate removal is a spontaneous process. Mechanism investigation discloses the dominating role of electrostatic attraction and hydrogen bonding. Moreover, the material performance and stability remained well upon five cycles.