Efficient removal of Pb() and Cr() from acidic wastewater using porous thiophosphoryl polyethyleneimine

Removing heavy metal ions from acidic mine wastewater is a big challenge. In this paper, a novel porous thiophosphoryl polyethyleneimine (TPEI) adsorbent was designed for removing Pb( ii ) and Cr( vi ) from acidic wastewater. The optimum adsorption pH value of TPEI for Pb( ii ) and Cr( vi ) is 3 and 2, respectively. At 298 K, the maximum adsorption capacity for Pb( ii ) and Cr( vi ) is 421.9 mg g −1 and 191.04 mg g −1 , respectively. The adsorption equilibrium time of Pb( ii ) and Cr( vi ) is 25 min and 10 min, respectively. The adsorption of Pb( ii ) and Cr( vi ) both conform to the pseudo-second-order model and the Langmuir isotherm model. The adsorption mechanism of Pb( ii ) depends on the chelation interaction, while Cr( vi ) depends on the electrostatic interaction. The regeneration test shows that the adsorbent is stable and reusable. This study provides a new strategy for the purification of acidic heavy metal wastewater. A porous thiophosphoryl polyethyleneimine was synthesized to remove Pb( ii ) and Cr( vi ) from acidic wastewater.