Surface Engineering of Electrified MXene Filter for Enhanced Phosphate Removal

The discharge of wastewater contaminated with low concentrationsof phosphate can have serious consequences, including environmentallydisastrous blooms of algae and harmful concentrations of phosphatein public water sources. Herein, we demonstrate an electrofiltrationsystem with a flow-through configuration that uses an electrifiedhydroxyl-terminated Ti3C2T x MXene (h-Ti3C2T x ) filter to achieve near complete removal of ultralow concentrationphosphate (5 mg P/L). Increasing either the applied voltage or theflow rate increases the phosphate sorption kinetics of the electrifiedh-Ti3C2T x filter.With a 6 mL/min recirculating flow rate, the h-Ti3C2T x filter exhibits a sorptionkinetics of 1.97 h(-1) and sorption capacity of 91.8mg P/g, which was 2.6- and 4.3-fold higher than that of a pristineTi(3)C(2)T( x ) filter,respectively. The enhanced electrofiltration kinetics and capacitiesare attributed to the synergistic effects of plentiful sites for sorption,electrochemical enhancement, and flow-through design. The mechanismfor phosphate sorption combined interlayer diffusion with surfacecomplexation at the outer level in terms of electrostatic attractionand at the inner level in terms of Ti-O-P interactions.Overall, our research elucidates the utilization of a flow-throughelectrified filter incorporating -OH groups that can boostthe sorption kinetics and capacity for phosphate, offering a promisingparadigm for efficient water purification.

Automated summary

In this study, an electrofiltration system with a flow-through configuration was demonstrated, using an electrified hydroxyl-terminated Ti3C2T x MXene (h-Ti3C2T x ) filter to achieve near complete removal of ultralow concentration phosphate (5 mg P/L). Increasing either the applied voltage or the flow rate enhanced the phosphate sorption kinetics of the filter, which is attributed to the synergistic effects of plentiful sorption sites, electrochemical enhancement, and flow-through design. The mechanism of phosphate sorption involved interlayer diffusion and surface complexation, offering a promising paradigm for efficient water purification.