Enhanced adsorption performance of dyes and heavy metal ions using zwitterion functionalized Ti3C2Tx MXene/polymer material

In this work, a multifunctional adsorbent based on zwitterion modified Ti 3 C 2 T x MXene (MPI) was synthesized by surface grafting polymerization, followed by modification with polyethylenimine and sodium chloroacetate. This adsorbent exhibited a high density of functional groups, switchable surface charge characteristics and plenty of active sites of iminoacetic acid chelating groups. Subsequently, methylene blue, congo red, Pb(II), and Cr(VI) were selected as model compounds for cationic/anionic dyes and heavy metal ions to estimate the adsorption performance. The material exhibited exceptional adsorption capacities, and the maximum adsorption capacities were determined as 479.8 mg/g for methylene blue, 481.9 mg/g for congo red, 300.6 mg/g for Pb(II) and 265.9 mg/g for Cr(VI), respectively. Adsorption equilibrium was reached within 10–120 min and the adsorbent showcased excellent removal efficiency. Moreover, the adsorbent demonstrated excellent reusability，with no significant changes after ten consecutive adsorption-desorption cycles. Mechanism studies revealed that electrostatic attraction and chelation played dominant roles in the adsorption process. These results suggest that MPI possesses advantages of simple preparation, multifunctional integration, high adsorption performance, and good stability, making it a promising universal adsorbent for the removal of both dyes and heavy metal ions from wastewater.