Adsorption of 2,4-dichlorophenoxyacetic acid over Fe–Zr-based metal-organic frameworks: Synthesis, characterization, kinetics, and mechanism studies

Abstract

The removal of herbicides remains challenging because of the complex synthesis process and poor performance of the adsorbent. Herein, we proposed a facile hydrothermal method for the synthesis of Fe–Zr-based metal-organic frameworks (FZM), which featured porous structure and high surface area of 1003 m3 g−1 with abundant functional groups and unique surface charge. The maximum adsorption capacity of FZM toward 2,4-D was 357.14 mg g−1 after nonlinear adsorption isotherm models were fitted. The adsorption isotherms and kinetics of 2,4-D on the FZM conforms to Langmuir isothermal model and pseudo-second-order kinetic model respectively the adsorption mechanism was discussed based on the characterization, FT-IR and XPS analysis showed that the adsorption mechanism was mainly attributed to the hydrogen bonds between molecules, π-π conjugates and electrostatic attraction. Furthermore, the reuse performance and regeneration method of FZM were optimized through experiments. FZM could maintain 77% efficiency even after multiple cycles, and was less affected by the complex matrix. These results provide new insights into the adsorption of pesticides in water by novel MOF.