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

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 m(3) 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, pi-pi 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.

Automated summary

Fe-Zr-based metal-organic frameworks (FZM) with porous structure and high surface area were synthesized through a facile hydrothermal method. FZM showed a high adsorption capacity for 2,4-D through hydrogen bonds, pi-pi conjugates, and electrostatic attractions. FZM also exhibited good performance in terms of reuse and regeneration.