A Novel Post-Synthesis Functional Ti-Based Mofs Composites for Efficient Removal of Pb (Ii)

In the field of water treatment, it is of importance to fabricate an adsorbent with large adsorption capacity and high reproducibility for efficiently removing heavy metal ions Pb (II) from polluted water. In this work, a novel Ti-based MOFs material (BDB-MIL-125(Ti)@Fe 3 O 4 ) was designed and prepared by modifying NH 2 -MIL-125(Ti) with sulfhydryl and amino groups. Due to the large number of active sites, the maximum Pb (II) adsorption capacity of BDB-MIL-125(Ti)@Fe 3 O 4 was 710.79 mg/g at pH=6 within 120 min corresponding to a maximum removal rate of 95.68%. The adsorbent also has extremely high selectivity and good cycling adsorption performance. The isotherms and kinetics of this adsorption process agree with the Langmuir model and the pseudo-second-order model, respectively, indicating that the adsorption was a chemisorption. Thermodynamic studies proves that spontaneous processes enhance Pb (II) adsorption at higher temperatures. DFT and FMOs calculations were used to discuss the adsorption mechanism, which shows that the sulfhydryl groups on the surface of organic ligands have a stronger affinity for Pb (II)