Fabrication and characterization of a novel magnetic MIL-101(Cr) nanocomposite for selective selenite removal

Herein, a novel magnetic composite consisting metal-organic framework was fabricated and applied as a sorbent for selenite ions removal (Se (IV)) from water samples. The sorbent made from a metal-organic framework (MIL-101(Cr)) as a selective receptor and modified magnetite nanoparticles@amino dithiocarbamate (MNPs@ADTC) as the magnetic core. Se (IV) ions were selectively absorbed into MIL-101(Cr)/MNPs@ADTC at lower pH (1.85), while Se (VI) ions remained in the initial solution. Optimization of the parameters that affect the removal efficiency was carried out by experimental design method. Three parameters such as adsorption time, MIL-101(Cr)/MNPs@ADTC dosage, and sample pH were considered as affecting factors and the optimum value for these factors was as following: pH, 1.85; adsorption time, 14.0 min; and (c) MIL-101(Cr)/MNPs@ADTC dosage, 16.0 mg. Afterwards, the equilibrium sorption data were studied using Langmuir and Freundlich models. The mechanism for adsorption of Se (VI) ions onto MIL-101(Cr)/MNPs@ADTC was found to follow Langmuir models. Accordingly, maximum adsorption capacity and Langmuir constant were 222 mg g-1 and 0.41 L mg-1, respectively. Finally, adsorption kinetic was evaluated by use pseudo first/second order models and the obtained data revealing a pseudo second order model based on the correlation coefficient.

Keywords:

Selective removal , Selenate , Magnetite composite , MIL-101(Cr) , Langmuir model