Jeroen De Decker

Ordered mesoporous phenolic resins: Highly versatile and ultra stable support materials

Ordered mesoporous phenolic resins and carbons - an advanced class of ultra-stable mesoporous materials - offer potential applications in the field of catalysis, electrodes and adsorbents. This review gives an extensive overview of the main principles and the recent progress made in the synthesis of these innovative materials using the soft-template method. Furthermore, the versatility towards functionalization and the incorporation of hetero-atoms in the organic framework of the mesoporous resins and carbons are considered. Finally, the broad range of potential applications is discussed and future perspectives in the field of mesoporous polymers and carbons are given.

Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium recovery from aqueous streams through adsorption

Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32mg U/g (pH 3) and 27.99mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375min. The adsorbed U(VI) is easily recovered by desorption in 0.1M HNO3. Three adsorption/desorption cycles were performed.

Carbamoylmethylphosphine Oxide-Functionalized MIL-101(Cr) as Highly Selective Uranium Adsorbent

The carbamoylmethylphosphine oxide (CMPO) functionalized MIL-101(Cr) was investigated as a potential uranium scavenger. This metal-organic framework-based adsorbent shows very high selectivity toward uranium, as well as thorium, in competition with various rare earth metals. Furthermore, it showed rapid adsorption kinetics, in both batch conditions and a dynamic (column) setup. The adsorbent is fully regenerable, using oxalate solution. Fast elution kinetics in the column setup were observed during the regeneration. In addition, reusability studies were performed under dynamic conditions. Five consecutive adsorption/desorption cycles were carried out, showing a consistent 100% recovery, at pH 4, using 0.1 M oxalate solution as an effective stripping agent. Additionally, the successive use over various adsorption/desorption cycles with constant performance proves the high stability of this adsorbent in an acidic, aqueous environment.