Adsorption of cerium (III) by HKUST-1 metal-organic framework from aqueous solution.

Cerium is an important rare earth element (REE), which can be used for many high-tech applications. From the industrial and environmental viewpoints, it is imperative to recover Ce3+ ions from aqueous solution. Herein, HKUST-1 metal-organic framework (MOF) was applied for adsorption and recovery of Ce3+ from aqueous solution. HKUST-1 showed a high adsorption efficiency and remarkable capacity of 353 mg/g at pH = 6. The isotherm, kinetics, effect of pH value and adsorption mechanism of the Ce3+ adsorption process were also studied. The results showed that the adsorption process fitted the Langmuir adsorption model, and the pseudo-second-order model described the kinetics well. The mechanism and reusability in Ce3+ adsorption were systematically investigated by various characterization techniques, suggesting the possible ion exchange between Ce3+ and Cu2+ and the formation of CeO covalent bonding. This work opens up a new way for Ce3+ recovery from water.

Adsorptive removal of antibiotic sulfonamide by UiO-66 and ZIF-67 for wastewater treatment.

Adsorptive removal of a toxic sulfonamide antibiotic, sulfachloropyradazine (SCP), from aqueous solution was studied on several metal organic frameworks, UiO-66 and ZIF-67, for the first time. UiO-66 exhibited a much higher adsorption capacity than ZIF-67, fast kinetics, and easy regeneration for reuse, demonstrating as a promising adsorbent in wastewater treatment processes. The batch adsorption shows an adsorption capacity of SCP at 417mg/g on UiO-66. The kinetic adsorption of SCP on UiO-66 reached equilibrium just in 10min and the kinetics fits accurately with a pseudo 2nd order model. A plausible mechanism was proposed based on pH effect, pKa value of the adsorbate and Zeta potential of UiO-66. The high adsorption is mainly contributed to hydrophobicity and π-π interactions along with electrostatic interactions. Thermodynamic studies show the spontaneous adsorption and exothermic process. The easy regeneration and high adsorption capacity confirms structural stability of the robust UiO-66 in wastewater treatment processes, making it suitable for a large scale application.

Metalloligands containing aminofulvene-aldiminate (AFA) ligands and their bimetallic complexes.

A simple and convenient route to η(5)-coordinated Ru and Rh aminofulvene-aldiminate (AFA) complexes is described. The metalloligands [Cp*Ru{η(5)-(Ph(2)AFAH)}][BF(4)] (3), [Cp*Ru{η(5)-(benzyl(2)AFAH)}][OTf] (7), [Cp*Rh{η(5)-(Cy(2)AFA)H}][BF(4)](2) (8) and [Cp*Rh{η(5)-(Cy(2)AFA)}][BF(4)] (9) have been synthesised and characterised. The basicity of 9 has been found to be significantly less than its neutral analogue and thus eliminates the need for a deprotonation step to ligate to a second metal in the κ(2)-N,N'-coordination mode. The reaction of 9 with a palladium precursor provides a mixed-metal complex [Cp*Rh(η(5)/κ(2)-Cy(2)AFA)PdCl(2)][BF(4)] (12). Cyclic voltammetry studies of the Ph(2)AFAH ligand shows an irreversible one electron oxidation peak at +1.0 V (vs. Fc/Fc(+)). Complex 3 shows an irreversible oxidation at +1.5 V and a reduction peak at -1.0 V. The oxidation of 3 occurs on the AFA ligand backbone whereas the structurally analogous neutral 1,2-bis(imidoyl)pentamethyl-ruthenocene shows reversible oxidation at the Ru center.