Quaternary ammonium-based task-specific ionic liquid: An efficient and ‘green’ separation for ‘f block’ elements

<p>Functionalized ionic liquid based on quaternary ammonium salt was investigated for the specific task of the efficient extraction of f block elements in different oxidation states. It deals with the investigation of extraction efficiency, mechanism, speciation and associated kinetics and thermodynamics. The extracted species of Pu⁴⁺, PuO₂²⁺, Am³⁺, Eu³⁺ were found to be Pu(Hptha)(H₂O)₆³⁺, PuO₂(Hptha)(H₂O)₂⁺, Am(Hptha)(H₂O)₇²⁺, Eu(Hptha)(H₂O)₇²⁺, respectively where (Hptha)⁻ is the anionic part of the ionic liquid. Effect of radiation exposure on the performance of the ionic liquid was also investigated. The suitable back extraction procedure from the ionic liquid phase was developed using aqueous soluble complexing agents.</p

Efficient removal of chemically toxic dyes using microorganism from activated sludge: Understanding sorption mechanism, kinetics, and associated thermodynamics

<p>A systematic investigation was carried out for demonstrating the simple and cost-effective removal of toxic dyes using activated sludge from municipal wastewater. The sorption process was found to follow Freundlich isotherm and pseudo-second-order rate kinetics. Difference in sorption efficiency for activated and deactivated sludge in aerobic and anaerobic conditions revealed the involvement of different microorganism in sorption process with the indication of biodegradation. The sorption process was found to be spontaneous but entropy driven for Remazol Brilliant Blue R and Eriochrome Black T while enthalpy driven for Congo Red. The process was established to be a combination of adsorption as well as biodegradation.</p

Insight into the Complexation of Actinides and Lanthanides with Diglycolamide Derivatives: Experimental and Density Functional Theoretical Studies

Extraction of actinide (Pu⁴⁺, UO₂²⁺, Am³⁺) and lanthanide (Eu³⁺) ions was carried out using different diglycolamide (DGA) ligands with systematic increase in the alkyl chain length from <i>n</i>-pentyl to <i>n</i>-dodecyl. The results show a monotonous reduction in the metal ion extraction efficiency with increasing alkyl chain length and this reduction becomes even more prominent in case of the branched alkyl (2-ethylhexyl) substituted DGA (T2EHDGA) for all the metal ions studied. Steric hindrance provided by the alkyl groups has a strong influence in controlling the extraction behavior of the DGAs. The distribution ratio reduction factor, defined as the ratio of the distribution ratio values of different DGAs to that of T2EHDGA, in <i>n</i>-dodecane follows the order UO₂²⁺ > Pu⁴⁺ > Eu³⁺ > Am³⁺. Complexation of Nd³⁺ was carried out with the DGAs in methanol by carrying out UV–vis spectrophotometric titrations. The results indicate a significant enhancement in the complexation constants upon going from methyl to <i>n</i>-pentyl substituted DGAs. They decreased significantly for DGAs containing alkyl substituents beyond the <i>n</i>-pentyl group, which corresponds to the observed trend from the solvent extraction studies. DFT-based calculations were performed on the free and the Nd³⁺ complexes of the DGAs both in the gas and the solvent (methanol) phase and the results were compared the experimental observations. Luminescence spectroscopic investigations were carried out to understand the complexation of Eu³⁺ with the DGA ligands and to correlate the nature of the alkyl substituents on the photophysical properties of the Eu­(III)-DGA complexes. The monoexponential nature of the decay profiles of the complex revealed the predominant presence of single species, while no water molecules were present in the inner coordination sphere of the Eu³⁺ ion